AD/DHC-3/40 Elevator Trim Tab Assembly (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.

DHC-3 (Otter) Series Aeroplanes

AD/DHC-3/40 Elevator Trim Tab Assembly 4/2006

Applicability:

Model DHC-3 “Otter” turbine-powered aircraft which incorporate Supplemental Type Certificate (STC) SA01-111, SA89-32, or SA02-15.

Requirement:

Install one of the following elevator flutter prevention kits:

a.    Viking Air Ltd. Retro Kit No. V3MK1148 Issue 3, or later Transport Canada approved revision; in accordance with Viking Air Ltd. STC SA99-219 Issue 3, or later Transport Canada approved revision;

b.    American Automotives Inc STC SA01059SE with new elevator servo-tab and redundant control linkage; or

c.    Other modifications, approved by Transport Canada, designed to prevent the elevator servo-tab flutter.

Note:  Transport Canada AD CF-2006-02 refers.

Compliance:

Within 300 flight hours after 13 April 2006 or before 31 May 2006, whichever occurs first.

This Airworthiness Directive becomes effective on 13 April 2006.

Background:

Transport Canada received several reports of incidents on turbine-powered DHC-3 aircraft whereby the control rod of the elevator servo-tab system detached from the servo-tab.  This failure can cause severe flutter of the elevator servo-tab and could lead to loss of control of the aircraft.

Turbine engines are more powerful, allow for a higher cruise speed, and therefore may reduce the elevator servo-tab flutter margins.  This Directive requires installation of a kit to reduce the probability of elevator servo-tab failure due to flutter.

David Punshon
Delegate of the Civil Aviation Safety Authority

1 March 2006