{"id":"F2006B02624","name":"AD/B727/101 Amdt 1 - Rear Pressure Bulkhead Web","slug":"ad-b727-101-amdt-1-rear-pressure-bulkhead-web","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41940,"registerId":"commonwealth-F2006B02624-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/101 Amdt 1 - Rear Pressure Bulkhead Web","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 727 Series Aeroplanes\n\nAD/B727/101\n\nAmdt 1\n\n  \nRear Pressure Bulkhead Web 9/86\n\nApplicability: All Model 727 aeroplanes.\n\nRequirement: Inspect in accordance with Figure 1 of Boeing Alert SB 727-53A0171 Revision 1, until modified in accordance with either:\n\n    Paragraph D of the Accomplishment Instructions in Boeing Alert S.B. 727- 53A0171, Revision 1; or\n\n    2. Paragraphs E and F of the same S.B.\n\nNote: FAA AD 86-02-06 Rev. 1 refers.\n\nCompliance: (a) before exceeding 33,000 flights; or\n\n(b) within the next 1,500 flights after 30 September 1986;\n\nwhichever is the later, and thereafter at intervals not exceeding 3,500 flights.\n\nBackground: This Directive implements Boeing Alert Service Bulletin 727-53-0171 Revision 1 which was raised following the discovery of cracks in thirty airframes. Cracking is attributed to fatigue under cabin pressure cycling. Amendment 1 to this Directive removes the repetitive inspection requirement for aircraft that have incorporated the preventative modification. It also requires that , within 15,000 landings after repair with the - 1 repair kit, certain aircraft must be modified by incorporation of a reinforcing strap.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1996},"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment refines existing maintenance requirements without expanding beyond the original safety objective of preventing rear pressure bulkhead structural failures. It reduces compliance burden for modified aircraft while adding specific reinforcement requirements for aircraft repaired with particular kits, reflecting updated technical understanding of fatigue patterns."},"complexity_factors":["Incorporation by reference of external technical documents (Boeing Alert Service Bulletin 727-53A0171 Revision 1 and FAA AD 86-02-06 Rev 1)","Conditional compliance dates with 'whichever is the later' logic","Alternative modification pathways (Paragraph D versus Paragraphs E and F)","Amendment logic that simultaneously removes requirements (repetitive inspections for modified aircraft) and adds new ones (reinforcing strap for repaired aircraft)","Technical aviation terminology requiring specialised engineering knowledge"],"plain_english_summary":"This safety directive for all Boeing 727 owners/operators requires inspection and eventual modification of the rear pressure bulkhead to detect and prevent fatigue cracks that can cause structural failure and rapid decompression. Initial and recurring inspections are mandated until a permanent modification from Boeing’s service bulletin is installed.\n\nAircraft repaired with the specified “-1” repair kit must receive an additional reinforcing strap; once permanently modified, aircraft are relieved of the repeated inspection cycle."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-101-amdt-1-rear-pressure-bulkhead-web","history":"/api/acts/ad-b727-101-amdt-1-rear-pressure-bulkhead-web/history","analysis":"/api/acts/ad-b727-101-amdt-1-rear-pressure-bulkhead-web/analysis","conflicts":"/api/acts/ad-b727-101-amdt-1-rear-pressure-bulkhead-web/conflicts","importantCases":"/api/acts/ad-b727-101-amdt-1-rear-pressure-bulkhead-web/important-cases","documents":"/api/acts/ad-b727-101-amdt-1-rear-pressure-bulkhead-web/documents"}}