{"id":"F2009L00083","name":"AD/B747/294 Amdt 2 - Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure","slug":"ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76494,"registerId":"commonwealth-F2009L00083-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 747 Series Aeroplanes","sectionType":"division","heading":"Boeing 747 Series Aeroplanes","content":"### Boeing 747 Series Aeroplanes\n\n| AD/B747/294 Amdt 2 | Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure | 2/2009 |\n| ------------------ | --------------------------------------------------------------------------------- | ------ |\n\n| Applicability: | All Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, -400D,-400F, 747SR, and 747SP series aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2006-10-16 Amdt 39-14600.Note: Boeing Alert Service Bulletins 747-55A2050 and 747-55A2050 Revision 1, or later FAA approved revision, refer.Corrective actions (repairs or repeat inspections) that are approved on an FAA form 8100-9 and approved by the Manager, Seattle Aircraft Certification Office or delegate as an Alternative Method of Compliance (AMOC) to the requirements of FAA AD 2006-10-16, may be carried out without the need to obtain an exclusion from CASA from this airworthiness directive.                                                                                                                                                                                                                               |\n| Compliance:    | As specified in the Requirement document.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n|                | This Amendment becomes effective on 12 February 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| Background:    | The FAA has received numerous reports of cracking from two operators of six 747 series aircraft. Of the 22 reports of cracking received, 20 of the reports were in an area not covered by the Zone A inspections required by FAA AD 2002-06-02 (AD/B747/271). This Directive requires certain inspections to detect such cracking, which if undetected, could lead to reduced structural capability of the outboard and centre sections of the horizontal stabiliser, and result in loss of controllability of the aircraft.This amendment allows the use of an FAA approved Alternative Method of Compliance (AMOC) to the requirements of this AD, without the need for the operator to continually apply for an exclusion for repairs that are already approved on a form 8100-9 as an AMOC by an FAA delegate. |\n\n|     | Amendment 1 of this AD became effective on 6 July 2006. |\n| --- | ------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n18 December 2008","sortOrder":0},{"sectionNumber":"AD/B747/294 Amdt 2","sectionType":"part","heading":"AD/B747/294 Amdt 2","content":"## AD/B747/294 Amdt 2","sortOrder":1},{"sectionNumber":"Horizontal Stabiliser Outboard Centre Se","sectionType":"part","heading":"Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure","content":"## Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure","sortOrder":2},{"sectionNumber":"2/2009","sectionType":"part","heading":"2/2009","content":"## 2/2009","sortOrder":3}],"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 2 to an existing airworthiness directive. The original AD addressed cracking in the horizontal stabiliser. This amendment narrows the scope slightly by streamlining the approval process for repairs — it does not expand the safety issue covered or add new inspection requirements. The core purpose (ensuring structural integrity of the tail) remains unchanged."},"complexity_factors":["Short, single-purpose instrument (approximately 300 words)","Only 3 defined concepts: 'Alternative Method of Compliance (AMOC)', 'FAA AD 2006-10-16', and 'Form 8100-9'","No nested conditional logic — simple 'inspect and repair if cracked' requirement","Single cross-reference to external FAA directive and Boeing service bulletins","Clear applicability table listing specific aircraft models","Straightforward compliance mechanism (follow the FAA document)"],"plain_english_summary":"This mandatory airworthiness directive orders operators of Boeing 747-100/200/300/400, 747SR and 747SP aircraft in Australia to inspect the horizontal stabiliser’s upper skin and rear spar for cracking and to repair any defects found.  \n\nIt also lets operators use FAA-approved repair methods (Form 8100-9) without separate CASA approval, speeding compliance to reduce the risk of tail-structure failure and potential loss of flight control."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"This Amendment expands the practical compliance scope by formally permitting the use of FAA-approved Alternative Methods of Compliance (AMOCs) documented on FAA Form 8100-9 and approved by the Manager, Seattle Aircraft Certification Office (or delegate) without requiring operators to seek a separate CASA exclusion. Mechanically, that reduces CASA’s separate exclusion process for those AMOCs and shifts some approval authority/administrative burden to the FAA delegate, while retaining the original substantive inspection and repair requirements inherited from FAA AD 2006-10-16. The core safety objective (detecting and correcting cracking in horizontal stabiliser outboard/centre sections) remains the original intent; the change alters the compliance pathway and administrative obligations rather than broadening the safety subject-matter itself."},"complexity_factors":["Long applicability list covering many 747 variants (multiple model suffixes listed).","External cross-reference to FAA AD 2006-10-16 for technical requirements (reliance on another instrument).","References to Boeing Alert Service Bulletins 747-55A2050 and Revision 1 (requires consulting multiple vendor documents).","Allowance for AMOCs approved on FAA Form 8100-9, with approval by the Manager, Seattle Aircraft Certification Office or delegate (cross-jurisdictional approval pathway).","Conditional logic: repairs/repeat inspections may be performed if approved as AMOC; otherwise, follow FAA AD — two parallel compliance paths. ","Prior AD interaction: identifies cracks outside inspection areas required by earlier FAA AD 2002-06-02 (adds historical cross-references).","Unspecified details are deferred to the FAA AD and Boeing service bulletins (requires reading and integrating multiple documents to determine exact inspection intervals and procedures).","Amendment history and effective-date mechanics (Amendment 1 and now Amendment 2) add versioning complexity."],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- Applies to: all Boeing 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, -400D, -400F, 747SR, and 747SP series aeroplanes (see \"Applicability\").\n- Requires operators to carry out the inspections and any corrective actions in accordance with the technical content of FAA Airworthiness Directive (AD) 2006-10-16 (see \"Requirement\").\n- Refers to Boeing Alert Service Bulletins 747-55A2050 and 747-55A2050 Revision 1 as the Boeing documents that describe the inspection/repair procedures (or later FAA‑approved revisions).\n- Allows corrective actions or repeat inspections that are already approved on FAA Form 8100-9 as an Alternative Method of Compliance (AMOC) and approved by the Manager, Seattle Aircraft Certification Office (or that Manager’s delegate) to be carried out without the operator having to separately apply to CASA for an exclusion from this AD.\n- Compliance timing and thresholds are as specified in the FAA AD and the referenced Boeing service bulletins (see \"Compliance\").\n- Effective date: 12 February 2009.\n\n**Why this was issued (official rationale and mechanical risk)**\n\n- The FAA received reports of cracking in the horizontal stabiliser outboard and centre section upper skin and rear spar structure on several 747s. Twenty of twenty-two reported cracks were outside the areas covered by the earlier Zone A inspections required by FAA AD 2002-06-02.\n- The stated safety risk: undetected cracking could reduce structural capability of the outboard and centre sections of the horizontal stabiliser and could lead to loss of aircraft controllability (see \"Background\").\n\n**Who it affects and who decides**\n\n- Who pays: aircraft owners/operators pay for the inspections, repairs and any associated aircraft downtime.\n- Who decides: the technical inspection and repair methods are specified by the FAA AD and Boeing service bulletins; acceptance of an alternate method (an AMOC) depends on approval by the Manager, Seattle Aircraft Certification Office (or their delegate). CASA enforces compliance with this AD but permits FAA‑approved AMOCs (on Form 8100-9) without a separate CASA exclusion.\n- What operators must do: follow the inspection schedule and procedures in FAA AD 2006-10-16 and the Boeing service bulletins; implement corrective actions where cracks or damage are found; keep records of compliance and approvals.\n\n**Practical effects, trade-offs and implementation notes**\n\n- Administrative effect: allowing FAA Form 8100-9 AMOCs to be used without a CASA exclusion reduces the need for operators to obtain repeated CASA approvals where an FAA delegate has already approved a repair method.\n- Cost and downtime: operators will incur maintenance costs and aircraft downtime to perform the additional inspections and repairs required by the FAA AD.\n- Shifts in decision-making: this AD formalises reliance on FAA technical determinations (and on FAA‑delegated approval authority) for alternate repairs, which reduces duplication of approval steps but increases reliance on FAA/Airworthiness Office decisions for compliance options.\n- Compliance complexity: operators must cross-reference the FAA AD and Boeing service bulletins and ensure any claimed AMOC is properly documented on FAA Form 8100-9 and approved by the specified FAA office or delegate.\n- Safety intent versus implementation burden: the declared purpose is to find and fix cracking outside the previously inspected area; that requires extra inspection scope and creates ongoing repeat-inspection or repair obligations for operators. Allowing FAA-approved AMOCs reduces administrative friction but transfers the control point for acceptance of non‑standard repairs to the FAA Manager (Seattle) or delegate.\n\n(References: statements and sections labelled \"Applicability\", \"Requirement\", \"Compliance\", and \"Background\" in the AD text.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure","history":"/api/acts/ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure/history","analysis":"/api/acts/ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure/analysis","conflicts":"/api/acts/ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure/conflicts","importantCases":"/api/acts/ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure/important-cases","documents":"/api/acts/ad-b747-294-amdt-2-horizontal-stabiliser-outboard-centre-sections-upper-skin-and-rear-spar-structure/documents"}}