AD/SD3-60/68 Elevator Trim Tab Balance Weight Brackets (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 39.1 (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.

Short SD3-60 Series Aeroplanes

AD/SD3-60/68 Elevator Trim Tab Balance Weight  Brackets 2/2005 DM

Applicability:

All Model SD3-60 aircraft with elevator trim tab balance weight brackets part No. SD3-07-6011xA installed in accordance with Part B of Short Brothers PLC Service Bulletin SD360-55-20, initial issue.

Requirement:

1.    For aircraft that have exceeded 250 flight hours since replacement of the elevator trim tab balance weight brackets originally installed in accordance with Short Brothers PLC Service Bulletin (SB) SD360-55-20, initial issue:

Inspect the elevator trim tab balance weight brackets in accordance with Part A of SB SD360-55-A21 initial issue, or later EASA approved revision.

2.    For aircraft that have not exceeded 250 flight hours since replacement of the elevator trim tab balance weight brackets originally installed in accordance with SB SD360-55-20, initial issue:

Inspect the elevator trim tab balance weight brackets in accordance with Part A of SB SD360-55-A21 initial issue, or later EASA revision.

3.    For all aircraft, replace the elevator trim tab balance weight brackets originally installed in accordance with SB SD360-55-20 initial issue, with reworked brackets in accordance with Part B of SB SD360-55-A21 initial issue, or later EASA approved revision.

Cracked brackets must be replaced with reworked brackets before further flight, in accordance with Part B of SB SD360-55-A21 initial issue, or later EASA approved revision.

Note:  UK CAA AD G-2004-0032 refers.

Compliance:

1.    Unless already accomplished, within 30 flight hours after 12 January 2004.  If no cracks are found, repeat the inspection at intervals not to exceed 250 flight hours.

2.    Before the accumulation of 250 flight hours since installation.  If no cracks are found, repeat the inspection at intervals not to exceed 250 flight hours.

3.    Before the accumulation of 1,750 flight hours since installation.

This Airworthiness Directive becomes effective on 12 January 2005.

Background:

During a routine structural inspection, an operator found that the elevator tab balance weight brackets on both trim tabs were cracked.  Examination of the cracked brackets by the aircraft manufacturer determined that they were not manufactured in conformity to the approved design standard.  The non-conformity has the potential to greatly reduce the fatigue life of the brackets, causing premature crack initiation and failure.

David Punshon
Delegate of the Civil Aviation Safety Authority

5 January 2005