AD/B747/268 - Trailing Edge Flap Transmission Torque Brake (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

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 39.1 (1) of CAR 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/B747/268 Trailing Edge Flap Transmission Torque Brake 5/2002

Applicability: Model 747 series aeroplanes line numbers 0001 to 1207, excluding line number 1174 and Model 747SP series aeroplanes.

Requirement: 1. Action in accordance with the technical requirements of CORRECTION FAA AD 2001-23-13 Amendment 39-12512 issued in Renton, Washington, on 7 February 2002.

2. No person shall install on any aircraft any transmission or torque brake assembly of the trailing edge flaps at positions 2 or 7 as identified in the "Existing Part Number" column of paragraph 2.E of Boeing Service Bulletin 747-27-2374 dated 18 November, 1999.

Compliance: Requirement 1: Within 13 months or 5,400 flight hours after the effective date of this Airworthiness Directive, whichever occurs later.

Requirement 2: From the date when this Directive becomes effective. This Airworthiness Directive becomes effective on 16 May 2002. Background: The manufacturer raised a Service Bulletin after it was found that the trailing edge flap transmission torque brake (Belleville spring design) does not lockout at the intended torque levels. If a flap jam occurred, and the torque brake failed to limit the torque of the transmission, the resultant force may cause the transmission mounts to fail. This Airworthiness Directive has therefore been raised to remove, rework or replace such torque brakes to prevent damage to the flap system, adjacent systems, or structural components; or excessive skew of the trailing edge flap, that could result in flap asymmetry and consequent reduced controllability of the aeroplane.