{"id":"F2006B07258","name":"AD/T5508D/1 - Inner Bevel Gear","slug":"ad-t5508d-1-inner-bevel-gear","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49162,"registerId":"commonwealth-F2006B07258-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS 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\nHoneywell International Turbine Engines \\- T5508D Series","sortOrder":0},{"sectionNumber":"AD/T5508D/1 Inner Bevel Gear 7/2003","sectionType":"part","heading":"AD/T5508D/1 Inner Bevel Gear 7/2003","content":"# AD/T5508D/1 Inner Bevel Gear 7/2003\n\nApplicability: Honeywell (Avco Lycoming) T5508D turboshaft engines fitted with engine accessory inner bevel gear Part Number (P/N) 2-070-005-02.\n\nRequirement: Replace the engine accessory inner bevel gear Part Number P/N 2-070-005-02 with gear P/N 2-070-030-01 in accordance with Avco Lycoming service bulletin No.\n\n5508-0013.\n\nNote: FAA AD 78-07-04 refers.\n\nCompliance: Prior to issue of an Australian certificate of airworthiness.\n\nThis Airworthiness Directive becomes effective on 10 July 2003.\n\nBackground: Replacement of the gear will prevent fatigue failure of the engine accessory inner bevel gear, which will lead to engine failure.\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 26 May 2003\n\n![](image.001.png)","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive targeting a specific known defect in a specific engine model. It has not expanded beyond its original purpose of mandating replacement of a single faulty component."},"complexity_factors":["Single, specific mechanical part targeted (P/N 2-070-005-02)","One clear action required (replacement with P/N 2-070-030-01)","Simple compliance trigger (prior to airworthiness certificate issuance)","Only 2 defined part numbers and 1 service bulletin reference","No nested conditions, exceptions, or cross-references to other legislation beyond a note about a related US FAA directive","Background provides straightforward safety rationale (fatigue failure prevention)"],"plain_english_summary":"This is a **safety order for aircraft engines**. The Civil Aviation Safety Authority (CASA) has identified a dangerous flaw in a specific engine part — the \"inner bevel gear\" in Honeywell T5508D turboshaft engines. \n\n**What it does:**\n- **Orders replacement** of a faulty gear (part number 2-070-005-02) with a safer version (part number 2-070-030-01)\n- **Applies to:** Specific helicopter engines made by Honeywell (formerly Avco Lycoming)\n- **When:** Before the aircraft can get an Australian airworthiness certificate\n\n**Why it matters:**\nThe faulty gear can crack from metal fatigue and break, causing **complete engine failure**. This is obviously catastrophic in a helicopter. The directive forces owners/operators to fix this before the aircraft is deemed safe to fly in Australia.\n\n**Key point:** This is a mandatory safety fix — not optional. Ignoring it means the aircraft cannot be legally certified as airworthy."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Scope is consistent with the original safety objective: it targets T5508D engines fitted with inner bevel gear P/N 2-070-005-02 and mandates replacement with P/N 2-070-030-01 before an Australian Certificate of Airworthiness is issued to prevent gear fatigue and potential engine failure."},"complexity_factors":["Single, mandatory mechanical action (replace one specific part) limits procedural complexity","Applicability confined to T5508D engines fitted with a particular part number (P/N 2-070-005-02)","Compliance deadline tied to a single event (prior to issue of Australian Certificate of Airworthiness)","Requires following an external service bulletin (Avco Lycoming SB 5508-0013) — external-document dependency","References an earlier FAA AD but provides no alternative compliance routes or inspections","Clear effective date provided (10 July 2003)"],"plain_english_summary":"This directive requires replacing the engine accessory inner bevel gear P/N 2-070-005-02 with P/N 2-070-030-01 on Honeywell (Avco Lycoming) T5508D turboshaft engines, following Avco Lycoming Service Bulletin 5508-0013. CASA’s delegate issued the AD; engine operators/owners must install the new gear before an Australian Certificate of Airworthiness is issued and bear replacement cost. The stated aim is to prevent fatigue failure of the gear that could cause engine failure."},"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-t5508d-1-inner-bevel-gear","history":"/api/acts/ad-t5508d-1-inner-bevel-gear/history","analysis":"/api/acts/ad-t5508d-1-inner-bevel-gear/analysis","conflicts":"/api/acts/ad-t5508d-1-inner-bevel-gear/conflicts","importantCases":"/api/acts/ad-t5508d-1-inner-bevel-gear/important-cases","documents":"/api/acts/ad-t5508d-1-inner-bevel-gear/documents"}}