Commonwealth legislation

AD/B747/137 - Nacelle - Strut Diagonal Brace

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Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

5/10 complexity

Requires operators of most Boeing 747s (Line Nos 001–781, excluding PW4000 and GE CF6-80 engine variants) to inspect the nacelle strut diagonal brace for cracks by detailed visual or a combined visual+ultrasonic method, at specified flight-intervals, and to replace the brace with a new-production part to remove the inspection requirement. The directive is designed to catch cracks originating at small machining marks; operators must follow Boeing SB 747-54-2123 Rev 2 and bear inspection and replacement costs.

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Current sections

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AD/B747/137 - Nacelle - Strut Diagonal Brace

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Boeing 747 Series Aeroplanes

AD/B747/137 Nacelle - Strut Diagonal Brace 5/95

Applicability: All B747 Line No 001 to 781 inclusive except aircraft with PW4000 and GE CF6-80 engines.

Requirement: Inspect the Diagonal Brace for cracks using a detailed visual or a combination of detailed visual and ultrasonic inspection methods. Inspect in accordance with Boeing SB 747-54-2123 Rev 2.

Note: FAA AD 90-20-20 refers.

Compliance: 1. Initially inspect before 10000 flights or within 1000 flights of 27 April 1995, whichever is the later.

2. Repeat the inspections at intervals not exceeding 1000 flights if only a detailed visual inspection is used. Repeat the inspections at intervals not exceeding 3000 flights if a combination of detailed visual and ultrasonic methods is used.

3. Replacement of the Diagonal Brace with a new production brace, which has a revised internal and external finish, cancels the inspection requirements of this AD.

Background: An operator has reported finding a severed diagonal brace. The failure originated at a 0.0025 deep machining mark. Inspection in accordance with this AD on similar production status braces will ensure crack detection before brace failure.

Source text

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

1 AD/B747/137 - Nacelle - Strut Diagonal Brace