{"id":"F2006B11217","name":"AD/LYC/99 - Diaphragm Fuel Pumps","slug":"ad-lyc-99-diaphragm-fuel-pumps","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56935,"registerId":"commonwealth-F2006B11217-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LYC/99 - Diaphragm Fuel Pumps","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nLycoming Piston Engines\n\nAD/LYC/99 Diaphragm Fuel Pumps 13/96 DM\n\nApplicability: 1. All Lycoming new, remanufactured and overhauled fuel injected L/IO-320, \\-360, \\- 540; AEIO-320, -360, -540; HIO-360, TO-360 and O-540-L engines released by Textron Lycoming between 18 July 1995 and 14 August 1996 and fitted with a diaphragm fuel pump part number (P/N) LW-15473 with an identification/date code of 154739506, 154739507 or 154739510, and\n\n    2. All Textron Lycoming fuel injected L/IO-320, \\-360, \\-540; AEIO-320, \\-360, \\-540; HIO-360, TO-360 and O-540-L engines which have had a new diaphragm fuel pump P/N LW-15473 with an identification/date code of 154739506, 154739507 or 154739510 installed since 18 July 1995, and\n\n    3. All spare diaphragm fuel pumps P/N LW-15473 with an identification code of 154739506, 154739507 or 154739510.\n\nRequirement: Inspect applicable fuel pumps in accordance with Textron Lycoming Mandatory Service Bulletin No. 525.\n\nNote: An FAA Airworthiness Directive on this subject is pending.\n\nCompliance: Installed engines: Within 10 hours time in service effective 30 October 1996.\n\nSpare engines and spare fuel pumps: Prior to installation in an a aircraft effective 30 October 1996.\n\nBackground: This directive has been issued to require the inspection of certain fuel pumps. The requirement addresses reports of sudden engine failure events which resulted from the fuel pump diaphragm retaining washer becoming separated from the pull rod assembly and lodging in the pump outlet valve. An investigation of the reports indicates the defect relates to a manufacturing fault.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific safety-critical manufacturing defect. It has not expanded beyond its original purpose of mandating inspections for a known faulty component."},"complexity_factors":["Highly specific applicability criteria requiring cross-referencing of engine models, part numbers, and date codes","Multiple categories of affected parties (installed engines, spare engines, spare pumps) with different compliance timelines","Reliance on external document (Textron Lycoming Mandatory Service Bulletin No. 525) for actual inspection procedures — the AD itself doesn't specify what to do, only that you must follow the bulletin","Reference to pending FAA directive suggesting international regulatory coordination"],"plain_english_summary":"This AD mandates urgent inspection of certain Lycoming piston engines’ diaphragm fuel pumps made July 1995–August 1996 to find a failing internal washer that can jam the fuel outlet and cause sudden engine failure. It affects owners, operators, and anyone with spare pumps or engines with those part/date codes.\n\nCompliance is mandatory and urgent (inspection within 10 flight hours for installed pumps or before installing spares) to prevent in-flight power loss."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive applies only to the specific pump part numbers/date codes and the listed engine models and spares and requires inspection per the manufacturer service bulletin. This scope aligns with the stated safety concern (diaphragm retaining washer separation) and does not expand obligations beyond inspection and pre‑installation checks."},"complexity_factors":["Narrow, part‑number and date‑code specific applicability (P/N LW‑15473; codes 154739506, 154739507, 154739510) increases precision but requires accurate parts tracking (Applicability).","Multiple engine models covered (L/IO‑320, ‑360, ‑540; AEIO‑; HIO‑; TO‑; O‑540‑L) requires cross‑checking fleet records.","Procedure delegated to an external document (Textron Lycoming Mandatory Service Bulletin No. 525) creates dependency on manufacturer instructions for technical steps (Requirement).","Short compliance window for in‑service pumps (within 10 hours TIS) imposes urgent operational scheduling and potential downtime (Compliance).","Spare parts control: spares must be inspected before installation, shifting some compliance burden to parts managers and maintenance planners (Applicability; Compliance).","Root cause identified as a manufacturing fault (retaining washer separation), so corrective action focuses on inspection rather than redesign within this directive (Background)."],"plain_english_summary":"AD/LYC/99 requires inspection of Lycoming diaphragm fuel pumps P/N LW‑15473 with identification codes 154739506, 154739507 or 154739510 when fitted to, released with, or held as spares for specified Lycoming fuel‑injected engines. Aircraft owners, operators and maintenance providers must perform the inspection per Textron Lycoming Mandatory Service Bulletin No. 525 within 10 hours TIS for installed pumps or before fitting spares (Applicability; Requirement; Compliance).\n\nThe directive responds to reports that a diaphragm retaining washer can separate and lodge in the pump outlet valve and cause sudden engine failure (Background)."},"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-lyc-99-diaphragm-fuel-pumps","history":"/api/acts/ad-lyc-99-diaphragm-fuel-pumps/history","analysis":"/api/acts/ad-lyc-99-diaphragm-fuel-pumps/analysis","conflicts":"/api/acts/ad-lyc-99-diaphragm-fuel-pumps/conflicts","importantCases":"/api/acts/ad-lyc-99-diaphragm-fuel-pumps/important-cases","documents":"/api/acts/ad-lyc-99-diaphragm-fuel-pumps/documents"}}