AD/F50/74 - Ground Idle Stop Assembly (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Fokker F50 (F27 Mk 50) Series Aeroplanes

AD/F50/74 Ground Idle Stop Assembly 6/97

Applicability: All Fokker F27 Mk 50 aircraft with serial numbers 20103 through 20317, 20321, 20324, 20327, 20329 and 20331.

Requirement : Modify the engine controls by installing a new ground-idle stop assembly and two placards in accordance with the accomplishment instructions of Fokker F50 Service Bulletin F50-76-016 dated December 20, 1996.

Note 1: RLD AD 1996-149(A) dated December 31, 1996, supersedes and cancels RLD AD 1996-128(A) dated October 31, 1996.

Note 2: A flight manual amendment correcting the "available accelerate-stop distance" initially required by RLD AD 1996-128(A) has been retained by RLD AD 1996-148(A) and is available from CASA on request.

Compliance: No later than 22 May 1998.

This Airworthiness Directive becomes effective on 22 May 1997.

Background: During flight tests of a Fokker F27 Mk 60 aircraft it was determined that the stop performance with rapid selection of reverse was less than expected. This condition also applies to the F27 Mk 50 aircraft.

The reduced performance is attributed to the slew-rate limiter that is a feature of the production propeller pitch control unit (PCU). The prototype PCU that was used during initial performance testing did not have the slew-rate limiter incorporated.

This directive provides a modification to the power levers and a revision to the flight manual to address this situation.