AD/SD3-60/69 Amdt 1 Rudder Horn Spar (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/SD3-60/69 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.

Short SD3-60 Series Aeroplanes

AD/SD3-60/69 Amdt 1 Rudder Horn Spar 4/2006

Applicability:

All Model SD3-60 aircraft.

Requirement:

1.    For aircraft not previously inspected in accordance with the original issue of this Directive, inspect the rudder in accordance with Part B of Shorts Alert Service Bulletin (ASB) SD360-55-A22 Revision 1, 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 Revision 1, or later EASA approved revision.

Aircraft previously inspected in accordance with the original issue of this Directive are considered to have satisfied the initial inspection requirement of Part B of ASB 360-55-A22 Revision 1, if;

No corrosion was detected, or;

Any detected corrosion was addressed in accordance with the Structural Repair Manual, or an approved repair.

2.    If the extent of the corrosion and any corrective actions cannot be established from the original inspection records, then accomplish Part B of ASB
SD360-55-A22 Revision 1, or later EASA approved revision.

3.    Repeat inspections in accordance with section 1.D of ASB SD360-55-A22 Revision 1, or later EASA approved revision.

Note:  UK CAA AD G-2006-0001 refers.

Compliance:

1.    Before further flight after 13 April 2006.

2.    Within 28 days after 13 April 2006.

3.    As specified in the Requirement document.

This Amendment becomes effective on 13 April 2006.

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.

Amendment 1 is issued in response to a new UK CAA AD, which was issued to address corrosion findings revealed as a result of the initial inspections and to incorporate repetitive inspection in accordance with the Recommended Maintenance Programme.

David Punshon
Delegate of the Civil Aviation Safety Authority

1 March 2006