{"id":"F2006B11255","name":"AD/M20/50 Amdt 1 - M20J Alternate Air Inlet Door","slug":"ad-m20-50-amdt-1-m20j-alternate-air-inlet-door","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57028,"registerId":"commonwealth-F2006B11255-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/M20/50 Amdt 1 - M20J Alternate Air Inlet Door","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)  \nMooney M20 Series Aeroplanes\n\nAD/M20/50\n\nAmdt 1\n\n  \nM20J Alternate Air Inlet Door 4/96\n\nApplicability: Model M20J aeroplanes serial numbers 24-0001 through 24-3243, 24-3244 through 24-3250 and 24-3252 through 24-3374.\n\nRequirement: Modify the alternate air inlet door in accordance with the instructions detailed in Mooney Aircraft Corporation Service Bulletin M20-250B or Service Bulletin M20- 253A, as applicable.\n\nCompliance: Effective 28 March 1996; within 10 hours time in service.\n\nBackground: This Directive was originally issued to require an inspection of the engine induction system for fitment and security of the alternate air inlet door bolt cotter pin. The requirement followed advice of a fatal M20J accident. This amendment requires the alternate air inlet door to be modified. The modification basically reverses the alternate air inlet door assembly bolt and introduces a securing castellated nut, washer and cotter pin now placed outside the induction box.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original safety purpose — addressing a specific mechanical defect in the M20J alternate air inlet door that caused a fatal accident. The amendment expands from inspection to mandatory modification, but this is a natural progression of the same safety issue rather than scope creep. The applicability (serial number ranges) and fundamental subject matter remain unchanged from the original directive."},"complexity_factors":["Very short document (approximately 200 words)","Only 3 defined applicability ranges (serial number blocks)","Single technical requirement with two alternative compliance paths (Service Bulletin M20-250B or M20-253A)","No nested exceptions or conditional logic","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Clear, single compliance deadline with simple calculation method (10 hours time in service)"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or modifications to aircraft.\n\n**What it does:** Orders owners and operators of specific Mooney M20J aeroplanes to modify the \"alternate air inlet door\" — a component in the engine's air intake system. The modification involves reversing a bolt and adding a securing nut, washer and cotter pin on the outside of the induction box (the part that channels air into the engine).\n\n**Who it affects:** Owners and operators of Mooney M20J model aeroplanes with serial numbers 24-0001 through 24-3243, 24-3244 through 24-3250, and 24-3252 through 24-3374.\n\n**Why it matters:** This directive was triggered by a fatal accident involving an M20J aircraft. The original version required inspection of a cotter pin (a small metal fastener that prevents bolts from loosening). This amended version goes further — it mandates a physical modification to prevent the bolt from failing or coming loose, which could cause engine failure.\n\n**Compliance deadline:** The work had to be completed within 10 hours of flying time after 28 March 1996.\n\n**Key takeaway:** If you own one of these specific Mooney aircraft, you must get this safety modification done to keep your plane legally airworthy and prevent potentially catastrophic engine failure."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Yes. The original directive required an inspection of the engine induction system for cotter-pin fitment and security; this amendment mandates a hardware modification—reversing the inlet-door bolt and relocating the castellated nut, washer and cotter pin outside the induction box—as set out in the Requirement and explained in the Background."},"complexity_factors":["Narrow applicability by precise serial-number ranges (Applicability) increases tracking and record-keeping for affected operators.","Technical instruction delegated to manufacturer service bulletins (Requirement) — requires access to and compliance with those external documents.","Very short compliance window: modification due within 10 hours time in service (Compliance) raises scheduling and operational disruption risk.","Cost and execution fall on aircraft owners/operators who must arrange the physical modification (Requirement).","Change replaces a prior inspection-only mandate with a mandatory hardware modification (Background), reducing ongoing inspection uncertainty but increasing one-off compliance burden.","Clear causal safety trigger noted (fatal accident) (Background), but little regulatory discretion or phased remedying allowed in the text."],"plain_english_summary":"Requires a specific mechanical change to the alternate air inlet door on listed Mooney M20J aeroplanes: reverse the inlet-door bolt and fit a castellated nut, washer and external cotter pin as detailed in Mooney Service Bulletin M20-250B or M20-253A. This applies to owners/operators of the listed serial-number aircraft and must be done within 10 hours time in service to address a safety issue identified after a fatal accident."}},"importantCases":[],"_links":{"self":"/api/acts/ad-m20-50-amdt-1-m20j-alternate-air-inlet-door","history":"/api/acts/ad-m20-50-amdt-1-m20j-alternate-air-inlet-door/history","analysis":"/api/acts/ad-m20-50-amdt-1-m20j-alternate-air-inlet-door/analysis","conflicts":"/api/acts/ad-m20-50-amdt-1-m20j-alternate-air-inlet-door/conflicts","importantCases":"/api/acts/ad-m20-50-amdt-1-m20j-alternate-air-inlet-door/important-cases","documents":"/api/acts/ad-m20-50-amdt-1-m20j-alternate-air-inlet-door/documents"}}