{"id":"F2006B03030","name":"AD/B747/129 - Fuselage Lower Frames at Body Stations 2200 and 2220","slug":"ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42389,"registerId":"commonwealth-F2006B03030-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/129 - Fuselage Lower Frames at Body Stations 2200 and 2220","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/B747/129 Fuselage Lower Frames at Body Stations 2200 and 2220\n\n  \n9/94\n\nApplicability: Boeing Model 747 aircraft, Line Numbers 1 to 757 inclusive, SP versions excepted.\n\nRequirement: Conduct a detailed visual inspection of the fuselage lower frames at body stations 2200 and 2220 for cracks in accordance with Boeing Service Bulletin 747-53-2302.\n\nNote: FAA AD 91-18-04 refers.\n\nCompliance: 1. For aircraft with less than 10000 flights as at 18 August 1994, inspect before 10000 flights or within 1000 flights, whichever occurs later.\n\n    2. For aircraft which have had the frames replaced in accordance with Boeing Service Bulletin 747-53-2302, inspect within 10000 flights from the date of frame replacement.\n\n    3. In all cases, repeat the inspection at intervals not exceeding 2000 flights.\n\n    4. If cracks are found as a result of para 1, 2, or 3 inspections, extend the inspection area to include the adjacent frames (BS 2180 and 2240), stringers, skin, skin lap joints and skin adjacent to the outflow valve.\n\nBackground: This Directive specifies regular visual inspections for cracks in the fuselage frames. If not detected, such cracks could lead to frame failure and sudden decompression of the fuselage.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused specifically on fuselage frame inspections. It has not expanded beyond its original safety purpose. The scope remains tightly constrained to the specific structural defect identified in the background."},"complexity_factors":["Short, single-purpose directive (approximately 250 words)","Only 4 defined applicability criteria (aircraft model, line numbers, SP exclusion, flight thresholds)","Simple conditional structure with 3 compliance pathways based on aircraft history","Single cross-reference to external technical document (Boeing Service Bulletin 747-53-2302)","One nested condition (crack discovery triggers expanded inspection scope)","No internal defined terms section — uses standard aviation terminology"],"plain_english_summary":"This CASA Airworthiness Directive mandates repetitive inspections of lower fuselage frames at body stations 2200 and 2220 on early Boeing 747s (Line Numbers 1–757, excluding SP models). It affects airlines, owners and maintenance crews of those aircraft, sets initial inspection timing based on flight cycles and repairs, and requires follow-up checks every 2,000 flights. The goal is to detect cracking that could cause frame failure and sudden decompression."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope remains focused on inspections of fuselage lower frames at BS 2200 and 2220 for the listed Boeing 747 aircraft. The AD does not broaden applicability beyond the specified line numbers or add new regulatory authorities; it prescribes inspection timing, repeat intervals, and expanded inspection triggers as stated."},"complexity_factors":["Limited, well‑defined applicability (specific Boeing 747 line numbers)","Clear inspection procedure reference (Boeing Service Bulletin 747‑53‑2302)","Multiple timing rules based on flight counts and replacement dates (compliance-calculation complexity)","Repeating interval requirement (every 2,000 flights) and trigger for expanded inspection if cracks found","Cross-reference to FAA AD (coordination/consistency considerations)","Technical interpretation required for what constitutes a 'detailed visual inspection' and extent of crack findings"],"plain_english_summary":"Requires operators of Boeing 747 aircraft (Line Nos. 1–757, non‑SP) to carry out detailed visual inspections of lower fuselage frames at body stations 2200 and 2220 for cracks, using Boeing Service Bulletin 747‑53‑2302. (Applicability; Requirement)\n\nThe AD sets timing: an initial inspection tied to flight-count thresholds or frame replacement, mandatory repeats every 2,000 flights, and expanded inspection if cracks are found. Operators pay for inspections and repairs; non‑compliance risks regulatory enforcement. (Compliance paras 1–4)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220","history":"/api/acts/ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220/history","analysis":"/api/acts/ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220/analysis","conflicts":"/api/acts/ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220/conflicts","importantCases":"/api/acts/ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220/important-cases","documents":"/api/acts/ad-b747-129-fuselage-lower-frames-at-body-stations-2200-and-2220/documents"}}