SERVICE

BULLETIN

Date: August 4, 2015 (M)

NO. 1257A

PIPER CONSIDERS

COMPLIANCE MANDATORY

Piper Aircraft, Inc.

2926 Piper Drive

Vero Beach, FL, U.S.A. 32960

Service Bulletin (SB) 1257A supersedes SB 1257 in its entirety. Aircraft that have previously complied with SB 1257 

are in compliance with SB 1257A until the next recurring scheduled maintenance event, as defined in this service 

bulletin’s COMPLIANCE TIME. 

Subject: Fuel Hose INSPECTION

Reason for Revision: SB 1257A clarifies the various power plants in the affected 

airplanes. 

Models Affected: Serial Numbers Affected:

PA-31-350 Navajo Chieftain 

with (L)TIO-540-J2BD engines 31-5001 thru 31-5004; 31-7305005 thru 31-7405497;

31-7552001 thru 31-8452021

PA-31-350 T1020 

with (L)TIO-540-J2B engines 31-8253001 thru 31-8553002

COMPLIANCE TIME: Initial compliance to coincide with the next regularly scheduled maintenance 

event, but not to exceed the next 25 hours time in service. Thereafter, recurring 

inspections are to be accomplished at intervals not to exceed 100 hours time in 

service. Additionally, compliance is to be accomplished whenever an engine fuel 

line or turbocharger support assembly is serviced, removed or replaced. 

APPROVAL: The engineering aspects of this service document have been shown to comply 

with the applicable Federal Aviation Regulations and are FAA approved.

PURPOSE: Some of the affected aircraft may have inadequate clearance between the fuel 

inlet or exit hose assemblies of engine mounted fuel pumps and Lycoming 

supplied turbocharger support assemblies. This condition may cause a fitting of 

the fuel inlet or exit hose to crack over time and leak fuel. 

This service bulletin defines a minimum clearance requirement between the fuel 

inlet and exit hose assemblies and turbocharger support assemblies described 

above. This service bulletin requires mandatory on-condition replacement of the 

fuel hose assembly as well as repair or replacement of the turbocharger support 

assembly.

For some of the affected aircraft, this service bulletin also provides instructions for 

identifying conforming fuel hoses. 

ATA: 7310

(OVER)

1
SERVICE BULLETIN NO. 1257A PAGE 2 of 5

Safety Intent: The safety intent of this service bulletin is to minimize the likelihood of fuel hoses 

chafing against adjacent structure, which, if not corrected, could result in a fuel 

leak, with the potential for fire in the engine compartment. 

Configuration

Description: Incorporating this service bulletin changes the orientation of a fuel fitting to 

ensure that fuel hoses in the engine compartment have adequate clearance from 

adjacent structure to prevent chafing.

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 service bulletin, if the RC steps 

can be done and the airplane can be put back in a serviceable condition.

NOTE: The instructions that follow apply to both left and right engines. Depending upon the specific aircraft 

model, the engines will be (L)TIO-540-J2BD or (L)TIO-540-J2B.

NOTE: When installing/rerouting fuel hoses, refer to the appropriate Piper maintenance manual, as well as FAA 

Advisory Circular AC 43.13-1B (Acceptable Methods, Techniques, and Practices – Aircraft Inspection and 

Repair), Chapters 8 and 9, for further guidance.

Note: Some of the affected serial numbered airplanes will have an engine driven fuel pump and inlet fuel hose 

configuration which is different from what is shown in this service bulletin. For those airplanes, the inlet 

fuel pump hoses may be routed differently from what is shown. For these installations, the exit fuel hose 

and inlet fuel hose should be checked for a 3/16 inch minimum clearance from all adjacent structures. 

1. RC – Remove upper and/or lower engine cowls as required to perform the instructions that follow. Refer to the 

appropriate maintenance manual for specific instructions.

2. RC – Identify the part number (P/N) of each fuel inlet hose assembly of each engine mounted fuel pump. If 

a fuel inlet hose assembly is not identified as Piper P/N 39995-034, then replace it with a serviceable Piper 

P/N 39995-034 (refer to Figure 1).

NOTE: A conforming 39995-034 fuel hose assembly will be 30 inches long (as measured from sealing 

surface to sealing surface; approximately the distance between the centers of the locking nuts at 

each end of the hose). The fitting common to the engine mounted fuel pump will be a 3/4-16 NF3 

thread, 45 degrees. The fitting at the opposite end will be a 3/4-16 NF3 thread, straight.

3. RC – Locate the area in each engine compartment where inlet and exit fuel hose assemblies are closest to the 

turbocharger support assembly, Lycoming P/N LW-18302. 

4. RC – Measure the clearance between the inlet and exit fuel hose assemblies where closest to the turbocharger 

support assembly. If necessary, adjust routing of fuel hose assembly to achieve a minimum clearance of 3/16 

inches.

NOTE: For the inlet fuel hose assembly of TIO-540-J2B engine, a slight rotation of the 90° elbow fuel pump 

fitting towards the vertical position may assist in achieving the required clearance (refer to Figure 

2). Since Lycoming installs this fitting into the fuel pump at the factory using sealant, any such 

adjustment will require complete removal of the fitting, cleaning of the threads common to the fitting 

and the fuel pump with methyl ethyl ketone (MEK) or acetone, and reinstallation of the fitting into the 

fuel pump using fresh Loctite® 545TM Thread Sealant. Removal of the fuel pump from the engine may 

be required to accomplish this procedure.
SERVICE BULLETIN NO. 1257A PAGE 3 of 5

Figure 1

Fuel Hose Assembly Proximity to Turbocharger Support

ENGINE

DRIVEN

FUEL PUMP

90° ELBOW FUEL PUMP FITTING

TURBOCHARGER SUPPORT

ASSEMBLY, LYCOMING

P/N LW-18302

3/16” CLEARANCE

INSPECTION AREA 3/16 IN. MIN.

FUEL HOSE ASSEMBLY, 

PIPER P/N 39995-034

VIEW LOOKING FORWARD AND UP

Representative Image - Fuel Inlet Fitting and Hose Assembly of a TIO-540-J2B Engine

5. RC – Inspect the fuel hose assemblies and associated fittings for evidence of leaks, cracks, chafing or damage. 

Replace on condition.

6. RC – Inspect the turbocharger support assembly for evidence of chafing or damage. Repair or replace on 

condition.

7. RC – If any fuel line component was adjusted, serviced or replaced, perform an engine run-up on the ground 

and check for leaks.

8. Reinstall engine cowls per maintenance manual instructions.

9. Make a logbook entry documenting compliance with this service bulletin.
SERVICE BULLETIN NO. 1257A PAGE 4 of 5

Figure 2

Fuel Inlet Fitting Positioning

BEFORE ADJUSTMENT TO IMPROVE CLEARANCE

Typical – Fuel Inlet Fitting of a TIO-540-J2B Engine

ENGINE DRIVEN FUEL PUMP

90° ELBOW FUEL PUMP FITTING

NOT VERTICAL

UP

FWD

FUEL HOSE ASSEMBLY, 

PIPER P/N 39995-034

TURBOCHARGER SUPPORT ASSEMBLY

AFTER ADJUSTMENT TO IMPROVE CLEARANCE

Typical – Fuel Inlet Fitting of a TIO-540-J2B Engine

90° ELBOW FUEL PUMP FITTING

TURBOCHARGER SUPPORT ASSEMBLY

vertical

FUEL HOSE ASSEMBLY, 

PIPER P/N 39995-034

UP

FWD

ENGINE DRIVEN FUEL PUMP
SERVICE BULLETIN NO. 1257A PAGE 5 of 5

MATERIAL REQUIRED: One (1) each (per engine), Fuel Hose Assembly, Piper P/N 39995-034, on 

condition

One (1) each (per engine), Turbocharger Support Assembly, Lycoming 

P/N LW-18302, on condition

AVAILABILITY OF PARTS: Piper P/N 39995-034: Your Factory Authorized Piper Service Facility

Lycoming P/N LW-18302: Your Lycoming Authorized Distributor

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