AD/F100/91 Fuel System Crossfeed Valve Actuator (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Fokker F100 (F28 Mk 100) Series Aeroplanes

AD/F100/91 Fuel System - Crossfeed Valve Actuator 9/2008

Applicability:

Fokker Aircraft B.V. F28 Mark 0070 and Mark 0100 aircraft, all serial numbers, if an actuator Part Number (P/N) 9409122 is installed on one or both fuel crossfeed valves.

Requirement:

Remove each fuel crossfeed valve actuator P/N 9409122 from the aircraft, replace it with a fuel crossfeed valve actuator P/N 53-0013 and accomplish the associated modifications in accordance with the Accomplishment Instructions of Fokker Service Bulletin (SB) SBF100-28-046 or later approved revision.

Note 1:  After installation of P/N 53-0013 fuel crossfeed valve actuators on an aircraft, the requirements of AD/F100/84 no longer apply to the fuel crossfeed valve actuators installed on that aircraft.

Note 2:  EASA AD 2008-0126 dated 8 July 2008 refers.

Compliance:

Within the next 12 calendar months after the effective date of this AD, unless previously accomplished.

This Airworthiness Directive becomes effective on 28 August 2008.

Background:

Due to their position on the aircraft, fuel crossfeed valve actuators P/N 9409122 are susceptible to freezing, which has an adverse effect on the operation of the valve.  This condition, if not corrected, may generate fuel asymmetry alerts when a valve remains in the open position after being selected closed.  It may also prevent the flight crew from correcting a fuel asymmetry when a valve remains in the closed position after being selected open.  One event was reported where, due to such problems, the flight crew shut down an engine in-flight and diverted the aircraft.

Aircraft with serial numbers 11244 through 11441 were delivered from the production line with actuators P/N 9401037 (“chimney type”) installed.  However, on some aircraft these actuators have subsequently been replaced in service with actuators P/N 9409122 (using mounting blocks P/N 7923505) on one or both fuel crossfeed valves.  As a result, those aircraft are also affected by this unsafe condition.

For the reasons described above, this AD requires the replacement of all P/N 9409122 fuel crossfeed valve actuators with a new actuator P/N 53-0013, which has improved reliability and are less susceptible to freezing.

James Coyne
Delegate of the Civil Aviation Safety Authority

16 July 2008