Commonwealth legislation

AD/DHC-6/35 Amdt 2 - Wing Rear Spar Attachment Fittings

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legislative instrument

Plain English Summary

4/10 complexity

Requires longer X‑ray exposure and a smaller beam angle when radiographically inspecting the wing rear spar attachment fittings, and mandates fitting de Havilland modification 6/1301 by 30 September 1993. Applies to DHC‑6 (Twin Otter) aircraft serial numbers 1–330 that have not already incorporated mods 6/1301 or 6/1630.

The change responds to inter‑rivet cracking in attachment cap parts C6WM1032‑1/‑2; it tightens inspection technique and converts an ongoing inspection regime into a terminating modification action.

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AD/DHC-6/35 Amdt 2 - Wing Rear Spar Attachment Fittings

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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DHC-6 (Twin Otter) Series Aeroplanes

AD/DHC-6/35

Amdt 2

Wing Rear Spar Attachment Fittings 3/92

Applicability: Model DHC-6, all series, with serial numbers 1 through 330 inclusive, not incorporating modification 6/1301 or 6/1630.

Requirement: 1. Action in accordance with de Havilland Service Bulletin 6/295 Revision B; subject to the following changes:

(a) Inspection Method A.1 (Radiographic) is to have the exposure time of 60 seconds increased to 120 seconds for the inboard X-ray tube location; and

(b) The X-ray beam angle of approximately 10 degrees is to be changed to approximately 5 degrees for all of the X-ray locations.

2. Incorporate de Havilland modification 6/1301.

Note: Transport Canada AD CF-73-03 R1 refers.

Compliance: 1. At intervals specified in the Requirement Document, until modified in accordance with Requirement 2.

Prior to 30 September 1993.

The compliance with paragraphs of the previous issue of this Directive were:

For Paragraph 1 - Within 200 hours time in service after 20 October 1972 and thereafter at intervals not exceeding 200 hours time in service.

For Paragraph 2 to 6 - Within the time limits as detailed in the respective paragraphs. This Amendment is effective from 6 March 1992.

Background: Inter-rivet cracking of the top flange of the attachment cap member, part number C6WM1032-1 and -2 located at the inboard end of the wing rear spar, has been found on a number of aircraft in service. Reports have also been received that the radiographic inspection set out in the de Havilland Service Bulletin 6/295 is not locating all the cracks.

Amendment 2 is issued to align this Directive with a revision of the related Country of Origin AD, which requires terminating action in lieu of ongoing inspections.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

1 AD/DHC-6/35 Amdt 2 - Wing Rear Spar Attachment Fittings