{"id":"F2006B03232","name":"AD/B747/51 - Fuselage Frames - Aft Cargo Bay","slug":"ad-b747-51-fuselage-frames-aft-cargo-bay","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42656,"registerId":"commonwealth-F2006B03232-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/51 - Fuselage Frames - Aft Cargo Bay","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/51 Fuselage Frames \\- Aft Cargo Bay 12/86\n\nApplicability: All models listed in Boeing ASB 747-53A2259. Requirement: Inspect in accordance with Boeing ASB 747-53A2259.\n\nCompliance: Before exceeding 7,000 landings, or within the next 500 landings after 31 December 1986, whichever occurs later; and,\n\nFor those frames which have improperly tapered side guide support brackets, repeat the inspection at intervals not exceeding 3,000 landings.\n\nIf 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.\n\nBackground: 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.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2692},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive maintains its original scope as issued in 1986, targeting specific structural inspections for Boeing 747 aircraft to address identified fatigue cracking risks in the aft cargo bay. No evidence of scope expansion beyond the original safety intent."},"complexity_factors":["Conditional compliance deadlines requiring calculation (7,000 landings vs 500 landings after a specific date)","Variable repeat inspection intervals contingent on repair status (3,000 vs 12,000 landings)","External technical reference to Boeing Alert Service Bulletin 747-53A2259 which contains the actual inspection procedures","Technical aviation terminology requiring domain knowledge (e.g., 'tapered side guide support brackets', 'fuselage frames', 'landings')"],"plain_english_summary":"This mandatory safety instruction requires operators of affected Boeing 747s to inspect rear-cargo-hold fuselage frames for cracks caused by improperly tapered side-guide support brackets that concentrate stress at bolt points. \n\nInitial and recurring inspections are required unless frames are reinforced per Boeing Alert Service Bulletin 747-53A2259, which, if installed, extends the inspection interval for those reinforced frames. This affects all operators of the 747 models listed in that service bulletin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-51-fuselage-frames-aft-cargo-bay","history":"/api/acts/ad-b747-51-fuselage-frames-aft-cargo-bay/history","analysis":"/api/acts/ad-b747-51-fuselage-frames-aft-cargo-bay/analysis","conflicts":"/api/acts/ad-b747-51-fuselage-frames-aft-cargo-bay/conflicts","importantCases":"/api/acts/ad-b747-51-fuselage-frames-aft-cargo-bay/important-cases","documents":"/api/acts/ad-b747-51-fuselage-frames-aft-cargo-bay/documents"}}