AD/B737/240 Flight Control Computer Software (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/B737/240 Flight Control Computer Software 6/2005

Applicability:

Model 737-600, -700, -800, and - 900 series aeroplanes identified in Boeing Alert Service Bulletin (ASB) 737-22A1164, dated 20 May 2004.

Requirement:

If not previously accomplished, install and test an updated version of the operational program software of the enhanced digital flight control system (EDFCS) flight control computers (FCCs), in accordance with ASB 737-22A1164.

Note:  FAA AD 2005-07-20 Amdt 39-14045 refers.

Compliance:

Within 12 months after the effective date of this Directive.

This Airworthiness Directive becomes effective on 9 June 2005.

Background:

This Directive requires installing and testing an updated version of the operational program software of the flight control computers.

The United States Federal Aviation Administration has received a report of an aeroplane pitching up with rapidly decreasing indicated airspeed after the flight crew set a new altitude into the autopilot.  This Directive is issued to prevent anomalous autopilot operation that produces a hazardous combination of aeroplane attitude and airspeed, which could result in loss of control of the aeroplane.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 April 2005