SERVICE No.
974
Piper Aircraft
2926 Piper Drive
Corporation BULLETIN
Vero Beach, Florida, U.S.A. 32960
PIPER CONSIDERS
COMPLIANCE MANDATORY
DATE: October 19, 1994 (MI
SUBJECT: Aileron Hinge Inspection and Replacement
MODELS AFFECTED: SERIAL NUMBERS AFFECTED;
PA-31, 31-300, 31-325 Navajo 31-2 through 31-8312019
PA-31-350 Navajo Chieftain 31-5001 through 31-8452021
PA-31-350 T1020 31-8253001 through 31-8553002
PA-31 P-350 Mojave 31P-8414001 through 31-8414050
PA-31 T3 T1040 31T-8275001 through 31T-5575001
COMPLIANCE TIME: At the next regularly scheduled maintenance event, but not to exceed the
next one hundred (100) hours of operation and at each one hundred (100) hours thereafter until reaching
one thousand (1000) hours cumulative time in service, at which time the aileron hinge must be replaced.
APPROVAL: The technical contents of this Service Bulletin has been approved by the
F.A.A.
PURPOSE: Reports have been received of small cracks developing in the aileron spar
and reinforcement doubler beneath the inboard aileron hinge attachment point.
Left uncorrected, the structural integrity of the aileron will be compromised to such a degree that aircraft
flight characteristics may be affected.
This Service Bulletin provides instructions for inspection and replacement of the inboard aileron hinges.
Installation of the replacement hinge will relieve the repetitive requirements of the Compliance Time
above.
INSTRUCTIONS: (REFER TO SKETCH “A” AS REQUIRED)
1. Remove left and right ailerons. Refer to the appropriate Maintenance Manual for specific instructions.
2. Remove existing inboard aileron hinge bracket exposing spar and doubler.
CAUTION: Do not confuse the aileron hinge with push/pull rod hinges.
(OVER)
ATA: 5750
SERVICE BULLETIN NO. 974 PAGE 2 OF 4
INSTRUCTIONS: (CONT’D)
3. Inspect the area beneath the inboard hinge on the aileron spar for cracks. If cracks are not visually
observed, use a suitable dye penetrant method for inspection.
4. If no cracks are found, re-inspect in accordance with the compliance time indicated. If a crack is
found, proceed to Instruction 5. If the time limit of one thousand (1000) hours time in service is
reached with no cracks, proceed to Instruction 7.
NOTE: A new hinge may be installed at any time. installation of the replacement hinge
will relieve the repetitive requirements of the Compliance Time above.
5. If the aileron spar is cracked, inspect the rib just behind the hinge for signs of cracking. If the spar
assembly and/or rib are cracked, replace them before proceeding further. Refer to the appropriate
Parts Catalog for applicable part numbers.
NOTE: New replacement aileron spar assemblies will have holes and nutplates
installed to accommodate the new aileron hinge bracket.
6. Install the new Hinge Bracket, Piper Part Number 74461-02 (left) and 74463-03 (right), utilizing
three (3) each AN3-5A Bolts, Piper Part Number 401-266, three (3) each AN960-10 Washers,
Piper Part Number 407-564, and one (1) each MS24694S53 Flush Screw, Piper Part Number
410-035, per Hinge Bracket.
NOTE: The flush screw location is at the bottom outboard
corner of each hinge bracket.
Burnish the area around the upper, outboard hole on the hinge brackets for ground strap installation.
Add one (1) each MS35338-43 Lock Washer, Piper Part Number 407-043, between the bolt head and
washer, place ground strap terminal against hinge bracket and install bolt. Apply standard torque to
each fastener.
7. If no cracks are present, it will be necessary to drill additional holes and add two (2) additional
nutplates to the existing aileron spar assembly. Temporarily install the new hinge bracket to the
aileron spar. Using the new hinge bracket as a template, drill two (2) new .191 inch holes in the spar
to match.
NOTE: Installation of the replacement hinge will relieve the repetitive
requirements of the Compliance Time above.
8. Remove enough rivets from the aileron skin to gain access to the inside of the aileron.
9. Inspect the aileron rib flange for cracks at the original hinge bracket attachment point and replace if
cracked. Install two (2) each NAS687A3 Nutplates, Piper Part Number 406-816, using two (2)
each MS20426AD3 rivets to attach each nutplate. Seal the open nutplate which was previously used
for the static ground strap attachment with RTV-106 sealant. Close the aileron skin using
MS20470AD3 rivets as were originally installed.
SERVICE BULLETIN NO. 974 PAGE 3 OF 4
INSTRUCTIONS (CONT’D):
1O. Install the new hinge brackets, utilizing three (3) each AN3-5A Bolts, Piper Part Number
407-266, three (3) each AN960-10 Washers, Piper Part Number 407-564, and one (1) each
MS24694S53 Flush Screw, Piper Part Number 410-035, per hinge bracket. Burnish the area
around the upper outboard hole on the hinge brackets for ground strap installation. Add one
(1) each MS35338-43 Lock Washer, Piper Part Number 407-043, between the bolt head and ”
washer. Place the ground strap terminal against the hinge bracket and install the bolt. Apply standard
torque to each fastener.
11. Touch-up the paint as required and check the balance of each aileron per the instructions contained in
the appropriate aircraft Maintenance Manual.
12. Reinstall the ailerons on the aircraft, check rigging, travels and clearances. Refer to the appropriate
aircraft Maintenance Manual as required.
13. Make appropriate logbook entry of compliance with this Service Bulletin.
MATERIAL REQUIRED: One (1) each Aileron Hinge Bracket, Piper Part Number 74461-02
(left) and one (1) each Aileron Hinge Bracket, Piper Part Number 74461-03 (right); four (4) each NAS
687A3 Nutplates, Piper Part Number 406-816; six (6) each AN3-5A Bolts, Piper Part Number 401-
266; six (6) each AN960-10 Washers, Piper Part Number 407-564; two (2) each MS24694S53 Flush
Screws, Piper Part Number 410-035; and two (2) each MS35338-43 Lock Washers, Piper Part
Number 407-043.
Your Piper Field Service Facility.
EFFECTIVITY DATE: This Service Bulletin is effective upon receipt.
SUMMARY: There is no applicable factory participation for this Service Bulletin.
Please contact your Factory Authorized Piper Field Service Facility to make arrangements for compliance
with this Service Bulletin in accordance with the Compliance Time indicated.
SUMMARY (CONT’D):
NOTE: If you are no longer in possession of this aircraft, please forward this
information to the present Owner/Operator and notify the factory of
address/ownership corrections. Changes should include aircraft model,
serial number, current owner’s name and address.
Corrections/Changes should be directed to:
PIPER AIRCRAFT CORPORATION
ATTN: Customer Services
2926 Piper Drive
Vero Beach, FL 32960
SERVICE BULLETIN NO. 974 PAGE 4 OF 4. :
TYPICAL AILERON ADD HOLES & NUTPLATES
/
INSPECT:
CRACKS WILL
APPEAR ALONG
SPAR FLANGE RIGHT AILERON
AND AT ATTACH
EXISTING HINGE HOLES
ADD HOLES & NUTPLATES
\ INSPECT:
CRACKS WILL
APPEAR ALONG
SPAR FLANGE
AND AT ATTACH
HOLES.
LEFT AIL .ERON
EXISTING HINGE HOLES
L INSTALL NEW HINGE
P/N’S 74461-02 (LEFT)
AND 74461-03 (RIGHT)
SKETCH A
