{"id":"F2006B03135","name":"AD/B747/237 - Thrust Reverser Auxiliary Track Assembly","slug":"ad-b747-237-thrust-reverser-auxiliary-track-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42507,"registerId":"commonwealth-F2006B03135-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.","sortOrder":0},{"sectionNumber":"AD/B747/237 Thrust Reverser Auxiliary Tr","sectionType":"part","heading":"AD/B747/237 Thrust Reverser Auxiliary Track Assembly 12/2000","content":"# AD/B747/237 Thrust Reverser Auxiliary Track Assembly 12/2000\n\nApplicability: Boeing 747-400 series aircraft powered by Pratt and Whitney PW4000 engines, line numbers 696 through 1100 inclusive.\n\nRequirement: 1. Carry out initial and repetitive inspections of the thrust reverser auxiliary beam assemblies in accordance with the technical instructions in FAA AD 2000-11-28, Paragraph (a). Repair or replace discrepant parts prior to further flight.\n\n2. Incorporate improved liner and slider assemblies in accordance with the technical instructions in FAA AD 2000-11-28, either Paragraph (b) or (c), as applicable.\n\nCompliance with Requirement 2 of this Directive constitutes terminating action for the inspections specified in Requirement 1 for each modified beam assembly.\n\nNote: Boeing Alert Service Bulletin 747-78A2164, Revision 2 refers.\n\nCompliance: 1. As detailed in the Requirement document with the effective date revised to 30 November 2000.\n\n2. No later than the respective period specified in the Requirement document. This Airworthiness Directive becomes effective on 30 November 2000.\n\nBackground: Excessive wear in the thrust reverser auxiliary track beam assemblies can lead to disengagement of a slider and separation of a portion of the thrust reverser.\n\nLiberation of thrust reverser parts could damage the aircraft structure or pose a hazard to persons on the ground.\n\n![Signature of Eugene Paul Holzapfel, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 24 October 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 1 November 2000.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The Directive implements corrective inspections and modification for a defined subset of 747-400s to address an unsafe condition (excessive wear and potential slider disengagement). The text mirrors the FAA-referenced requirements and adds an Australian effective date; there is no indication in the instrument that the scope was broadened or narrowed from its stated corrective purpose."},"complexity_factors":["Cross-reference to external mandatory documents: FAA AD 2000-11-28 and Boeing Alert Service Bulletin 747-78A2164 Revision 2 — requires operators to obtain and follow other technical publications.","Technical inspection and repair work on thrust reverser auxiliary beam assemblies — requires specialist maintenance skills and parts.","Limited applicability by aircraft line numbers and engine type — necessitates fleet-specific tracking to determine affected airframes.","Interplay of repetitive inspections and a defined terminating action (installation of improved liner/slider) — creates procedural decision points for operators.","\"Repair or replace prior to further flight\" imposes immediate operational constraints and potential schedule disruption.","Compliance timing provisions (effective date and specified periods) create scheduling and logistical burdens for maintenance planning and parts procurement."],"plain_english_summary":"This Directive requires operators of Boeing 747-400 aircraft with Pratt & Whitney PW4000 engines (line numbers 696–1100) to perform initial and repeated inspections of the thrust reverser auxiliary beam assemblies, repair or replace any defects before further flight, and install improved liner and slider assemblies. Installing the improved parts removes the need for further inspections on that beam. CASA issued the AD to prevent slider disengagement and possible separation of thrust reverser parts that could damage the aircraft or endanger people on the ground. Operators pay for inspections, repairs and parts; CASA enforces compliance."},"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":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It addresses a specific mechanical defect in a defined subset of Boeing 747-400 aircraft. The document does not expand beyond its original safety purpose of mandating inspection and repair of thrust reverser auxiliary track assemblies."},"complexity_factors":["Short, single-purpose document (approximately 300 words)","Only 3 defined applicability criteria (aircraft model, engine type, line number range)","Two main requirements with clear sequential logic (inspect first, then modify)","Single cross-reference to external technical document (FAA AD 2000-11-28) rather than internal legislative cross-referencing","Simple compliance structure with specific effective date","No nested exceptions or conditional logic beyond the terminating action clause","Technical aviation terminology used but explained through context (thrust reverser, auxiliary track beam, slider assembly)"],"plain_english_summary":"The Civil Aviation Safety Authority has issued a mandatory safety order for Boeing 747-400s with Pratt & Whitney PW4000 engines (line numbers 696–1100) after excessive wear in thrust reverser auxiliary track beam assemblies risked sliders disengaging and parts departing in flight.  \n\nAffected operators must inspect and repair or replace worn parts per FAA guidance and fit upgraded liner/slider assemblies; the directive prevents in-flight breakaway debris, protects passengers and people on the ground, and ends repetitive inspections once upgrades are installed."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-237-thrust-reverser-auxiliary-track-assembly","history":"/api/acts/ad-b747-237-thrust-reverser-auxiliary-track-assembly/history","analysis":"/api/acts/ad-b747-237-thrust-reverser-auxiliary-track-assembly/analysis","conflicts":"/api/acts/ad-b747-237-thrust-reverser-auxiliary-track-assembly/conflicts","importantCases":"/api/acts/ad-b747-237-thrust-reverser-auxiliary-track-assembly/important-cases","documents":"/api/acts/ad-b747-237-thrust-reverser-auxiliary-track-assembly/documents"}}