{"id":"F2008L00877","name":"AD/AB139/5 - Exhaust Tailpipe Assembly","slug":"ad-ab139-5-exhaust-tailpipe-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72996,"registerId":"commonwealth-F2008L00877-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Agusta AB139 and AW139 Series Helicopter","sectionType":"division","heading":"Agusta AB139 and AW139 Series Helicopters","content":"### Agusta AB139 and AW139 Series Helicopters\n\n| AD/AB139/5 | Exhaust Tailpipe Assembly | 4/2008 |\n| ---------- | ------------------------- | ------ |\n\n| Applicability: | AB 139 and AW 139 helicopters, all serial numbers, except 31002, 31003, 31004 and 31007, if equipped with Tailpipe Assemblies having Part Number (P/N) 3G7800L00131 (LH) or 3G7800L00231 (RH).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For AB 139 helicopters - inspect the tailpipe assembly in accordance with the instructions of Agusta BT 139-069 Revision A dated 8 November 2006 or later approved revision.2. For AW 139 helicopters - inspect the tailpipe assembly in accordance with the instructions of Agusta BT 139-069 Revision A or later approved revision.3. If heat damage or cracks are found in the exhaust area residing inside the cowling, replace the damaged tailpipe assembly with an airworthy part in accordance with the Agusta AW139 Aircraft Maintenance Publication (AMP).4. If cracks are found in the exhaust area residing outside the cowling that turn off abruptly from the original direction or are outside the allowable limits established by Agusta BT 139-069 Rev. A, or later approved revision, replace the cracked tailpipe assembly with an airworthy part in accordance with the Agusta AW139 Aircraft Maintenance Publication. (AMP).5. If cracks are found in the exhaust area residing outside the cowling that are within the allowable limits established by Agusta BT 139-069 Rev. A, or later approved revision one of the following repairs must be accomplished:a) Drill a stop hole at the end of the crack and perform an inspection to verify that crack length does not increase. If the crack length increases to the limits established by Agusta BT 139-069 Rev. A, or later approved revision, replace the cracked tailpipe assembly with an airworthy part in accordance with the Agusta AW139 Aircraft Maintenance Publication (AMP).b) Repair in accordance with the instructions of Agusta BT 139-069 Rev. A.6. Thereafter, repeat the applicable inspection as detailed in Requirement 1 or 2 of this AD and accomplish the follow-up actions, as required. |\n\n|             | Repair or replacement of the affected tailpipe assembly does not constitute terminating action for the repetitive inspection as detailed in Requirement 6 of this AD.Note: EASA AD 2006-0360-E dated 29 November 2006 refers.                                                                                                                                                                                   |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. Within 30 days after the effective date of this AD unless previously accomplished.2. Within 30 days after the effective date of this AD unless previously accomplished.3. Before further flight after the effective date of this AD.4. Before further flight after the effective date of this AD.5. Before further flight after the effective date of this AD.6. At intervals not to exceed 25 flight hours. |\n|             | This Airworthiness Directive becomes effective on 10 April 2008.                                                                                                                                                                                                                                                                                                                                                |\n| Background: | Field reports have shown that the Agusta AB/AW 139’s Tailpipe Assembly is prone to cracks. To prevent any cracks from developing into failure of the exhaust tailpipe assembly, a repetitive inspection and, if necessary, replacement is required by this AD.                                                                                                                                                  |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n27 February 2008","sortOrder":0},{"sectionNumber":"AD/AB139/5","sectionType":"part","heading":"AD/AB139/5","content":"## AD/AB139/5","sortOrder":1},{"sectionNumber":"Exhaust Tailpipe Assembly","sectionType":"part","heading":"Exhaust Tailpipe Assembly","content":"## Exhaust Tailpipe Assembly","sortOrder":2},{"sectionNumber":"4/2008","sectionType":"part","heading":"4/2008","content":"## 4/2008","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD as drafted applies only to AB139/AW139 helicopters fitted with the two listed tailpipe P/Ns and excludes four serial numbers; it prescribes inspections, repairs, replacements and ongoing 25-flight-hour repeats. The instrument does not expand or narrow applicability beyond the stated list within its text, nor does it provide any terminating action for the repetitive inspections."},"complexity_factors":["Applicability scope narrows by specific part numbers and excludes four serial numbers, requiring careful aircraft-by-aircraft applicability checks (Applicability).","Multiple inspection paths: Requirements 1 and 2 reference Agusta BT 139-069 Rev A (or later approved revision) for inspection instructions — reliance on an external document increases interpretation effort (Requirement 1–2).","Different remedial rules depending on crack location and characteristics (inside cowling → replace; outside cowling → replace if off-direction or out of allowable limits; otherwise drill stop-hole and monitor or repair per BT 139-069) requiring judgement and measurement against manufacturer limits (Requirement 3–5).","Repetitive inspection mandate (every 25 flight hours) creates ongoing compliance scheduling and record-keeping burden; repair/replacement is explicitly not terminating action for the repetitive inspections (Requirement 6; Compliance).","Mixed compliance timings: some inspections must occur within 30 days, others before further flight, increasing short-term logistical pressure (Compliance).","References to later approved revisions and the Agusta AW139 Aircraft Maintenance Publication introduce regulatory/engineering discretion about which revision applies and accepted repairs (Requirements 1–6).","Cross-reference to EASA AD 2006-0360-E and manufacturer documents requires operators to consult multiple sources to confirm exact procedures and limits (Note/Background)."],"plain_english_summary":"Mechanically: this Airworthiness Directive requires repetitive inspections of specified exhaust tailpipe assemblies (P/N 3G7800L00131 LH and 3G7800L00231 RH) on Agusta AB139/AW139 helicopters (all serials except 31002, 31003, 31004 and 31007), and mandates repair or replacement before further flight if heat damage or certain cracks are found; inspections repeat every 25 flight hours. The AD states its purpose is to prevent cracks developing into tailpipe failure. It affects helicopter operators and maintenance organisations, who must schedule, perform and pay for inspections and any repairs or part replacements."},"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":4,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive focused on a specific known defect in a specific aircraft part. The scope remains tightly constrained to exhaust tailpipe inspections and maintenance for the identified helicopter models and part numbers."},"complexity_factors":["Multiple conditional pathways: 6 numbered requirements with nested sub-requirements (5a, 5b)","Dual applicability tracks: different inspection procedures for AB139 vs AW139 variants despite being nearly identical aircraft","Cross-references to external technical documents: Agusta BT 139-069 Revision A and AW139 Aircraft Maintenance Publication","Geographic/location-based conditions: different repair rules depending on whether cracks are 'inside the cowling' or 'outside the cowling'","Temporal complexity: mix of one-time actions (initial inspection), conditional actions (repair/replace), and ongoing repetitive actions (25-hour intervals)","Non-terminating requirement: explicitly states that repair/replacement does NOT stop the need for future inspections"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice, but for aircraft parts.\n\n**What it does:**\nOrders owners and operators of specific Agusta AB139 and AW139 helicopters to inspect the exhaust tailpipe assembly for cracks and heat damage. If problems are found, the tailpipe must be repaired or replaced. After that, the inspection must be repeated every 25 flight hours.\n\n**Who it affects:**\n- Owners and operators of AB139 and AW139 helicopters (all serial numbers except 31002, 31003, 31004 and 31007)\n- Only applies if the helicopter has specific tailpipe part numbers: 3G7800L00131 (left-hand side) or 3G7800L00231 (right-hand side)\n\n**What must be done:**\n- **Initial inspection:** Within 30 days of the directive taking effect\n- **If damage found inside the engine cowling:** Replace the tailpipe before flying again\n- **If cracks found outside the cowling:** Either repair or replace depending on severity\n- **Ongoing:** Repeat inspections every 25 flight hours indefinitely (repair or replacement doesn't end this requirement)\n\n**Why it matters:**\nCracks in the exhaust tailpipe can worsen and cause complete failure of the exhaust system — a serious safety risk. This directive prevents accidents by catching problems early through mandatory, repeated checks."},"summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This instrument imposes a mandatory inspection and repair regime solely for certain exhaust tailpipe assemblies on Agusta AB139 and AW139 helicopters. It does not alter any other regulatory requirements."},"complexity_factors":["Mandatory airworthiness directive with specific inspection criteria","Multiple conditional repair or replacement paths depending on crack location and severity","Ongoing repetitive inspection requirement that is not terminated by repair or replacement","Applicability depends on specific part numbers and excludes certain serial numbers"],"plain_english_summary":"This AD requires owners/operators of Agusta AB139 and AW139 helicopters (all serials except 31002, 31003, 31004 and 31007) fitted with LH tailpipe P/N 3G7800L00131 or RH P/N 3G7800L00231 to inspect the exhaust tailpipe assembly within 30 days of 10 April 2008 and repeat every 25 flight hours. Find heat damage or disqualifying cracks and replace before further flight; limited repairs are allowed but inspections must continue. The aim is to detect cracks early and prevent tailpipe failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ab139-5-exhaust-tailpipe-assembly","history":"/api/acts/ad-ab139-5-exhaust-tailpipe-assembly/history","analysis":"/api/acts/ad-ab139-5-exhaust-tailpipe-assembly/analysis","conflicts":"/api/acts/ad-ab139-5-exhaust-tailpipe-assembly/conflicts","importantCases":"/api/acts/ad-ab139-5-exhaust-tailpipe-assembly/important-cases","documents":"/api/acts/ad-ab139-5-exhaust-tailpipe-assembly/documents"}}