COMPONENT MAINTENANCE MANUAL

WITH ILLUSTRATED PARTS LIST

DC GENERATOR CONTROL UNIT

51525-014A

Original Issue: April 14, 1999

Revision 1: October 15, 2001

"THESE COMMODITIES, SOFTWARE, OR TECHNOLOGY WERE EXPORTED FROM THE UNITED STATES
IN ACCORDANCE WITH THE EXPORT ADMINISTRATION REGULATION. DIVERSION CONTRARY TO U.S
LAW IS PROHIBITED."

© Copyright 2001 TRW Aeronautical Systems, Lucas Aerospace (formerly Lucas Aerospace
and also Lear Siegler). Copyright in this manual and associated documents and drawings
belongs to TRW Aeronautical Systems, Lucas Aerospace. All rights reserved. No
reproduction of all or part of this manual shall be made without the prior written consent of
TRW Aeronautical Systems, Lucas Aerospace. This document contains information that may
be confidential. Disclosure to others of information contained herein requires the written
consent of TRW Aeronautical Systems, Lucas Aerospace. This manual produced at the
Aurora, OH plant.
TITLE PAGE Oct 15/01

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© 2001 TRW Aeronautical Systems

 Component Maintenance Manual with Illustrated Parts List
DC Generator Control Unit, 51525-014A

EXCLUSIVE DISTRIBUTORS
The Equipment Service organization at TRW Aeronautical Systems, Lucas Aerospace is
complemented by the TRW Aeronautical Systems, Lucas Aerospace Equipment Service
Centers (ESC), the exclusive stocking distributor of TRW Aeronautical Systems, Lucas
Aerospace parts and technical publications.

REGION ADDRESS COMMUNICATIONS

AMERICAS: TRW Aeronautical Systems PHONE (1) 201 567 6400
Lucas Aerospace ESC AOG (1) 201 567 6411
30 Van Nostrand Avenue FAX (1) 201 541 7610
Englewood, NJ 07631-4396 USA FAX (1) 201 894 1965

EUROPE/ TRW Aeronautical Systems PHONE (44) 121 451 5788

MIDEAST/ Lucas Aerospace ESC AOG (44) 121 451 5904
AFRICA: Stratford Road FAX (44) 121 451 5881
Solihull B90 4LA England
ASIA/ TRW Aeronautical Systems PHONE (65) 545 9975
PACIFIC: Lucas Aerospace ESC AOG (65) 545 6253
35 - 37 Loyang Way FAX (65) 545 0419
Republic of Singapore 1750
TRW Aeronautical Systems PHONE (61) 2 9315 3700
Lucas Aerospace ESC AOG (61) 2 9937 2553
84-92 Epsom Road FAX (61) 2 9313 7676
Zetland, Sydney
NSW 2017 Australia
TRW Aeronautical Systems PHONE (86) 592 573 0089
Lucas Aerospace ESC AOG (86) 592 573 1098
Lucas TAECO Aerospace FAX (86) 592 573 0090
(Xiamen) Co. Ltd.
GAOQI International Airport
Xiamen 361006 Fujian
Peoples Republic of China

Parts and assemblies not authorized for repair in the field must be sent to the TRW Aeronautical
Systems, Lucas Aerospace Repair and Overhaul (R&O) at the location below.

REGION ADDRESS COMMUNICATIONS

ALL: TRW Aeronautical Systems PHONE (1) 330 995 1000
Lucas Aerospace FAX (1) 330 995 1117
777 Lena Drive
Aurora, OH 44202 USA

CAUTION: Any use of parts, materials, or processes not authorized by TRW Aeronautical
Systems, Lucas Aerospace for the maintenance or service of these units may
affect their continued airworthiness or invalidate certification.

EXCLUSIVE DISTRIBUTORS Page ii

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HIGHLIGHTS
TO: Holders of Component Maintenance Manual with IPL for DC Generator Control Unit Model
51525-014A.
Attached to this transmittal letter is Revision 1 of Component Maintenance Manual with IPL
(basic issue dated April 14, 1999).
REVISION 1, DATED 15 OCTOBER, 2001

Revised pages are listed below together with the highlights of the revision. This revision
contains all pages. Replace the pages with Revision 1 dated October 15, 2001. Retain
Highlights page(s) in the front of the manual for future reference.
HIGHLIGHTS

Page Description of Change

Title Changed and updated to reflect this revision.
ii Added exclusive distributors for Australia and China.
iii Added revision number and date to reflect this revision.
xi Pages updated to reflect this revision.
xv Table of Contents updated to reflect this revision.
Testing (12 places), “ ARMATURE (J1-y)” to “armature GCU SUPPLY (J1-y)”.
1005 Step (4)(c), “GEN BRUSH (J1-m)” to “GEN BRUSH (J1-M)”.
1009 Steps (13)(g) to (13)(n) changed to Steps (13)(a) to (13)(h).
Step (13)(f) revised, “Apply a voltage” to “Read a voltage”.
9003 Figure 9001 updated to reflect this revision.

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RECORD OF REVISIONS

Revision Number Date Issued Date Inserted into Initials

CMM

Original Issue Apr 14/99

Revision 1 Oct 15/01

Retain this record in the front of the CMM. On receipt of revisions, insert affected pages
into the manual. Record revision number, date issued, date inserted into the CMM, and
initials on this page.

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RECORD OF TEMPORARY REVISIONS

Temporary Revision Page Date Date Initials Date Initials

Number Number Issued Inserted Removed

Retain this record in the front of the CMM. On receipt of temporary revisions, insert
affected pages into the manual. Record the temporary revision number, page number,
date issued, date inserted into the CMM, and initials on this page. When temporary
revisions are removed from the CMM, record the date removed and initials.

RECORD OF TEMPORARY REVISIONS Page v

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SERVICE BULLETIN LIST

SERVICE SERVICE
REVISION DATE REVISION DATE
BULLETIN STATUS BULLETIN STATUS
NUMBER ISSUED NUMBER ISSUED
NUMBER NUMBER

51525-014A-24-01 Active

51525-014A-24-02 Active

Retain this record in the front of the CMM. On receipt of service bulletins, record the service
bulletin number, status (valid or invalid), revision number (if applicable) and the date issued.

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SERVICE INFORMATION LETTER LIST

SERVICE SERVICE
REVISION DATE REVISION DATE
INFORMATION STATUS INFORMATION STATUS
NUMBER ISSUED NUMBER ISSUED
LETTER NUMBER LETTER NUMBER

Retain this record in the front of the CMM. On receipt of Service Information Letters, record
the Service Information Letter number, status, revision number (if applicable) and the date
issued.

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LIST OF EFFECTIVE PAGES

Title Page Date

TITLE PAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i Oct 15/01

EXCLUSIVE DISTRIBUTOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii Oct 15/01
RECORD OF REVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Oct 15/01
iv Blank
RECORD OF TEMPORARY REVISIONS . . . . . . . . . . . . . . . . . . . . . . . v Oct 15/01
vi Blank
SERVICE BULLETIN LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Oct 15/01
viii Blank
SERVICE INFORMATION LETTER LIST. . . . . . . . . . . . . . . . . . . . . . . . ix Oct 15/01
x Blank
LIST OF EFFECTIVE PAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Oct 15/01
xii Oct 15/01
xiii Oct 15/01
xiv Blank
TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Oct 15/01
xvi Blank
LIST OF ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii Oct 15/01
xviii Blank
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix Oct 15/01
xx Blank
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi Oct 15/01
xxii Oct 15/01
xxiii Oct 15/01
xxiv Oct 15/01
DESCRIPTION AND OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Oct 15/01
2 Oct 15/01
3 Oct 15/01
4 Oct 15/01
5 Oct 15/01
6 Oct 15/01
7 Oct 15/01
8 Oct 15/01
9 Oct 15/01
10 Oct 15/01
11 Oct 15/01
12 Oct 15/01

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LIST OF EFFECTIVE PAGES (Continued)
Subject Page Date
TESTING AND FAULT ISOLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001 Oct 15/01
1002 Oct 15/01
1003 Oct 15/01
1004 Oct 15/01
1005 Oct 15/01
1006 Oct 15/01
1007 Oct 15/01
1008 Oct 15/01
1009 Oct 15/01
1010 Oct 15/01
1011 Oct 15/01
1012 Oct 15/01
1013 Oct 15/01
1014 Oct 15/01
1015 Oct 15/01
1016 Oct 15/01
1017 Oct 15/01
1018 Oct 15/01
1019 Oct 15/01
1020 Blank
SCHEMATICS AND WIRING DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . 2001 Oct 15/01
2002 Blank
DISASSEMBLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3001 Oct 15/01
3002 Oct 15/01
CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4001 Oct 15/01
4002 Oct 15/01
CHECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5001 Oct 15/01
5002 Oct 15/01
REPAIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6001 Oct 15/01
6002 Oct 15/01
6003 Oct 15/01
6004 Blank
ASSEMBLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7001 Oct 15/01
7002 Oct 15/01
7003 Oct 15/01
7004 Blank
FITS AND CLEARANCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8001 Oct 15/01
8002 Blank

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LIST OF EFFECTIVE PAGES (Continued)

Subject Page Date

SPECIAL TOOLS, FIXTURES, AND EQUIPMENT . . . . . . . . . . . . . . . . 9001 Oct 15/01

9002 Blank
9003 Oct 15/01
9004 Blank
9005 Oct 15/01
9006 Blank
9007 Oct 15/01
9008 Blank
ILLUSTRATED PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10001 Oct 15/01
10002 Oct 15/01
10003 Blank
10004 Oct 15/01
10005 Oct 15/01
10006 Blank
SPECIAL PROCEDURES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11001 Oct 15/01
11002 Oct 15/01
REMOVAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12001 Oct 15/01
12002 Blank
INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13001 Oct 15/01
13002 Blank
SERVICING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14001 Oct 15/01
14002 Blank
STORAGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15001 Oct 15/01
15002 Oct 15/01
REWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16001 Oct 15/01
16002 Blank

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TABLE OF CONTENTS
Title Page

EXCLUSIVE DISTRIBUTOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
RECORD OF REVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
RECORD OF TEMPORARY REVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
SERVICE BULLETIN LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
SERVICE INFORMATION LETTER LIST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
LIST OF EFFECTIVE PAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
LIST OF ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
DESCRIPTION AND OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
TESTING AND FAULT ISOLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001
SCHEMATICS AND WIRING DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2001
DISASSEMBLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3001
CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4001
CHECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5001
REPAIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6001
ASSEMBLY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7001
FITS AND CLEARANCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8001
SPECIAL TOOLS, FIXTURES, AND EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9001
ILLUSTRATED PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10001
SPECIAL PROCEDURES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11001
REMOVAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12001
INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13001
SERVICING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14001
STORAGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15001
REWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16001

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LIST OF ILLUSTRATIONS
Figure Title Page

1 51525-014A DC Generator Control Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 51525-014A DC Generator Control Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
9001 Typical Open Loop Test Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9003
9002 Typical Closed Loop Test Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9005
9003 Kit, Software Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9007
10001 DC Generator Control Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10004
11001 Interface Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11002

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LIST OF TABLES
Table Title Page

1 Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 EICAS Indication for System Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 EICAS Indication for System Faults - Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1001 Test Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1001
1002 Auxiliary Power Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1002
1003 Driver and Associated Connector Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1004
1004A GCU J1 Connector Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1010
1004B GCU Serial Port J1-Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1010
1005 Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1011
1006 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1015
4001 Cleaning Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4001
5001 Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5002
6001 Repair Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6001
6002 Repair Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6002
7001 Assembly Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7001
7002 Assembly Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7001
9001 Special Tools, Fixtures, and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9001
15001 Packaging Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15001

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INTRODUCTION
1. Purpose

This Component Maintenance Manual (CMM) provides detailed instructions for servicing
of TRW Aeronautical Systems, Lucas Aerospace, Model No. 51525-014A Generator
Control Unit (GCU).

A. GCU Maintenance
Included in GCU Maintenance is:

• Replacement of non-reusable parts such as miscellaneous hardware.

• Cleaning of exterior.

• Inspection & Acceptance Testing.

• Reconditioning of minor surface damage.

• Replacement of parts as required.

B. Service Repair Requirements

An Illustrated Parts List for GCU is included in this CMM for part identification and
ordering of approved replacement parts. Structure and content of this CMM is in
accordance with requirements established by the Air Transport Association of
America (ATA) for aircraft CMMs. This CMM is formatted to conform to ATA
Specification No.100.

All weights and measures used in this manual are in English units, followed by the
Système Internationale (SI) equivalent in parentheses.

Give careful attention to applicable warnings and cautions. Before starting any repair
procedure, become thoroughly familiar with capabilities and limitations of equipment.
Make sure all necessary safety equipment, test equipment, repair materials, special
tools, and fixtures are available before starting.

If an error, omission, or other technical discrepancy is found in this CMM, please fill
out a copy of the Technical Publication Comment Form found at the back of this CMM
and send to Technical Publications Department at TRW Aeronautical Systems, Lucas
Aerospace, Aurora.

2. User Qualification and Certification Requirements

Information contained in this CMM is intended for use by persons trained and certified in
repair and overhaul of aircraft electrical accessories. Eligibility and certification of overhaul
technicians shall be in accordance with guidelines established by the U.S. Federal Aviation
Administration (FAA) or an equivalent regulatory authority. Refer to U.S. Code of Federal
Regulations 14 CFR, Chapter 1, paragraphs 65.101 through 65.103 and paragraphs
145.39.

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Where special processes are included by reference to military or commercial standards,
qualifications and certification of personnel performing process shall be the same as
indicated in cited standard. Make sure to follow the detailed requirements of all cited
military or commercial standards used in repair of this equipment.

3. Quality Assurance Requirements

Repair station’s Quality Assurance activity is responsible for correct performance of all
tests and inspections specified in this CMM. Quality Assurance activity shall also be
responsible for maintaining all necessary tests, inspection, and maintenance records for
each unit received for service. All instrumentation and inspection equipment used shall
be calibrated and controlled in accordance with ISO 10012-1 with all standards traceable
to National Bureau of Standards or an equivalent standards regulatory authority.

Quality Assurance activity shall be responsible for certifying that personnel, skills, and
material meet the requirements of work to be performed. Components of the GCU
undergoing maintenance, that are recovered as products of disassembly, shall be
examined 100% to determine serviceability. Quality Assurance activity shall maintain
documentation during repair of GCU’s as evidence.

4. Safety Advisory

This CMM describes physical and chemical processes, which require use of chemicals,
or other commercially available materials that require precautionary attention.

WARNINGS, CAUTIONS and NOTES are used throughout the text to highlight and
emphasize important points, as they become necessary. WARNINGS give information
that must be followed precisely to avoid personal injury and/or possible death. CAUTIONS
contain information that must be followed to avoid damage to equipment. NOTES assist
the reader and make the technician's job easier.

5. Components and Processes Policy

TRW Aeronautical Systems, Lucas Aerospace, Aurora authorizes the use of genuine
TRW Aeronautical Systems, Lucas Aerospace, Aurora spare parts, and parts from
authorized vendors as listed in IPL, which meet stringent engineering design specifications
and quality standards, and have traceability to having been certified to these specifications
by TRW Aeronautical Systems, Lucas Aerospace, Aurora Quality Assurance incoming
and in-process inspection systems.

All repair and overhaul facilities are obligated to provide FAA, or any other in-county air
authority, with proper traceability documentation indicating approval of all spare parts,
materials and processes to ensure configuration compliance and continued air worthiness.

Use of any unauthorized parts, or any parts not having been submitted to the TRW
Aeronautical Systems, Lucas Aerospace, Aurora Quality Assurance inspection system
will invalidate any and all factory warranties. All TRW Aeronautical Systems, Lucas
Aerospace, Aurora warranties are automatically voided on any TRW Aeronautical
Systems, Lucas Aerospace, Aurora designed unit that has been modified by installation
of any unauthorized parts, materials or unapproved processes supplied by other outside
services. Repair station’s Quality Assurance activity shall assume product liability for all
units that have been modified in this fashion.

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Damage resulting from use of unauthorized replacement parts, materials or processes is
not covered by the TRW Aeronautical Systems, Lucas Aerospace, Aurora warranty or
service policy for any product or for any application.

6. Abbreviations

The following is a list of the abbreviations & acronyms used in this document.

A Ampere
AC Alternating Current
A/D Analog to Digital
AR As Required
ASC Auxiliary Start Contactor
ATA Air Transport Association
BIT Built In Test
CMM Component Maintenance Manual
CPU Central Processing Unit
D/A Digital to Analog
DC Direct Current
ESD Electrostatic Discharge
ESDS Electrostatic Discharge Sensitive
FAA Federal Aviation Administration
GCS Generator Control Switch
GCU Generator Control Unit
Hz Hertz or Cycles per Second
ISO International Standardization Organization
kPa Killopascals
L Liter
Lbs. Pounds
LRU Line Replaceable Unit
MIL Military Specification
ms Millisecond
O/C Overcurrent
OSHA Occupational Safety and Health Act
PI Proportional, Integral Control
POR Point of Regulation
PP Peak to Peak
PSIG Pounds per Square Inch Gauge

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PWB Printed Wiring Board
PWM Pulse Width Modulated
RAM Random Access Memory
RC Resistance/Capacitance
rms Root Mean Squared
RPM Revolutions Per Minute
SI Systeme Internationale
TTL Transistor – Transistor Logic
V Volt or Voltage
Vcc Voltage, Power Supply
Ω Ohm

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DESCRIPTION AND OPERATION

1. Introduction

CAUTION: This equipment contains parts sensitive to damage by electrostatic

discharge (ESDS). Use ESDS precautionary procedures when touching,
removing, or inserting parts or assemblies.

The 51525-014A Generator Control Unit (GCU) is a microprocessor based, convection

cooled, bolt-down unit that contains the voltage regulation, control, and protection logic
for coordinated system performance during normal and abnormal system operating
conditions. The GCU is housed within an aluminum enclosure which provides secure
mounting and a good heat sink for those components which must dissipate heat. The
electronic circuitry is contained on a chassis/motherboard assembly, and two printed
wiring boards.

2. Design and Construction

A. General
The voltage regulator functions of the 51525-014A are completely solid state and
have no moving parts. The design and construction of component parts enable the
GCU to have a minimum shelf life of five years. However, Acceptance Testing must
be done after storage. The GCU uses no liquid, gas, vacuum, or device which
depends on elevated temperature for operation.

B. Corrosion Resistance
The GCU is constructed entirely of corrosion-resistant materials or materials
processed to resist corrosion. Electrolytic corrosion is prevented by the design of
minimum contact between dissimilar metals. Where contact is unavoidable, suitable
protection is provided between the two abutting surfaces.

C. Nonmetallic Materials
Non-metallic materials used in the GCU are moisture resistant and do not support
fungus growth. These materials are not affected by weather, sunlight, aircraft fluids,
temperatures, and ambient conditions encountered during operation of the aircraft.
Materials which support combustion are not used.

D. Finish
(1) Aluminum Alloy Parts

Aluminum alloy parts are anodized per MIL-A-8625 or receive a chemical film
per MIL-C-5541.

(2) Electrical Bonding

The enclosure and mounting provisions allow electrical bonding in accordance

with MIL-B-5087 when the unit is installed in the aircraft.

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E. Dielectric Strength
Dielectric strength is a potential of 220 - 250 V (rms), 60 Hz. for one (1) minute
between the combined receptacle pins, and the chassis.

F. Leading Particulars

Characteristic 51525-014A GCU

Height 4.25 inches (108 mm) max.
Width 3.50 inches (88.9 mm) max., (4.42 inches (112 mm)
including base)
Length 6.22 inches (158 mm) max.
Weight 2.5 lbs. (1.14 Kgram) max.
Table 1 - Physical Characteristics

Connector (Not Shown)

Retainer - Card Locking Front Cover
Chassis\Mother
Board Assembly Chassis\Mother
Board Assembly
Heat Sink

Voltage Regulator PWB

Extruded Enclosure
Microprocessor PWB (Partially Shown)

A GCU 00011
Figure 1 - 51525-014A DC Generator Control Unit

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REAR VIEW TOP VIEW

FRONT VIEW SIDE VIEW

A-GCU-00020

Figure 2 - 51525-014A DC Generator Control Unit

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G. Structure
The 51525-014A GCU utilizes a chassis/mother board assembly and two printed
wiring boards.

3. Operation

A. General
The 51525-014A GCU is microprocessor based, utilizing a chassis/motherboard
assembly and two printed wiring boards.

B. Microprocessor
The GCU utilizes a microcontroller to provide both the protection and control logic.
The microcontroller embeds a microprocessor which contains the RAM, the program
memory, a serial communications port, and two counter/timers. Supporting the
microcontroller is a regulated power supply, a 12 bit/8 channel A/D, and a power
supply monitor/watchdog timer.

C. Electrical Interfaces
The GCU is designed to operate with all TRW Aeronautical Systems, Lucas
Aerospace, Aurora 30 V, 400 A, Model number 23080 Series DC Starter-Generators.
All electrical interconnections with the unit are made through a single cylindrical
connector.

D. Control Functions
(1) Voltage Regulator

The output of the voltage regulator is a pulse width modulated (PWM) which
switches the voltage applied to the generator field to produce a DC current.
By adjustment of the PWM duty cycle, field current is adjusted to regulate the
point of regulation (POR) voltage.

The voltage regulator employs proportional, integral control (PI). The

proportional component quickly sets the PWM duty cycle to approximately the
required level. The integrator more slowly trims the regulation so that the POR
precisely matches the reference.

The two components compliment one another, the integrator eliminates any
error caused by the proportional component and the proportional component
compensates for any high gain of the integrator. The result is a stable regulator
with flat regulation overspeed, loading and environment.

(2) Field Transistor/Short Circuit Protection

The field driver is a high power N-channel MOSFET. The MOSFET is highly
efficient which means cooler operation and improved reliability.

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The field transistor is protected against overloading due to generator/aircraft
wiring errors or other sources of short circuits. If an overload occurs, the field
transistor output is current limited by PWM. The level of current limit has a “fold
back” characteristic; the greater the severity of the fault, the greater the level of
limiting. If the fault remains for over 500 ms, the field is tripped by the
microcontroller.

(3) Parallel Operation (Load Equalization)

If more than one generating channel is operated in parallel, the GCU utilizes a
software based PI control to provide load equalization. When the GCU closes
its line contactor to parallel with opposite GCU’s, the equalization bus is
energized forming a current sensing loop.

The equalization bus connects the opposite channel’s current sensing signal to
the generator interpole via shunt resistors. Equalization is achieved when no
signal current flows through the loop indicating a balance between the interpole
and the opposite channel.

The microcontroller senses error current through analog-to-digital (A/D)

measurements and uses the level to generate a reference voltage through a
digital-to-analog (D/A) converter. This reference voltage biases the voltage
regulator up or down as necessary until equalization is achieved. The
microcontroller is allowed limited authority over the regulator by hardware during
equalization and cannot bias regulation by more than ±2.5 VDC.

(4) Current Limiting

The 51525-014A GCU has generator current limiting capability. Current limiting
is activated by connecting the cross start current limit input to a +28 V source.
The current limiting control function is completely software controlled and is
preset by software.

(5) Contactor Control

The microcontroller enables the contactor drivers to energize the line contactor
or start contactor. Power for the contactors is supplied through the drivers via
the aircraft control switches assuring breaking of contactor current outside of
the GCU’s control. To provide additional safety, relay contacts are included
providing redundant means of interrupting the contactor coil current.

(6) Short Circuit Protection

Each of the contactor drivers can supply 8 A in-rush current. The start contactor
driver is rated for 5 A continuous, and the line contactor driver is rated for 4 A.
Similar to the field transistor overload protection, the contactor drivers are
protected against short circuits by a pulse mode current limiter.

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(7) Start Control and Protection

The start contactor (KSR) is energized by the GCU when the start switch is
closed and the generator speed is below the cut-off threshold. Speed is
measured through the generator’s magnetic pick-up unit which produces 42
pulses for each rotation of the generator shaft.

This signal is conditioned by a differentially sensing, zero crossing detector, and

fed to a counter internal to the microcontroller. The microcontroller measures
the signal frequency by comparing it to its internal time base. When the speed
exceeds the start cut-off threshold, the start contactor de-energizes.

(8) Field Weakening

As the aircraft’s engine begins to assume more of the load torque, the torque
supplied by the starter generator decreases. To compensate, field weakening
reduces field current, biasing the starter generator’s back electromotive force
(back emf) lower, which limits the starter current to no less than the continuous
machine rating. With the starter current held constant at the machine rating, the
torque decreases at a reduced rate.

Field weakening continues to be active for 200 ms after the starter cut-off is
reached and the GCU commands the start contactor to open. By maintaining
a positive current into the starter, a possible transient reverse current into the
ground cart during the contactor transfer is avoided.

(9) Open Shunt Protection

Open shunt protection protects the starter generator from loss of field excitation
during a start mode. The field return detect circuit senses field return current
(current flowing through the free-wheeling diode during the OFF portion of the
field transistor’s PWM duty cycle).

Upon initiation of the start cycle and once the field is fully energized, the
microcontroller turns Off the field transistor for 1 ms out of every 500 ms until
field weakening begins. Each time the field transistor is turned OFF, the
microcontroller queries the field return detect circuit.

If no field return current is detected, the field shunt is assumed to be open and
the field relay (KFR) and the start contactor (KSR) are tripped. Since the circuit
senses field return current, it not only checks the integrity of the circuitry which
energizes the field, but also the circuitry through which the field is de-energized
(the return path). In this way, an open field return wire can also be detected
providing protection for the field transistor which otherwise would be damaged.

(10) Line Contactor Control and Protection

The line contactor control functions are non-latching and act to open the line
contactor without de-energizing the generator.

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(a) Differential Voltage

Differential Voltage inhibits closure of the line contactor if point of regulation

(POR) is less than the load bus side of the line contactor.

(b) Underspeed

Underspeed opens the line contactor when the engine speed falls below
the speed required by the generator for regulation. This function is inhibited
of the speed sensor is detected as faulty.

(c) Reverse current

Reverse current senses a polarity reversal of the Interpole voltage caused

by a current flow into the armature. The absence of these conditions, and
closure of the generator control switch (GCS) energizes the line contactor.

(11) Backup Power/Generator Control Switch (GCS)

The GCU includes provisions to utilize back-up power for excitation and control
if an overload is applied, which would cause the generator output to drop below
the hold-in voltage of the line contactor. This provides the generating system
with enough capacity to clear faults through circuit breakers or fuses. During
short circuits, the battery backup power requirement can exceed 8 A.

To assure manual override of the line contactor, back-up power for the line
contactor is routed through the GCS separately from field flash power. Back-up
power cannot be routed to supply both the line contactor driver and field flash
since the generator residual for field flash may be smaller than the 0.7 V diode
drop in the GCU’s backup diodes.

The power for the line contactor must then be routed from the generator armature
voltage backed up by the battery, while the field flash must be routed from the
generator armature alone. To assure that the GCU will not attempt to energize
the field when the generator is shut down, the back-up power is routed through
an auxiliary contact of the line contactor.

E. Protective Functions
(1) Overvoltage Protection

NOTE: The overvoltage protection offered by the 51525-014A GCU fully

complies with the requirements of MIL-STD-704E.

Overvoltage protection is implemented in two basic steps. First, an integrator

forms the basis for a time delay inversely proportional to the level of over-voltage
sensed at the POR. This delay provides protection against transients up to 50 V.
Second, a Qik Trip© (quick trip) overvoltage function is implemented which
assures the fault is limited to 50 V.

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Overvoltage protection acts to trip the field relay (KFR). This assures clearing
of the faults which would cause an over-voltage of less than 50 V. However, if
the field transistor has shorted, the KFR would be too slow to trip the field based
on the inverse time delay alone and transient voltages as high as 80 V could
occur.

To prevent these high voltage transients, the field must be tripped before the
inverse time delay protection can activate, but without tripping on normal voltage
transients. In normal operation, sudden load removals can cause voltage
transients.

The voltage regulator responds by commanding the PWM to immediately turn

off the field transistor, resulting in field return current. The QikTrip© portion of
over-voltage protection discriminates normal transients from faults through the
use of the field return detect circuit. If the field transistor has failed short,
QikTrip© detects the absence of field return current while the POR voltage is
increasing above 32 V.

Since a properly operating voltage regulator should have turned OFF the field
transistor resulting in field return current at or below 40 V, QikTrip© energizes
the field relay trip coil and 5 ms later, while the POR is still less than 50 V, the
field relay contacts complete their transition to the trip position and the field
de-energizes.

(2) Redundant Overvoltage

Redundant protection from overvoltage is provided by monitoring the GCS ON

switch voltage which is derived from the generator’s armature voltage. If this
voltage exceeds 34 VDC, the line contactor is de-energized until the voltage
returns to the normal operating range.

(3) Overexcitation

When operating multiple channels in parallel, overexcitation protection is

provided to isolate a faulted generating system. Overexcitation is provided
primarily through a combination of reverse current protection and overvoltage
protection. The faulted channel causes the unfaulted channel to detect reverse
current into its generator causing it to momentarily open its line contactor based
on reverse current protection.

The voltage on the faulted channel then exceeds the overvoltage threshold and
is tripped. Once the faulted channel trips off line, the reverse current condition
is cleared and the unfaulted channel then closes its line contactor to assume
the system load.

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(4) Overcurrent (O/C)

Generator overload protection is based on the generator Interpole voltage. The

Interpole resistance drops a voltage that is proportional to output current and
generator temperature. By basing O/C protection on Interpole voltage, the
protection time increases as generator overload capacity increases due to lower
operating temperature and load. The O/C protection is designed to protect the
generator over its normal operating range as listed below.

• From stabilized at the rated load of 400 A to no load.

• From maximum inlet air temperature of 50º centigrade to a minimum of 0º

centigrade.

• Speed is assumed to be 12,000 RPM.

Overload protection is coordinated with the system bus tie and line contactor to
isolate faults. Nearly all of the generator capacity is available for fault clearing.
If the fault does not clear, the bus tie relay is tripped by energizing ATB O/C
PROT for 100 ms. If the fault still remains one second later, GEN O/C PROT
is energized for 100 ms and the line contactor is tripped. Immediately following
activation of GEN O/C PROT, the generator is de-energized.

The higher the load and/or inlet air temperature within the specified operating
range, the faster the trip will occur within the specified zone; based on the
assumption that a restrictive air inlet is used. If a less restrictive air inlet is used,
the generator operating temperature decreases, decreasing the Interpole
resistance, increasing the protection time.

(5) Build-up Ground Fault Protection

A feeder fault is detected if generator armature current is sensed during

generator build-up, while the start contactor is open and before the line contactor
is energized.

(6) KFR Trip/Anticycle

The KFR is a magnetically latched relay used to de-energize the field under fault
conditions. The KFR may be reset by application of armature residual voltage
to the GCU reset pin (J1-c). Build-up occurs supplying the voltage necessary
to reset the KFR.

Cycling of the KFR under fault conditions while the GCS switch is held in the
reset position is prevented by the application of anticycle voltage from an
independent bus to the GCU anticycle pin (J1-v). This maintains control power
in the GCU preventing field buildup after the generator is tripped. Other
protective functions which de-energize the generator are listed below.

(a) Open GCU Ground

Detects a large voltage difference between the GCU ground and the
generator Interpole.

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(b) Open POR

Detects a large voltage difference between the generator armature and

the POR

(c) Feeder Interrupt

Detects a ground level status signal from the feeder protection relay.
Inhibited during the engine start.

(d) Reverse Polarity

Detects a reverse polarity build-up of the generator.

(e) Manual GCU trip

Detects a +28 V level status signal and trips the field relay independently
of the microcontroller.

F. Built-in Testing (BIT)

(1) Monitoring Bit

Monitor BIT continually checks system operation for anomalous conditions

which may have occurred due to a component failure. This function also
performs fault isolation logic which isolates system faults to the faulty LRU.
Monitor BIT is passive, it does not change or stimulate the operation of the GCU
to check its operation. The fault isolation logic for the EICAS indications is
provided by monitor BIT with the exception of the GCU failures which are
determined by initiated BIT.

Monitor BIT also provides hardware independent of the microcontroller to

monitor its control power and timing. Timing is monitored by a watchdog timer
which is triggered cyclically by the microcontroller. If a fault corrupts the
microcontroller program counter in such a way that the keyword test (KEYTST)
does not detect it, the watchdog timer detects the absence of the cyclical trigger
and interrupts the microcontroller. Monitor BIT also detects failure of the
components listed below.

• Microcontroller and its power supply

• Generator speed pick-up

• Start contactor

• Contactor drivers

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(2) Initiated BIT

At power-up, the GCU runs several tests to confirm its operation. These tests
concentrate on the protective functions which are provided by the microcontroller
and its support circuitry. The support circuitry tested by initiated BIT is comprised
of the analog to digital converter and the Watchdog timer. Initiated BIT is only
conducted while the aircraft is on the ground, based on the WOW switch.

(3) Stimulated BIT

The GCU includes a stimulated BIT function. This function is intended to allow
periodic verification of the GCU’s EICAS outputs, field relay (KFR) trip function,
and overcurrent outputs and related aircraft components. The stimulated BIT
sequence is initiated by applying a ground signal to connector pin J1-q.
Additionally, the GCS must be in the “OFF/RESET” position and the aircraft on
the ground based on the WOW switch.

During a stimulated BIT cycle, the GCU sequentially activates the ATB O/C and
the GEN O/C outputs energizing the associated aircraft relays. These outputs
will be activated in the same manner as they would occur during an actual
overcurrent fault. Additionally, the GCU will verify operation of the KFR trip
function. If a failed KFR is detected, GCU FAIL will be activated. The GCU’s
logic elements may be reset by cycling the GCS switch. For testability, cycling
the test switch three times in three seconds activates the GEN O/C and ATB
O/C signals for as long as the test switch is closed.

NOTE: The KFR will not be reset unless the GCS is cycled while the generator
is rotating within its operational speed range.

(4) EICAS Interface

The 51545-014A GCU provides three (3) EICAS outputs. These are GCU FAIL,
GEN FAIL and ASC FAIL. Each of these outputs provides a ground level signal
which can sink a minimum of 200 mA when active and an open when inactive.
Once activated, the fault signal remains active for a minimum of 0.7 seconds.
A holdup capacitor is used to provide at least 0.7 seconds of power for EICAS
logic if no other power source is available to the GCU, as would be the case if
the GCU de-energized the generator and no back-up supply were available to
power GCU logic through pins.

A fourth category of faults identified by the GCU covers those which cause the
generator to trip off line, but do not fall into any of the above categories. Fault
isolation logic of EICAS indication is defined in Table 2 of this manual.

NOTE: A trip of the line contactor or start contactor is differentiated from a trip
of the field relay which de-energizes the generator.

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Fault/Operation Action EICAS

Condition LC/SC Gen Field Indication

Normal operation None (Note 1)

BIT detected internal GCU Trip (Note 2) GCU Fail
fault
Overvoltage Trip Trip GCU Fail
Overexcitation Trip Trip GCU Fail
Overcurrent Trip (Note 3) Trip (Note 3) None
Speed sensor failure GEN Fail
Build-up ground fault Trip Trip None
Open ground (both pins FF Trip Trip None
and EE)
Open field Trip Trip (Note 4) None (Note 5)
Interpole open Trip None (Note 5)
Start contactor failed open ASC Fail
or closed
Start contactor driver failed GCU Fail
short (On)
Line or start contactor coil Trip None
shorted
Line contactor failed closed None
Line contactor driver failed GCU Fail
short (On)
Table 2 - EICAS Indication for System Faults

Number Note
1 Or the same state since the GCU was last initialized.
2 Trip depends on criticality of the GCU fault. RAM, ROM, and
watchdog time-out lead to a trip.
3 Depending on the fault zone.
4 During start mode only.
5 The most common cause of this fault is an open in the
interconnect wiring.
Table 3 - EICAS Indication for System Faults - Notes

NOTE: Imbedded Software is in accordance with RTCA/DO-178A Guidelines.

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TESTING AND FAULT ISOLATION

1. Introduction

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

The test procedures in this section reflect the use of standard test equipment. Perform
the tests upon service, and replacement of assemblies or acceptance of the Generator
Control Unit (GCU). Various tests are outlined to diagnose and locate malfunctions.
Figure 9001 illustrates a typical open loop (bench) test tool. To verify actual connections
and switch locations, follow the complete test procedure step-by-step.

“Any arcing as evidenced by flashover (surface discharge), sparkover (air discharge),

breakdown (puncture discharge) shall be evidence of damp, dirty, weak or defective
components and shall constitute a failure.”

2. Test Conditions

Parameter Operating Condition

Ambient Temperature 50° to 104°F (10° to 40°C)
Barometric pressure Ambient pressure
Cooling air None required.
Mounting Although the unit functions normally in any position,
it should be mounted so that its base is down and
horizontal.
Line Impedance The line impedance between the generator output
terminal and the point of regulation (POR) shall be
such as to give no more than 5 VDC differential at
full rated generator load.
Starter Generator The starter-generator shall be operated within its
respective generator speed range. The voltage
regulator tests shall be conducted using a TRW
Aeronautical Systems, Lucas Aerospace, Aurora
Model 23080-014 Starter-Generator.
Table 1001 - Test Conditions
WARNING: DURING OPERATION, STARTER GENERATORS CAN PRODUCE
A HIGH OUTPUT CURRENT THAT CAN CAUSE SEVERE SHOCK
OR DEATH. MAKE SURE THAT ALL POWER IS SHUT OFF BEFORE
REMOVING OR REPLACING TEST EQUIPMENT, INSTRUMENTS,
OR ASSEMBLIES. TAKE EXTREME CAUTION WHEN PERFORMING
“LIVE CIRCUIT” TESTS AND FAULT ISOLATION PROCEDURES.

NOTE: “If repairs were made prior to this test, record the SN of the assembly that was
replaced on the Acceptance Test Data Sheet.”

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3. Test Equipment

Use instruments with accuracy and calibration in compliance with ISO-10012-1.

A. Meters
Suitable instruments, properly calibrated, shall be used for all measurements and
shall have an error no greater than one percent of full scale, except as specifically
defined in a detail requirement.

B. Kit, Software Interface

The Software Interface Kit, 51525-014SW, allows the GCU to communicate through
its serial port, pin Z, with a PC for the purpose of fault analysis and Acceptance Testing.
Through the hardware interface, the GCU provides real time information about its
status, including information about voltage, current and speed. This information can
be plotted or stored.

The software itself monitors the GCU to provide the generating system status and
specific parameter measurements. This information can be used as an aid in
diagnosing system problems as well as monitor parameters specified by the
Acceptance Testing.

The software is required to perform the final test of the GCU. It is used to improve
the “testability” of the GCU as well as reduce the test time. The software also has
provisions for logging data transmitted by the GCU. This data may be saved in
“comma delimited” format that is readable by Microsoft Excel™ and similar programs.
Logged data allows for additional analysis and plotting.

Reference Figure 9002 for the physical appearance for the Software Kit. For
installation instruction, see the “Special Procedures” section, page 11001, for both
software and hardware.

Power Supply (Load) Minimum Rating

armature GCU SUPPLY Voltage 0 - 35 VDC
(J1-y)
FIELD BACKUP (J1-JJ) Current 20 ADC
GCS ON (J1-K) Voltage 0 - 35 VDC
START (J1-A) Current 9 ADC
All Other DC Inputs Voltage 0 - 35 VDC
Current 0.5 ADC
SPEED SENSE (J1-X to Y) Voltage (Sinusoidal) 1 Vrms
Frequency 8 KHz
Load Resistance Resistance 0 - 15 Ω
Continuous Rating 2 ADC
Table 1002 - Auxiliary Power Sources

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Power Supply (Load) Minimum Rating

½ Second Rating 20 ADC
Table 1002 - Auxiliary Power Sources

NOTE: Figure 9001 illustrates a typical open loop (bench) test tool. To verify actual
connections and switch locations, follow the complete test procedure
step-by-step.

4. Acceptance Tests

Acceptance Tests will consist of bench testing of the control and protective functions.
Figure 9001 shall be applicable. Voltage regulator tests will be performed in a closed loop
system with TRW Aeronautical Systems, Lucas Aerospace, Aurora Model number
23080-014 Starter-Generator.

Record observations on the Acceptance Test Data Sheet.

CAUTION: If an Acceptance Test limit is exceeded even by a small margin; do not

continue to test the unit. Be aware that further testing after an acceptance
limit is exceeded can damage the unit.

CAUTION: Failure to turn OFF the power supplies before connecting or disconnecting
high voltage electrical leads can cause serious damage to the GCU.

A. Perform an initial inspection.

The parameters of this inspection are located in paragraph 3. of the CHECK section.

B. Perform a dielectric test.

(1) Connect all pins in the J1 connector together with the exception of pin z.

(2) Apply a potential of 200-250 Vrms (at a rate not exceeding 100 volts per second)
at commercial frequency between the combined pins of J1 and pin z.

Failure can be detected by fluctuations and/or a steady increase in leakage

current.

C. Bench Tests
• Unless otherwise stated, all measurements shall be made with respect to the GCU’s
signal ground, J1-EE.

• Connector designations referred to in the test procedures relate to the J1 connector

located on the front face of the GCU.

• Unless otherwise stated, the GCU shall be grounded to the power supplies through
J1-FF.

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• A driver is considered energized when its output voltage exceeds 75% of its
associated power supply connector pin. See Table 1003. Conversely, a driver is
considered to be de-energized when its output voltage is less than 25% of its
associated power supply connector pin.

• The BTR (J1-f) and GCU O/C (J1-u) drivers are considered to be closed when they
sink 0.5 ± 0.1 A with no more than 1.5 V drop. The BTR (J1-f) driver is considered
to be open when it sink less than 0.05 A.

• The illumination or de-illumination of indicators by the output connector pins will be

considered as adequate evidence of being energized or de-energized, or as in the
case of the BTR driver, closed or open, except where the test procedure requires
that a voltage level be measured.

Driver Power Supply J1 Connector

Designation Connector Pin Pin
FIELD y or JJ AA
KLC K L
KSR A J
Table 1003 - Driver and Associated Connector Pins
(1) Back-up Power

While monitoring the voltage on PROG1 (J1-b), increase the J1-s voltage to
25 ± 1 VDC.

The GCU power consumption shall not exceed 50 mA (ADAPTOR P/S, J1-F
open).

The voltage on J1-b shall be 10.2 ± 0.5 VDC (CPU power supply).

(2) Regulation Adjustment

Closed Loop simulation

(a) Simulate closed loop regulation by connecting the POR (J1-B) to the field
(J1-AA) through an RC filter with a resistance of 50 ± 10 Ω and a
capacitance of 50 ± 20 µF.

(b) Connect a variable DC supply to armature GCU SUPPLY (J1-y) and apply
33 ± 1 VDC.

(c) Apply 7 ± 1 VDC to FIELD RTN (J1-DD).

(d) Reset the GCU by momentarily connecting the RESET (J1-c) to GEN ON
(J1-d).

The field shall energize.

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(e) Using the voltage adjustment potentiometer, adjust the GCU’s regulation
of POR (J1-B) voltage to 28.50 ± 0.05 V.

(f) Measure the POR voltage at the GCU’s external test jacks.

The POR voltage shall be within ±0.1 VDC of the setting in step (e).

(g) Set the FIELD (J1-AA) load in the range of 30 mA to 500 mA.

The frequency of the FIELD (J1-AA) voltage shall be 1.2 ± 0.3 KHz.

(3) Initial Operating Conditions

(a) Connect the variable DC supply to the POR (J1-B), the armature GCU
SUPPLY (J1-y), and the GSC ON (J1-K), and apply 25 ± 1 VDC.

(b) Connect a variable DC power supply to the INTERPOLE (J1-W) and apply
0.0 ± 0.1 VDC.

(c) Apply 2.0 ± 0.5 Vpp (0.7 ± 0.2 Vrms) sinewave at 8.0 ± 0.5 KHz from the
SPEED SENSE (J1-X) to (J1-Y).

(d) Ground (J1-FF) to the FIELD RTN (J1-DD) and the EQUALIZER (J1-p).

(e) GCU Reset

1 Momentarily connect the GEN ON (J1-d) to the RESET (J1-c).

The following shall be energized: FIELD (J1-AA), KLC (J1-P) and KLC
BACKUP (J1-C).

(4) Stimulated Built-in Test

Test Mode

(a) Connect a 25 VDC power supply to the GSC RESET (J1-c).

(b) Connect the GROUND to the WOW (J1-k).

(c) Cycle the connection to the TEST (J1-q) open/GROUND 3 times within
3 seconds, leaving (J1-q) connected to the ground on the last cycle.

The following shall be energized: ASC FAIL (J1-h), GEN FAIL (J1-x), GCU
FAIL (J1-BB), GEN BRUSH (J1-M), GEN O/C (J1-u), and BTR (J1-f).

(d) Open the connection to the armature GCU SUPPLY (J1-y).

The ASC FAIL (J1-h) shall remain energized for a minimum of 0.7 seconds
after opening the connection.

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(5) Build-up

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) In sequence, connect a variable DC supply to the armature GCU SUPPLY

(J1-y) and apply 7.00 ± 0.25 VDC.

(c) Apply a 14 ± 2 Ω load to the field (J1-AA).

The voltage at the FIELD (J1-AA) shall be 4.5 ± 0.5 VDC.

(6) Anti-cycle

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Apply 25 ± 3 VDC to BACKUP (J1-s), ANTI-CYCLE (J1-v), and RESET

(J1-c).

(c) Open the connection to the armature GCU SUPPLY (J1-y).

The FIELD (J1-AA) shall de-energize.

(d) Momentarily apply 25 ± 3 VDC to the TRIP (J1-t).

(e) Apply 25 ± 3 VDC to the armature GCU SUPPLY (J1-y).

The FIELD shall remain de-energized.

(7) Open Shunt Protection

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Apply a 2.0 ± 0.3 ADC (14 ± 2 Ω) load to the FIELD (J1-AA).

(c) Connect a variable supply to the FIELD RTN (J1-DD) and apply 0.0 ± 0.5
VDC.

(d) Momentarily apply 25 ± 3 VDC to the TRIP (J1-t).

(e) Adjust the FIELD RTN (J1-DD) voltage until the state of the “Field Return
Detect” bit as transmitted from the GCU’s serial port changes from inactive
to active.

The FIELD RTN (J1-DD) voltage shall be 3 ± 2 VDC.

(8) Open Ground Protection

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

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(b) Connect a variable DC supply to the armature GCU SUPPLY (J1-y).

(c) Open the connection to the GCU GROUND (J1-FF and J1-EE).

The GCU shall trip, de-energizing the FIELD (J1-AA).

(d) Reconnect J1-FF to the ground.

The FIELD shall remain de-energized.

(9) Line Contactor Overvoltage

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Connect a variable DC supply to the POR (J1-B) and the armature GCU
SUPPLY (J1-y), and apply 25 ± 3 VDC.

(c) Increase the voltage on the GSC ON (J1-K) until the KLC de-energizes.

The voltage level on the GSC ON shall be 34.5 ± 1.5 VDC.

(10) KLC Driver Overload Protection

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Power the GSC ON (J1-K) through the GEN ON (J1-d).

(c) Set the KLC/KSR (J1-L) loading to 5.0 ± 0.5 ADC.

The KLC (J1-P) shall remain energized.

(d) Set the KLC/KSR loading to 2.0 ± 0.5 Ω and maintain for 0.5 seconds
minimum.

The KLC shall de-energize.

(e) Remove the KLC/KSR load.

The KLC shall remain de-energized.

(f) Momentarily open the connection to the GSC ON (J1-K).

The KLC shall energize.

(11) KSR Driver Overload protection

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Connect a variable DC supply to the START (J1-A) and apply 25 ± 3 VDC.

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(c) Momentarily apply 25 ± 3 VDC to the TRIP (J1-t).

The GCU shall trip de-energizing the FIELD (J1-AA) and the KLC (J1-P).

(d) Lower the frequency of the J1-X to J1-Y signal to 3.0 ± 0.5 KHz.

(e) Momentarily open the connection to the START (J1-A).

The KSR (J1-J) and the ASC FAIL (J1-h) shall energize. The FIELD
(J1-AA) shall remain de-energized.

(f) Set the KLC/KSR (J1-L) loading to 5.0 ± 0.5 ADC (or 5.0 ± 0.5Ω).

The KSR shall remain energized.

(g) Set the KLC/KSR loading to 2.0 ± 0.5 Ω and maintain the load for 0.5
seconds minimum.

The KSR shall de-energize.

(h) Remove the KLC/KSR load.

The KSR shall remain de-energized.

(i) Momentarily open the connection to the START (J1-A).

The KSR shall energize.

(12) Field Driver Overload Protection

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Apply 15 ± 2 ADC load to the FIELD (J1-AA).

The FIELD shall remain energized.

(c) Apply 25 ± 3 VDC to the FIELD BACKUP (J1-JJ).

(d) Open the connection to the armature GCU SUPPLY (J1-y).

The FIELD shall remain energized.

(e) Apply a 1.0 ± 0.2 Ω load to the FIELD, and maintain it for a 2 second
minimum.

The FIELD shall de-energize.

(f) Remove the FIELD (J1-AA) load.

The FIELD shall remain de-energized.

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(13) Equalization

Adjust Low

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

(b) Simulate closed loop regulation by connecting the POR (J1-B) to the FIELD
(J1-AA) through an RC filter with a resistance of 50 ± 10 Ω and a
capacitance of 50 ± 20 µF.

(c) Apply 32 ± 1 VDC to the armature GCU SUPPLY (J1-y).

(d) Apply 7 ± 1 VDC to the FIELD RTN (J1-DD).

(e) Reset the GCU by momentarily connecting the RESET (J1-c) to the GEN
ON (J1-d).

(f) Read a voltage in the range of 22 to 32 VDC to the GCS ON (J1-K).

(g) Apply 1.0 ± 0.1 VDC to the EQUALIZER (J1-p).

The POR (J1-B) voltage shall drop by 2.3 ± 0.5 VDC from 28.50 ±
0.05 VDC.

(h) Apply −1.0 ± 0.1 VDC to the EQUALIZER (J1-p).

The POR (J1-B) voltage shall increase by 1.0 ± 0.5 VDC from 28.50 ±
0.05 VDC.

(14) Analog Signals

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

1 Apply −0.5 ± 0.1 VDC to the INTERPOLE (J1-W).

2 Apply 27 ± 1 VDC to the LOAD BUS (J1-R).

The KLC (J1-P) shall be energized.

3 According to Table 1004A compare the signal measured at the GCU’s

J1 connector pins with the corresponding readings from GCU’s serial
port (J1-Z).

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Connector Pins Measured at J1 Acceptable

Reference
(+) (−) Error

Armature y EE ± 0.4 VDC

Int-Equal W p ± 30 mVDC
POR B EE ± 0.4 VDC
Interpole W EE ± 30 mVDC
Speed X Y ± 40 Hz
Load-POR R B ± 0.1 VDC
Table 1004A - GCU J1 Connector Pins

Reference Reading
Vcc 5.0 ± 0.2 V
Program 2.5 ± 0.2 V
Brush 12.0 ± 0.5 V
Int-Equal 0 ± 20 mV
Table 1004B - GCU Serial Port J1-Z

NOTE: Software for reading byte information is available from TRW Aeronautical
Systems, Lucas Aerospace, Aurora.

(b) KEQ/Vac

1 Open the connection to GCS ON (J1-K).

2 Apply 10 K Ω from the PROG VOLTAGE (J1-m) to the ground (J1-FF).

3 Apply 20 K Ω from the BRUSH WEAR (J1-G) to the POR (J1-B).

The GCU’s serial port readings shall be within the limits specified in
Table 1004B.

(15) Switch Inputs

(a) Establish an Initial Operating Condition as instructed in paragraph 4.C.(3)

of this Acceptance Test section.

From the GCU’s serial port (J1-Z), the KFR TRIP AUX status shall be
inactive.

(b) For each of the input signals listed in Table 1005, make and break the
specified connection and verify the corresponding serial communication
status bit changes accordingly.

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Signal Label Connections State

CROSS START (J1-r) to 25 ± 1 VDC Active = Connected, Inactive = Open
START ABORT (J1-b) to J1-w Active = Connected, Inactive = Open
FEEDER (J1-v) to J1-U Active = Connected, Inactive = Open
INTERRUPT (trips the field relay)
WEIGHT ON (J1-k) to J-GG Active = Connected, Inactive = Open
WHEELS
KFRTRIPAUX — Active
Table 1005 - Inputs

(16) Software Checksum/Revision

(a) Read the software CHECKSUM and VERSION from the GCU’s serial port
(J1-Z).

The CHECKSUM shall be 0Bh.

The VERSION shall be 0Ah.

(b) Manual Trip: Applying 25 ± 1 VDC to the TRIP (J1-t).

The field relay (KFR) should trip.

D. Closed-loop Tests
Closed loop tests shall be conducted in a closed loop system using model number
23080-014 or electrically equivalent starter generator. The unit shall have
successfully passed all open loop tests before starting closed loop testing. The unit
shall be tested with all covers and hardware installed.

WARNING: DURING OPERATION, STARTER GENERATORS CAN PRODUCE

A HIGH OUTPUT CURRENT THAT CAN CAUSE SEVERE SHOCK
OR DEATH. MAKE SURE THAT ALL POWER IS SHUT OFF TO THE
STARTER GENERATOR BEFORE REMOVING OR REPLACING
TEST EQUIPMENT, INSTRUMENTS, OR ASSEMBLIES. TAKE
EXTREME CAUTION WHEN PERFORMING “LIVE CIRCUIT” TESTS
AND FAULT ISOLATION PROCEDURES.

CAUTION: Before connecting the test unit, the field switch must be in the OFF
position.

CAUTION: If an Acceptance Test limit is exceeded even by a small margin, do not

continue to test the unit. Be aware that further testing after an
acceptance limit is exceeded can damage the unit.

CAUTION: Failure to turn OFF the power supplies before connecting or

disconnecting high voltage electrical leads can cause serious damage
to the GCU.

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(1) Connection

(a) Connect the GCU in a closed loop system. The EQUALIZER BUS (J1-p)
shall not be connected.

(b) Operate the starter generator at nominal rated speed for regulation.

(c) Reset the GCU by momentarily connecting the GEN ON (J1-d) to the GCS
RESET (J1-c).

(2) Regulation

(d) Apply no load

The POR (J1-B) voltage shall be within ± 0.05 VDC of 28.50 VDC. Set
adjustment potentiometer to achieve this regulation.

(e) Apply a full rated load.

Regulation shall be maintained within ± 0.07 VDC of the voltage set in

paragraph D.(2)(a).

The regulation shall be free from sustained oscillation.

(3) Manual Trip

Momentarily connect the TRIP (J1-t) to the armature GCU SUPPLY (J1-y).

The GCU’s field relay shall trip, and the generator shall de-energize.

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(4) Acceptance Test Data Sheet

Test Acceptance Limits / Readings

Paragraph Observations

2. Serial Number of any

replacement assembly

4.A. Initial inspection

4.B. (2) Dielectric

4.C. (1) CPU power supply

check

4.C. (2) (d) Reset

4.C. (2) (f) POR measurement

4.C. (2) (g) Field load

4.C. (3) (e) 1 Reset

4.C. (4) (c) TEST/GROUND

4.C. (4) (d) ARMATURE

4.C. (5) (c) Field load

4.C. (6) (c) Anticycle set up

4.C. (6) (e) Anticycle

4.C. (7) (e) FIELD RTN

4.C. (8) (c) Open ground

R.C. (8) (d) Reconnect ground

4.C. (9) (c) GSC ON

4.C. (10) (c) KLC/KSR Load

4.C. (10) (d) Set KLC/KSR

4.C. (10) (e) Remove KLC/KSR Load

4.C. (10) (f) Open connection

4.C. (11) (c) TRIP

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(4) Acceptance Test Data Sheet (continued)

Test Acceptance Limits / Readings

Paragraph Observations

4.C. (11) (e) Open START

connection

4.C. (11) (f) KLC/KSR Load

4.C. (11) (g) Set KLC/KSR Load

4.C. (11) (h) Remove KLC/KSR Load

4.C. (11) (i) Open connection

4.C. (12) (b) FIELD

4.C. (12) (d) Open ARMATURE

connection

4.C. (12) (e) FIELD Load

4.C. (12) (f) Remove FIELD Load

4.C. (13) (g) EQUALIZER

4.C. (13) (h) - EQUALIZER

4.C. (14) (a) 2 LOAD BUS

4.C. (14) (a) 3 A/D readings

4.C. (14) (b) 3 BRUSH WEAR

4.C. (15) (a) Initial Operating

Condition

4.C. (15) (b) Switch input sensing

4.C. (16) (a) CHECKSUM

4.C. (16) (b) Manual Trip

4.D. (2) (a) No load

4.D. (2) (b) Full load

4.D. (3) Manual Trip

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(5) Troubleshooting

Troubleshooting and repair of 51525-014A GCU consists generally of

replacement of entire assemblies, either one of the two plug-in PWB assemblies
or the chassis assembly itself. The problem assembly must be returned to TRW
Aeronautical Systems, Lucas Aerospace, Aurora for repair. Table 1006 is
provided as a guide for the replacement of the proper assembly related to the
Acceptance Test failure.

When more than one assembly might cause a test failure, the troubleshooting
actions are listed in order of the likelihood of correcting each specific problem.
One assembly should be replaced at a time and the problem test should then
be repeated before replacing the next assembly listed. After the problem is
corrected, a complete Acceptance Test must be performed on the GCU prior to
being returned to service.

Test Paragraph Test Corrective Action

4.A. Initial inspection Replace affected part or assembly
4.B. (1) Test set up N/A
4.B. (2) Dielectric Replace 51525-303 Chassis/cover assembly
4.C. (1) CPU power supply Replace 51525-373A assembly
check Replace 51525-303 Chassis/cover assembly
4.C. (2) (a) - (c) Test set up N/A
4.C. (2) (d) Rest Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
Replace 51525-363 assembly
4.C. (2) (e) Test set up N/A
4.C. (2) (f) POR measurement Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
4.C. (2) (g) Field load Replace 51525-363 assembly
4.C. (3) (a) - (d) Test set up N/A
4.C. (3) (e) 1 Reset Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
Replace 51525-363 assembly
4.C. (4) (a) - (b) Test set up N/A
4.C. (4) (c) TEST/GROUND Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (4) (d) ARMATURE Replace 51525-363 assembly
Replace 51525-373A assembly
4.C. (5) (a) - (b) Test set up N/A
4.C. (5) (c) Field load Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
Table 1006 - Troubleshooting

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DC Generator Control Unit, 51525-014A

(5) Troubleshooting (continued)

Test Paragraph Test Corrective Action

4.C. (6) (a) - (b) Test set up N/A
4.C. (6) (c) Anticycle set up Check test connections
Replace 51525-303 Chassis/cover assembly
4.C. (6) (d) Test set up N/A
4.C. (6) (e) Anticycle Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
4.C. (7) (a) - (d) Test set up N/A
4.C. (7) (e) FIELD RETURN Replace 51525-363 assembly
DETECT Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (8) (a) - (b) Test set up N/A
4.C. (8) (c) Open ground Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
4.C. (8) (d) Reconnect ground Replace 51525-303 Chassis/cover assembly
Replace 51525-363 assembly
4.C. (9) (a) - (b) Test set up N/A
4.C. (9) (c) GSC ON Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (10) (a) - (b) Test set up N/A
4.C. (10) (c) KLC/KSR Load Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (10) (d) Set KLC/KSR Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (10) (e) Remove KLC/KSR Replace 51525-373A assembly
Load Replace 51525-303 Chassis/cover assembly
4.C. (10) (f) Open connection Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (11) (a) - (b) Test set up N/A
4.C. (11) (c) TRIP Replace 51525-373A assembly
4.C. (11) (d) Test set up N/A
4.C. (11) (e) Open START INH Replace 51525-373A assembly
connection Replace 51525-303 Chassis/cover assembly
Replace 51525-363 assembly
4.C. (11) (f) KLC/KSR Load Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
Table 1006 - Troubleshooting (continued)

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(5) Troubleshooting (continued)

Test Paragraph Test Corrective Action

4.C. (11) (g) Set KLC/KSR Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
4.C. (11) (h) Remove KLC/KSR Replace 51525-373A assembly
Load
4.C. (11) (i) Momentarily open Replace 51525-303 Chassis/cover assembly
connection Replace 51525-373A assembly
4.C. (12) (a) Test set up N/A
4.C. (12) (b) FIELD Replace 51525-303 Chassis/cover assembly
Replace 51525-363 assembly
4.C. (12) (c) Test set up N/A
4.C. (12) (d) Open ARMATURE Replace 51525-303 Chassis/cover assembly
connection
4.C. (12) (e) FIELD load Replace 51525-303 Chassis/cover assembly
Replace 51525-363 assembly
4.C. (12) (f) Remove FIELD load Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
4.C. (13) (a) - (f) Test set up N/A
4.C. (13) (g) EQUALIZER Replace 51525-373A assembly
Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
4. C. (13) (h) - EQUALIZER Replace 51525-373A assembly
Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
4.C. (14) (a) 1 Test set up N/A
4.C. (14) (a) 2 LOAD BUS Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (14) (a) 3 A/D readings Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (14) (b) 1-2 Test set up N/A
4.C. (14) (b) 3 BRUSH WEAR Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (15) (a) Initial Operating Replace 51525-373A assembly
Condition Replace 51525-303 Chassis/cover assembly
4.C. (15) (b) Switch input sensing Replace 51525-373A assembly
Replace 51525-303 Chassis/cover assembly
4.C. (16) (a) CHECKSUM Replace 51525-373A
Table 1006 - Troubleshooting (continued)

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(5) Troubleshooting (continued)

Test Paragraph Test Corrective Action

4.C. (16) (b) Manual Trip Replace 51525-303 Chassis/cover assembly
Replace 51525-363 assembly
4.D. (1) (a) - (c) Test set up N/A
4.D. (2) (a) No load Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
4.D. (2) (b) Full load Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
Replace 51525-373A assembly
4.D. (3) Manual Trip Replace 51525-363 assembly
Replace 51525-303 Chassis/cover assembly
Table 1006 - Troubleshooting (continued)

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SCHEMATICS AND WIRING DIAGRAMS

1. Introduction

This section is unassigned.

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DISASSEMBLY
1. Introduction

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

This section provides disassembly procedures for the 51525-014A DC Generator Control
Unit (GCU). Additional disassembly of major components is not necessary unless further
disassembly is instructed in the CHECK or the TESTING AND FAULT ISOLATION
sections.

2. Disassembly of the Generator Control Unit (GCU)

Numbers in parentheses ( ) refer to item numbers in Figure 10001 of the ILLUSTRATED

PARTS LIST, unless otherwise specified.

NOTE: Before proceeding with disassembly, perform an Acceptance Test in accordance

with paragraph 4. of the TESTING AND FAULT ISOLATION section and the
CLEANING section.

A. Access cover (5).

(1) Remove the screw (10) and flat washer (15) that attach the access cover to the
enclosure (70).

(2) Remove access cover (5).

B. Back cover assembly (20).

(1) Cut and remove the lockwire and seal from the screws (35).

(2) Remove screws (25, 35) and flat washers (30) from back side of the unit that
attach the back cover (20) to the enclosure (70).

(3) Remove back cover (20).

C. Printed wiring boards (PWB) (40, 45).

CAUTION: Use extra care when handling the printed wiring boards (PWB) once
unsecured to avoid cracking and flexing the boards.

Pull PWB (40) out. Repeat the procedure for PWB (45).

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D. Chassis cover assembly (50).
(1) Remove screws (55) and flat washers (60) from front of the unit that attach the
chassis cover assembly to the enclosure (70).

(2) Loosen hex socket head fasteners located at the back side of the unit to relax
the retainers (65).

(3) Pull chassis cover assembly out.

NOTE: The two rigid segments of chassis cover assembly, when assembled, are at
right angles. Once removed from the enclosure, the two rigid segments will
flex at the connecting ribbon.

CAUTION: Use extra care when handling the two rigid segments to avoid damaging
the flexible connection ribbon.

E. Shoulder washers (75, 80).

Pull shoulder washers (75, 80) out from enclosure (70).

NOTE: Remove shoulder washers only if they have become damaged.

F. Identification Plate (85).

NOTE: Before discarding the old identification plate, transfer all information to a
replacement Identification Plate.

NOTE: Remove the Identification Plate from the enclosure only if it has become
damaged, the information is unreadable, or service bulletin instructions
require the removal.

Remove drive screws (90) and remove the Identification Plate.

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CLEANING
1. Introduction

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

This section provides cleaning procedures for the 51525-014A DC Generator Control Unit
(GCU).

2. Cleaning Materials

Table 4001 lists the materials required for GCU cleaning.

NOTE: Equivalent materials may be used for those listed in Table 4001.

Material Description/Specification Source

Brush Non-metallic, soft bristle Commercially available
Cleaning pads/Wiping Lint-free, soft fabric Commercially available
cloths
Isopropyl alcohol TT-I-735, Grade A Commercially available
Table 4001 - Cleaning Materials

3. Cleaning Procedures

Before performing DISASSEMBLY, CHECK, REPAIR, ASSEMBLY, Acceptance Testing,

and final inspection, clean according to the following procedure.

WARNING: ISOPROPYL ALCOHOL IS TOXIC AND FLAMMABLE; DO NOT USE

NEAR OPEN FLAMES, WELDING AREAS, OR ON HOT SURFACES.
INHALATION OF VAPORS CAN CAUSE DROWSINESS, DIZZINESS,
AND HEADACHE. CONTACT WITH SKIN CAN CAUSE IRRITATION.
USE IN A WELL-VENTILATED AREA.

WARNING: COMPRESSED AIR USED FOR CLEANING MUST BE FREE OF OIL AND
WATER. WHEN USING COMPRESSED AIR FOR CLEANING OR
DRYING, DO NOT EXCEED 30 PSIG (207 KPA). WEAR GOGGLES OR
A FACE SHIELD TO PROTECT EYES. CARELESS USE OF
COMPRESSED AIR CAN RESULT IN SERIOUS INJURY OR DEATH.

Clean exterior metal parts and exterior electrical connector.

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(1) Wash parts with isopropyl alcohol. Use a soft-bristle brush to loosen oily films
and built up deposits.

(2) Dry parts with cleaning cloths or clean, dry, low-velocity compressed air
[30 psig (207 kPa)] maximum pressure.

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CHECK
1. Introduction

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

This section provides assembly level and component inspection criteria for 51525-014A
DC Generator Control Units (GCU). The inspection procedures are visual and require
bright lighting and a 2.5x magnifier. Do not disassemble the GCU for inspection purposes.
Inspect only components and assemblies that are accessible as a result of disassembly
or repair procedures.

2. Initial Inspection

A. Visually inspect the general condition of the GCU. If large dents, severe
discoloration, or obvious structural damage is found, notify supervisor.
B. Inspect the lockwire. If the lockwire is missing, notify supervisor.

3. Inspection of GCU assemblies and components

Unless otherwise specified, numbers in parentheses ( ) after assembly or component

names in Table 5001, refer to item numbers in Figure 10001 of the ILLUSTRATED PARTS
LIST.

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Inspection Corrective Action

A. Back cover assembly (20) Repair the damage if it is not excessive.
(1) Inspect the back cover assembly Replace the back cover assembly if the
for cracks, nicks, dents, and damage is excessive.
scratches.
(2) Inspect all surfaces for corrosion.
B. Chassis cover assembly (50) Repair the damage if it is not excessive.
(1) Inspect the chassis cover Replace the chassis cover assembly if
assembly for cracks, nicks, the damage is excessive.
dents, and scratches.
(2) Inspect all surfaces for corrosion.
C. Identification Plate (85) Replace the Identification Plate if damage
(1) Inspect the Identification Plate for is found.
dents, nicks, cracks, or gouges.
(2) Inspect the printing and markings
on the Identification Plate for
legibility.
(3) Check that the drive screws Replace loose or missing drive screws.
holding the Identification Plate in
place are tight.
D. Printed Wiring Boards Assemblies
(40) and (45)
(1) Inspect the printed wiring boards Replace the PWB if damage is found.
(PWB) for evidence damage.
(2) Inspect the PWB for cracks, Replace the PWB if damage is found.
breaks, loose lead wires, or
discoloration.
(3) Inspect the PWB for Replace the PWB if damage is found.
delamination, cracks, and broken
lands.
(4) Check all wiring connections for Replace the PWB if damage is found.
discoloration, corrosion and
loose solder joints.
(5) Check the board resin coatings Replace the PWB if damage is found.
for cracking or the exposure of
board or component surfaces.
Table 5001 - Inspection

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REPAIR
1. Introduction

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

This section provides authorized repair procedures for 51525-014A DC Generator Control
Units (GCU). Repairs are limited to:

• minor repair of damaged surfaces

• repair of surface coatings

• replacement of faulty printed wiring boards

Only the repairs in this manual are authorized by TRW Aeronautical Systems, Lucas
Aerospace, Aurora.

2. Repair Tools

In addition to standard electrical/electronic repair shop tools, the tools listed in Table 6001
are required for GCU repair.

Tool Description Reference

Brush, soft-bristle Commercially available
Cleaning Pads/Wiping Cloths (lint-free, soft Commercially available
fabric)
India stone Commercially available
Sandpaper (400/600 grit) Commercially available
Table 6001 - Repair Tools
CAUTION: Steel wool, steel wire brushes and abrasives containing iron or iron oxide
shall not be used at any time during repair.

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3. Repair Materials

Table 6002 lists the materials required for GCU repair. Equivalent materials may be used.

Item Description/Material Specification Source

Chemical conversion MIL-C-5541, Class 1A or 3 (Alodine Commercially
coating 1200) available
Isopropyl alcohol TT-I-735, Grade A Commercially
available
Humiseal Type 1B31 Commercially
available
Table 6002 - Repair Materials

WARNING: ISOPROPYL ALCOHOL IS FLAMMABLE. DO NOT USE NEAR

OPEN FLAMES, WELDING AREAS, OR ON HOT SURFACES.
INHALATION OF VAPORS CAN CAUSE DROWSINESS, DIZZINESS,
AND HEADACHE. CONTACT WITH SKIN CAN CAUSE IRRITATION.
AVOID PROLONGED EXPOSURE AND USE THESE MATERIALS IN
A WELL-VENTILATED AREA.

WARNING: CHEMICAL CONVERSION MATERIALS ARE EXTREMELY TOXIC

AND ARE EXPLOSIVE FIRE HAZARDS WHEN IN CONTACT WITH
ACIDS, REDUCING AGENTS, AND COMBUSTIBLE AND OXIDIZING
MATERIALS. SEPARATE STORAGE IS MANDATORY. ALWAYS
WEAR RESPIRATORY PROTECTION, A RUBBER APRON, GLOVES,
AND GOGGLES OR A FACE SHIELD WHEN WORKING WITH THESE
MATERIALS. USE CHEMICAL CONVERSION MATERIALS IN A
WELL-VENTILATED AREA, AWAY FROM HEAT, OPEN FLAMES,
OR SPARKS. FOLLOW APPROVED TOXIC WASTE DISPOSAL
PROCEDURES.

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4. Surface Repair

Repair formed metal components that have surface damage or corrosion but qualify for
repair.

Remove corrosion and raised surfaces caused by burrs, nicks, or scratches from metal
surfaces with an India stone or 400/600 grit sandpaper.

(1) Lightly sand the area of minor damage.

(2) Clean area with isopropyl alcohol and allow to air dry.

(3) Apply chemical conversion coating according to MIL-C-5541. Coat the areas
where the base metal has been exposed.

(4) Allow the coating to air dry.

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ASSEMBLY
1. Introduction

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

CAUTION: The use of parts, materials, or processes not authorized by TRW

Aeronautical Systems, Lucas Aerospace, Aurora for the maintenance or
repair of these units may affect their continued flightworthiness or invalidate
certification.

Assemble Generator Control Unit (GCU) as required to replace parts that were removed
during DISASSEMBLY, CHECK, or REPAIR.

2. Assembly Tools

In addition to standard electrical/electronic assembly shop tools, the tools listed in Table
7001 are required for GCU assembly.

Tool Description Source

Cleaning pads/Wiping cloths (lint-free, soft fabric) Commercially available
Sandpaper (400/600 grit) Commercially available
Table 7001 - Assembly Tools

3. Assembly Materials

NOTE: Equivalent substitutes may be used for the materials listed in Table 7002.

Description/Military or Federal
Material Source
Specification
Isopropyl TT-I-735, Grade A Commercially available
Alcohol
Lockwire Corrosion-resistant steel, 0.02 inch dia. Commercially available
/MS20995C20
Seal Lead Chandler and Fisher Co.
Cleveland, OH
Humiseal Type 1B31 Commercially available
Table 7002 - Assembly Materials

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WARNING: ISOPROPYL ALCOHOL IS TOXIC AND FLAMMABLE; DO NOT USE
NEAR OPEN FLAMES, WELDING AREAS, OR ON HOT SURFACES.
INHALATION OF VAPORS CAN CAUSE DROWSINESS, DIZZINESS,
AND HEADACHE. CONTACT WITH SKIN CAN CAUSE IRRITATION.
USE IN A WELL-VENTILATED AREA.

WARNING: COMPRESSED AIR USED FOR CLEANING MUST BE FREE OF OIL AND
WATER. WHEN USING COMPRESSED AIR FOR CLEANING OR
DRYING, DO NOT EXCEED 30 PSIG (207 KPA). WEAR GOGGLES OR
A FACE SHIELD TO PROTECT EYES. CARELESS USE OF
COMPRESSED AIR CAN RESULT IN SERIOUS INJURY OR DEATH.

4. Assembly of the DC Generator Control Unit

The following procedure details the assembly of the 51525-014A GCU. Unless otherwise
specified, numbers in parentheses ( ) after assembly or component name, refer to Figure
10001 of the ILLUSTRATED PARTS LIST.

A. If the Identification Plate (85) was removed at disassembly, transfer all

information from the old Identification Plate to the replacement.
(1) Place replacement Identification Plate on enclosure (70) and attach using four
drive screws (90).

(2) Coat Identification Plate with Humiseal. (Refer to the repair section, Table 6002.)

B. If removed, press shoulder washers (75, 80) into enclosure (70).

C. Install chassis cover assembly (50) into enclosure (70).
(1) Slide the longer, rigid section of the chassis cover assembly containing the
retainers (65) into the wider set of guides of the enclosure (70).

(2) Form a right angle with the two rigid sections of the chassis cover assembly and
seat chassis cover assembly (50) into enclosure (70).

(3) Attach chassis cover assembly (50) to enclosure (70) using screws (55) and
washers (60).

(4) Tighten retainers (65).

D. Attach the two printed wiring boards (PWB) (40, 45) into the chassis cover
assembly (50).
(1) Slide PWB (40) into inner most set enclosure of guides.

(2) Push PWB until it seats into its socket.

(3) Slide PWB (45) into outer most set of enclosure guides.

(4) Push PWB until it seats into its socket.

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E. Attach back cover assembly (20)
(1) Attach back cover assembly (20), to enclosure (70), spacer pad facing the two
printed wiring boards (40, 45) with screws (25, 35) and washers (30).

(2) Install MS20995C20 lockwire through the drilled holes of screws (35) in
accordance with MS33540 and lock twisted ends with a lead seal.

F. If removed, attach access cover (5) with screw (10) and washer (15) to chassis
cover assembly (50).

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FITS AND CLEARANCES

1. Introduction

No special fits and/or clearances apply to this unit other than typical good assembly and
maintenance procedures and practices.

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SPECIAL TOOLS, FIXTURES, AND EQUIPMENT

1. Introduction

The following tools, in Table 9001, are approved for use during Acceptance Testing of
the 51525-014A DC Generator Control Unit.

Nomenclature Figure Part Number

Test Tool (schematic diagram) Open Loop 9001 N/A
Test Tool (schematic diagram) Closed Loop 9002 N/A
Kit, Software Interface 9003 51525-014SW
Table 9001 - Special Tools, Fixtures, and Equipment

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ADJ FIXED
S2
GCS S1
ON RESET
d
F ADAPTER P/S
GCS SUPPLY c S22
JJ FIELD BACKUP
K S23
S3 KK ASC STAT
ANTI-CYCLE v
S7 S6 S4 C KLC BACKUP
(+) (+) START A
OPEN LOOP h ASC FAIL
PS 2 PS 1 ARMATURE y
S5 GEN FAIL
(-) (-) x
POR B
CL SIMULATE BB GCU FAIL
KLC P
u GEN O/C
COMPONENT PARTS LIST BTR f
C7 50 uF, 50 DC S8 BRUSH 20K
BACKUP s WEAR
G
. R4 50 OHM, 1/8 WATT S9 CROSS START r
. R3 1 KOHM, WATT
CLOSED LOOP SIMULATE S10 TRIP
. R1 . t
S13 * USED BY 51525-014 A
. . . + STIM BIT* START INH Q
. . . R4 C7 S14
WOW* PROGRAM 3 k
. . . FUNCTION
. . . GENERATOR GCU LOGIC GND GG
. . . KLC
KLC/KSR LOAD SEL S15 LOAD BUS R

51525 GCU
. . .
. . . A S11
P34
. . . KSR X
. . . R1 KSR
SPEED SENSE
. . . Y
S12 KLC/KSR
. . . L
KLC RETURN A
FIELD LOAD
KSR J
FIELD KSR RETURN HH
ADJ S16
FIELD AA
PS 5 GND
FIELD RTN DD
(5 - 30 VDC)
S18
START ABORT * b
(-) (+)
PROGRAM 1 w
S17 S19
SPARE FEEDER INT* V
28VDC EICAS
PROGRAM 2 U
5

SERIAL PORT OUTPUT Z

CLEAR TO SEND T
GND FLT
1

S20 GEN BRUSH

COMPUTER M
PORT PROG VOLTAGE CT(-)
ADAPTER KIT m
RS-232
INT/GF
INTERPOLE W
OPEN GND P.S. GND FF
(+)
INTPL
PS3 METER GND EE
(-) R3 S21
10K
CHS GND z
P.S. GND
COMPONENT TOLERANCE TO BE +/- 10 % UNLESS OTHERWISE NOTED. P
*ADJUST VALUE FOR 100 mA ** TOTAL LOAD ON GCU INPUT REVERSE POLARITY METER GND CHS GND
TOTAL LOAD ON GCU INPUT PIN PIN IS TO BE 0.8 AMPERES
*** TOLERANCE TO BE +/- 10 % EQUALIZER

GND

Figure 9001 - Typical Open Loop Test Tool

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Figure 9002 - Typical Closed Loop Test Tool

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DC Generator Control Unit, 51525-014A

Figure 9003 - Kit, Software Interface

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ILLUSTRATED PARTS LIST

1. Introduction

This section contains a listing of assemblies and detail parts for 51525-014A Generator
Control Unit (GCU). Each list is arranged in disassembly sequence, except that attaching
parts are listed immediately after parts they attach, under heading ATTACHING PARTS.

All replacement parts are manufactured or source-controlled by TRW Aeronautical

Systems, Lucas Aerospace, Aurora with exception of those parts assigned a military
standard or Army Navy (AN) standard part number.

WARNING: ANY USE OF PARTS, MATERIALS OR PROCESSES NOT AUTHORIZED

BY TRW AERONAUTICAL SYSTEMS, LUCAS AEROSPACE, AURORA
FOR MAINTENANCE OR REPAIR OF THESE UNITS MAY AFFECT
CONTINUED AIRWORTHINESS OR INVALIDATE CERTIFICATION.

2. Arrangement of Parts List

A. Figure and Item Number Column

First number indicates the figure where the part is illustrated. Each number (without
a dash) corresponds to a part illustrated in the figure. Item numbers preceded by a
dash identify units and /or assemblies, which have not been illustrated. Some item
numbers may have a letter following the number (e.g. 10A). This indicates part
corresponds to base number (e.g. 10) and is the same in function and location but
may differ in form and/or material.

B. Part Number Column

Part numbers listed in this column are the only authorized parts for replacement and
repair of the GCU. This list mainly consists of TRW Aeronautical Systems, Lucas
Aerospace, Aurora part numbers, but does include military standard (MS) and Army
Navy (AN) standard part numbers.

C. Nomenclature Column
Proper name of each part is provided in this column. Description of each item is
indented by columns to indicate the relationship to next higher assembly. Number of
indentures depicts the relationship of item to associated next higher assembly as
follows:

12345
Assembly
Detail Parts for Assembly
Sub-Assembly
Attaching Parts for Sub-Assembly
Detail Parts for Sub-Assembly

Interchangeability relationship between parts is identified in NOMENCLATURE

column of parts list. A list of terms used to show interchangeability and their definition
is as follows:

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Parts List
Term Abbreviation Definition
Alternate Alt. Either part may be used.
Modification Mod Modification (Mod) status details information about the
effectivity of parts in regard to upgrades and modifications.
Alpha variants (A through Y) (except I O Q S X and Z) are
assigned to existing model numbers when necessary
Order The part is not furnished as part of the generator control
separately unit.
Superseded SUPSD BY The part number listed is obsolete and must be replaced by
the new part listed at the next overhaul or repair. The
superseded part is not to be installed or reinstalled.
Supersedes SUPSDS The part number listed must replace the obsolete part
number at the next overhaul or repair
Replaced by REPLD BY The part number listed is discontinued and should be
replaced by the new part number. The original part may be
used until the current stock is depleted and then must be
replaced by the new part listed.
Replaces REPLS The part listed replaces and is interchangeable with the
item number shown in the notation.

D. Quantity Per Assembly Column

The numbers appearing in this column are the total quantity of the listed part required
in the immediate assembly. For bulk items, abbreviation “AR” is used to indicate part
quantity is “As Required”. Abbreviation “REF” and gray text indicate that item is listed
for “Reference” only.

E. Effectivity Code Column

Each GCU model is assigned a unique effectivity code letter. Part variations between
different models are indicated by letter symbols placed in this column, e.g. A =
23080-002, B = 23080-004, C = 23080-006. When parts are used on all models, the
column is left blank.

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50

65 65

55
85 10 60
90
15

75
80
5

40

45

70

20

25
30
30
35
A-GCU-00012

Figure 10001 - DC Generator Control Unit

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NOMENCLATURE QTY
FIGURE PART EFFECT PER
AND ITEM NUMBER CODE
1 2 3 4 5 ASSY
10001-
51525-014A DC GENERATOR CONTROL UNIT . . . . . . REF
---------- * ----------
5 51065-1230 COVER, Access . . . . . . . . . . . . . . . . . . . . . 1
(ATTACHING PARTS)
10 MS35206-227 • SCREW, Pan Head 1
15 NAS620-6L • WASHER, Flat 1

---------- * ----------
20 51525-1031 BACK COVER Assembly . . . . . . . . . . . . . . 1
(ATTACHING PARTS)
25 MS35206-227 SCREW, Pan Head. . . . . . . . . . . . . . . . . . . 4
30 NAS620-6L WASHER, Flat . . . . . . . . . . . . . . . . . . . . . . 6
35 MS35265-27 SCREW, Fillister Head . . . . . . . . . . . . . . . . 2
---------- * ----------
40 51525-363 PRINTED WIRING BOARD, 1
Voltage Regulator . . . . . . . . . . . . . . . . . . . .
45 51525-373A PRINTED WIRING BOARD, 1
Microprocessor . . . . . . . . . . . . . . . . . . . . . .
50 51525-303 COVER CHASSIS Assembly . . . . . . . . . . . 1
(ATTACHING PARTS)
55 MS35206-227 SCREW, Pan Head. . . . . . . . . . . . . . . . . . . 6
60 NAS620-6L WASHER, Flat . . . . . . . . . . . . . . . . . . . . . . 6
---------- * ----------
65 03-0072-02 • • RETAINER, Printed Wiring Board 2
70 51525-1001 • ENCLOSURE, Machining 1

(ATTACHING PARTS)
75 02-4220-24 • WASHER, Shoulder, Black 1
80 02-4220-25 • WASHER, Shoulder, Red 1
---------- * ----------
85 06-5102-92 • PLATE, Identification 1
(ATTACHING PARTS)
90 MS21318-13 SCREW, Drive . . . . . . . . . . . . . . . . . . . . . . 4

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SPECIAL PROCEDURES
1. Introduction

This section includes minimum computer equipment requirements to operate the software,
included in the Software Interface Kit (51525-014SW), used to perform Acceptance Tests.
Also included in this section are software and hardware installation instructions.

2. Minimum System Requirements

Generator Control Unit (GCU) Diagnostic Software is designed to work properly with the
following minimum system configuration:

• IBM compatible computer

• Pentium Processor, 60 MHz or faster

• 16MB RAM or greater

• 40MB free Hard Drive space (minimum)

• 2X CD-ROM Drive or greater

• Windows 95 or later

• Internet Explorer 4.X or later

3. Software Installation

A. Insert TRW Aeronautical Systems, Lucas Aerospace, Aurora GCU Diagnostic

Software CD-ROM,
51900-9000A, into the drive.
B. Windows 95: From the Start menu, choose Run.
C. Type D:\SETUP.EXE (where “D” is the drive letter of your CD) and click OK.
D. Follow instructions on the screen, the Setup program will provide guidance
through the installation process.
4. Hardware Connection Diagram

CAUTION: This equipment contains parts sensitive to damage by

electrostatic discharge (ESDS). Use ESDS precautionary
procedures when touching, removing, or inserting parts
or assemblies.

The Software Interface Kit allows the GCU to communicate with a PC for the purpose of
fault analysis and Acceptance Testing. Through the hardware interface, the GCU provides
real time information about its status, and includes information about voltage, current and
speed. This information can be plotted or stored. Reference Figure 11001 for the following
instructions.

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A. Connect the Serial Port Connector, of 51545-900-1 Interface Assembly, to the
Serial Port connector of the computer.
B. Connect 51545-900-2 Cable Assembly to pins of the 51525-014A Connector.
C. Connect 51545-900-2 Cable Assembly connector to the 51545-900-1 Interface
Assembly connector.
The GCU will be sufficiently grounded for testing through the floating ground at the Serial
Port. Be sure that notebook computer (if not operating from battery) is plugged into a
receptacle with a true Earth ground.

5. System Help

If any help is required during this procedure, reference the software Help file within the
GCU Diagnostic Software Program.

1' Cable

51545-900-1
Interface Assembly
Pin Connections:
51545-900-2 Cable Assembly to GCU Connector

51545-900-2
Cable Assembly

23' Cable Connect Pins to

GCU Connector

Serial Port
Connection

Notebook Computer

Figure 11001 - Interface Assembly

NOTE: A notebook computer is assumed, a desktop PC may be used.

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REMOVAL
1. Introduction

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INSTALLATION
1. Introduction

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SERVICING
1. Introduction

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STORAGE
1. Storage

Materials required for packaging the 51525-014A GCU are listed below in Table 15001.

Description Specification Quantity

Tag Commercially available 1 (domestic)
2 (overseas)
Bag - waterproof, vapor-proof. The bag Kraft-Foil (or equivalent) 1 each
must be large enough to totally enclose
the GCU and then be sealed.
Cushioning material - shock absorbing, Commercially available As required
one-inch thick.
Box - domestic class, single wall, PPP-B-636 (or 1 each
corrugated cardboard. The box must be equivalent)
large enough to totally enclose the
bagged and cushioned GCU, and still
restrain it.
Tape - waterproof, pressure sensitive Commercially available As required
Box - WC5 overseas shipping container, PPP-B-636 1 each
sized to completely enclose the domestic (or equivalent)
class packaging.
Table 15001 - Packaging Material
A. General information
(1) Before preparing GCU for shipment or storage, the unit shall have successfully
completed the TESTING AND FAULT ISOLATION section of this manual.

(2) Verify lockwire and lead seal are in place.

(3) Record the following information to the tag(s):

• GCU Model Number

• GCU Serial Number

• GCU Mod Status

• GCU Test Date (PASSED)

NOTE: If GCU will be stored for more than 12 months, re-test according to TESTING
AND FAULT ISOLATION section before placing into service.

(4) Select the packaging materials as described in Table 15001.

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B. Domestic Packaging
(1) Place GCU into a waterproof and vapor-proof bag.

(2) Remove as much air as possible from bag. Heat seal the bags opening.

(3) Wrap all six sides of GCU with a one (1) inch thick shock absorbing, cushioning
material.

(4) Place bagged and cushioned GCU into the box. Securely and completely, seal
all flapped openings of box with tape.

(5) Tape tag to exterior of box. Make sure all information is visible.

C. Overseas Shipment on surface vessels

(1) Accomplish domestic packaging of GCU.

(2) Place domestically packaged GCU into WC5 shipping container.

(3) Securely and completely, seal all flapped openings of shipping container with
tape.

(4) Tape tag to exterior of shipping container. Make sure all information is visible.

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REWORK
1. Introduction

This section is unassigned.

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TECHNICAL PUBLICATIONS COMMENT FORM

ATTACH A COPY OF EACH AFFECTED PAGE Date of submittal:

List the technical publication(s) and page(s) included with this form:

Suggested technical publication(s) addition(s), deletion(s), or correction(s):

Reason(s) for recommendation(s):

Company / Organization: Organization type (check one):

( ) Owner/Operator
Address (include country): ( ) Repair station
( ) Other (please specify)
_______________________________
Name / Title:

Telephone (include area/country code): Fax:

www. E-Mail:
Forward completed form along with affected page(s) to: Lucas Aerospace, Aurora
Technical Publications Supervisor
777 Lena Drive
Aurora, Ohio 44202
USA
Fax (1) 330 995 1113

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