{"id":"F2006B08619","name":"AD/CL-600/56 - APU Cooling Air Exhaust","slug":"ad-cl-600-56-apu-cooling-air-exhaust","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51574,"registerId":"commonwealth-F2006B08619-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)![](image.001.png)AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nBombardier (Canadair) CL-600 (Challenger) Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/CL-600/56 APU Cooling Air Exhaust 7/2","sectionType":"part","heading":"AD/CL-600/56 APU Cooling Air Exhaust 7/2002","content":"# AD/CL-600/56 APU Cooling Air Exhaust 7/2002\n\nApplicability: CL-600-2B19 series 100/200 aircraft serial numbers 7003 through 7067 inclusive, and serial numbers 7069 through 7254 inclusive.\n\nRequirement: Modify the APU cooling air exhaust in accordance with Bombardier SB 601R-49- 015.\n\nNote: Canadian AD CF-2002-21 refers.\n\nCompliance: Unless previously accomplished; within 2000 flight hours from the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 11 July 2002.\n\nBackground: Incomplete drainage of the APU enc losure has been reported when operating on the ground. This can be a potential fire hazard. Negative pressure may contribute to this problem. Reworking of the APU enclosure will prevent negative pressure from developing and subsequently reduce drainage problems from the enclosure.\n\n![Signature of James Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 23 May 2002\n\nPage 1 of 1","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Scope aligns with the directive’s stated corrective purpose: it targets a defined subset of CL-600-2B19 airframes and mandates a manufacturer-specified modification within a set flight-hour window to address reported drainage and fire risks. The instrument does not expand or narrow applicability beyond those serial numbers or alter the stated corrective measure in this text."},"complexity_factors":["Narrow, serial-numbered applicability (Applicability: serial numbers 7003–7067 and 7069–7254)","Single, specific corrective action referenced to a manufacturer service bulletin (Requirement: Bombardier SB 601R-49-015)","Fixed compliance window tied to usage (Compliance: within 2000 flight hours)","Technical maintenance work with safety rationale (Background: drainage/negative pressure/fire hazard)","Regulatory enforcement under CAR 1998 subregulation 39.1(1) (opening paragraph delegates authority)","Dependence on external document for implementation details (SB referenced rather than reproduced)"],"plain_english_summary":"This AD requires modification of the APU cooling-air exhaust on specified Bombardier CL-600-2B19 aeroplanes (serial numbers 7003–7067 and 7069–7254) by following Bombardier Service Bulletin 601R-49-015, to be completed within 2,000 flight hours. CASA says the change prevents incomplete drainage and a potential fire hazard by eliminating negative pressure in the APU enclosure. Aircraft owners/operators must arrange and pay for the modification, incurring maintenance cost and downtime and relying on the manufacturer’s service instructions."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific unsafe condition in a specific aircraft model. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific aircraft type and narrow serial number range (no broad applicability)","Only one requirement: follow a single referenced service bulletin","Simple compliance condition: time-based (flight hours) with single exception (if already done)","No defined terms section, no cross-references to other legislation beyond the enabling regulation (CAR 1998 subreg 39.1(1))","Background is one paragraph with clear causal explanation","Total length: approximately 250 words"],"plain_english_summary":"This AD requires owners/operators of certain Bombardier Challenger 600 series (CL-600-2B19) jets (specific serials listed in the AD) to modify APU cooling-air venting per Bombardier Service Bulletin 601R-49-015. It fixes water drainage and negative-pressure issues in the APU bay that create a fire risk. Compliance is mandatory within 2,000 flight hours after 11 July 2002; non‑compliance grounds the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cl-600-56-apu-cooling-air-exhaust","history":"/api/acts/ad-cl-600-56-apu-cooling-air-exhaust/history","analysis":"/api/acts/ad-cl-600-56-apu-cooling-air-exhaust/analysis","conflicts":"/api/acts/ad-cl-600-56-apu-cooling-air-exhaust/conflicts","importantCases":"/api/acts/ad-cl-600-56-apu-cooling-air-exhaust/important-cases","documents":"/api/acts/ad-cl-600-56-apu-cooling-air-exhaust/documents"}}