AD/SD3-60/69 Rudder Horn Spar (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.

Short SD3-60 Series Aeroplanes

AD/SD3-60/69 Rudder Horn Spar 9/2005 TX

Applicability:

All Model SD3-60 aircraft.

Requirement:

1.    Inspect the rudder in accordance with Part A of Shorts Alert Service Bulletin (ASB) SD360-55-A22 original issue or later EASA approved revision.  If any damage is observed or suspected, before further flight, inspect the rudder in accordance with Part B of ASB SD360-55-A22 original issue or later EASA approved revision.

And, if not accomplished concurrently with Requirement 1:

2.    For any aircraft that has experienced a heavy landing, inspect the rudder in accordance with Part B of ASB SD360-55-A22 original issue or later EASA approved revision.

Or,

3.    For aircraft that have accumulated 28,800 hours or 50,000 flight cycles, or greater, and have not experienced a heavy landing, inspect the rudder in accordance with Part B of ASB SD360-55-A22 original issue or later EASA approved revision.

Or,

4.    For aircraft that have accumulated between 25,000 and 50,000 flight cycles since new and have not experienced a heavy landing, inspect the rudder in accordance with Part B of ASB SD360-55-A22 original issue or later EASA approved revision.

Or,

5.    For aircraft that have accumulated less than 25,000 flight cycles since new and have not experienced a heavy landing, inspect the rudder in accordance with Part B of ASB SD360-55-A22 original issue or later EASA approved revision.

Any damage observed when performing the inspections required by this Directive must be assessed, monitored and repaired in accordance with the instructions provided in ASB SD360-55-A22 original issue or later EASA approved revision.

Note:  UK CAA AD G-2005-0021 refers.

Compliance:

1.    Within 5 flights after 8 July 2005.

2.    Within 20 flights or one week after 8 July 2005, whichever occurs first.

3.    Within 20 flights or one week after 8 July 2005, whichever occurs first.

4.    Within 40 flights or two weeks after 8 July 2005, whichever occurs first.

5.    Within 80 flights or four weeks after 8 July 2005, whichever occurs first.

This Airworthiness Directive becomes effective on 8 July 2005.

Background:

There have been several in-service reports of cracking of the rudder horn spar.  On one aircraft, the cracking had progressed to the point where the spar failed and the lower mass balance weight detached from the rudder horn spar, causing secondary structural damage to the rudder’s front spar, rib 14 and outer skin.  Initial investigation indicates the failure is due to fatigue cracking of the rudder horn spar and rib cleats.  Loss of a mass balance can have an adverse effect on aircraft flutter characteristics, and with sufficient penetration of rib 14 the potential exists for restriction or jamming of the rudder.

David Villiers
Delegate of the Civil Aviation Safety Authority

7 July 2005