AD/SF340/105 Landing Gear Emergency Extension Valve (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.

SAAB SF340 Series Aeroplanes

AD/SF340/105 Landing Gear - Emergency Extension Valve 5/2008

Applicability:

SAAB AB, Saab Aerosystems SAAB SF340A and 340B aeroplanes.

Requirement:

1.    Perform a functional check of the landing gear emergency extension valve in accordance with SAAB Service Bulletin (SB) 340-32-136 or later NAA approved revision; or in accordance with SAAB 340 MRB Report, Section F, Revision 6, task number 323106.

2.    When, during any of the functional checks as detailed in Requirement 1 of this AD, discrepancies are found, restore functionality.  A full system description is provided in the SAAB 340 Aircraft Maintenance Manual (AMM), Chapter 32.

Note:  EASA AD 2008-0054 dated 5 March 2008 refers.

Compliance:

1.    Within the next 6 months after the effective date of this AD, and repetitively thereafter at intervals not to exceed 2 years.

2.    Before further flight, after the effective date of this AD.

This Airworthiness Directive becomes effective on 8 May 2008.

Background:

Several landing gear emergency extension valves have been found seized when performing checks according to the SAAB 340 Maintenance Review Board (MRB) Report, Section F (Airworthiness Limitation Section) task number 323106.  The valves have seized due to lack of internal lubrication.  This condition, if not corrected, could result in malfunctioning of the landing gear release during an operational emergency.  Because the valve lubrication performance is dependant on calendar time since last valve operation, SAAB has revised the check to cycle the emergency release handle 5 times and amended the interval in MRB section F from 5,000 FH to every 2 years.  For the reasons described above, this AD requires a functional check of the landing gear emergency extension valve at the newly established intervals.

David Punshon
Delegate of the Civil Aviation Safety Authority

6 March 2008