SERVICE NO.

1273B
Piper Aircraft, Inc.
2926 Piper Drive
BULLETIN
Vero Beach, FL, U.S.A. 32960
PIPER CONSIDERS
COMPLIANCE MANDATORY
Date: June 22, 2016 (M)

Service Bulletin (SB) 1273B supersedes SB 1273A and SB 636A in their entireties. Aircraft that were previously
made compliant with SB 636A must be made compliant with SB 1273B. Aircraft that were previously made compliant
with SB 1273 and/or SB 1273A must also be made compliant with Part III of SB 1273B.

Subject: Bulkhead Modification at Fuselage

Station 317.75

Reason for Revision: SB 1273B adds Part III, Potential Discrepancies in Aircraft
Configuration, to address issues encountered in the field
during the installation of Piper Kit P/N 764-028.

Models Affected: Serial Numbers Affected:

PA-31/PA-31-300/325 Navajo 31-2 thru 31-900; 31-7300901 thru 31-8312019
PA-31-350 Chieftain/T-1020 31-5001 thru 31-5004; 31-7305005 thru 31-8553002

Compliance Time: For aircraft with 2,000 or more hours of time in service (TIS), compliance is to
coincide with the next regularly scheduled maintenance event, but not to exceed
the next 100 hours TIS

Approval: The engineering aspects of this service document have been shown to comply
with the applicable Federal Aviation Regulations and are FAA approved.

Purpose: A review of service history reveals that cracks may develop in the bulkhead
assembly located at fuselage station (FS) 317.75, Piper part number (P/N)
40682-008. This service bulletin provides instructions for repair of these cracks,
as well as installation of structure which has been shown to prevent cracks from
developing.

Safety Intent: The safety intent of this service bulletin is to reduce the likelihood of cracks
developing in the bulkhead assembly at FS 317.75. If not identified and repaired,
such a crack in the airframe structure could expand to a critical length and result in
loss of structural integrity of the vertical fin front spar attachment.

ATA/JASC: 5300

(OVER)
SERVICE BULLETIN NO. 1273BPAGE 2 of 9

CONFIGURATION
DESCRIPTION: Incorporating this service bulletin results in installing a doubler and supporting
structure on the forward upper surface of the bulkhead assembly located at
FS 317.75. Depending on the existing configuration of the aircraft, this doubler
may replace a smaller doubler at the same location. For some aircraft, the required
doubler may already be installed. For these aircraft, no airframe modification is
required.

Instructions:

NOTE: Some steps in these instructions are identified as “required for compliance” (RC). If this service bulletin
is mandated by an airworthiness directive (AD), the steps identified as RC must be done to comply with
the AD. Steps not identified as RC are recommended and may be deviated from, done as a part of other
actions, or done with accepted methods different from those given in this SB, if the RC steps can be done
and the airplane can be put back in a serviceable condition.

NOTE: Temporary removal of some components and/or access panels may be required in order to accomplish
the instructions described in this service bulletin.

NOTE: The part number naming convention used by Piper has changed over the years. A dash number with zeros
in front is equivalent to the same dash number with no zeros in front. For example, part number (P/N)
40682-008 is equivalent to P/Ns 40682-08 and 40682-8. All three part numbers describe the same part.

Part I. Inspection and Repair

1. RC – Gain visual access to the bulkhead assembly at FS 317.75, as shown in Figure 1, Sheet 1.
2. RC – Inspect
a. Prior to inspection, wipe surfaces clean using a soft cloth dampened with isopropyl alcohol, mineral spirits,
naphtha, or other suitable cleaning agent or method.
b. Examine the area shown in Figure 1, View A–A, labeled “INSPECTION AREA” for cracks. The inspection
shall be accomplished using a 10X magnifier, a mirror and a suitable light source or other equipment
capable of providing equal or better resolution.
3. RC – Assess inspection results
a. If a crack is found, follow repair instructions described in Piper Kit P/N 764-028 Rev. 160606, “Bulkhead
Reinforcement and Drag Angle Installation.” Repairs must be accomplished prior to next flight.
WARNING: FLIGHT WITH KNOWN CRACKS IN THE AIRCRAFT STRUCTURE IS NOT ALLOWED. AN
AIRPLANE WITH A CRACK IN STRUCTURE NO LONGER MEETS ITS TYPE DESIGN AND
MAY NO LONGER POSSESS ITS TYPE DESIGN STRENGTH. ANY CRACKS DISCOVERED
IN THE AIRCRAFT STRUCTURE MUST BE REPAIRED PRIOR TO THE NEXT FLIGHT.
b. If no cracks are found, complete one of the following steps:
1) Prior to next flight: accomplish Part II – Modification.
2) Continuing inspection until modification
a) Make a logbook entry documenting the initial inspection.
b) Within 500 hours TIS, accomplish Part II – Modification.
Until modification is accomplished, the inspection from Step 2 must be performed on a recurring
basis, at an interval not to exceed every 100 hours TIS. Make a logbook entry for each recurrent
inspection. If any cracks are found during any inspection, they must be repaired prior to the
next flight.
SERVICE BULLETIN NO. 1273BPAGE 3 of 9

BL
RBL 00.00 INSPECTION LBL
4.70 RIVET 4.70
(TYPICAL)
AREA

BULKHEAD ASSEMBLY

NOTE: Fuselage skins omitted for clarity.

VIEW A−A
LOOKING AFT AT FS 317.75
INSPECTION AREA

B
A

A
B WL
0

UP FS
317.75
FWD

Figure 1, Sheet 1
Aft Fuselage Inspection Area
SERVICE BULLETIN NO. 1273BPAGE 4 of 9

CONFIGURATION 1

FUSELAGE SKIN See Part II, Step 1.b.2),

& DOUBLER C for disposition

RADIUS BLOCK
40682-011

DOUBLER
SPACER
40682-009
40682-010
C
BULKHEAD
ASSEMBLY
40682-008 FWD

CONFIGURATION 2
VIEW C−C

CONFIGURATION 3

VIEW B−B
CONFIGURATIONS 1 – 3
LOOKING AFT AT F.S. 317.75

Figure 1, Sheet 2
Aft Fuselage Inspection Area
SERVICE BULLETIN NO. 1273BPAGE 5 of 9

Part II. Modification

1. RC – Examine the existing configuration of the bulkhead assembly at FS 317.75. Match it with one of the three
configurations shown in View B–B. Complete Step a., b. or c., depending on the existing configuration.
a. Configuration 1: Order Piper Kit P/N 764-028 Rev. 160606, “Bulkhead Reinforcement and Drag Angle
Installation,” and install per kit instructions.
b. Configuration 2: Order Piper Kit P/N 764-028 Rev. 160606, “Bulkhead Reinforcement and Drag Angle
Installation,” and install per kit instructions, with the following exceptions:
1) Remove these parts from the airplane, and discard:
• P/N 40682-009 Spacer
• P/N 40682-010 Doubler – Reinforcement
• P/N 40682-011 Block – Radius
2) Removal of the parts listed in Step 1), above, results in two (2) open holes not addressed by the
instructions in Piper Kit P/N 764-028 Rev. 160606. These holes are identified in View B–B, illustration
“Configuration 2” with the text “See Part II, Step 1.b.2), for disposition.”
a) At the two fastener locations, match drill 0.144 inch diameter holes in the new P/N 71681-002
Reinforcement Doubler to match existing holes in the P/N 40682-008 Bulkhead Assembly.
b) Install NAS1739B4-3 rivets (or other industry standard rivets of equivalent or higher strength)
through the reinforcement doubler and bulkhead assembly.
3) Discard the following kit components, which are already installed on the airplane:
• P/N 71059-006 Angle – Drag, Left
• P/N 71059-007 Angle – Drag, Right
c. Configuration 3: Piper Kit P/N 764-028, “Bulkhead Reinforcement and Drag Angle Installation,” has already
been installed. Additional rework may be required. Follow instructions in Part III of this service bulletin.
2. Make a logbook entry documenting compliance with Part II of this service bulletin.

Part III. Potential Discrepancies in Aircraft Configuration

RC – Described below are several discrepancies that may occur during the installation of Piper Kit
P/N 764-028 Rev. 160606, along with corrective actions. The location of each potential discrepancy is identified
in Figure 2, labeled with the paragraph numbers below.
1. Installation of doubler P/N 71681-002 moves the pulley brackets forward by 0.040 inches. Pulley brackets P/N
41676 and 41677 both have an upper flange that shares three (3) rivets with the fuselage skin. Consequently,
the three (3) rivet holes in the pulley bracket flanges will be misaligned with the three (3) rivet holes in the
fuselage skin when reinstalling the pulley brackets.
Address this condition as follows:
a. Use a drill to open up the three (3) holes in the top flange of pulley brackets P/N 41676 and 41677 to
0.175 – 0.180 inches diameter (#16 drill bit) in order to achieve clean, round rivet holes through the pulley
brackets and skin.
b. Install NAS1242AD5 rivets in the three (3) holes. Maintain a 0.28 minimum edge distance.
2. Due to an accumulation of manufacturing tolerances, the flange of pulley bracket P/N 41676 common to doubler
P/N 71681-002 may interfere with installation of the specified rivet. If interference exists, address it in one of two
ways:
• It is acceptable to trim the edge of the pulley bracket flange 0.100 maximum depth with a trim radius of 0.25.
The 2D edge distance must be maintained for all fasteners.
• Alternatively, it is acceptable to install an NAS1241AD4 rivet in this location. Install the rivet with countersink
manufactured head on the doubler P/N 71681-002 side to provide a flush surface for the pulley bracket
flange. The countersink depth shall be 0.023 – 0.027. Shave the rivet flush with the doubler surface.
SERVICE BULLETIN NO. 1273BPAGE 6 of 9

3. Installation of Kit 764-028 Rev. 160606 may require the removal of components in the area identified which may
result in six (6) open holes in the bulkhead assembly. This is due to the removal of MS20426AD3 rivets. Below
are the six possible configurations and instructions to address each condition:
a. Kit 764-028 Rev. 160606 is installed and the six (6) MS20426AD3 rivets go through the entire stack up.
This condition is acceptable as is.
b. Kit 764-028 Rev. 160606 is installed and there are no open holes in the bulkhead P/N 40682-6 and
doubler P/N 40630. This condition is acceptable as is.
c. Kit 764-028 Rev. 160606 is installed, the six (6) MS20426AD3 rivets are missing and there are open holes.
The proper actions are, first, to drill holes through entire stack up. Next, install the six (6) MS20426AD3
rivets through the entire stack up with the manufactured countersink heads on the doubler P/N 40630 side.
d. The spacer P/N 40682-009 and doubler P/N 40682-010 are installed, and the six (6) BB3 rivets go
through the entire stack up. The proper actions are, first, to remove P/N 40682-009 and 40682-010. Next,
install kit 764-028 Rev. 160606 and the six (6) MS20426AD3 rivets through the entire stack up with the
manufactured countersink heads on the 40630 doubler side.
e. The spacer P/N 40682-009 and doubler P/N 40682-010 are installed and the six (6) MS20426AD3 rivets
do not connect through bulkhead P/N 40682-6 and doubler P/N 40630. The proper actions are, first, to
remove P/N 40682-009 and 40682-010, then, install Kit 764-028 Rev. 160606. Do not install the six (6)
MS20426AD3 rivets.
f. The spacer P/N 40682-009 and doubler P/N 40682-010 are not installed and there are no open holes
through bulkhead P/N 40682-6 and doubler P/N 40630. The proper action is to install Kit 764-028 Rev.
160606. Do not install the six (6) MS20426AD3 rivets.
4. The upper, outboard corner of angles P/N 40682-004 and 40682-005 (identified in Figure 2) may be trimmed
as needed to clear the adjacent structure that is installed by Kit 764-028 Rev. 160606. Maintain a minimum
edge distance of 0.25 inches from the nearby 5/16 inch bolt hole. Pulley bracket P/N 40683-000 (which is
riveted to angle P/N 40682-005) may also be trimmed, if necessary, to clear adjacent structure.
5. The identified forward facing edge of the radius blocks (refer to Figure 2, View A–A) may be trimmed as needed
to clear adjacent structure. Maintain a minimum edge distance of 1.50 times the nominal rivet diameter for all
rivets installed through the radius block. As an example; for a number 4 rivet which has a nominal diameter of
0.125 inches, adjacent surfaces of the radius block may be trimmed, provided that the minimum edge distance
of the trimmed surface to the centerline of the rivet hole is 0.188 inches. Break all sharp corners and ensure a
smooth blend.
6. The periphery of the 71681-002 doubler may be trimmed in the area identified in Figure 2, if required, to clear
an adjacent grommet that may be installed in a hole in the bulkhead. Maintain minimum rivet edge distance of
0.25 inches. Break all sharp corners and ensure a smooth blend.
SERVICE BULLETIN NO. 1273BPAGE 7 of 9

7. Instructions for installing Kit 764-028 Rev. 160606 components includes the statement:
“Align the tool hole in the doubler with the tool hole in the bulkhead, install AN3-5A bolt in tool hole and
secure with nut.”
This is a temporary fastener, used to align parts during installation. Remove and discard this bolt and nut prior
to returning the aircraft to service.
In some configurations, the tooling holes may not align sufficiently to allow an AN3 size bolt to pass through. It
is permissible to use a smaller size temporary fastener, subject to the following constraints:
a. Nest the upper flange of the doubler into the bulkhead flange as completely as possible, using hand
pressure.
b. Remove the temporary fastener prior to returning the aircraft to service.

Note: Treat all bare metal surfaces with primer conforming to MIL-PRF-85582D Type 1 Class C2 primer or any
one of the primers in the table below.

Piper P/N Vendor Name Vendor Product No./Description

279-179 PPG Aerospace PRC-DeSoto EWDE072A/B
279-506 Akzo Nobel Aerospace Coatings 10P8-10NF/EC-283
279-108 Akzo Nobel Aerospace Coatings 10P30-5/EC-275
N/A Deft (PPG Industries) 44GN036
279-240 Axalta Coating Systems 13550S Epoxy Primer
SERVICE BULLETIN NO. 1273BPAGE 8 of 9

FWD
FUSELAGE
SKIN

BULKHEAD
5
DOUBLER 40630 RADIUS BLOCK

DOUBLER 71681-002

VIEW A−A

RADIUS BLOCK 71681-003

or
RADIUS BLOCK - CENTER 71681-006
RADIUS BLOCK - OUTBD 71681-005 (2)

ANGLE 40682-004 ANGLE 40682-005

7
4 4
BRACKET 40683-000
1
A 1
3
PULLEY
BRACKET
41676
PULLEY BULKHEAD
BRACKET A FS 371.75
41676 40682
6
2

DOUBLER
71681-002

BRACKET
40865-002

VIEW LOOKING AFT

Figure 2
Potential Discrepancies
SERVICE BULLETIN NO. 1273BPAGE 9 of 9

MATERIAL REQUIRED: On condition, one (1) each per aircraft, Piper P/N 764-028 Rev. 160606, Bulkhead
Reinforcement and Drag Angle Installation Kit

AVAILABILITY OF PARTS: Your Factory Authorized Piper Service Facility

Effectivity date: This service bulletin is effective upon receipt.

Summary: Please contact your Factory Authorized Piper Service Facility to make
arrangements for compliance with this service bulletin in accordance with the
compliance time indicated.

Note: Please notify the factory of any address/ownership corrections. Changes should include aircraft model,
serial number, and current owner’s name and address.

Corrections and/or changes should be directed to:

PIPER AIRCRAFT, INC.
Attn: Customer Service
2926 Piper Drive
Vero Beach, FL 32960
U.S. Department Small Airplane Directorate
of Transportation Atlanta Aircraft Certification Office
Federal Aviation 1701 Columbia Ave.
Administration College Park, Georgia 30337

January 11, 2017

In reply, refer to FAA correspondence #: 117A-17010-12

Eric Wright, ODA administrator

Piper Aircraft, Inc.
2926 Piper Drive
Vero Beach, Florida 32960

Subject: Alternative Method of Compliance (AMOC) for Airworthiness Directive

2016-05-01, Paragraph (g) "Inspection/Repair" and (h) "Modification"

Dear Mr. Wright:

The Federal Aviation Administration (FAA) received your letter dated December 20, 2016,
proposing a global alternative method of compliance (AMOC) to Airworthiness Directive (AD)
2016-05-01. This AD requires owners/operators of affected aircraft to repetitively inspect the
bulkhead assembly at FS 317.75 for cracks, repair cracks as necessary, and install a reinforcement
modification. The actions are to be in accordance with Piper Service Bulletin (SB) 1273A dated
October 22, 2015.

Piper and the FAA received reports from operators attempting to comply with paragraph (g) and (h)
of the AD 2016-05-01 instructions and discovering an existing installation of Piper kit 764-028
earlier than the AD's required kit revision of 10/26/2015. AD 2016-05-01 superseded AD 96-12-12,
adding new aircraft serial numbers and requiring additional work for some previously modified
airplanes (reference configuration 1 and 2 of Piper SB 1273A). AD 2016-05-01 paragraph (i) did not
explicitly authorize previously installed revisions of kit 764-028 (reference configuration 3 of Piper
SB 1273A) per AD 96-12-12 as an acceptable means of compliance. Note: AD 96-12-12 referenced
kit 764-028 revised June 18, 1990.

We have reviewed the design data, substantiating data and compared the revisions of kit 764-028.
The Atlanta Aircraft Certification Office (ACO) approves your global AMOC proposal to authorize
existing installations of Piper kit 764-028 revisions between June 18, 1990, and October 26, 2015, as
alternative methods of compliance with paragraph (g) and (h) of AD 2016-05-01. This approval
applies to all Piper Model PA-31, PA-31-300, PA-31-325 and PA-31-350 airplanes listed in
paragraph (c) "Applicability" of the AD. All provisions of AD 2016-05-01 that are not specifically
referenced above remain fully applicable and must be complied with accordingly. Please include a
copy of this AMOC when distributing SBs 1273A, 1273B or 636A.

Before using this AMOC, notify your appropriate principal inspector, or lacking a principal
inspector, the manager of the local flight standards district office/certificate holding district office.
The preceding paragraph also applies to any applicable foreign-registered aircraft upon transfer of the
aircraft to the U.S. registry if compliance with the AMOC has not been accomplished.
 This AMOC only applies to the FAA AD listed above. The FAA does not have the authority to
approve this as an AMOC to any AD issued by another civil aviation authority (CAA). Approval of
an AMOC to another CAA's AD must come from that CAA. A copy of this response will be
forwarded to the CAA where these aircraft are registered for their consideration.

When complying or verifying compliance with AD 2016-05-01 using this AMOC, a copy of this
letter shall be inserted into the maintenance records of the airplane.

This FAA AMOC is transferable with the aircraft to an operator who operates the aircraft under U.S.
registry.

If you have any questions or need additional information, please contact Gregory K. (Keith) Noles at
(404) 474-5551, fax at (404) 474-5606, or electronic mail at gregory.noles@faa.gov.

Sincerely,

~
kchristina M. Underwood, Manager,
Atlanta Aircraft Certification Office