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.
Viking Air DHC-4 Series Aeroplanes
AD/DHC-4/1
Cracking of Upper Engine Mount Brackets
3/2012
 
Applicability:
All Viking Air (formerly Bombardier Inc.) model DHC-4 and DHC-4A aircraft.

Requirement:
Carry out a fluorescent penetrant inspection of upper engine mount bracket assemblies in accordance with Canadian Airworthiness Directive CF-2007-26 dated
7 November 2007 or later approved revision.
Note:  Viking Air Ltd. All Operator Message No. 2007-4-11-02 refers.

Compliance:
If the aircraft has an Australian certificate of airworthiness: before further flight after the effective date of this Directive.
If the aircraft does not have an Australian certificate of airworthiness: prior to issue of the certificate of airworthiness.

 
This Airworthiness Directive becomes effective on 24 February 2012.

Background:
A DHC-4 fleet operator discovered that five out of ten aircraft had cracked upper engine mount brackets.  As an interim action, this Directive mandates a one-time inspection.  Subsequent corrective action may be implemented in the future pending results of the investigation.

Mike Higgins
Delegate of the Civil Aviation Safety Authority
8 February 2012