DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
Amendment 39-4658; AD 82-20-01
Airworthiness Directives; BENDIX: Applies to Bendix Engine Products Division Magnetos
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82-20-01 BENDIX: Amendment 39-4658. Applies to Bendix Engine Products Division magnetos with type designations listed below:
Compliance required within the next 10 hours of engine operation unless
already accomplished for all affected impulse couplings having less than
300 operating hours. (Compliance with this AD is not required for magneto
impulse couplings having more than 300 operating hours.)
|S4LN-21/S4RN-21||Except Bendix Red Label magnetos above |
|S6LN-21/S6RN-21||Serial Nos. B-001171 or A297043|
|S4LN-1225/S4RN-1225 ||Except Bendix Red Label magnetos above|
|S4LN-1225/S4RN-1227||Serial Nos. B-001162 or A297043|
|S4LN-200 P/N 10-163005-7||Except Bendix Red Label magnetos above |
Serial Nos. B-001732 or A297043.
|D4LN-2021/D4RN-2021||Except Bendix Red Label magnetos above|
|D4LN-2031/D4RN-2031||Serial Nos. 35550|
|D4LN-3000/D6RN-3000||Except Bendix Red Label magnetos above |
Serial Nos. B-000249 or 5806.
|All Blue Label impulse |
coupled magnetos of the
|Except Serial Nos. 8236001 and above. |
To prevent failure of impulse coupling due to improperly heat treated
(soft) flyweights resulting in engine damage or failure, accomplish the following:
(Ref. Bendix Service Bulletin No. 623 dated September 1982.)
NOTE: The magneto should be removed from the engine only to the extent
necessary to perform the inspection described herein. Depending on the engine
application, it may not be necessary to remove the harness from the magneto
for the inspection procedure.
NOTE: All magnetos with the impulse coupling recessed into the magneto
flange must have the impulse coupling removed from the magneto to perform
the inspection. This is a bench operation and will required the magneto
to be completely removed from the engine and the harness removed from the
NOTE: Whenever an impulse coupling is removed from a magneto, it must
be removed following the manufacturer's published procedures, paying strict
attention to notes and conditions. Upon reassembly, the castellated nut
securing the impulse coupling to the drive shaft must be torqued to 15-25
ft. lb. (Emergency AD 82-20-01 issued September 7, 1982, specified 18-28
ft. lb. torque. If compliance has already been accomplished based on AD
82-20-01, it is not necessary to retorque to 15-25 ft. lb.) The cotter pin,
Bendix P/N 10-90751-18 removed during disassembly, must be discarded and
1. Remove the magneto from the engine in accordance with the engine/aircraft manufacturer's published instructions.
2. Place the magneto in a suitable work stand with the impulse coupling facing up.
3. Use finger pressure to push inward on the toe (see Figure 1) of
each flyweight so that the flyweight heel protrudes outward.
4. Using a fine #1, double cut, 1/2-inch wide file at least 3/32-inch
thick, pass the file across the heel of the flyweight attempting to remove
material (see Figure 1). If the flyweight has been properly heat treated,
the file will "glide" smoothly over the heel of the flyweight, removing no
material. If the flyweight is not properly heat treated (soft), the file
will not "glide" easily across the surface of the flyweight heel, and material
will be removed.
5. If an improperly heat treated (soft) flyweight is found, immediately
remove and replace the cam assembly and/or the impulse coupling assembly
with an assembly meeting the requirements of this AD, following procedures
in the magneto overhaul instructions, and paying strict attention to notes
6. Inspect the impulse coupling stop pins for wear and replace as necessary.
7. After flyweights have been identified, stop pins inspected, and
the impulse coupling reinstalled on the magneto (if removed), identify the
magneto by stamping a 1/16-inch letter "F" in the upper right corner of the
identification plate to indicate that this AD and Bendix Service Bulletin
No. 623 have been complied with.
8. Reinstall the magneto on the engine following the manufacturer's published procedures.
9. Make an appropriate engine logbook entry, recording magneto serial
number to indicate that this AD and Bendix Service Bulletin No. 623 have
been complied with.
10. Inspect all spare impulse coupling assemblies, cam assemblies,
and magnetos following the same procedures described in Steps 3 and 4 of
this AD. If both flyweights are found acceptable, identify the cam assembly
by applying yellow dyken or yellow lacquer to the heel of each flyweight.
Stamp "F" on data plate as described in Step 7.
11. An equivalent method of compliance with this AD may be used if
approved by the Manager, New York Aircraft Certification Office, Federal
Aviation Administration, 181 South Franklin Avenue, Room 202, Valley Stream,
New York 11581.
This amendment becomes effective June 14, 1983, as to all persons except
those to whom it was made immediately effective by priority mail, issued
September 19, 1982.
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