AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B737/180 and issues the following AD under subregulation 39.1 (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/B737/180 Amdt 1 Speedbrake Operation Limitation - 2 13/2003 Applicability: All Model 737-600, -700, and -700C series aircraft. Requirement: Revise the Limitations Section of the Aircraft Flight Manual to include the following information: "Do not operate the aircraft at speeds in excess of 300 KIAS with speedbrakes extended". WARNING: Use of speedbrakes in excess of 320 KIAS could result in a severe vibration, which in turn, could cause extreme damage to the horizontal stabiliser. Note 1: This requirement may be accomplished by inserting a copy of this Directive into the Limitations Section of the Aircraft Flight Manual. Note 2: Modification or retrofit of the elevator tab assembly in accordance with a method approved by the Manager, Seattle ACO, FAA, constitutes terminating action for the Aircraft Flight Manual revision requirement of this Directive. Note 3: Emergency FAA AD 2002-08-52 refers. Compliance: Within 24 hours after 15 April 2002, unless already accomplished. Compliance with AD/B737/210 (FAA AD 2003-03-22) constitutes terminating action for the requirements of this Directive. The compliance time remains unchanged by this issue. This Amendment becomes effective on 25 December 2003. Background: The FAA received a report indicating that severe vibration of the horizontal stabiliser occurred on a Model 737-700 aircraft. The high frequency vibration was initiated by deployment of the speebrakes during descent of the aircraft. The FAA and the manufacturer have determined that the vibration was due to a "limit cycle oscillation" of the elevator and elevator tab assembly attached to the horizontal stabiliser. Severe vibration of the elevator and elevator tab assembly following deployment of the speedbrakes, if not corrected, could result in severe damage to the horizontal stabiliser, followed by possible loss of controllability of the aircraft. Boeing 737 Series Aeroplanes AD/B737/180 Amdt 1 (continued) Amendment 1 is issued to introduce terminating action for the requirements of this Directive. The original issue of this Airworthiness Directive became effective on 15 April 2002. David Villiers Delegate of the Civil Aviation Safety Authority 13 November 2003 The above AD is notified in the Commonwealth of Australia Gazette on 3 December 2003.