{"id":"F2008L04388","name":"AD/B737/344 - Nacelle Strut Midspar Fitting Fuse Pins","slug":"ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76345,"registerId":"commonwealth-F2008L04388-current","compilationNumber":null,"startDate":"2026-04-02","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/B737/344 | Nacelle Strut Midspar Fitting Fuse Pins | 13/2008 |\n| ----------- | --------------------------------------- | ------- |\n\n| Applicability: | All Model 737-300, -400, and -500 series aircraft.                                                                                                                                                                                                                                                                                                                                              |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2008-21-03 Amdt 39-15687.Note: Boeing Special Attention Service Bulletin 737-54-1044 dated10 December 2007, refers.                                                                                                                                                                                                              |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of18 December 2008.                                                                                                                                                                                                                                                                                                     |\n|                | This Airworthiness Directive becomes effective on 18 December 2008.                                                                                                                                                                                                                                                                                                                             |\n| Background:    | The FAA received a report of corrosion damage of the chrome runout on the head side on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. This Directive requires repetitive inspections for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n28 October 2008","sortOrder":0},{"sectionNumber":"AD/B737/344","sectionType":"part","heading":"AD/B737/344","content":"## AD/B737/344","sortOrder":1},{"sectionNumber":"Nacelle Strut Midspar Fitting Fuse Pins","sectionType":"part","heading":"Nacelle Strut Midspar Fitting Fuse Pins","content":"## Nacelle Strut Midspar Fitting Fuse Pins","sortOrder":2},{"sectionNumber":"13/2008","sectionType":"part","heading":"13/2008","content":"## 13/2008","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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This Directive adopts the FAA-mandated inspection requirement for nacelle midspar fuse pins and limits applicability to all Boeing 737-300, -400 and -500 series aircraft. It does not expand applicability or add measures beyond the referenced FAA AD and Boeing service bulletin; the only procedural change noted is the revised effective date of 18 December 2008."},"complexity_factors":["Cross-reference to FAA AD 2008-21-03 and Boeing Service Bulletin 737-54-1044 creates a dependency on external technical documents","Repetitive inspections impose ongoing maintenance scheduling and record-keeping obligations on operators","Potential need for parts replacement introduces supply and cost considerations for operators","Narrow applicability (specific 737-300/-400/-500 models) reduces administrative complexity but concentrates costs on affected fleets","Effective date revision (18 December 2008) requires operators to update compliance planning"],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737-300, -400 and -500 aeroplanes to perform repetitive inspections of the four midspar fuse pins in each nacelle strut for corrosion and loss of chrome plating, following the technical instructions of FAA AD 2008-21-03 and the referenced Boeing service bulletin. It affects aircraft operators and maintenance organisations, who must carry out inspections, record results and pay for any remedial work; it matters because degraded fuse pins can affect the nacelle strut attachment."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive addressing a specific safety defect in specific aircraft. It has not expanded beyond its original purpose of mandating inspections for corroded fuse pins."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly used ('Applicability' refers to specific aircraft models)","No cross-references to other legislation — only references to external FAA directive and Boeing service bulletin","Single, clear requirement: repetitive inspections per external technical document","No conditional logic, exceptions, or nested provisions","Straightforward compliance date structure"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order for aircraft. It applies to **Boeing 737-300, -400, and -500 series planes**.\n\n**What it does:**\n- Requires airlines to **repeatedly inspect** specific metal pins (called \"fuse pins\") that connect the engine housing (nacelle strut) to the wing\n- These pins have been found to **corrode and lose their protective chrome plating**, which could weaken the connection between the engine and wing\n\n**Why it matters:**\n- If these pins fail, the engine could **detach from the wing** — obviously catastrophic\n- The directive makes these inspections **legally mandatory** for all affected aircraft operating in Australia\n\n**Who must comply:**\n- Owners and operators of the specified Boeing 737 models\n- They must follow the technical instructions from the US Federal Aviation Administration (FAA AD 2008-21-03) and a Boeing service bulletin\n\n**When:**\n- The directive took effect on **18 December 2008**"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins","history":"/api/acts/ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins/history","analysis":"/api/acts/ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins/analysis","conflicts":"/api/acts/ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins/conflicts","importantCases":"/api/acts/ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins/important-cases","documents":"/api/acts/ad-b737-344-nacelle-strut-midspar-fitting-fuse-pins/documents"}}