AD 81-15-51 R1

81-15-51 R1 ROCKWELL: Amendment 39-4377. Applies to all Rockwell NA-265-60 airplanes modified in accordance with STC SA687NW and equipped with Lear Siegler Flap Actuation System, and all Rockwell NA-265-80 airplanes modified in accordance with STC SA847NW. To prevent improper flap motion caused by a failure in the flap actuation system, accomplish the following unless already accomplished:

A. Within the next 20 landings following the effective date of this AD, or prior to the accumulation of 200 landings after incorporation of STC SA687NW or STC SA847NW, whichever comes later, rework the power drive unit and flap jackscrew actuators in accordance with paragraphs 1(a) and 1(b) of Rockwell International Sabreliner Service Bulletin 81-5, dated July 10, 1981. During rework of the flap jackscrew actuators, replace any drive shaft, part No. 57400-1640, found to have an extra hole with a new part that does not contain an extra hole.

B. Repetitively, on or before every 200 landings following the accomplishment of paragraph (A.) above, remove and replace the power drive unit and flap jackscrew actuators in accordance with paragraphs 3(a) and 3(b) of Rockwell International Sabreliner Service Bulletin 81-5, Revision 1, dated December 15, 1981.

Airplanes may be flown to a maintenance base for repairs or replacement in accordance with FAR 21.197 and FAR 21.199.

Alternate means of compliance or other actions which provide an equivalent level of safety may be used when approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Mountain Region.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the addresses listed above. These documents may also be examined at FAA Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington 98108.

This amendment becomes effective May 18, 1982 and was effective earlier to those recipients of Telegraph AD T81-15-51 dated July 9, 1981.