{"id":"F2006B03035","name":"AD/B747/133 - Fuselage - Upper Deck Floor Beams at BS 860 and 980","slug":"ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42394,"registerId":"commonwealth-F2006B03035-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/133 - Fuselage - Upper Deck Floor Beams at BS 860 and 980","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/B747/133 Fuselage \\- Upper Deck Floor Beams at BS 860 and 980\n\n  \n11/94\n\nApplicability: B747-300, -400 and -100B series aircraft delivered with Stretched Upper Decks (SUD) Line numbers 570 to 843 inclusive and all aircraft modified to have SUD.\n\nRequirement: 1. Conduct a high frequency eddy current inspection of the BS 860 and 980 upper deck floor beams at LBL 46.83 and RBL 46.83 in accordance with Boeing SB 747-53-2327 Revision 1.\n\n2. Modify the BS 860 and 980 upper deck floor beams at LBL 46.83 and RBL 46.83 in accordance with Boeing SB 747-53-2327 Revision 1 and Boeing drawing 624U0014.\n\nNote: FAA AD 92-24-07 refers.\n\nCompliance: 1. Inspect and modify, B747-300, \\-400 and \\-100B series aircraft delivered with SUD, before 20000 flights or within 1000 flights of 13 October 1994 whichever is the later.\n\n2. Inspect and modify B747 aircraft modified to have SUD before 20000 flights after the modification or within 1000 flights of 13 October 1994 whichever is the later.\n\nBackground: Cracking of the floor beams was experienced during the B747-400 full scale fatigue test at 35000 pressure cycles. Inspection and modification in accordance with this AD will extend the fatigue life of the floor beams.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural fatigue issue identified during testing. The scope remains tightly focused on the original purpose: preventing fatigue cracking in upper deck floor beams of specific Boeing 747 variants. No scope creep is evident."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined technical terms (BS 860/980, LBL/RBL 46.83, SUD, SB 747-53-2327)","Simple two-step requirement structure (inspect, then modify)","Clear applicability criteria based on aircraft model and modification status","Straightforward compliance timeline with simple 'whichever is later' logic","No nested exceptions or conditional sub-clauses","Single cross-reference to FAA AD 92-24-07 (informational only)"],"plain_english_summary":"This AD mandates high-frequency eddy-current inspections and required modifications of upper-deck floor beams on Boeing 747s with Stretched Upper Decks (factory-built or later-modified) to detect and repair fatigue cracks. It affects 747-300, -400, and -100B SUD aircraft and aims to prevent catastrophic structural failure after cracking was observed in fatigue tests."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD applies specifically to B747‑300, ‑400 and ‑100B aircraft delivered with SUD (line numbers 570–843) and any aircraft modified to SUD, targeting cracking of upper‑deck floor beams identified in the B747‑400 full‑scale fatigue test (Background). The text contains no indication that this AD expands or narrows that original target scope."},"complexity_factors":["Technical inspection method: requires high‑frequency eddy‑current inspections of specific beam locations (Requirement 1).","Structural modification: mandates physical modification per a manufacturer drawing (Boeing drawing 624U0014) and SB (Requirement 2).","Narrow applicability: applies only to SUD‑delivered aircraft line numbers 570–843 and aircraft modified to SUD (Applicability), requiring operators to check airframe history.","Timing rules tied to flight counts and a fixed date (Compliance), which creates scheduling pressure and possible fleet‑wide coordination.","Reliance on manufacturer documents (Boeing SB and drawing) introduces dependency on available instructions, parts and approved repair methods.","Operational impacts: inspections/mods may require aircraft downtime, certified personnel and possible engineering approvals, affecting costs and dispatch reliability."],"plain_english_summary":"This directive requires operators of Boeing 747‑300, ‑400 and ‑100B aircraft fitted with a Stretched Upper Deck (SUD) (line numbers 570–843) and any aircraft later modified to SUD to inspect and modify the upper‑deck floor beams at BS 860 and 980 (LBL/RBL 46.83) per Boeing SB 747‑53‑2327 Rev 1 and drawing 624U0014.\n\nCompliance is by flight count (before 20,000 flights or within 1,000 flights of 13 Oct 1994); operators therefore fund and schedule the inspections/modifications. The stated aim is to remedy fatigue cracking found in full‑scale tests and extend beam life."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980","history":"/api/acts/ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980/history","analysis":"/api/acts/ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980/analysis","conflicts":"/api/acts/ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980/conflicts","importantCases":"/api/acts/ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980/important-cases","documents":"/api/acts/ad-b747-133-fuselage-upper-deck-floor-beams-at-bs-860-and-980/documents"}}