Commonwealth legislation

AD/DHC-6/60 Amdt 4 - Wing Front Spar Attachment Adaptors

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legislative instrument

Plain English Summary

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Requires inspection of aluminium wing-to-fuselage front adaptor fittings on DHC‑6 (Twin Otter) aeroplanes and mandates replacement of all aluminium fittings with steel fittings by 1 September 1995. Replacing the fittings ends the recurring inspections.

Applies to aircraft owners/operators; it prescribes inspection intervals (250 hours for reworked fittings, 500 hours for other aluminium fittings) and a mandatory modification that shifts costs to operators (parts, labour, downtime) in exchange for removing the ongoing inspection requirement. (Source: Applicability; Requirement; Compliance; Background.)

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AD/DHC-6/60 Amdt 4 - Wing Front Spar Attachment Adaptors

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-6/60

Amdt 4

Wing Front Spar Attachment Adaptors 5/92

Applicability: Model DHC-6 series fitted with aluminium wing to fuselage front adaptor fittings.

Requirement: 1. Inspect fittings in accordance with de Havilland Service Bulletin No 6/476 Revision C.

Replace all aluminium fittings with steel fittings in accordance with de Havilland Service Bulletin No 6/500 Revision C. This ends the need for the inspections of para 1 above.

Note: Transport Canada AD CF-85-12R3 refers.

Compliance: 1. Inspect fittings reworked in accordance with de Havilland Service Bulletin No A6/476 at intervals not exceeding 250 hours time in service. Inspect all other aluminium fittings at intervals not exceeding 500 hours time in service.

Replace all aluminium fittings with steel fittings before 1 September 1995.

Background: Fatigue and stress corrosion cracks have been widely reported in the aluminium fittings. Earlier issues of this directive controlled the problem by means of regular inspections, and permitted rework of fittings found to be cracked. Amendment 4 requires mandatory modification - the installation of steel fittings - in line with the recommendations of Transport Canada’s Aging Aircraft program.

Source text

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

1 AD/DHC-6/60 Amdt 4 - Wing Front Spar Attachment Adaptors