AD 75-14-06

75-14-06 MCDONNELL DOUGLAS: Amendment 39-2250. Applies to all DC-9-10, -20, -30, -40 Series, and Military C-9A, C-9B, and VC-9C Series airplanes, manufacturer's fuselage numbers 1 through 765. Fuselage numbers subsequent to 765 are exempt, provided the thrust reverser driver links and rigging have not been altered subsequent to delivery by the manufacturer.

Compliance required as indicated.

To prevent unwanted deployment of the engine reverser doors, accomplish the following inspections, checks, repairs and replacements on aircraft whose thrust reversers have in excess of 8000 reverser cycles, on or after the effective date of this AD.

NOTE: Thrust reversers whose cycles cannot be determined must be considered to have in excess of 8000 cycles.

(a) Within 72 hours after the effective date of this AD, inspect or check the upper and lower thrust reverser door fairings on each day on which the airplane is operated, to verify the alignment of the door fairing.(1) If the upper door extends more than one-quarter inch higher than the fixed fairing, deploy the reverser and visually inspect the driver links for separation. Replace failed upper driver links prior to further flight.

(2) If a driver link is broken on the lower door, it will gap similar to the upper door while hanging on the lock latch and a reverse unlock indication will be present in the cockpit. Inspect the lower door driver link for separation. If the link is failed, replace failed lower link, or deactivate the reverser door per DC-9 Maintenance Manual, Chapter 78, prior to further flight.

NOTE: McDonnell Douglas Telegram DC-9-COM-10-JER, dated April 26, 1975, covers this subject.

(b) Within 1600 additional hours of flight operation or six months after the effective date of this airworthiness directive, whichever occurs first, inspect by dye penetrant all thrust reverser driver links, P/N 5958782-1 and/or 5958782-501, in accordance with the procedures described in McDonnell Douglas Service Bulletin 78-36, Revision 1, dated June 19, 1975, or later FAA-approved revisions. All links found acceptable for proper flange thickness (undercutting) and exhibiting no evidence of corrosion or cracks as described in paragraph 2C of S.B. 78-36, Revision 1, must be checked for proper rigging in accordance with procedures outlined in paragraphs 2D through paragraph 2J of S.B. 78-36, Revision 1, prior to returning the aircraft to service.

(c) Links may be returned to service, if within the limits specified herein, provided that, at intervals not to exceed 800 cycles in service thereafter from the last inspection, a dye penetrant inspection is performed per the procedures of paragraph (b), above. Serviceable links shall include:

(1) Flange thickness of .085 - .095 inches, with or without evidence of corrosion, pits or cracks as determined by paragraph 2C(3) and 2C(4) of McDonnell Douglas Service Bulletin, Revision 1, dated June 19, 1975, or laterapproved revisions.

(2) Flange thickness of .090 inches or more with properly blended out cracks and with or without corrosion pits as described per paragraph 2C(4) and 2C(5) of the above referenced Service Bulletin.

(3) Flange thickness of .095 or more with corrosion pits as described in paragraph 2C(4) of the above referenced Service Bulletin.

(4) Links checked for crown height and found to be over .243 inches deflection per paragraph 2F(1) of the above referenced Service Bulletin.

Links determined to be unserviceable by paragraph 2C(2) must be scrapped.

NOTE: Reverser links determined to be in categories (1) through (4), above, must be permanently identified as described in McDonnell Douglas Service Bulletin 78-36, Revision 1, or later FAA-approved revisions to preclude reinstallation as a normal replacement.

(d) Further action under this AD may be discontinued as to that airplane when the following conditions are met.

(1) All links have beeninspected and no evidence of cracks, corrosion pits or undercutting exists and crown height is found to be in limits when properly rigged.

(2) Links have been replaced, if necessary, and rigged in accordance with the procedures outlined in the McDonnell Douglas Service Bulletin 78-36, Revision 1, or later FAA-approved revisions.

(e) Equivalent inspections and installations may be approved by the Chief, Aircraft Engineering Division, FAA Western Region, upon submission of adequate substantiating data.

This supersedes the telegraphic AD adopted June 4, 1975.

This amendment becomes effective July 7, 1975.