1AD/B747/51 - Fuselage Frames - Aft Cargo Bay

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/B747/51 Fuselage Frames - Aft Cargo Bay 12/86

Applicability: All models listed in Boeing ASB 747-53A2259. Requirement: Inspect in accordance with Boeing ASB 747-53A2259.

Compliance: Before exceeding 7,000 landings, or within the next 500 landings after 31 December 1986, whichever occurs later; and,

For those frames which have improperly tapered side guide support brackets, repeat the inspection at intervals not exceeding 3,000 landings.

If the tapered strap reinforcement is accomplished in accordance with the ASB, the repeat inspection interval may be extended to 12,000 landings for reinforced frames only.

Background: The manufacturer has advised that some aircraft may have side guide support brackets which have not been properly tapered. Those which have little or no taper cause high load transfer at the end fastener, with consequent cracking. This Directive implements the intent of the FAA AD, with some local variations. One which should be noted is the requirement to carry out precautionary inspections after reinforcement, to cover the possibility of further cracking in fatigue-damaged structure which has not been replaced.