{"id":"F2006B11256","name":"AD/M20/51 - Main Landing Gear Side Brace Bolt","slug":"ad-m20-51-main-landing-gear-side-brace-bolt","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57031,"registerId":"commonwealth-F2006B11256-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/M20/51 - Main Landing Gear Side Brace Bolt","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/M20/51 Main Landing Gear Side Brace Bolt 1/99\n\nApplicability: The following models and serial numbers: Models Serial Numbers\n\nM20J 24-3415 and 24-3416\n\nM20K 25-2018 through 25-2021\n\nM20M 27-0241\n\nM20R 29-0135 through 29-0138\n\nRequirement: Accomplish the following in accordance with the Instructions section of Mooney Service Bulletin M20-265:\n\n    Grind the surface of the main landing gear (MLG) leg bracket, part number (P/N) 510010. Inspect the affected area of the P/N 510010 MLG leg bracket for cracks.\n\n    2. Replace any cracked P/N 510010 bracket found as a result of the Requirement 1 inspection with a new P/N 510010 MLG leg bracket. Accomplish this replacement in accordance with the applicable maintenance manual.\n\nNote: FAA AD 98-21-26 Amdt 39-10834 refers.\n\nCompliance: 1. With 100 hours time in service after 28 January 1999.\n\n2. Before further flight.\n\nThis Airworthiness Directive becomes effective on 28 January 1999.\n\nBackground: The manufacturing of MLG leg brackets, using laser pattern cutting, prompted the actions required by this directive. The brackets, when manufactured using this process, develop minor cracks at the bends which could propagate over time. The actions required by this directive are intended to prevent failure of the MLG side brace bolt caused by cracking of the MLG leg bracket, and consequent collapse of the landing gear.","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":2,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific manufacturing defect in specific aircraft. It has not expanded beyond its original purpose of preventing landing gear failure in the identified Mooney aircraft models."},"complexity_factors":["Very short document (under 300 words)","Only 4 specific aircraft models affected with enumerated serial numbers","Single mechanical issue with straightforward two-step remedy (inspect, then replace if needed)","No defined terms section or interpretation provisions","Minimal cross-referencing (only one reference to FAA AD 98-21-26 and Mooney Service Bulletin M20-265)","Simple compliance timeline (100 hours or before next flight)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of specified Mooney M20 aircraft to inspect (by grinding and examining) the main landing gear leg bracket (part 510010) and replace any cracked brackets before further flight. It targets a limited set of serial numbers across M20J, M20K, M20M and M20R models because some brackets were laser-cut and can develop cracks.\n\nThe measure prevents landing-gear collapse that could cause serious injury or death; inspections were to be completed within 100 flight hours after 28 January 1999 or immediately if cracks are found."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope aligns with the stated objective in the instrument: to inspect and, if cracked, replace P/N 510010 MLG leg brackets on the listed serial numbers due to cracks from laser pattern cutting. The directive targets those specific aircraft and parts and does not broaden applicability or introduce additional subjects beyond the described inspections, grinding and replacements."},"complexity_factors":["Narrow applicability — only specific Mooney M20 models and serial numbers listed (Applicability).","Clear technical tasking — inspect/grind and replace a single part (P/N 510010) (Requirement).","Dependence on external guidance — work must follow Mooney Service Bulletin M20‑265 and the applicable maintenance manual (Requirement).","Fixed compliance deadlines — 100 hours TIS after 28 January 1999 and replacement before further flight (Compliance).","Safety consequence — failure could cause landing gear collapse, so noncompliance has immediate airworthiness risk (Background).","Logistics and cost considerations — potential need for replacement parts and maintenance facility time, creating out‑of‑pocket costs for owners/operators (Requirement/Compliance).","Traceability and oversight — AD references FAA AD 98‑21‑26, so compliance may involve cross‑checking international airworthiness guidance (Note/Background)."],"plain_english_summary":"Requires owners/operators of listed Mooney M20 aeroplanes to inspect and grind the main landing gear leg bracket (P/N 510010) and replace any cracked brackets per Mooney Service Bulletin M20‑265. Compliance is within 100 hours time‑in‑service after 28 January 1999; replacement must be done before further flight.\n\nPurpose stated: to prevent MLG side brace bolt failure and landing gear collapse caused by cracks from laser‑pattern cutting. Aircraft owners/operators pay for inspections, repairs and replacements and must follow the service bulletin and maintenance manual."}},"importantCases":[],"_links":{"self":"/api/acts/ad-m20-51-main-landing-gear-side-brace-bolt","history":"/api/acts/ad-m20-51-main-landing-gear-side-brace-bolt/history","analysis":"/api/acts/ad-m20-51-main-landing-gear-side-brace-bolt/analysis","conflicts":"/api/acts/ad-m20-51-main-landing-gear-side-brace-bolt/conflicts","importantCases":"/api/acts/ad-m20-51-main-landing-gear-side-brace-bolt/important-cases","documents":"/api/acts/ad-m20-51-main-landing-gear-side-brace-bolt/documents"}}