{"id":"F2008L00499","name":"AD/J4100/10 - Forward Fuselage Stn 4 to Stn 8 Diaphragms","slug":"ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":119326,"registerId":"commonwealth-F2008L00499-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"BAe Systems (Operations) Jetstream 4100 ","sectionType":"division","heading":"BAe Systems (Operations) Jetstream 4100 Series Aeroplanes","content":"### BAe Systems (Operations) Jetstream 4100 Series Aeroplanes\n\n| AD/J4100/10 | Forward Fuselage Stn 4 to Stn 8 Diaphragms | 4/2008 DM |\n| ----------- | ------------------------------------------ | --------- |\n\n| Applicability: | Model Jetstream Series 4100 aircraft, constructor’s numbers 41004 through 41104.                                                                                                                                                                                                                                             |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect in accordance with BAe Systems Alert Service Bulletin J41-A53-023 original issue, or later CAA/EASA approved revision.Note: UK CAA AD 007-12-96 refers.                                                                                                                                                              |\n| Compliance:    | Initial inspection:For aircraft with less than 4,200 landings, accomplish before the accumulation of 4,500 landings.For aircraft with 4,200 or more landings, accomplish within 300 landings.Repeat inspection:Within 3,000 landings after the initial inspection, and thereafter at intervals not to exceed 3,000 landings. |\n|                | This Airworthiness Directive becomes effective on 20 February 2008.                                                                                                                                                                                                                                                          |\n| Background:    | The manufacturer’s fatigue tests have shown a need to inspect two diaphragms that support the upper structure of the forward equipment compartment.                                                                                                                                                                          |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n15 February 2008","sortOrder":0},{"sectionNumber":"AD/J4100/10","sectionType":"part","heading":"AD/J4100/10","content":"## AD/J4100/10","sortOrder":1},{"sectionNumber":"Forward Fuselage Stn 4 to Stn 8 Diaphrag","sectionType":"part","heading":"Forward Fuselage Stn 4 to Stn 8 Diaphragms","content":"## Forward Fuselage Stn 4 to Stn 8 Diaphragms","sortOrder":2},{"sectionNumber":"4/2008 DM","sectionType":"part","heading":"4/2008 DM","content":"## 4/2008 DM","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific structural fatigue issue in a specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 250 words)","Only 1 defined term implicitly used ('landings' — understood as aircraft cycles)","No cross-references to other legislation or complex conditional chains","Single compliance pathway with clear thresholds (4,200/4,500 landings)","Refers to external technical document (Service Bulletin) for actual inspection procedures rather than embedding them"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of BAe Jetstream 4100 (c/n 41004–41104) to inspect two forward-fuselage diaphragms between Station 4 and 8 for fatigue cracking, using BAe Systems Alert SB J41-A53-023 (or later approved revisions). \n\nIt imposes initial and recurring landing-based inspection intervals to catch cracks early—protecting structural integrity and preventing catastrophic failure for affected airlines, charter operators, and private owners."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The provided text specifies applicability, inspection method and intervals and cites the manufacturer's fatigue tests as the basis. There is no indication in this document that the scope has been widened or narrowed from an earlier intent."},"complexity_factors":["Narrow, specific applicability to constructor’s numbers 41004–41104 reduces the population affected but requires accurate fleet tracking (Applicability).","Mandates inspection in accordance with an external BAe Alert Service Bulletin (J41-A53-023) or a later CAA/EASA‑approved revision, creating dependence on an external document and its approved revisions for procedural detail (Requirement).","Initial inspection timing is conditional on accumulated landings: before 4,500 landings if <4,200, or within 300 landings if ≥4,200 — this creates calculation and scheduling complexity for operators (Compliance).","Repeating inspection interval of 3,000 landings requires ongoing maintenance record‑keeping and long‑term scheduling (Compliance).","The AD cites manufacturer's fatigue tests as the reason for inspection but does not itself set repair methods or limits; it therefore leaves corrective action detail and approval (and associated costs) to the service bulletin or regulatory approval process, creating operational discretion and potential cost variance (Background / Requirement).","Effective date and formal promulgation (becomes effective 20 February 2008; delegate signature noted) create a short administrative lead time for compliance planning (Compliance / administrative).","Reliance on CAA/EASA approval for later revisions introduces inter‑authority dependency for any procedural updates, affecting how changes are adopted (Requirement).","Economic burden falls on aircraft operators (inspection and any repairs; scheduling impacts to aircraft availability) — the AD prescribes actions but not funding or compensation (Applicability / Compliance)."],"plain_english_summary":"**Requires inspections of two forward fuselage diaphragms (Stn 4–8) on Jetstream 4100 aircraft (constructor’s nos 41004–41104) per BAe Alert Service Bulletin J41‑A53‑023 or a later CAA/EASA‑approved revision.** The manufacturer reports fatigue-test findings as the reason; the directive sets landing-count‑based initial and repeat inspection intervals, so affected operators must plan, perform and pay for those inspections and any resulting repairs."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms","history":"/api/acts/ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms/history","analysis":"/api/acts/ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms/analysis","conflicts":"/api/acts/ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms/conflicts","importantCases":"/api/acts/ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms/important-cases","documents":"/api/acts/ad-j4100-10-forward-fuselage-stn-4-to-stn-8-diaphragms/documents"}}