Original Issue 19 August, 2011

Revision : N/R

STARTER GENERATOR

INSTALLATION MANUAL

STARTER GENERATOR SERIES:

150SG 250SG
160SG 300SG
200SG 300SGL
200SGL 400SG

PROPRIETARY INFORMATION NOTICE

The information contained in this document is Skurka Aerospace Inc. (SAI) proprietary information and is disclosed in
confidence. It is the property of Skurka Aerospace Inc. and shall not be used, disclosed to others or reproduced without
the express written consent of Skurka Aerospace Inc. If consent is given for reproduction in whole or in part, this notice
and the notice set forth on each page of this document shall appear in any such reproduction in whole or in part.

This technical data is considered ITAR and/or EAR controlled pursuant to 22 CFR Part 120-130 and 15 CFR Parts
730-774 respectively. Transfer of this data by any means to a Non-US Person, whether in the United States or abroad,
without the proper U.S. Government authorization (e.g., License, exemption, NLR, etc.), is strictly prohibited.

Skurka Aerospace Inc.

4600 Calle Bolero
P. O. Box 2869
Camarillo, CA 93011

Internet: www.skurka-aero.com
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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

PARTS DISTRIBUTION and PRODUCT SUPPORT

Skurka Aerospace Inc. (SAI) in house Product Support and Sales Organizations are
augmented by an extensive network of SAI Approved Distribution Organizations. The
approved Distributor Network is located at most regions worldwide, including the
Americas, U.K., France, Canada, Hong Kong, Singapore, Australia, Holland, New
Zealand, Denmark, Germany, and Sweden.

For current list of Approved SAI Distributors, and Overhaul Service Centers, you may
contact our main office

Skurka Aerospace Inc.

4600 Calle Bolero
P. O. Box 2869
Camarillo, CA 93011

Internet: www.skurka-aero.com

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

RECORD OF REVISIONS

Revision Number Date Issued Date Inserted Into Initials

Manual
Original Issue 19 August, 2011 Factory

Retain this record in front of Manual. Only the latest revision level of this manual is considered
valid for current work being performed on SAI starter generators. Operators/maintainers shall
dispose of superseded material in accordance with their own technical documentation
procedures.

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SERVICE BULLETIN CONTROL

Service Bulletin Revision Latest Rev. Status

Number Level Date
SB 150SG114 C Dec. 9, 2009 Incorporated

Retain this record in front of Manual. On receipt of Service Bulletins, record service
bulletin number, status (valid, invalid, etc.), revision, and date issued. Unless
invalidated, all service bulletins affecting SAI starter generators should be kept with
this manual.

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SERVICE LETTER CONTROL

Service Letter Revision Latest Rev. Status

Number Level Date
134 B Dec. 9, 2009 Incorporated
115 B Dec. 9, 2009 Incorporated
225 N/R Jan. 25, 2011 Incorporated

Retain this record in front of Manual. On receipt of Service Letters, record the Service
Letter number, status (valid, invalid, etc.), revision, and date issued. Unless invalidated,
all Service Letters affecting the SAI starter generators should be kept with this Manual.

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

TABLE OF CONTENTS
SECTION PAGE
AL AIRWORTHINESS LIMITATIONS AL-1
AL-1 Airworthiness Limitations Statement AL-1
AL-2 Recommended Overhaul Period AL-1
AL-3 Field Servicing Limits AL-1
AL-4 Start Cycles AL-1
AL-5 Storage Limits AL-1
I INTRODUCTION 1-1
II INSTALLATION INSTRUCTIONS 2-1
1. Removal of Starter-Generator 2-1
2. Prior to Installation 2-1
3. Installation of Starter-Generator 2-2
4. Electrical Connections 2-3

III SERVICE BULLETINS 3-1

IV SERVICE LETTERS 4-1

TECHNICAL DOCUMENTATION SUGGESTION FORM

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

LIST OF ILLUSTRATIONS

FIGURE DESCRIPTION PAGE

1 Drive Shaft Alignment 2-4

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

LIST OF TABLES

Table # Description Page

I Recommended Electrical Connection Torque Values 2-3

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

DESCRIPTION OF REVISIONS

Revision
Page No. Description Approved
Date
Entire 5 August, 2011
Initial issue.
Manual

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

AL-1 AIRWORTHINESS LIMITATIONS

The Airworthiness Limitations section is FAA compliant and specifies maintenance required
under 14 CFR §§ 43.16 and 91.403, unless an alternative program has been FAA
approved.

There are no airworthiness limitations for this series of starter generators.

AL-2 RECOMMENDED OVERHAUL PERIOD

Unless established otherwise in the aircraft operator’s own Airworthiness Limitations or

Operating Specifications, the recommended overhaul period for SAI starter-generators is
1,000 hours with a minimum of 1 brush change prior.

AL-3 FIELD SERVICING LIMITS

Recommended field service on starter-generator units is limited to brush inspection only.

All other repair and/or overhaul activity should be carried out by an authorized repair
station.

Except for brush inspections, aircraft airworthiness is accomplished through removal and
replacement of the starter-generator.

NOTE

Consult the Service Letters section of this manual for information on

brush life calculations.

AL-4 START CYCLES

After every start cycle, the starter-generator as well as the engine should have the
opportunity to cool off. The minimum cooling times are stated below:

30 seconds ON – 1 minute OFF

30 seconds ON – 1 minute OFF
30 seconds ON – 30 minutes OFF

AL-5 STORAGE LIMITS

If the starter-generator has been in storage for longer than 24 months, it should not be
installed on an aircraft. It must be returned to an SAI authorized repair facility for testing
and if necessary, repair.

Bearing grease shelf life is 5 years from date of manufacture of the bearing.

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SECTION I
INTRODUCTION

1-1 GENERAL

1-2 This manual contains introductory information and installation data for Skurka
Aerospace Inc. starter-generators. These starter-generators are manufactured
by:

Skurka Aerospace Inc.

4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011
Internet: www.skurka-aero.com

NOTE:
If an error, omission, or other discrepancy is found in this manual, please
fill out a copy of the Technical Documentation Suggestion Form found at
the back of this manual and forward to the attention of “Sales—Product
Line Manager” at Skurka Aerospace Inc.

1-2a CHANGES TO STARTER-GENERATOR

1-2b Changes to the starter-generator that may affect this manual are communicated
and distributed by manual revisions, and by Service Bulletins (SB’s) or Service
Letters (SL’s). SB’s and SL’s may be incorporated at the next revision change
when applicable. Active or valid service information pertinent to this manual is
located in the appropriate section of the manual. Any service information issued
after the effective date of this manual should be documented on the appropriate
control sheet in the Table of Contents and kept with this manual.

1-3 PURPOSE OF EQUIPMENT

1-4 The Starter-Generator is used as an engine-driven source of DC power in a

28 volt aircraft electrical system and as a source of starting power for light-weight
turbine engines. An efficient integral fan draws air in at the anti-drive end of
generator to permit self-cooled operation.

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4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SECTION II

INSTALLATION INSTRUCTIONS

Expanded procedures have been developed to remove or install the starter-generator in

conjunction with the procedures provided in current applicable maintenance manuals. These
procedures should be utilized each time the starter-generator is removed or installed to
assist in improving the service life of the starter generator bearings, brushes and drive shaft
friction disc.

NOTE:

In all cases, refer to the applicable aircraft maintenance manual for

proper torque, safetying and other detailed removal and installation
instructions that may be particular to the aircraft model. The
information in the aircraft maintenance manual should be used if
there is a conflict with information contained in these instructions.

Two mechanics are required to properly remove or install the

starter-generator.

CAUTION

Slight misalignment and/or binding of the starter-

generator driveshaft can reduce the unit’s service life.

1. Removal of Starter-Generator

a. Disconnect power and then electrical connections per aircraft manual.

b. One mechanic is to maintain the alignment of the starter-generator by holding the

unit in position by keeping the starter generator mounting surfaces flush with the
Quick Attach/Detach adapter (QAD pad), while the other mechanic loosens and
removes the ‘V’ band clamp.

c. Carefully remove the starter-generator from the QAD pad by maintaining the
spline’s alignment to prevent binding of the starter-generator driveshaft.
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4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

2. Prior to Installation, Verify:

a. There are no burrs or foreign objects on the starter-generator shaft.

b. The starter-generator guide pins are clean and not bent or damaged.

c. The mounting surfaces of the starter-generator and the QAD pad are clean and
free of burrs.

d. The QAD pad is properly secured to the engine.

e. The QAD pad guide pin holes are free of burrs, foreign objects and in good
condition.

f. For wet spline starter-generators check ‘O’ ring on drive shaft to see if it is worn
or cut. Replace if necessary.

g. Drive shaft is concentric to the armature of the starter-generator (See Fig. 1). If
the drive shaft appears to be out of position, lightly tap on the drive shaft spline,
using a soft faced mallet to move it back into full concentric position.

CAUTION
Do not use driveshaft spline as a grip to lift starter
generator.

h. Verify V band clamp nut tightening torque from band clamp surface.

3. Installation of the Starter-Generator

a. One mechanic is to gently align the starter-generator to the QAD pad, being
careful not to put the starter-generator drive spline in a bind.

b. After the starter-generator has been properly aligned, one mechanic should hold
the unit in position by keeping the starter generator mounting surfaces flush with
the QAD pad while the other mechanic installs and secures the ‘V’ band clamp
(note the installation torque on clamp ring).

While tightening the nut on the T-bolt to its recommended torque value, tap
around the circumference of the clamp ring with a soft faced hammer
to position the clamp firmly on the generator.

The recommended torque value for the clamp is stamped on the clamp ring.

SKURKA AEROSPACE INC. -- PROPRIETARY INFORMATION Installation Manual

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

4. Electrical Connections

a. Make all terminal block electrical connections between the aircraft wiring and the
starter-generator, as indicated in the applicable aircraft maintenance manual.
Recommended torque values for terminal block connections are shown in Table I.

TABLE I

RECOMMENDED TERMINAL BLOCK ELECTRICAL

CONNECTION NUT TORQUE VALUES

Terminal Size Torque Value

(pound-inches)
# 3/8-24 Stud 160 – 190*
# 10-32 Stud 20 – 25
*May be increased to 200-235 in lbs. if needed for multiple wires on
a single terminal.

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

Figure 1.

Drive Shaft Alignment

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SECTION III

SERVICE BULLETINS

No installation related Service Bulletins apply as of this manual’s date of issuance.

Applicable Service Bulletins issued after this manual’s issuance date should be kept in
this section and recorded on the Service Bulletin Control page.

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4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SECTION IV

SERVICE LETTERS

SL 115 Brush Life Calculations for 150/160SG

SL 132 Brush Life Calculations for 200SGL
SL 178 Brush Life Calculations for 200/250SG
SL 193 Brush Life Calculations for 300SG/300SGL
SL 214 Brush Life Calculations for 400SG

Installation Manual SKURKA AEROSPACE INC. -- PROPRIETARY INFORMATION

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 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

SERVICE LETTER NO.: SL115

TO: ALL HOLDERS OF SKURKA AEROSPACE INC. (SAI) 150SG and 160SG
SERIES STARTER-GENERATORS

FROM: S. SHERMAN

SUBJECT: DATA WHICH WILL ALLOW YOU TO CALCULATE YOUR BRUSH LIFE
FOR YOUR SAI STARTER-GENERATORS

We have found that repeated brush inspections of Starter-Generators can result in rapid brush
wear and even hang-ups. When inspecting brushes, many operators will slide the brush cover
off the back of the generator causing the brush leads to be misplaced.

Sliding the cover forward again, further misplaces the brush leads. If the generator is mounted
on the engine while the inspection is being made, some brush boxes cannot be seen, making
brush lead positioning impossible.

Removing brushes from brush boxes can cause the brush position in the box and the
relationship to the commutator of the brush to be disturbed. The disturbed brush may wear
faster than normal.

One brush inspection between overhauls of the SAI generator is all that may be required of the
SAI brushes.

In essence, this procedure allows the operator to determine his time between brush changes
and may help fix the overhaul periods to be at the same time brushes must be replaced.

At 300 hours, remove the generator for brush inspection. Remove the shortest brush only to
measure the remaining brush life. Do not remove more than one brush, as brush seating will be
affected. Your brush inspection time will be obtained by measuring three different generators
and using the shortest brush length, as the basis for determining your fleet wide brush life.
Filling in the attached form, will show you how to determine remaining brush life. Using this
procedure will aid you in determining your Mean Time Between Overhauls (MTBO). The
generator must be overhauled at 1,000 hours, at which time the bearing must be replaced.

The SAI 150SG and 160SG ampere Starter-Generators can usually operate for a minimum of
500-800 hours without brush change. At 1,000 hours time, the generator must be removed for
overhaul and bearings changed, unless the SAI overhaul manual or aircraft manufacturer states
the bearings can be operated in excess of 1,000 hours.

Please note, this procedure can only be accomplished with a new generator or a generator that
has been overhauled in accordance with SAI Overhaul Procedures and the commutator has
been turned (resurfaced) in a lathe.

PAge 1 of 3
SL115 Revision B.
DEC 9, 2009
 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

GENERATOR SERIES 150SG/160SG SAMPLE CALCULATION PROCEDURE

At 300 hours, remove the generator for brush inspection. Remove the shortest brush only. Do
not remove more than one brush as brush seating will be affected.

SAMPLE CALCULATION
Date: 01/09/97

Generator P/N: 150SG111Q Serial No.: 1200

Calculate brush life left as per example below:

Maximum wear length of a new 150SG1009-5 Brush (1) .520

Brush wear left (as measured from shortest brush) (2) .300

TOTAL BRUSH WEAR (3) .220

Hours brush has operated: (4) 300

(3) .220 ÷ (4) 300 = (5) .0007 Rate of brush wear per hour
Total Brush Hours Brush
Wear (from #3 Operated (from
above) #4 above)
Hours of brush left before brushes must be
(2) .300 ÷ (5) .0007 = (6) 429 replaced
Brush Wear Left Rate of Brush
(from Item #2 Wear per Hour
above) (from Item #5
above)

Generator Operating Hours: 429 + 300 = 729

Hours Left Total Hours on Total Hours Generator
(from Item #6) Generator Thus Far Can Operate Before
(from Item #4) Brush Change

If 150 hours or more of brush life is left, reinstall the brush and operate the generator for the
remaining hours of brush wear left, as calculated above or for a maximum of 1,000 hours. At
that time, return the unit to an Authorized SAI Repair Station for overhaul.

New Brush Shortest Brush from Generator

Remove the generator the second time after the additional operating hours established by your
calculations has been reached. Inspect the brushes. If all are below the maximum brush wear
mark, the generator MTBO has been established. If you desire, two or three more generators
can be tested to establish an average brush life.

PAge 2 of 3
SL115 Revision B.
DEC 9, 2009
 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

GENERATOR SERIES 150SG/160SG SAMPLE CALCULATION PROCEDURE

At 300 hours, remove the generator for brush inspection. Remove the shortest brush only. Do
not remove more than one brush as brush seating will be affected.

Date:

Generator P/N: Serial No.:

Calculate brush life left as per example below:

Maximum wear length of a new 150SG1009-5 Brush (1) .520

Brush wear left (as measured from shortest brush) (2)

TOTAL BRUSH WEAR (3)

Hours brush has operated: (4)

(3) ÷ (4) = (5) Rate of brush wear per hour

Total Brush Hours Brush
Wear (from #3 Operated (from
above) #4 above)
Hours of brush left before brushes must be
(2) ÷ (5) = (6) replaced
Brush Wear Left Rate of Brush
(from Item #2 Wear per Hour
above) (from Item #5
above)

Generator Operating Hours: + =

Hours Left Total Hours on Total Hours Generator
(from Item #6) Generator Thus Far Can Operate Before
(from Item #4) Brush Change

If 150 hours or more of brush life is left, reinstall the brush and operate the generator for the
remaining hours of brush wear left, as calculated above or for a maximum of 1,000 hours. At
that time, return the unit to an Authorized APC Repair Station for overhaul.

New Brush Shortest Brush from Generator

Remove the generator the second time after the additional operating hours established by your
calculations has been reached. Inspect the brushes. If all are below the maximum brush wear
mark, the generator MTBO has been established. If you desire, two or three more generators
can be tested to establish an average brush life.

PAge 3 of 3
SL115 Revision B.
DEC 9, 2009
 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SERVICE LETTER NO.: SL132

TO: ALL HOLDERS OF SAI 200SGL SERIES STARTER- GENERATORS

SUBJECT: DATA WHICH WILL ALLOW YOU TO CALCULATE YOUR BRUSH LIFE
FOR YOUR SAI STARTER-GENERATORS

We have found that repeated brush inspections of Starter-Generators can result in rapid brush wear
and even hang-ups. When inspecting brushes, many operators will slide the brush cover off the back
of the generator causing the brush leads to be misplaced.

Sliding the cover forward again, further misplaces the brush leads. If the generator is mounted on the
engine while the inspection is being made, some brush boxes cannot be seen, making brush lead
positioning impossible.

Removing brushes from brush boxes can cause the brush position in the box and the relationship to
the commutator of the brush to be disturbed. The disturbed brush may wear faster than normal.

One brush inspection between overhauls of the SAI generator is all that may be required of the SAI
brushes.

In essence, this procedure allows the operator to determine his time between brush changes and may
help fix the overhaul periods to be at the same time brushes must be replaced.

At 300 hours, remove the generator for brush inspection. Remove the shortest brush only to measure
the remaining brush life. Do not remove more than one brush, as brush seating will be affected. Your
brush inspection time will be obtained by measuring three different generators and using the shortest
brush length, as the basis for determining your fleet wide brush life. Filling in the attached form, will
show you how to determine remaining brush life. Using this procedure will aid you in determining your
Mean Time Between Overhauls (MTBO). The generator must be overhauled at 1,000 hours, at which
time the bearing must be replaced.

The SAI 200SGL ampere Starter-Generators can usually operate for a minimum of 400-800 hours
without brush change. At 1,000 hours time, the generator must be removed for overhaul and bearings
changed, unless the SAI overhaul manual or aircraft manufacturer states the bearings can be operated
in excess of 1,000 hours.

Please note, this procedure can only be accomplished with a new generator or a generator that has
been overhauled in accordance with SAI Overhaul Procedures and the commutator has been turned
(resurfaced) in a lathe.

Page 1 of 3 SL 132 Rev. B

Feb. 10, 2010
 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

GENERATOR SERIES 200SGL SAMPLE CALCULATION PROCEDURE

BRUSH P/N 200SGL1009

At 300 hours, remove the generator for brush inspection. Remove the shortest brush only. Do not remove more
than one brush as brush seating will be affected.

SAMPLE CALCULATION
Date: 16 Dec 1998

Generator P/N: 200SGL117Q Serial No.: 1200

Calculate brush life left as per example below:

Maximum wear length of a new 150SG1009-5 Brush (1) .625

Brush wear left (as measured from shortest brush) (2) .310

TOTAL BRUSH WEAR (3) .315

Hours brush has operated: (4) 300

(3) .315 ÷ (4) 300 = (5) .00105 Rate of brush wear per hour
Total Brush Hours Brush
Wear (from #3 Operated (from
above) #4 above)
Hours of brush left before brushes must
(2) .310 ÷ (5) .00105 = (6) 295 be replaced
Brush Wear Rate of Brush
Left (from Item Wear per Hour
#2 above) (from Item #5
above)

Generator Operating Hours: 295 + 300 = 595

Hours Left Total Hours on Total Hours Generator
(from Item #6) Generator Thus Can Operate Before
Far (from Item #4) Brush Change

If 150 hours or more of brush life is left, reinstall the brush and operate the generator for the remaining hours of
brush wear left, as calculated above or for a maximum of 1,000 hours. At that time, return the unit to an
Authorized SAI Repair Station for overhaul.

New Brush Shortest Brush from Generator

Remove the generator the second time after the additional operating hours established by your calculations has
been reached. Inspect the brushes. If all are below the maximum brush wear mark, the generator MTBO has
been established. If you desire, two or three more generators can be tested to establish an average brush life.

Page 2 of 3 SL 132 Rev. B

Feb. 10, 2010
 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

GENERATOR SERIES 200SGL SAMPLE CALCULATION PROCEDURE

BRUSH P/N 200SGL1009

At 300 hours, remove the generator for brush inspection. Remove the shortest brush only. Do not remove more
than one brush as brush seating will be affected.

Date:

Generator P/N: Serial No.:

Calculate brush life left as per example below:

Maximum wear length of a new 150SG1009-5 Brush (1) .625

Brush wear left (as measured from shortest brush) (2)

TOTAL BRUSH WEAR (3)

Hours brush has operated: (4)

(3) ÷ (4) = (5) Rate of brush wear per hour

Total Brush Hours Brush
Wear (from #3 Operated (from
above) #4 above)
Hours of brush left before brushes must
(2) ÷ (5) = (6) be replaced
Brush Wear Rate of Brush
Left (from Item Wear per Hour
#2 above) (from Item #5
above)

Generator Operating Hours: + =

Hours Left Total Hours on Total Hours Generator
(from Item #6) Generator Thus Can Operate Before
Far (from Item #4) Brush Change

If 150 hours or more of brush life is left, reinstall the brush and operate the generator for the remaining hours of
brush wear left, as calculated above or for a maximum of 1,000 hours. At that time, return the unit to an
Authorized SAI Repair Station for overhaul.

New Brush Shortest Brush from Generator

Remove the generator the second time after the additional operating hours established by your calculations has
been reached. Inspect the brushes. If all are below the maximum brush wear mark, the generator MTBO has
been established. If you desire, two or three more generators can be tested to establish an average brush life.

Page 3 of 3 SL 132 Rev. B

Feb. 10, 2010
 Skurka Aerospace Inc.
4600 Calle Bolero, P.O. Box 2869
Camarillo, CA 93011

SAI

SAI

SAI
SAI

SAI

SAI

1 of 3 SL178 Revision A

Mar. 17, 2010

 Skurka Aerospace Inc.
4600 Calle Bolero, P.O. Box 2869
Camarillo, CA 93011

SAI

2 of 3 SL178 Revision A

Mar. 17, 2010

 Skurka Aerospace Inc.
4600 Calle Bolero, P.O. Box 2869
Camarillo, CA 93011

SAI

3 of 3 SL178 Revision A

Mar. 17, 2010

 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

SERVICE LETTER NO.: SL193

ATTENTION: ALL HOLDERS OF NEW 300SG & 300S GLS ERIES STARTER-GENERATORS

S UBJ ECT: BRUS H LIFE CALCULATIONS AT FIRS T INS P ECTION OF THE

STARTER-GENERATOR

This inspection allows you to determine the time between brush changes and helps fix overhaul periods at the same
time brushes must be replaced.

The SAI 300 ampere Starter-Generator can usually operate for 800 - 1000 hours without brush change. At
that time, the generator can be removed for overhaul. Using this procedure will aid you in determining your
overhaul times.

Please note, this procedure can only be accomplished with a new generator or a generator that has been
overhauled in accord with SAI Overhaul Procedures and the commutator has been turned (resurfaced) in on
lathe.

1 of 6
SL193 Revision B
JAN 15, 2010
 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

ACCOMPLISHMENT INSTRUCTIONS

CAUTION: USE CARE WHEN MOVING THE COVER FORWARD AS IT WILL MISPLACE THE BRUSH
LEADS. WHEN THE STARTER GENERATOR IS MOUNTED ON THE ENGINE WHILE THE
INSPECTION IS BEING MADE, SOME BRUSH LEADS CANNOT BE SEEN.

1. Remove Brush Strap. See Figure 1. (Note position of screw head.)

Figure 1
Brush Strap

2. Remove Brush screw from Brush Set #1. (Terminal Block to left of brush set.) See Figure 2.

3. Gently release Brush Springs and remove Brush Set #1.

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 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

Figure 2
Brush Set #1

4. Use a flashlight to visibly inspect the condition of the commutator surface. If severe damage
(i.e., arced, pitted, etc.) is noted, then replace unit. See Figure 3 for an example of a damaged
commutator.

Figure 3
Damaged Commutator

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 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

5. Using calipers, measure from the wear indicator line to the end of the brush following the figures on
page 5 of the bulletin as guide.

6. Use pages 5 and 6 of this Service Letter to calculate remaining hours of operation.

CAUTION: MAKE SURE NOT TO SNAP THE BRUSH SPRINGS. THIS CAN CAUSE DAMAGE
TO THE BRUSH SET AND DECREASE BRUSH LIFE.

7. If there are sufficient hours are left, reinstall Brush Set #1. Refer to Figure 4 of this Service Letter
for proper brush lead position. If there are not sufficient hours left, then replace unit.

Figure 4
Positioning of Brush Leads

8. Finally, reinstall Brush Strap. (Note position of screw head.)

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 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

GENERATOR SERIES 300SG, BRUS H P/N 300SGL1009-5

S AMP LE CALCULATION PROCEDURE

Date: ________________

Generator P/N: ____________________ Serial No.: ____________

Calcu late b ru s h life left as p er exam p le b elow:

Maximum wear length of a new 300SGL1009-5 Brush (1) .700

Brush wear left (as measured from brush set #1) (2) .375

TOTAL BRUSH WEAR (3) .325

Hours brush has operated: (4) 500

(3) .325 ÷ (4) 500 = (5) .00065 Rate of brush wear per hour
Hours Brush
Total Brush Operated
Wear (from (from
#3 above) #4 above)
Hours of brush left before
(2) .375 ÷ (5) .00065 = (6) 577 brushes must be replaced
Brush Wear Rate of Brush
Left (from Wear per Hour
Item #2 (from Item #5
above) above)

Generator Operating Hours: 577 + 500 = 1077

Hours Left Total Hours on Total Hours
(from Item #6) Generator Thus Generator Can
Far (from Item Operate Before
#4) Brush Change

If 250 hours or more of brush life is left, reinstall the brush and operate the generator for the remaining hours
of brush wear left, as calculated above. At that time, return the unit to Skurka Aerosapce Inc. for overhaul.

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 Skurka Aerospace Inc.
4600 Calle Bolero; P.O Box 2869
Camarillo, CA 93011

GENERATOR S ERIES 300S G AND 300S GL

Date: ________________

Generator P/N: ____________________ Serial No.: ____________

Calculate brush life left as per example below:

Maximum wear length of a new 300SGL1009-5 Brush (1) .700

Brush wear left (as measured from brush set # 1) (2)

TOTAL BRUSH WEAR (3)

Hours brush has operated: (4)

(3) ÷ (4) = (5) Rate of brush wear per hour

Total Brush Hours Brush
Wear (from Operated (from
#3 above) #4 above)
Hours of brush left before
(2) ÷ (5) = (6) brushes must be replaced
Brush Wear Rate of Brush
Left (from Wear per Hour
Item (from Item #5
#2 above) above)

Generator Operating Hours: + =

Hours Left Total Hours on Total Hours
(from Item Generator Thus Generator Can
#6) Far (from Item Operate Before
#4) Brush Change

If 250 hours or more of brush life is left, reinstall the brush and operate the generator for the remaining hours
of brush wear left, as calculated above. At that time, return the unit to Skurka Aerospace Inc. for overhaul.

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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

SERVICE LETTER # 214

DATA WHICH WILL ALLOW YOU TO CALCULATE YOUR BRUSH LIFE FOR YOUR
SAI STARTER-GENERATOR

______________________________________________________________________

We have found that repeated brush inspections of starter-generators, can result in rapid
brush wear and even cause brush hang-ups. When inspecting brushes, many operators
will slide the brush cover off the back of the generator causing the brush leads to be
misplaced.

Sliding the cover forward again further misplaces the brush leads. If the generator is
mounted on the engine while the inspection is being made, some brush boxes cannot
be seen, making brush lead positioning impossible.

Removing brushes from brush boxes will cause brush position in the box and
relationship to the commutator to be disturbed. The mispositioned brush will wear faster
than normal.

One brush inspection between overhauls of the SAI generator is all that may be
required of SAI brushes.

That one inspection can possibly be eliminated if the accompanying procedure is

adhered to.

In essence, this procedure allows you to determine the time between brush changes
and helps fix overhaul periods at the same time brushes must be replaced.

The SAI 400 ampere Starter-Generator can usually operate for 800 - 1000 hours
without brush change. At that time, the generator can be removed for overhaul. Using
this procedure will aid you in determining your overhaul times.

Please note, this procedure can only be accomplished with a new generator or a
generator that has been overhauled in accord with SAI Overhaul Procedures and the
commutator has been turned (resurfaced) in on lathe.

Page 1 of 3 SL 214 Original Issue

August 11, 2010
 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

GENERATOR SERIES 400SG SAMPLE CALCULATION PROCEDURE

(Brush P/N 400SG1009-5 used as example)

SAI

Page 2 of 3 SL 214 Original Issue

August 11, 2010
 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

GENERATOR SERIES 400SG CALCULATION PROCEDURE WORKSHEET

brush.

SAI

Page 3 of 3 SL 214 Original Issue

August 11, 2010
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 Skurka Aerospace Inc.
4600 Calle Bolero, P. O. Box 2869
Camarillo, CA 93011

TECHNICAL DOCUMENTATION SUGGESTION FORM

Suggested Additions(s), deletions(s), or corrections(s):

Pleases attach a copy of each affected page Submittal Date:____________

Company/Organization Name/Title

Full Address: Telephone:

Fax:

Please send completed Form to the attention of “Sales— Skurka Aerospace Inc.
Product Line Manager”, at: 4600 Calle Bolero
P. O. Box 2869
Camarillo, CA 93011

Internet: www.skurka-aero.com