AD/B747/370 - Heat Exchanger Shells (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 747 Series Aeroplanes AD/B747/370 Heat Exchanger Shells 3/2008

Applicability: Boeing Model 747-400 series aeroplanes, as identified in Boeing Service Bulletin (SB) 747-21A2439, Revision 2, dated 24 May 2007. Requirement: 1. Do the actions sspecified in 1a) and 1b) of this AD by accomplishing all the actions specified in the Accomplishment Instructions of the service bulletin.

a) Do repetitive general visual inspections to detect discrepancies (i.e., cracks, creases, deformation, deflection, and interference with the rudder and/or elevator cables) of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and do the applicable corrective actions, until the actions required by 1b) of this AD are done.

b) Do an inspection to identify the part number, shop code, and build date of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and do the applicable corrective actions.

Accomplishing the actions in Requirement 1b) ends the repetitive inspections as detailed in Requirement 1a) of this AD.