{"id":"F2021L01093","name":"AD/CON/56 Amdt 2 Number Two Crankcase Main Bearing Integrity","slug":"ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":102000,"registerId":"commonwealth-F2021L01093-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Continental Aerospace Technologies (Cont","sectionType":"part","heading":"Continental Aerospace Technologies (Continental Motors) Piston Engines","content":"# Continental Aerospace Technologies (Continental Motors) Piston Engines\n\n| AD/CON/56 Amdt 2 | Number Two Crankcase Main Bearing Integrity | 16/2021 |\n| ---------------- | ------------------------------------------- | ------- |\n\n| Applicability: | Continental Motors Model TSIO-520BE engines Serial Numbers 528001 through 528337.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Inspect crankcase for end play in accordance with Teledyne Continental Motors (TCM) Service Bulletin (SB) M89-14 Section A as in force on the commencement date of this AD.2. Carry out thru-bolt torque check in accordance with TCM SB M89-14 Section B as in force on the commencement date of this AD.3. Inspect number two crankcase main bearing in accordance with TCM SBM89-14 Section C as in force on the commencement date of this AD.Note 1: The repetitive checks and inspections detailed in Requirements No. 1 and No. 3 may be discontinued following disassembly of the crankcase assembly to a depth sufficient to inspect the crankcase mating flanges for evidence of fretting, and new bearings are installed.Note 2: United States of America Federal Aviation Administration (FAA) Airworthiness Directive 89-14-01 is the basis for this AD. |\n| Compliance:    | 1. Before further flight after the commencement date of this AD, unless accomplished previously, and thereafter at intervals not to exceed 25 hours’ time in service.2. Before further flight after the commencement date of this AD, unless accomplished previously.3. Before further flight after the commencement date of this AD unless accomplished previously, and thereafter at intervals not to exceed 200 hours’ time in service.                                                                                                                                                                                                                                                                                                                                                                                                                              |\n|                | This AD commences on 20 August 2021.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| Background:    | Advice from the engine manufacturer indicates, loss of thru-bolt torque results in fretting of the crankcase mating flanges and possible migration of the number two main bearing. Until that fretting is addressed, the integrity of the number two main bearing is suspect and repetitive inspections as detailed in TCM SB M89-14 is justified.Amendment 1 introduced terminating action.                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n|                | Amendment 2 removes obsolete references and makes minor editorial changes to reflect current requirements.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n\n![Text\nDescription automatically generated](image.001.jpeg)\n\nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n6 August 2021","sortOrder":0},{"sectionNumber":"AD/CON/56 Amdt 2","sectionType":"part","heading":"AD/CON/56 Amdt 2","content":"## AD/CON/56 Amdt 2","sortOrder":1},{"sectionNumber":"Number Two Crankcase Main Bearing Integr","sectionType":"part","heading":"Number Two Crankcase Main Bearing Integrity","content":"## Number Two Crankcase Main Bearing Integrity","sortOrder":2},{"sectionNumber":"16/2021","sectionType":"part","heading":"16/2021","content":"## 16/2021","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 2 of an existing Airworthiness Directive. The amendment history indicates it only removes obsolete references and makes minor editorial changes. The scope remains focused on the original safety issue: number two crankcase main bearing integrity in specific Continental Motors engine models. No expansion of applicability or substantive new requirements."},"complexity_factors":["Short, single-purpose directive with only 3 requirements","No defined terms section — relies on external technical references (TCM Service Bulletin M89-14)","Simple conditional logic: repetitive inspections continue until terminating action (disassembly and bearing replacement) is performed","Clear compliance dates and intervals (25 hours and 200 hours time-in-service)","Minor cross-referencing to FAA Airworthiness Directive 89-14-01 and TCM Service Bulletin","Amendment 2 described as removing obsolete references and making minor editorial changes only"],"plain_english_summary":"This AD mandates safety inspections for Continental Motors TSIO-520BE engines (S/N 528001–528337): immediate and recurring crankcase end‑play checks (every 25 flight hours), a one‑time thru‑bolt torque check before next flight, and #2 main‑bearing inspection before next flight and every 200 hours. \n\nIt addresses thru‑bolt loosening and fretting that can let the #2 bearing migrate, risking catastrophic engine failure — affecting aircraft owners and maintenance organizations operating these engines."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Amendment 2 makes editorial updates and removes obsolete references without adding new inspection requirements or expanding applicability. The substantive scope—mandatory inspections, torque checks, intervals, and the terminating action introduced by Amendment 1—remains unchanged (see 'Amendment 2 removes obsolete references...' and 'Amendment 1 introduced terminating action')."},"complexity_factors":["Technical specificity: requires engine internal inspections and torque checks tied to mechanical failure modes (crankcase fretting and bearing migration).","External mandatory reference: directs compliance to TCM Service Bulletin M89‑14 'as in force on the commencement date' (dependency on external document versioning).","Limited applicability: applies only to a defined serial-number range (S/N 528001–528337), requiring accurate aircraft/engine tracking.","Multiple inspection intervals and conditions: different repeat intervals (25 hours and 200 hours) and a discontinuation/terminating action condition after disassembly and bearing replacement (Compliance; Requirement notes).","Regulatory layering: AD is based on FAA AD 89-14-01 and incorporates amendment history (Amendment 1 introduced terminating action; Amendment 2 editorial changes), creating cross-jurisdictional reference points.","Operational burden: immediate 'before further flight' actions required on commencement date, creating short-term scheduling and downtime costs for operators."],"plain_english_summary":"This AD requires owners/operators of Continental Motors TSIO‑520BE engines (serial numbers 528001–528337) to perform crankcase end‑play inspections, thru‑bolt torque checks and number‑two main bearing inspections following Teledyne Continental Motors Service Bulletin M89‑14, at specified initial and repetitive intervals. Operators pay for inspections and any repairs; the Civil Aviation Safety Authority enforces compliance. The measures are intended to detect fretting and prevent migration of the number‑two main bearing caused by loss of thru‑bolt torque. (Requirements 1–3; Compliance.)"},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity","history":"/api/acts/ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity/history","analysis":"/api/acts/ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity/analysis","conflicts":"/api/acts/ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity/conflicts","importantCases":"/api/acts/ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity/important-cases","documents":"/api/acts/ad-con-56-amdt-2-number-two-crankcase-main-bearing-integrity/documents"}}