1AD/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.