{"id":"F2007L04027","name":"AD/ATR 42/20 - Main Landing Gear - Side Brace Assembly","slug":"ad-atr-42-20-main-landing-gear-side-brace-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":160815,"registerId":"commonwealth-F2007L04027-current","compilationNumber":null,"startDate":"2026-04-04","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Avions de Transport Regional ATR 42 Seri","sectionType":"division","heading":"Avions de Transport Regional ATR 42 Series Aeroplanes","content":"### Avions de Transport Regional ATR 42 Series Aeroplanes\n\n| AD/ATR 42/20 | Main Landing Gear - Side Brace Assembly | 12/2007 DM |\n| ------------ | --------------------------------------- | ---------- |\n\n| Applicability: | ATR 42-200, 42-300 and 42-320, all serial numbers, unless MLG side brace assemblies P/N D22710000 with suffix “-9” are installed on both sides, as specified in ATR Service Bulletin (SB) ATR 42-32-0092 (ATR modification No. 8463).                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Carry out inspections and actions as required by EASA AD 2007-0263, dated3 October 2007.Note: The referenced EASA AD 2007-0263 supersedes EASA AD 2007-0112, issued 27 April 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Compliance:    | As per requirement document (EASA AD 2007-0263), with a revised effective date of 25 October 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n|                | This Airworthiness Directive becomes effective on 25 October 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Background:    | An ATR 42-300 experienced a collapse of the Right (Starboard) Main Landing Gear when taxiing. The cause of the failure was subsequently found to be a crack in the side brace assembly originating from a corrosion pit in a very highly stressed area of the upper arm. The dimensions of the corrosion pit were lower than the minimum defect size that can be detected during overhaul inspections.This AD is issued to require re-inspection of MLG side brace assemblies previously inspected in accordance with Rev 1 of Messier Dowty SB 631-32-191 and reduces the inspection interval initially proposed in EASA AD 2007-0112 in order to maintain the same level of confidence. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n5 October 2007","sortOrder":0},{"sectionNumber":"AD/ATR 42/20","sectionType":"part","heading":"AD/ATR 42/20","content":"## AD/ATR 42/20","sortOrder":1},{"sectionNumber":"Main Landing Gear - Side Brace Assembly","sectionType":"part","heading":"Main Landing Gear - Side Brace Assembly","content":"## Main Landing Gear - Side Brace Assembly","sortOrder":2},{"sectionNumber":"12/2007 DM","sectionType":"part","heading":"12/2007 DM","content":"## 12/2007 DM","sortOrder":3}],"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This AD narrows operational risk by reducing inspection intervals and mandating re-inspection of MLG side brace assemblies previously inspected under Messier Dowty SB 631-32-191 Rev 1, thereby changing the inspection regime set out in the earlier EASA AD 2007-0112 (Requirement; Background). It also excludes aircraft that already have P/N D22710000-\"-9\" assemblies installed on both sides (Applicability)."},"complexity_factors":["Cross-references to external mandatory documents: EASA AD 2007-0263 and Messier Dowty SB 631-32-191 Rev 1 (Requirement; Background).","Conditional applicability based on part-number suffix: exemptions where MLG side brace assemblies P/N D22710000-\"-9\" are installed on both sides (Applicability).","Change in inspection regime: shortened inspection intervals relative to the earlier EASA AD 2007-0112 and a re-inspection mandate (Requirement; Background).","Safety-critical inspection and corrective-action tasks that require technical competence and may incur parts/labour costs for operators (Requirement; Background).","Effective date and compliance deadline mechanics that create a near-term implementation obligation (Compliance; Effective date: 25 October 2007).","Traceability and records burden implied by re-inspection of parts previously inspected under a specified service bulletin (Background; Requirement)."],"plain_english_summary":"This Airworthiness Directive requires operators of `ATR 42-200/300/320` aeroplanes (unless both sides already have MLG side brace assemblies P/N D22710000 with suffix “-9”) to carry out inspections and corrective actions specified in EASA AD 2007-0263. It is effective 25 October 2007. The measure responds to a main landing gear collapse caused by a crack from a corrosion pit and shortens inspection intervals compared with an earlier AD, including re-inspection of assemblies previously checked under Messier Dowty SB 631-32-191 Rev 1."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific mechanical failure mode in a defined aircraft fleet. The scope remains precisely focused on the original safety concern (MLG side brace assembly cracking) without expansion into unrelated systems or operational requirements."},"complexity_factors":["Short, single-purpose directive (approximately 250 words of substantive content)","Only 1 defined applicability criterion with a single exception clause","References external technical documents (EASA AD 2007-0263 and ATR Service Bulletin) rather than reproducing detailed procedures inline","Simple conditional structure: applies to all aircraft EXCEPT those with specific modification","No nested exceptions or multi-layered compliance pathways","Single compliance pathway with clear effective date"],"plain_english_summary":"Owners/operators of ATR 42-200/300/320 series must inspect main landing gear side brace assemblies for corrosion-induced cracking. Prompted by a taxiing gear collapse traced to corrosion pitting too small for routine overhaul detection, the AD adopts EASA inspection procedures with tighter intervals (effective 25 Oct 2007). Aircraft already fitted with upgraded “-9” side braces are exempt."}},"importantCases":[],"_links":{"self":"/api/acts/ad-atr-42-20-main-landing-gear-side-brace-assembly","history":"/api/acts/ad-atr-42-20-main-landing-gear-side-brace-assembly/history","analysis":"/api/acts/ad-atr-42-20-main-landing-gear-side-brace-assembly/analysis","conflicts":"/api/acts/ad-atr-42-20-main-landing-gear-side-brace-assembly/conflicts","importantCases":"/api/acts/ad-atr-42-20-main-landing-gear-side-brace-assembly/important-cases","documents":"/api/acts/ad-atr-42-20-main-landing-gear-side-brace-assembly/documents"}}