AD/B737/278 Elevator Input Torque Tube Assembly (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/B737/278 Elevator Input Torque Tube Assembly 3/2006

Applicability:

Boeing 737 aeroplanes as listed in Table 1 below.

Table 1: Affected B737 Aeroplanes.

Boeing aeroplane models -	As identified in Boeing Alert Service Bulletin-
737-100, -200, -200C, -300, -400, and -500 series aeroplanes	737-27A1274, dated 17 February 2005.
737-600, -700, -700C, -800 and -900 series aeroplanes	737-27A1271, dated 16 December 2004.

Requirement:

Modify the elevator input torque tube assembly by doing all the actions in accordance with the Accomplishment Instructions of the applicable service bulletin in Table 1 of this AD.

Note:  FAA AD 2005-26-03 Amdt 39-14424 refers.

Compliance:

Within 60 months after the effective date of this AD

This Airworthiness Directive becomes effective on 16 March 2006.

Background:

This AD results from a report of a restriction in the pilot's elevator input control system.  Although the cause of the incident was indeterminate, a design review performed on the elevator input torque tube assembly in the course of the investigation discovered possible failure modes that could lead to a jam of the elevator control system.  The actions detailed in this AD are intended to prevent loss of elevator control and consequent reduced controllability of the aeroplane.

James Coyne
Delegate of the Civil Aviation Safety Authority

1 February 2006