{"id":"F2006B03367","name":"AD/B767/191 - Nacelle Strut Diagonal Brace Aft Pitch Load Fitting","slug":"ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42817,"registerId":"commonwealth-F2006B03367-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B767/191 - Nacelle Strut Diagonal Brace Aft Pitch Load Fitting","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Safety Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\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 CASR 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.\n\n![](image.001.png)  \n\nBoeing 767 Series Aeroplanes\n\nAD/B767/191 Nacelle Strut Diagonal Brace Aft Pitch Load\n\nFitting\n\n  \n3/2004\n\nApplicability: Model 767-200, \\-300, and 300F series aircraft, as listed in Boeing Alert Service Bulletin 767-54A0102, dated November 8, 2001.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 2004-01-02 Amdt 39-13415\n\nNote: Boeing Alert Service Bulletin 767-54A0102 refers\n\nCompliance: As specified in the Requirement document, with a revised effective date of 18 March 2004\n\nThis Airworthiness Directive becomes effective on 18 March 2004.\n\nBackground: This Directive requires modification of the aft pitch load fitting of the diagonal brace of the nacelle strut of each wing. This action is necessary to prevent loss of the fuse pin of the pitch load fitting due to fatigue caused by improper clearance between the fuse pin and bushing, which could result in increased loads in the wing-to-strut joints and consequent separation of the strut and engine from the wing.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.002.png)  \n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 4 February 2004\n\n![](image.001.png)\n\nThe above AD is notified in the Commonwealth of Australia Gazette on 25 February 2004.\n\n  \n\nPage 1 of 1","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD remains narrowly focused on correcting a specific unsafe condition (fuse pin fatigue on the aft pitch-load fitting of the nacelle strut diagonal brace) for specified Boeing 767 models. It does not broaden the subject matter beyond that original safety purpose; the AD simply adopts the technical instructions given by the FAA AD and Boeing service bulletin (Applicability; Requirement; Background)."},"complexity_factors":["Short, single-item directive focused on one modification (aft pitch-load fitting).","Relies on two external documents for technical content: FAA AD 2004-01-02 and Boeing Alert Service Bulletin 767-54A0102 (cross-reference increases practical complexity).","Limited number of conditional elements — single revised effective date and applicability to specific model variants.","Technical execution requires certified maintenance organisations and likely specialised parts/tools (technical complexity outside the text).","No nested legal exceptions or numerous defined terms within the AD itself (low textual complexity)."],"plain_english_summary":"**What this instrument requires (mechanical change)\n\n- Operators of Boeing 767-200, -300 and -300F series aircraft must modify the aft pitch-load fitting of the diagonal brace in each wing nacelle strut. The AD does not set out the step‑by‑step technical work itself; it directs operators to carry out the actions specified in FAA Airworthiness Directive 2004-01-02 and to follow the Boeing Alert Service Bulletin 767-54A0102 (Applicability; Requirement).  \n\n**Why the change is required (stated safety concern)\n\n- The stated reason is to prevent loss of the fuse pin in the pitch-load fitting caused by fatigue from improper clearance between the fuse pin and its bushing. Loss of that fuse pin can increase loads at the wing‑to‑strut joints and could ultimately result in separation of the strut and engine from the wing (Background).  \n\n**Who is affected\n\n- Aircraft owners/operators of the listed Boeing 767 models (Applicability).  \n- Maintenance organisations and licensed engineers who perform the modification and record compliance.  \n\n**Who decides and who pays\n\n- The Civil Aviation Safety Authority (CASA), acting through its delegate, issues the AD and requires compliance (signature block; Requirement).  \n- Technical instructions are supplied by the FAA AD and Boeing service bulletin; maintenance providers carry out the work.  \n- Direct costs (parts, labour, aircraft downtime) are borne by the aircraft owner/operator.  \n\n**How it works in practice (procedural points)\n\n- The AD is effective from 18 March 2004 and requires operators to perform the modification in accordance with the referenced FAA AD and the Boeing service bulletin (Compliance; Requirement).  \n- Operators must schedule the modification into maintenance programmes, use approved data and record the work in the aircraft maintenance log so that the aircraft remains legally airworthy.  \n\n**Trade-offs, incentives and implementation issues (analyst note)\n\n- Safety vs cost: The AD imposes a one‑time safety modification intended to reduce catastrophic structural risk (Background). Operators incur immediate costs: parts, skilled labour, and loss of aircraft revenue while the work is performed.  \n- Supply and scheduling risk: If parts or approved modification kits are in limited supply, operators may face scheduling delays and additional downtime.  \n- Compliance complexity: The AD defers technical detail to an external FAA AD and a Boeing service bulletin (Requirement). That reduces duplication but requires operators and maintainers to obtain and correctly apply those external documents.  \n- Competitive incidence: All operators of the affected models are treated uniformly by the AD. However, smaller or less well‑capitalised operators may feel a larger relative financial and scheduling burden.  \n- Behavioural effect: Operators will either (a) perform the modification within the required time window, or (b) ground or limit operations for aircraft not modified if regulators require it. This shifts decisions about timing to operators and maintenance providers, within the regulatory deadline.  \n- Administrative burden: CASA’s action is prescriptive but brief; enforcement relies on standard continuing airworthiness oversight and certificate‑of‑airworthiness processes.\n\n**Net practical effect (concise)**\n\n- The AD mandates a safety modification to a specific structural fitting on listed Boeing 767 models, implemented by following FAA and Boeing technical documents. It increases maintenance cost and operational downtime for those aircraft but is intended to remove a fatigue failure mode that could lead to major structural failure (Applicability; Requirement; Background; Compliance)."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow, technical scope. It addresses a specific structural fatigue issue on a specific aircraft type through a specific modification. There is no evidence of scope creep; the directive precisely targets the unsafe condition described in the background section without expanding into broader operational or maintenance requirements."},"complexity_factors":["Short, single-page document with straightforward structure","Only 3 defined applicability criteria (specific Boeing 767 models)","Single technical requirement that cross-references an external FAA document rather than reproducing detailed instructions","No nested exceptions or conditional logic — compliance is mandatory for all applicable aircraft","Minimal legislative cross-referencing (only mentions CASR 1998 subregulation 39.1(1) as enabling power)","Technical aviation terminology requires specialist knowledge (fuse pin, bushing, nacelle strut, pitch load fitting) but terms are explained in context"],"plain_english_summary":"This CASA Airworthiness Directive mandates modification of the aft pitch load fitting on the diagonal brace of certain Boeing 767 engine struts to address excessive clearance between a fuse pin and its bushing that can cause fatigue and risk engine/strut separation in flight. It applies to 767-200, -300 and 300F aircraft listed in Boeing Alert Service Bulletin 767-54A0102 and requires compliance with the FAA AD 2004-01-02 technical instructions by the specified deadlines (effective 18 March 2004)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting","history":"/api/acts/ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting/history","analysis":"/api/acts/ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting/analysis","conflicts":"/api/acts/ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting/conflicts","importantCases":"/api/acts/ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting/important-cases","documents":"/api/acts/ad-b767-191-nacelle-strut-diagonal-brace-aft-pitch-load-fitting/documents"}}