{"id":"F2006B03228","name":"AD/B747/48 Amdt 2 - Nacelle Strut Midspar Fitting Lugs","slug":"ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42626,"registerId":"commonwealth-F2006B03228-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/48 Amdt 2 - Nacelle Strut Midspar Fitting Lugs","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/B747/48\n\nAmdt 2\n\n  \n\nNacelle Strut Midspar Fitting Lugs 13/93 DM\n\nApplicability: All Model 747 series aircraft.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 93-17-07 Amdt 39- 8678.\n\nNote: Boeing ASB 747-54A2152 refers.\n\nCompliance: As specified in the Requirement Document with a revised effective date of 13 October 1993 for Australian registered aircraft.\n\nBackground: Fatigue cracking had been reported in the lug bores. The cracking was thought to have initiated at corrosion pits. Terminating action for repeated inspections consisted of removal of the existing press-fit bushings from the midspar fitting, inspection of the lugs, removal of any corrosion, and installation of roller-swaged, shrink-fit bushings.\n\nAmendment 1 was issued to align this Directive with the issue of a FAA AD which reduced certain inspection intervals, removed the optional terminating action for repetitive inspections of the lugs, and added aircraft to the applicability of the AD. This action was in response to a report of fatigue cracking which occurred well below the inspection threshold, and additionally, numerous reports of migration of the press- fit and roller-swaged, shrink-fitted bushings.\n\nAmendment 2 is issued in response to the issue of a new FAA AD which is prompted by the results of flight tests, conducted to determine strut-to-wing interface loads, and by additional reports of cracked lugs.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original scope — addressing structural fatigue in Boeing 747 engine strut attachment fittings. The amendments have refined and expanded the technical requirements (adding aircraft, adjusting inspection intervals, incorporating new flight test data) but have not expanded beyond the original safety purpose of preventing lug cracking and bushing migration in the nacelle strut midspar fittings."},"complexity_factors":["Heavy reliance on external technical documents — the actual work requirements are contained in FAA AD 93-17-07 and Boeing ASB 747-54A2152, not in the text itself","Specialised aviation engineering terminology throughout (nacelle strut, midspar fitting lugs, roller-swaged bushings, lug bores)","Amendment history creates layered context — understanding Amendment 2 requires knowing what Amendments 0 and 1 changed","Cross-references to US regulatory framework (FAA AD system) requiring dual-jurisdiction awareness","Conditional compliance structure with both repetitive inspections AND terminating actions as alternative paths (though Amendment 1 removed the optional terminating action for some cases)"],"plain_english_summary":"This CASA Airworthiness Directive requires Australian-registered Boeing 747s to inspect and repair fatigue cracking in nacelle strut midspar fitting lugs — the engine‑to‑wing attachment points — following FAA AD 93‑17‑07. It mandates repeated inspections and replacement of old press‑fit bushings with roller‑swaged shrink‑fit bushings to prevent lug cracking, corrosion, and possible engine separation. Amendment 2 tightens requirements based on new US stress data and additional cracking reports."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"Yes. The Directive's scope has expanded and tightened since the original action: Amendment 1 shortened inspection intervals, removed an optional terminating action and added affected aircraft (Background; Amendment 1). Amendment 2 further revised requirements in response to flight-test data and additional cracking reports, prompting additional or modified actions and a revised effective date for Australian aircraft (Background; Amendment 2). These changes increase mandatory inspection/repair obligations and reduce optional compliance routes."},"complexity_factors":["Cross-reference to an external FAA airworthiness directive (Requirement) — requires reading/complying with another instrument.","Technical maintenance and modification actions (Background) — removal/installation of specific bushings and inspection for corrosion/cracks.","History of iterative amendments (Background; Amendment 1; Amendment 2) — prior changes reduced intervals and removed optional terminating action, then further revised requirements after flight tests.","Applicability to all Model 747 aircraft (Applicability) — wide fleet scope increases operational impact.","Compliance timing requirement with a revised effective date (Compliance) — creates an enforceable deadline for operators to meet.","Reference to manufacturer service bulletin (Note: Boeing ASB 747-54A2152) — adds another technical document to interpret and follow."],"plain_english_summary":"Mandates that all Australian-registered Boeing 747 aircraft comply with the technical actions set out in FAA AD 93-17-07: inspect, repair and where required modify nacelle strut midspar fitting lugs to detect and stop fatigue cracking. It requires operators and maintenance organisations to carry out inspections, remove corrosion, and fit approved bushings or other terminating repairs.\n\nThis affects aircraft owners/operators and MROs because it changes inspection intervals, removes optional inspection-termination routes, and sets an enforceable compliance date, creating direct maintenance cost, scheduling and record-keeping obligations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs","history":"/api/acts/ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs/history","analysis":"/api/acts/ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs/analysis","conflicts":"/api/acts/ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs/conflicts","importantCases":"/api/acts/ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs/important-cases","documents":"/api/acts/ad-b747-48-amdt-2-nacelle-strut-midspar-fitting-lugs/documents"}}