COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
DHC-6 (Twin Otter) Series Aeroplanes
AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/DHC-6/31 Amdt 2 and issues the following AD under subregulation 39.1 (1) of CAR 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.
AD/DHC-6/31
Amdt 3
Structural Component Inspection, Modification and Life Limitation
8/2000
Applicability: All DHC-6 aircraft.
Requirement: 1. Inspect, modify, and/or retire the affected structural components as specified in Bombardier PSM 1-6-11 Revision 5 dated 11 January 2000.
2. For aircraft that are approaching or have exceeded the threshold of the new or revised inspections introduced by PSM 1-6-11 Revision 5, compliance with the threshold inspection may be modified as detailed in Compliance 2.
Note: Transport Canada AD CF-2000-14 refers.
Compliance: 1. As specified in the Requirement document.
2. Pre. Mod. 6/1117 Wing Assemblies
- If the previous inspection of the wing main spar, attachment lug fastener holes, conducted prior to 10 August 2000, was an eddy current inspection carried out in accordance with instructions supplied by Bombardier, conduct the repeat high frequency eddy current inspection in accordance with the schedule in PSM 1-6-11 Revision 5.
b. If the previous inspection of the wing main spar, attachment lug fastener holes, conducted prior to 10 August 2000, was an ultrasonic inspection carried out in accordance with Bombardier Service Bulletin 6/525, conduct the first high frequency eddy current inspection within 1,000 hours flight time or 2,000 flights, whichever occurs first, after the last ultrasonic inspection.
Post Mod 6/1117 and Post Mod 6/1630 Wing Assemblies
If the inspection threshold for the lower wing skin, stringers and aft spar lower flange WS122 TO WS263 (ribs 8 to 20) has been exceeded or will be exceeded within 6 months after 10 August 2000, conduct the initial inspection within 500 hours flight time or 1,000 flights, whichever occurs first, but not later than 6 months after 10 August 2000.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
This Amendment becomes effective on 10 August 2000.
Background: Tests by the manufacturer established the need, endorsed by Transport Canada, for modification and retirement of items of primary structure at the periods specified in the Structural Components Service Life Limits Manual.
Amendment 1 reflected the amendment status of SB 6/268 and PSM 1-6-11.
Amendment 2 reflected the structural re-evaluation of the de Havilland DHC-6 airframe. This re-evaluation resulted in life extensions for some structural components and life reductions for others, as well, new structural inspections have been introduced. The most notable determination was a life limit for the aircraft structure.
Amendment 3 is issued in response to a new Transport Canada AD which introduces a revision of the service life information for the DHC-6 aircraft, as reflected in Structural Components Service Life Limits Manual, PSM 1-6-11 Revision 5, dated 11 January 2000. This new version of PSM 1-6-11 changes the main wing spar, attachment lug fastener hole inspection of Pre Mod 6/1117, wings from an ultrasonic inspection to a high frequency eddy current inspection and revises the schedule for this inspection. Revision 5 also introduces a new detailed visual inspection of the lower wing skin, stringers and aft spar lower flange WS122 TO WS263.
Amendment 1 of this Airworthiness Directive became effective on 30 September 1981.
Amendment 2 of this Airworthiness Directive became effective on 2 January 1997.
The original issue of this Airworthiness Directive became effective on 31 December 1971.
Bernard Malcolm Hole
Delegate of the Civil Aviation Safety Authority 30 June 2000
The above AD is notified in the Commonwealth of Australia Gazette on 12 July 2000.