{"id":"F2006L01688","name":"AD/DHC-8/122 - Engine Exhaust Shroud V-band Coupling","slug":"ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":59444,"registerId":"commonwealth-F2006L01688-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier (Boeing Canada/De Havilland) ","sectionType":"division","heading":"Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","content":"### Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\n| AD/DHC-8/122 | Engine Exhaust Shroud V-band Coupling | 7/2006 |\n| ------------ | ------------------------------------- | ------ |\n\n| Applicability: | Bombardier Inc. Model DHC-8-400, DHC-8-401 and DHC-8-402 Serial Numbers 4001 through 4098 with engine exhaust shroud V-band clamps (part numbers VC1642A-1875-A or VC1642A-2030-A) that have manufacturer batch stamp dated earlier than 08 02 (August 2002).                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Unless previously accomplished carry out an inspection and replacement (as required) of the V-band clamps to ensure a proper gap, in accordance with Bombardier SB84-78-01, Revision A, dated 15 September 2005, or later Transport Canada approved revisions.Note: Transport Canada AD CF-2006-06 dated 4 April 2006 refers.                                                                                                                                                                                                                                                                                                                                                                                                |\n| Compliance:    | Within 5000 flight hours after the effective date of this AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n|                | This Airworthiness Directive becomes effective on 6 July 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | There have been reports of a discrepancy on a V-band clamp located on the engine exhaust duct shroud during maintenance inspections. The clamp ends were found touching with the correct fastener torque applied, resulting in reduced clamp force on the flanges.Investigation revealed that a batch of V-band clamps was not manufactured to the drawing specifications. If not corrected, this condition may cause vibration and fretting of the V-band clamp flanges, leading to flange cracking and local area overheating. This situation can trigger the fire warning system and result in an in-flight emergency such as the flight crew requiring to shut down the engine and activate the fire suppression system. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n24 May 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/122","sectionType":"part","heading":"AD/DHC-8/122","content":"## AD/DHC-8/122","sortOrder":1},{"sectionNumber":"Engine Exhaust Shroud V-band Coupling","sectionType":"part","heading":"Engine Exhaust Shroud V-band Coupling","content":"## Engine Exhaust Shroud V-band Coupling","sortOrder":2},{"sectionNumber":"7/2006","sectionType":"part","heading":"7/2006","content":"## 7/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive remains narrowly focused on correcting a specific manufacturing non‑conformance in a batch of V-band clamps to prevent flange damage and possible engine fire indications. It does not broaden the subject matter beyond that original safety purpose. The mechanism (inspection and replacement per the manufacturer’s service bulletin, with a regulator-approved revision pathway and a 5,000 flight-hour compliance window) is consistent with the ordinary approach to airworthiness corrections and does not materially expand scope."},"complexity_factors":["Short, single-issue directive focused on one part (V-band clamp).","Applicability limited to specific aircraft serial numbers (4001–4098) and two part numbers with a batch-stamp cutoff (pre-08 02).","One mandatory action (inspect and replace as required) with a single compliance window (5000 flight hours).","Cross-reference to a single service bulletin (Bombardier SB84-78-01 Rev A) and allowance for later Transport Canada–approved revisions.","No layered exceptions or nested conditional provisions beyond the 'unless previously accomplished' clause."],"plain_english_summary":"**What this airworthiness directive does**\n\n- Requires operators of certain Bombardier DHC-8-400 series aeroplanes to inspect the engine exhaust shroud V-band clamps and replace any that do not meet the required gap specification. (See: Requirement.)\n\n**Which aeroplanes are affected**\n\n- Bombardier DHC-8-400, DHC-8-401 and DHC-8-402 with serial numbers 4001 through 4098, but only where the exhaust shroud V-band clamps have part numbers VC1642A-1875-A or VC1642A-2030-A and carry a manufacturer batch stamp dated earlier than \"08 02\" (August 2002). (See: Applicability.)\n\n**What the operator must do and by when**\n\n- Unless the inspection/replacement has already been done, carry out the inspection and replace any defective clamps to ensure the correct gap, following Bombardier Service Bulletin SB84-78-01, Revision A, dated 15 September 2005 (or a later Transport Canada–approved revision). (See: Requirement.)\n- The work must be completed within 5,000 flight hours after the AD’s effective date. The AD became effective 6 July 2006. (See: Compliance and Effective date.)\n\n**Why the rule was made (technical cause)**\n\n- Maintenance inspections found some V-band clamp ends touching even when fasteners were correctly torqued. Investigation showed a batch of clamps was not manufactured to drawing specifications. This can reduce clamp force, allow vibration and fretting, cause flange cracking and local overheating, possibly triggering a fire warning and resulting in engine shutdown and fire suppression by the crew. (See: Background.)\n\n**Practical effects, who pays, and who decides**\n\n- Who pays: Aircraft operators (airlines, lessors or owners) must organise and pay for the inspection and any required clamp replacements, and for any downtime while the work is done. (Requirement; Compliance.)\n- Who decides: The directive prescribes the inspection and replacement procedure and refers operators to the manufacturer’s service bulletin; Transport Canada approval governs any later revisions to that bulletin. The regulator (through the AD) sets the requirement and the compliance window. (Requirement.)\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: material (replacement clamps where faulty), labour for inspection and replacement, and aircraft out-of-service time. Those costs are concentrated on the affected aircraft operators and any maintenance organisations doing the work. (Applicability; Requirement; Compliance.)\n- Safety benefit: reduces risk of in-flight engine shutdowns that could follow a false fire warning or actual local overheating. (Background.)\n- Supply and timing risk: if a significant number of clamps need replacement, demand for replacement parts may rise in the short term; the 5,000 flight-hour compliance window spreads the work over time but does not eliminate potential short-term bottlenecks. (Compliance.)\n- Compliance burden: routine maintenance organisations can perform the inspection under the service bulletin; operators must track batch stamps and maintenance records to determine applicability and whether the work is already done. (Applicability; Requirement.)\n- Regulatory discretion and updates: the AD lets operators use later Transport Canada–approved revisions of the service bulletin, which centralises approval of procedural changes with the regulator. (Requirement.)\n\n**Implementation and enforcement considerations**\n\n- Inspectors must check part numbers and batch stamps; incomplete or inaccurate records increase the chance of non-compliance or unnecessary replacements. (Applicability.)\n- The AD is targeted and limited in scope (specific serial numbers, part numbers and batch stamps), which simplifies enforcement but requires careful record checks. (Applicability.)\n\nReferences in the text: Applicability; Requirement (Bombardier SB84-78-01, Rev A); Compliance (5,000 flight hours; effective date 6 July 2006); Background (manufacturing non-conformance, possible consequences)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original, narrow scope. It addresses a specific manufacturing defect in a specific batch of parts on specific aircraft. There is no evidence of scope creep; the directive remains tightly focused on the exhaust clamp safety issue identified in the background."},"complexity_factors":["Single, specific mechanical issue (V-band clamp manufacturing defect)","Narrow applicability: only 3 aircraft models, specific serial number range, specific part numbers, specific manufacturing date cutoff","Clear, single compliance action (inspect and replace per referenced service bulletin)","Simple time-based compliance deadline (5,000 flight hours)","No nested exceptions, conditional logic, or alternative compliance methods","Minimal cross-referencing (only to Bombardier service bulletin and Transport Canada AD)","No defined terms section — uses standard aviation terminology"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and, if necessary, replacement of specific V‑band engine exhaust clamps on Bombardier DHC‑8‑400 series (serials 4001–4098). Clamps with part numbers VC1642A‑1875‑A or VC1642A‑2030‑A manufactured before Aug 2002 can gap when tightened, risking exhaust flange cracks, overheating, false fire warnings and possible in‑flight engine shutdown. Compliance per Bombardier service instructions is mandatory within 5,000 flight hours after 6 July 2006."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling","history":"/api/acts/ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling/history","analysis":"/api/acts/ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling/analysis","conflicts":"/api/acts/ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling/conflicts","importantCases":"/api/acts/ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling/important-cases","documents":"/api/acts/ad-dhc-8-122-engine-exhaust-shroud-v-band-coupling/documents"}}