{"id":"F2005L03555","name":"AD/B737/258 - Forward Engine Mount Support Fitting","slug":"ad-b737-258-forward-engine-mount-support-fitting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39079,"registerId":"commonwealth-F2005L03555-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/258 | Forward Engine Mount Support Fitting | 13/2005 |\n| ----------- | ------------------------------------ | ------- |\n\n| Applicability: | Model 737-100, -200, and -200C series aircraft, line numbers 1 through 1585.                                                                                                                                                                                                                                                                                                                                                                                            |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 98-14-09Amdt 39-10642.Note: Boeing Service Bulletins 737-54A1012 Revision 4, 737-54-1007 Revision 1, 737-54-1009 Revision 1, or later FAA approved revisions, refer.                                                                                                                                                                                                                                     |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of22 December 2005.                                                                                                                                                                                                                                                                                                                                                                             |\n|                | This Airworthiness Directive becomes effective on 22 December 2005.                                                                                                                                                                                                                                                                                                                                                                                                     |\n| Background:    | The FAA received reports of fatigue cracks on the lower flange of the forward engine mount support fitting, broken bolts and bolts with loose or detached nuts on the upper inboard attachment of the support fitting, and cracked or severed lugs at the outboard support link attachment of the support fitting. Undetected fatigue cracking and other discrepancies of the support fitting and its attachments could result in an in-flight separation of an engine. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n10 November 2005","sortOrder":0},{"sectionNumber":"AD/B737/258","sectionType":"part","heading":"AD/B737/258","content":"## AD/B737/258","sortOrder":1},{"sectionNumber":"Forward Engine Mount Support Fitting","sectionType":"part","heading":"Forward Engine Mount Support Fitting","content":"## Forward Engine Mount Support Fitting","sortOrder":2},{"sectionNumber":"13/2005","sectionType":"part","heading":"13/2005","content":"## 13/2005","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific structural fatigue issue on specific early Boeing 737 models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined elements: applicability (specific aircraft models), requirement (reference to external FAA AD), compliance date, and background","No nested conditional logic — the requirement is absolute and unconditional for affected aircraft","Single cross-reference to external FAA AD and Boeing Service Bulletins, but no internal cross-referencing","No exceptions, exemptions, or alternative compliance paths stated in the document itself","Straightforward command structure: 'Action in accordance with...'"],"plain_english_summary":"Owners and operators of early Boeing 737s (‑100, ‑200, ‑200C; line numbers 1–1585) must inspect and repair the forward engine‑mount support fitting under FAA AD 98‑14‑09 (as amended) and the referenced Boeing Service Bulletins. Fatigue cracks, broken bolts, and failed lugs have been found; without correction an engine could separate in flight. The AD took effect 22 Dec 2005 to prevent catastrophic structural failure and loss of control."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The AD maintains the same applicability (Boeing 737-100/-200/ -200C, line numbers 1–1585) and requires action per FAA AD 98-14-09Amdt 39-10642; the primary change recorded in the instrument is a revised effective date of 22 December 2005 (Compliance)."},"complexity_factors":["Cross-reference to an FAA airworthiness directive (FAA AD 98-14-09 Amdt 39-10642) makes compliance dependent on external technical requirements (Requirement).","Multiple Boeing service bulletins are referenced (737-54A1012 Rev 4; 737-54-1007 Rev 1; 737-54-1009 Rev 1), creating version-control and approval considerations (Requirement).","Technical inspections and corrective actions are required; these are safety-critical, involve structural fatigue detection and repair, and may need specialist maintenance capability (Background; Requirement).","Applicability is narrow and line-number specific (Model 737-100, -200, -200C; line numbers 1–1585), which complicates fleet-level compliance tracking (Applicability).","The AD includes a revised effective date (22 December 2005), introducing a compliance-timing change that operators must monitor (Compliance).","Safety consequence (in-flight engine separation risk) increases urgency and may affect scheduling, parts provisioning and operational downtime (Background)."],"plain_english_summary":"It requires operators of Boeing 737‑100 and ‑200 series aeroplanes (line numbers 1–1585) to carry out inspections and corrective actions on the forward engine mount support fitting, following the technical requirements of FAA AD 98‑14‑09 Amdt 39‑10642 and referenced Boeing service bulletins. Compliance requires operators to conduct inspections and corrective actions, incurring inspection, repair, parts and downtime costs. The directive addresses fatigue cracks and attachment defects that could result in in‑flight engine separation (Background section)."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-258-forward-engine-mount-support-fitting","history":"/api/acts/ad-b737-258-forward-engine-mount-support-fitting/history","analysis":"/api/acts/ad-b737-258-forward-engine-mount-support-fitting/analysis","conflicts":"/api/acts/ad-b737-258-forward-engine-mount-support-fitting/conflicts","importantCases":"/api/acts/ad-b737-258-forward-engine-mount-support-fitting/important-cases","documents":"/api/acts/ad-b737-258-forward-engine-mount-support-fitting/documents"}}