{"id":"F2006L02982","name":"AD/BELL 427/5 - Tail Rotor Gearbox Case Oil Feed Gallery","slug":"ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":60259,"registerId":"commonwealth-F2006L02982-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bell Helicopter Textron 427 Series Helic","sectionType":"division","heading":"Bell Helicopter Textron 427 Series Helicopters","content":"### Bell Helicopter Textron 427 Series Helicopters\n\n| AD/BELL 427/5 | Tail Rotor Gearbox Case Oil Feed Gallery | 10/2006 |\n| ------------- | ---------------------------------------- | ------- |\n\n| Applicability: | Bell Helicopter Textron Canada (BHTC) Model 427 Helicopters serial number (S/N) 56001 through 56031, 58001 and 58002, equipped with tail rotor gearbox case, part number (P/N) 406-040-406-109.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Unless previously accomplished, identify the tail rotor gearbox case installed on the helicopter and, if applicable, check for the presence of the oil feed gallery as per instructions provided in Part I of BHTC ASB 427-03-09, or later Transport Canada approved revisions. If the oil feed gallery is present, re-identify the case assembly as per instructions in BHTC ASB 427-03-09. If the oil feed gallery is not present, proceed to requirement 2 of this AD.2. Create the oil feed gallery as per instruction provided in Part II of BHTC ASB 427-03-09 or later Transport Canada approved revisions.3. For affected tail rotor gearbox cases held as spares, accomplish requirements 1 and 2 of this AD, if applicable.Note: Transport Canada AD CF 2003-11 dated 28 April 2003 refers. |\n| Compliance:    | 1. At the next gearbox disassembly or within 1800 hours time in service after the last overhaul of the gearbox, whichever occurs first after the effective date of this AD.2. Before further flight after completion of requirement 1 of this AD.3. Prior to the installation on the helicopter.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |\n|                | This Airworthiness Directive becomes effective on 28 September 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| Background:    | Transport Canada has informed that a number of tail rotor gearboxes are lacking the required oil feed gallery. This situation reduces the oil supply to duplex bearing P/N 406-040-432-103, which could lead to bearing failure.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |\n\n|     | It has been determined that the splash lubrication of the duplex bearing without the oil feed gallery is sufficient to prevent abnormal wear up to the 1800 hours overhaul period. |\n| --- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n14 August 2006","sortOrder":0},{"sectionNumber":"AD/BELL 427/5","sectionType":"part","heading":"AD/BELL 427/5","content":"## AD/BELL 427/5","sortOrder":1},{"sectionNumber":"Tail Rotor Gearbox Case Oil Feed Gallery","sectionType":"part","heading":"Tail Rotor Gearbox Case Oil Feed Gallery","content":"## Tail Rotor Gearbox Case Oil Feed Gallery","sortOrder":2},{"sectionNumber":"10/2006","sectionType":"part","heading":"10/2006","content":"## 10/2006","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope matches the safety objective stated in the source: ensure adequate oil supply to the duplex bearing by mandating identification and modification of specific tail rotor gearbox cases (Applicability; Requirement; Background). It includes both in-service gearboxes and spares, and sets explicit compliance timing tied to maintenance intervals (Requirement 3; Compliance 1–3)."},"complexity_factors":["Technical modification required: creation of an oil feed gallery per Part II of BHTC ASB 427-03-09 (Requirement 2).","Identification burden: must identify affected tail rotor gearbox cases by part and serial numbers before action (Applicability; Requirement 1).","Timing constraint tied to maintenance events: compliance due at next gearbox disassembly or within 1800 hours after last overhaul, whichever comes first (Compliance 1).","Spares management: affected spare gearbox cases must be inspected and modified before installation (Requirement 3; Compliance 3).","Dependence on external documents and approvals: work is specified by BHTC ASB 427-03-09 and any later Transport Canada–approved revisions (Requirement 1 and 2).","Temporary mitigation note: splash lubrication considered sufficient up to the 1800‑hour window, which sets an operational tolerance and scheduling incentive for operators (Background)."],"plain_english_summary":"This directive requires operators of certain Bell 427 helicopters (specific serial numbers fitted with tail rotor gearbox case P/N 406-040-406-109) to check whether the gearbox case has an oil feed gallery and, if it does not, to create one using the procedures in the Bell service bulletin. Spares must be checked and modified before fitting. The rule sets specific timing for compliance (next gearbox disassembly or within 1800 flight hours) to protect a duplex bearing from oil-starvation-related failure."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific manufacturing defect in a limited production run of Bell 427 helicopters. The requirements remain tightly focused on the tail rotor gearbox oil feed gallery issue identified by Transport Canada, with no expansion into unrelated systems or broader helicopter models."},"complexity_factors":["Single, specific technical issue (missing oil gallery) with clear mechanical remedy","Limited applicability — only 33 specific helicopter serial numbers and one part number affected","Straightforward conditional logic: check if gallery exists → if yes, relabel; if no, create it","Three distinct compliance deadlines based on operational status (installed vs. spare, time-in-service vs. next disassembly)","References external technical document (BHTC ASB 427-03-09) for detailed instructions rather than embedding them","No nested exceptions or complex definitional sections — only one defined term (S/N = serial number) used conventionally","Short document (approximately 250 words of substantive content)"],"plain_english_summary":"This AD requires owners/operators of specified Bell 427 helicopters (serials 56001–56031, 58001–58002) with tail rotor gearbox case P/N 406-040-406-109 to inspect and, if needed, machine an oil feed gallery or re-label compliant cases per the manufacturer’s procedures. \n\nIt matters because missing the gallery starves the duplex bearing of lubrication, risking bearing failure and loss of helicopter control; compliance is due at next disassembly or within 1,800 flight hours (spare cases must be checked before installation)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery","history":"/api/acts/ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery/history","analysis":"/api/acts/ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery/analysis","conflicts":"/api/acts/ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery/conflicts","importantCases":"/api/acts/ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery/important-cases","documents":"/api/acts/ad-bell-427-5-tail-rotor-gearbox-case-oil-feed-gallery/documents"}}