AD/EMB-120/29 Amdt 4 Elevator Trim System (Cth)
AIRWORTHINESS DIRECTIVE
On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/EMB-120/29 Amdt 3 and issues the following 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.
Embraer EMB-120 (Brasilia) Series Aeroplanes
| AD/EMB-120/29 Amdt 4 | Elevator Trim System | 10/2007 |
Applicability: | All Model EMB-120 aircraft. |
Requirement: | Action in accordance with the instructions contained in Brazil ANAC AD The flight manual amendment required by this Directive is incorporated into the Aircraft Flight Manual at Revision 67, dated 5 June 2001. Once the Flight Manual has been amended to include this revision, the copy of the AD, which ANAC AD Note: Embraer Service Bulletins 120-25-0262, 120-27-0095, and 120-27-0096, all original issues, or later ANAC approved revisions, refer. |
Compliance: | As specified in the Requirement document. |
| This Amendment becomes effective on 27 September 2007. | |
Background: | The occurrence of pitch trim upsets, caused by spring back effect of the elevator trim system control cables, was found to be due to sudden autopilot disengagement during flight descent phase. The problem results from jammed or frozen trim actuators associated with the autopilot trim servo action stretching the cables up to the servo torque limit and consequent release. Amendment 1 required the installation of placards on the cockpit main instrument panel glareshield in addition to the current requirements. Amendment 2 modified the text of the placards on the cockpit main instrument panel glareshield. Amendment 3 was issued to allow the copy of the Brazilian AD which the AD requires to be inserted into the Flight Manual to be removed from the Flight Manual once the Flight Manual has been amended to include the relevant requirements. |
| Amendment 4 is issued in response to a revision of the related ANAC AD, which requires modification of the elevator trim system. |
Charles Lenarcic
Delegate of the Civil Aviation Safety Authority
17 August 2007
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