{"id":"F2006B08643","name":"AD/CON/66 Amdt 2 - Fuel Pump Drive Coupling","slug":"ad-con-66-amdt-2-fuel-pump-drive-coupling","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51684,"registerId":"commonwealth-F2006B08643-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CON/66 Amdt 2 - Fuel Pump Drive Coupling","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)  \nTeledyne Continental Motors Piston Engines\n\nAD/CON/66\n\nAmdt 2\n\n  \nFuel Pump Drive Coupling 10/96\n\nApplicability: All Teledyne Continental Motors (TCM) piston engines, as listed by model number below, which incorporate a fuel pump as listed by part number (P/N) in TCM Mandatory Service Bulletin Number MSB95-6 or are fitted with a fuel pump, regardless of P/N, which has had a P/N 646176 fuel pump shaft installed.\n\nIO-346-A\n\nIO-520-B, BA, BB, C, CB, M, MB IO-550-A, B, C, G\n\nTSIO-520-B, BB, D, DB, E, EB, J, JB, K, KB, L, LB, N, NB, UB, VB, WB TSIO-550-B\n\nTSIOL-550-A, B\n\nRequirement: To prevent the disengagement of the fuel pump drive coupling which may result in the loss of engine power:\n\n1. a. Remove the fuel pump and inspect the fuel pump shaft in accordance with TCM Mandatory Service Bulletin MSB95-6, Figure 1, to determine the part number of the shaft fitted, and\n\n    b. If a current style P/N 646176 fuel pump shaft is found fitted, ensure only a new style P/N 653359 drive coupling is installed when reassembling the fuel pump to the engine. Fuel pumps incorporating an early style P/N 643689 shaft may continue in service until next engine overhaul with either the old style P/N 631263 or a new style P/N 653359 drive coupling fitted.\n\n    2. Replace the old style fuel pump drive coupling P/N 631263 with a new style drive coupling P/N 653359.\n\nNote 1: Requirement 2 is only applicable to fuel pumps found, during compliance with Requirement 1, to have the early style P/N 643689 fuel pump shaft incorporated.\n\nNote 2: FAA Airworthiness Directive 93-16-15 refers.\n\nCompliance: Requirement 1: Unless previously accomplished in accordance with amendment 1 of this directive; within 30 hours time in service effective on 12 September 1996.\n\nRequirement 2: At next engine overhaul after 12 September 1996.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBackground: This directive was originally issued on 30 May 1993 to require an inspection of the fuel pump drive coupling for correct engagement. Amendment 1 was issued on 29 February 1996 to include IO-346 engines and fuel pumps incorporating a P/N 646176 shaft. This amendment corrects an ambiguity in the applicability of engines fitted with a fuel pump incorporating the P/N 646176 shaft. Teledyne Continental Motors has confirmed, only \"Permold\" engine models as listed in TCM MSB95-6 are affected, regardless of the fuel pump configuration.\n\nThe original issue of this Airworthiness Directive became effective on 30 May 1993. Amendment 1 of this Airworthiness Directive became effective on 29 February 1996.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive has been amended since its original 1993 issue (amendment 1 added some engine models and shaft types; amendment 2 clarified applicability to the TCM “Permold” models listed in MSB95-6). These are adjustments and clarifications to the original airworthiness objective (preventing fuel-pump drive disengagement) rather than a substantive expansion beyond that safety purpose, so the core scope and intent have not grown significantly beyond the original directive."},"complexity_factors":["Lists ~32 engine model/variant entries in applicability (multiple specific engine variants).","Four part numbers referenced with conditional rules (P/N 646176, 653359, 643689, 631263).","Two-tier requirements with timing differences (Requirement 1 within 30 flight hours; Requirement 2 at next overhaul).","Conditional logic: different actions depending on which shaft style is fitted; Note 1 limits applicability of Requirement 2.","Cross-reference to external documents (TCM Mandatory Service Bulletin MSB95-6 and FAA AD 93-16-15) required to complete the steps.","Background amendments and an applicability clarification (amendment history creates interpretive steps for operators)."],"plain_english_summary":"**What this directive does (mechanically)**\n\n- It requires removing and inspecting the aircraft fuel pump to check which fuel-pump shaft is fitted, following Teledyne Continental Motors (TCM) Mandatory Service Bulletin MSB95-6 (Figure 1). (Requirement 1a)\n- If the pump has the current-style shaft P/N 646176, the pump must be reassembled using only the new-style drive coupling P/N 653359. (Requirement 1b)\n- If the pump has an early-style shaft P/N 643689, that pump may continue in service until the next engine overhaul, but at overhaul the old-style drive coupling P/N 631263 must be replaced with the new-style P/N 653359. (Requirement 2; Note 1)\n\nCompliance timing:\n\n- The inspection (Requirement 1) must be done within 30 flight hours from the effective date given in the directive unless it was already done under the previous amendment. (Compliance: Requirement 1)\n- The replacement of the old-style coupling (Requirement 2) is required at the next engine overhaul after the effective date. (Compliance: Requirement 2)\n\nWhich engines and pumps are covered:\n\n- The AD lists specific TCM piston-engine model numbers (about 32 model/variant entries, including IO-346, IO-520 series, IO-550 series, TSIO-520 series, TSIO-550-B, and TSIOL-550 variants). It applies where the engine incorporates a fuel pump listed in TCM MSB95-6 or where a pump (regardless of its part number) has had a P/N 646176 pump shaft installed. (Applicability)\n\nWhy the rule exists (as stated):\n\n- The stated safety objective is to prevent disengagement of the fuel pump drive coupling, which can cause loss of engine power. The AD references a related FAA Airworthiness Directive (FAA AD 93-16-15) and TCM service information. (Requirement; Background)\n\nPractical implications, costs and who decides/acts\n\n- Who pays: aircraft owners/operators pay for the inspection, labour and any replacement parts (drive couplings). Maintenance organisations perform the inspections and replacements.\n- Timing and downtime: the inspection requires removal of the pump and visual/parts inspection (per TCM MSB95-6); this causes shop labour and aircraft downtime. Replacement of the coupling is required immediately if a 646176 shaft is present, or at overhaul if the earlier 643689 shaft is present.\n- Supply and vendor effects: compliance requires specific part numbers. Owners will need access to P/N 653359 couplings; in practice those parts are typically sourced from the engine/parts supplier or aftermarket vendors.\n\nImplementation risks and compliance burden\n\n- Identification: the directive relies on correct identification of shaft and coupling part numbers (requires part-number verification against the TCM bulletin figure). Misidentification could lead to non-compliance or unnecessary parts replacement.\n- Recordkeeping: operators must keep maintenance records showing the inspection and any parts changed to demonstrate compliance.\n- Scope clarity: the amendment corrected ambiguity about which engines are affected (TCM confirmed the issue is limited to the “Permold” engine models listed in MSB95-6). That reduces uncertainty about which aircraft need action.\n\nTrade-offs and incentives\n\n- Safety vs. cost: the directive trades one-time inspection and possible part replacement costs for reduced risk of fuel-pump disengagement (the safety gain is concentrated on aircraft occupants and third parties; the cost is paid by aircraft owners/operators).\n- Supplier demand concentration: mandating a specific replacement part (P/N 653359) concentrates aftermarket demand for that part; that benefits suppliers who stock it and may increase parts sales to affected operators.\n\nCross-references\n\n- The AD explicitly references TCM Mandatory Service Bulletin MSB95-6 for the inspection method and FAA AD 93-16-15 for related U.S. action. (Note 2 / Background)\n\nBottom line (nutshell)\n\n- Inspect the fuel pump shaft per TCM MSB95-6 within the specified short time window. If a current-style shaft (P/N 646176) is present, reassemble only with the new drive coupling (P/N 653359). If an early-style shaft (P/N 643689) is present, replace the old coupling at the next engine overhaul with P/N 653359. The rule aims to avoid fuel pump disengagement and consequent engine power loss; owners/operators bear inspection and parts costs and must manage records and downtime to comply."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original 1993 directive required inspection for correct engagement of the drive coupling. Amendment 1 in 1996 expanded scope to include IO-346 engines and fuel pumps with P/N 646176 shafts. This Amendment 2 further refines the scope by correcting an ambiguity—it clarifies that only 'Permold' engine models are affected regardless of fuel pump configuration, effectively narrowing the applicability from what might have been interpreted more broadly under Amendment 1. The directive has evolved from a simple engagement check to a complex part-number-specific replacement mandate."},"complexity_factors":["Multiple part numbers (P/N 646176, 653359, 643689, 631263) that must be cross-referenced to determine applicability","Conditional logic: Requirement 2 only applies if Requirement 1 reveals a specific shaft type (early-style P/N 643689)","Nested applicability: The directive applies to engines with certain fuel pumps, but only if those pumps have certain shafts, creating a two-level filtering system","Version history references: Must track whether previous compliance was under Amendment 1","Specific compliance timelines tied to flight hours and maintenance events (engine overhaul)","Cross-reference to external document (TCM Mandatory Service Bulletin MSB95-6) for inspection procedures"],"plain_english_summary":"This airworthiness directive requires owners/operators of certain Teledyne Continental piston engines to inspect fuel pump shafts and replace vulnerable drive couplings to prevent fuel-pump disengagement and in‑flight power loss. It targets engines with specific pump shaft configurations (notably P/N 646176 and earlier P/N 643689) and mandates timely inspection and coupling replacement at the next overhaul.\n\nThe measure closes a safety gap from the earlier 1993 directive and aims to prevent catastrophic engine stoppage due to loss of fuel drive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-con-66-amdt-2-fuel-pump-drive-coupling","history":"/api/acts/ad-con-66-amdt-2-fuel-pump-drive-coupling/history","analysis":"/api/acts/ad-con-66-amdt-2-fuel-pump-drive-coupling/analysis","conflicts":"/api/acts/ad-con-66-amdt-2-fuel-pump-drive-coupling/conflicts","importantCases":"/api/acts/ad-con-66-amdt-2-fuel-pump-drive-coupling/important-cases","documents":"/api/acts/ad-con-66-amdt-2-fuel-pump-drive-coupling/documents"}}