{"id":"F2006B01927","name":"AD/A320/37 - Thrust Reverser Check Valve Replacement","slug":"ad-a320-37-thrust-reverser-check-valve-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41149,"registerId":"commonwealth-F2006B01927-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A320/37 - Thrust Reverser Check Valve Replacement","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-description: CASA Airworthiness Directive\nmeta-generator: Aspose.Words for .NET 22.10.0\nmeta-keywords: Issue 7/1994,Aircraft above 5700 kg,Airbus Industrie A319, A320 and A321 Series Aeroplanes,Thrust Reverser Check Valve Replacement,37\ntitle: Airworthiness Directive - AD/A320/37 - Thrust Reverser Check Valve Replacement\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Airbus Industrie A319, A320 and A321 Series Aeroplanes\n\n \n\nAD/A320/37 Thrust Reverser Check Valve Replacement 7/94\n\nApplicability: All A320 aircraft not incorporating Airbus Industrie modification 22537 or SB A320- 29-1048 R1.\n\nRequirement: Action in accordance with Airbus Industrie Service Bulletin A320-29-1048 R1.\n\nNote: DGAC AD 94-059-054(B) dated 16 March 1994 refers.\n\nCompliance: No later than 31 December 1994.\n\nBackground:  Airbus Industrie advise that this action is required to prevent pressurisation of the Hydraulic Control Unit return line in the event of failure in the closed position of the check valve in the thrust reverser hydraulic return line.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Scope aligns with the stated safety objective: it targets aircraft lacking a specified modification or service bulletin and mandates a single corrective action by a set date. There is no indication in the text that the AD expands affected types or imposes obligations other than the valve replacement per the Airbus Service Bulletin."},"complexity_factors":["Narrow applicability: only A319/A320/A321 aircraft without mod 22537 or SB A320‑29‑1048 R1 (Applicability).","Single, specific technical action: replacement per a single Airbus Service Bulletin (Requirement).","Fixed compliance deadline creates scheduling pressure: no later than 31 December 1994 (Compliance).","Safety-critical hydraulic component: consequence of failure is pressurisation of the Hydraulic Control Unit return line (Background).","Reliance on manufacturer procedure means operator compliance depends on access to the specified SB and parts (Requirement).","Administrative tracking required to show conformity with the AD and deadline (Applicability; Compliance)."],"plain_english_summary":"This directive requires operators of Airbus A319/A320/A321 aeroplanes that have not incorporated modification 22537 or Service Bulletin A320‑29‑1048 R1 to replace the thrust‑reverser hydraulic check valve in accordance with Airbus Service Bulletin A320‑29‑1048 R1. Compliance is mandated by the Civil Aviation Safety Authority no later than 31 December 1994 (Applicability; Requirement; Compliance).\n\nThe stated purpose is to prevent pressurisation of the Hydraulic Control Unit return line if the check valve fails closed (Background). Aircraft owners/operators pay for parts, labour and scheduling and must follow the manufacturer's procedure."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical component in specific aircraft models. It has not expanded beyond its original purpose of mandating a valve replacement to prevent hydraulic pressure issues."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined applicability criteria (aircraft model and modification status)","Single, unambiguous compliance action (replace valve per specified service bulletin)","No nested exceptions or conditional logic — compliance is binary (do it or don't based on modification status)","No cross-references to other legislation beyond a single note referencing the French aviation authority's equivalent directive","Clear, fixed deadline with no alternative compliance methods or phased implementation"],"plain_english_summary":"This CASA Airworthiness Directive required operators of certain Airbus A319/A320/A321 aircraft (unless already modified per Airbus mod 22537/Service Bulletin A320‑29‑1048 R1) to replace a faulty thrust reverser check valve. Failure of the valve in the closed position could build harmful hydraulic pressure, damage the Hydraulic Control Unit or impair thrust reverser function, risking reduced stopping ability after landing. The replacement was mandatory by 31 December 1994."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a320-37-thrust-reverser-check-valve-replacement","history":"/api/acts/ad-a320-37-thrust-reverser-check-valve-replacement/history","analysis":"/api/acts/ad-a320-37-thrust-reverser-check-valve-replacement/analysis","conflicts":"/api/acts/ad-a320-37-thrust-reverser-check-valve-replacement/conflicts","importantCases":"/api/acts/ad-a320-37-thrust-reverser-check-valve-replacement/important-cases","documents":"/api/acts/ad-a320-37-thrust-reverser-check-valve-replacement/documents"}}