AD/B737/355 - Forward Airstair Doorway Backup Intercostals and Upper Sill Web (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.

Boeing 737 Series Aeroplanes AD/B737/355 Forward Airstair Doorway Backup 7/2009 Intercostals and Upper Sill Web

Applicability: Model 737-100, -200, -200C, -300, -400 and -500 series aircraft, as identified in Boeing Alert Service Bulletin 737-53A1269, dated 17 May 2007, or later FAA approved revision. Requirement: Action in accordance with the technical requirements of FAA AD 2009-09-06 Amdt 39-15892. Compliance: As specified in the Requirement document, with a revised effective date of 2 July 2009. This Airworthiness Directive becomes effective on 2 July 2009. Background: The FAA received a report indicating that cracks were detected in the backup intercostals and upper sill web of the forward airstair doorway. Such fatigue cracking, unless detected and corrected, could result in a rapid loss of cabin pressure.

David Villiers Delegate of the Civil Aviation Safety Authority

22 May 2009