{"id":"F2009L01180","name":"AD/BELL 407/33 - Tailboom Assembly","slug":"ad-bell-407-33-tailboom-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":122034,"registerId":"commonwealth-F2009L01180-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bell Helicopter Textron Canada (BHTC) 40","sectionType":"division","heading":"Bell Helicopter Textron Canada (BHTC) 407 Series Helicopters","content":"### Bell Helicopter Textron Canada (BHTC) 407 Series Helicopters\n\n| AD/BELL 407/33 | Tailboom Assembly | 5/2009 DM |\n| -------------- | ----------------- | --------- |\n\n| Applicability: | Bell Helicopter Textron Canada (BHTC) Model 407 helicopters with tailboom part number 407-030-801-201, -203 or -205 installed.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Verify whether tailboom part number 407-030-801-201, -203 or -205 is installed on the helicopter; and,Enter the appropriate part number as indentified into the helicopter technical records and also the accumulated flight hours of the tailboom. If the accumulated flight hours of the tailboom is unknown, for the purpose of this Directive, it shall be considered to have more than 8,600 flight hours.Using the following, establish the inspection schedule applicable to the tailboom affected.2. Inspection schedule:- Less than 6,900 tailboom flight hours:Accomplish Part II of BHTC ASB 407-08-84 original issue, or later Transport Canada approved revision.- Less than 8,600 but more than 6,900 tailboom flight hours:Accomplish Part II and Part III of BHTC ASB 407-08-84 original issue, or later Transport Canada approved revision.- With 8,600 or more tailboom flight hours:Accomplish Part II, Part III and Part IV of BHTC ASB 407-08-84 original issue, or later Transport Canada approved revision.Note: Transport Canada AD CF-2009-07 refers. |\n| Compliance:    | 1. Within 25 flight hours after 6 April 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n\n|             | 2. Inspection schedule compliance for Part II, Part III and Part IV of ASB407-08-84:Part II. At intervals not to exceed 300 flight hours inspect with a 10x magnifying glass.Part III. At intervals not to exceed 150 flight hours inspect with a 10x magnifying glass; or,At intervals not to exceed 500 flight hours inspect by Eddy Current Method.Part IV. At intervals not to exceed 50 flight hours inspect with a 10x magnifying glass; or,Daily Visual Check during the pre-flight check followed by a 10x magnifying glass inspection at the next scheduled inspection. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 6 April 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| Background: | A recent stress analysis of the chemically milled tailboom skin has revealed a possibility of skin cracking due to high stress concentration areas. This condition, if not detected, could result in serious damage to the tailboom.                                                                                                                                                                                                                                                                                                                                             |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n20 March 2009","sortOrder":0},{"sectionNumber":"AD/BELL 407/33","sectionType":"part","heading":"AD/BELL 407/33","content":"## AD/BELL 407/33","sortOrder":1},{"sectionNumber":"Tailboom Assembly","sectionType":"part","heading":"Tailboom Assembly","content":"## Tailboom Assembly","sortOrder":2},{"sectionNumber":"5/2009 DM","sectionType":"part","heading":"5/2009 DM","content":"## 5/2009 DM","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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard single-issue Airworthiness Directive addressing a specific structural defect in a defined aircraft population. The scope remains tightly focused on tailboom inspection requirements for the identified part numbers, with no evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Multiple conditional inspection schedules based on accumulated flight hours (three distinct thresholds: <6,900, 6,900-8,600, and ≥8,600 hours)","Cross-reference to external technical document (BHTC ASB 407-08-84) without reproducing its contents — compliance requires obtaining and understanding this separate bulletin","Alternative compliance methods for higher-hour tailbooms (visual vs. eddy current inspection options)","Assumed flight hours provision (unknown hours default to >8,600) creating a conservative safety presumption","Reference to parallel Canadian aviation regulation (Transport Canada AD CF-2009-07) suggesting harmonised international requirements"],"plain_english_summary":"This AD requires owners/operators of Bell 407 helicopters with tailboom P/Ns ending in -201, -203, or -205 to check records and begin repetitive inspections for tailboom skin cracking—with inspection intervals that become more frequent as tailboom flight hours increase (including options for magnified visual or Eddy Current checks). A cracked tailboom could cause structural failure in flight. Initial record check must be done within 25 flight hours after 6 April 2009."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive's scope is limited to Bell Model 407 helicopters with tailboom P/Ns 407-030-801-201, -203 or -205 and prescribes inspection and recordkeeping requirements tied to accumulated tailboom hours. The instrument does not expand applicability beyond those parts or introduce new corrective actions beyond the tiered inspection programme and associated record entries as set out in the text."},"complexity_factors":["Narrow applicability to specific tailboom part numbers (Applicability).","Tiered inspection triggers based on accumulated tailboom flight hours with three bands (<6,900; 6,900–8,600; ≥8,600) (Requirement: Inspection schedule).","Mandatory recordkeeping of part number and accumulated tailboom hours; unknown hours defaulted to >8,600 (Requirement: verify and enter into technical records).","Multiple inspection parts (Part II, III, IV of ASB 407-08-84) with different methods and intervals (Requirement: Inspection schedule details).","Alternative inspection methods with different intervals (10x magnifying glass vs Eddy Current) creating operational choice and equipment needs (Compliance: inspection intervals and methods).","Short initial compliance window (within 25 flight hours after 6 April 2009) increasing near‑term operational impact (Compliance).","High‑frequency checks possible (e.g. Part IV: every 50 flight hours or daily visual pre‑flight + 10x at next inspection) increasing maintenance burden for some operators (Compliance: Part IV).","Dependency on Transport Canada AD and BHTC ASB revisions — references to later approved revisions create potential for administrative updates (Requirement: refer to ASB and Transport Canada AD)."],"plain_english_summary":"This directive applies to Bell 407 helicopters fitted with tailboom part numbers 407-030-801-201, -203 or -205. Operators must record the tailboom part number and accumulated flight hours (treat unknown hours as >8,600) and carry out a tiered inspection programme—using 10x magnification or Eddy Current methods at specified flight‑hour bands—to detect possible chemically‑milled skin cracking. Compliance was required within 25 flight hours after 6 April 2009."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-407-33-tailboom-assembly","history":"/api/acts/ad-bell-407-33-tailboom-assembly/history","analysis":"/api/acts/ad-bell-407-33-tailboom-assembly/analysis","conflicts":"/api/acts/ad-bell-407-33-tailboom-assembly/conflicts","importantCases":"/api/acts/ad-bell-407-33-tailboom-assembly/important-cases","documents":"/api/acts/ad-bell-407-33-tailboom-assembly/documents"}}