AD/At/30 Rudder and Vertical Fin (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.

Airtractor AT-300, 400 and 500 Series Aeroplanes

AD/AT/30 Rudder and Vertical Fin 13/2008

Applicability:

Model AT-402, AT-402A, and AT-402B aircraft, serial numbers 0694 through 1176.

Requirement:

1.    Visually inspect the rudder and vertical fin hinge attachment for loose fasteners, and inspect the rudder or vertical fin skins, spars, hinges, and brackets for cracks and/or corrosion in accordance with Snow Engineering Co. Service Letter
No. 247, Revised 2 June 2008, or later FAA approved revision.

If any damage is detected during any Requirement 1 inspection, before further flight, replace any damaged parts with new parts, and accomplish the installation of the external doubler at the upper rudder hinge as specified in Requirement 2.

2.    Accomplish the installation of the external doubler at the upper rudder hinge in accordance with Snow Engineering Co. Service Letter No. 247, Revised 2 June 2008, or later FAA approved revision, and Snow Engineering Co. Process Specification Number 145, dated 6 December 1991.

The installation of the external doubler at the upper rudder hinge terminates the Requirement 1 repetitive inspections.

As of 18 December 2008, do not install any rudder that does not have the external doubler at the upper rudder hinge incorporated.

Note:  FAA AD 2008-21-08 Amdt 39-15692 refers.

Compliance:

1.    Initially inspect when the aircraft accumulates a total of 3,500 hours time in service or within 100 hours time in service after 18 December 2008, whichever occurs later.  Thereafter, repetitively inspect at intervals not to exceed 100 hours time in service until the external doubler at the upper rudder hinge is incorporated.

2.    When the aircraft accumulates a total of 5,000 hours time in service, or within 100 hours time in service after 18 December 2008, whichever occurs later, unless already accomplished.

This Airworthiness Directive becomes effective on 18 December 2008.

Background: The FAA received a report of a loose upper rudder hinge on a Model AT-402 aircraft that was caused by fatigue.  This Directive requires inspections to detect and correct loose fasteners; cracks in the rudder or vertical fin skins, spars, hinges, or brackets; or corrosion of the rudder and vertical fin hinge attachment structure.  Hinge failure adversely affects ability to control yaw and has led to the rudder folding over during flight.  This condition could allow the rudder to contact the elevator and affect ability to control pitch with consequent loss of control.

David Villiers
Delegate of the Civil Aviation Safety Authority

28 October 2008