{"id":"F2006B11154","name":"AD/LEARJET/37 - Outflow/Safety Valve","slug":"ad-learjet-37-outflow-safety-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56845,"registerId":"commonwealth-F2006B11154-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET/37 - Outflow/Safety Valve","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nGates Learjet 24 & 25 Series Aeroplanes\n\nAD/LEARJET/37 Outflow/Safety Valve 3/96\n\nApplicability: Learjet 24/25 series aircraft as identified in Learjet Service Bulletin SB 24/25-21-4.\n\nRequirement: 1. Unless previously carried out, revise the Aircraft Flight Manual to amend the aircraft maximum operating altitude to 41,000 feet by;\n\n    (a) inserting a CASA 'green page' amendment issued under CASA approval number \"24 Initial\" or \"25 Initial\" or,\n\n    (b) inserting Learjet Temporary Flight Manual Change 94-15 dated 9 January 1995.\n\n    2. Unless previously carried out, action in accordance with paragraph 2B and 2C of Learjet Service Bulletin 24/25-21-4 dated 3 January 1995.\n\n    3. Remove the aircraft flight manual change introduced in Requirement 1 by application through the CASA District Airworthiness Office responsible for the aircraft.\n\nNote: FAA AD 95-20-03 Amdt 39-9381 refers and supersedes FAA AD 94-26-01 Amdt 39-9097.\n\nCompliance: Requirement 1. Prior to 1 April 1996.\n\nRequirement 2. Prior to 28 February 1997. Requirement 3. On compliance with Requirement 2.\n\nBackground: The manufacturer has advised that valves identified in Allied Signal Service Bulletin 130406-21-A4011 Revision 3 or 102850-21-4021 Revision 2 may experience fracture or cracking of the poppet valve which could cause rapid decompression of the aircraft. Until affected valves can be replaced a flight manual amendment has been inserted in the Australian flight manual.","sortOrder":0}],"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 AD maintains its original narrow scope — addressing a specific mechanical defect in specific aircraft models. It has not expanded beyond its initial safety purpose."},"complexity_factors":["Short, single-purpose directive with only 3 requirements","Minimal defined terms (only standard aviation terminology like 'CASA' and 'Aircraft Flight Manual')","Simple conditional logic ('Unless previously carried out')","Two external document references (Learjet Service Bulletin and FAA AD) but clear incorporation by reference","Straightforward compliance timeline with only two deadlines","No nested exceptions or complex cross-referencing within the instrument itself"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Gates Learjet 24/25 series in Australia to limit maximum altitude to 41,000 ft until specified inspections and any replacements of outflow/safety valves are completed, to reduce risk of valve failure and rapid decompression. It applies to aircraft covered by the relevant service bulletin and included compliance deadlines in 1996–1997."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"No. The directive keeps its original, narrow scope: impose a temporary AFM limit (41,000 ft), require the inspection/replacement actions in Learjet Service Bulletin 24/25-21-4 (paragraphs 2B/2C), set compliance deadlines, and require formal removal of the AFM change via CASA. It applies only to Learjet 24/25 aircraft identified in the referenced service bulletin."},"complexity_factors":["Limited, specific applicability to Learjet 24/25 aircraft identified in Learjet Service Bulletin 24/25-21-4 (narrows scope)","Two alternative methods to implement the AFM amendment (CASA 'green page' or Learjet TFM change) adds modest procedural choice","Mandated actions reference specific paragraphs (2B and 2C) of the Learjet service bulletin, requiring operators to follow technical instructions outside the AD text","Staged compliance deadlines for AFM amendment (prior to 1 Apr 1996) and valve actions (prior to 28 Feb 1997) introduce scheduling obligations","Removal of the AFM change requires formal application through the CASA District Airworthiness Office (administrative step and regulator discretion)","Cross-reference to FAA ADs increases traceability but requires operators to track related foreign directives"],"plain_english_summary":"**What it does:** Requires operators of Gates Learjet 24/25 aeroplanes identified in the referenced service bulletin to temporarily limit the aircraft's maximum operating altitude to 41,000 ft (by inserting a CASA 'green page' or Learjet Temporary Flight Manual change) and to carry out the inspection/valve-replacement actions set out in Learjet Service Bulletin 24/25-21-4. The AFM change remains until the valve work is completed and the amendment is removed through the CASA District Airworthiness Office. Operators bear the compliance cost and the temporary operational limit."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-37-outflow-safety-valve","history":"/api/acts/ad-learjet-37-outflow-safety-valve/history","analysis":"/api/acts/ad-learjet-37-outflow-safety-valve/analysis","conflicts":"/api/acts/ad-learjet-37-outflow-safety-valve/conflicts","importantCases":"/api/acts/ad-learjet-37-outflow-safety-valve/important-cases","documents":"/api/acts/ad-learjet-37-outflow-safety-valve/documents"}}