AD/AMD 50/45 Wing Primary Structure (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.

AMD Falcon 50 and 900 Series Aeroplanes

AD/AMD 50/45 Wing Primary Structure 4/2008

Applicability:

Model Falcon 50 aircraft, all serial numbers.

Requirement:

Perform Maintenance Procedure MP 57-401 Non-Destructive Test inspection of the wing lower panels stiffeners between ribs 13 and 17.

Note 1:  Maintenance Procedure MP 57-401 is introduced through Temporary Change 74 of the Mystere-Falcon Aircraft Maintenance Manual.

Note 2:  EASA AD 2008-0021 refers.

Compliance:

Upon the accumulation of 14,200 flight cycles since new.  Repeat thereafter at intervals not to exceed 5,350 flight cycles.

This Airworthiness Directive becomes effective on 10 April 2008.

Background:

An analysis of in-service events revealed that corrosion of wing fuel tank pressure relief valves was likely to occur well before reaching the overhaul time.  This situation could result in valves stuck in the closed position.  There is the possibility that some aircraft could have experienced wing overpressure with the latent failure of both valve units.  An overpressure, although not sufficient to cause static damage, could have impaired the fatigue damage tolerance of the wing structure.

David Villiers
Delegate of the Civil Aviation Safety Authority

26 February 2008