{"id":"F2006B07217","name":"AD/SWSA226/74 Amdt 3 - Landing Gear Stress Corrosion","slug":"ad-swsa226-74-amdt-3-landing-gear-stress-corrosion","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48999,"registerId":"commonwealth-F2006B07217-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SWSA226/74 Amdt 3 - Landing Gear Stress Corrosion","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)  \nFairchild (Swearingen) SA226 and SA227 Series Aeroplanes\n\nAD/SWSA226/74\n\nAmdt 3\n\n  \nLanding Gear Stress Corrosion 2/98\n\nApplicability: Models SA226-T, SA226-AT, SA226-TC, SA226-T(B), SA227-AC, SA227-AT,\n\nSA227-BC, SA227-TT, SA227-CC, and SA227-DC, all serial numbers, equipped with one or more of the following Ozone Industries Inc:\n\n    MLG Yoke P/n OAS5453 all dash numbers up to and including \\-19 or\n    NLG yoke P/n OAS5451 all dash numbers up to and including -17 Requirement: 1. Inspect and protect, in accordance with the following Fairchild SBs as revised\n\n28 September 1995, and as applicable:\n\na. SB 226-32-065,\n\nb. SB 227-32-039, or\n\nc. SB CC7-32-007.\n\nNote: Requirement document Effective pages are as follows:\n\na. 1, 5, and 8 Revised 28 September 1995\n\nb. 2, 3, 4, 6, 7, and 9 Issued 16 August 1995.\n\n2. Replace cracked NLG and MLG yokes.\n\nNote 1. Replacement of a yoke assembly with an approved part other than that specified in the Applicability statement terminates the repetitive inspection requirement for that landing gear.\n\nNote 2. FAA AD 96-19-05 refers.\n\nCompliance: 1. Unless already accomplished, within 75 hours time in service after 29 January 1998, or prior to the installation of a replacement nose or main landing gear; thereafter, at intervals not exceeding 2500 hours time in service or 12 months, whichever occurs first.\n\n2. Prior to further flight.\n\nThis amendment becomes effective on 29 January 1998.\n\nBackground: The actions specified in this Directive are intended to prevent MLG or NLG failure caused by stress corrosion cracks in the yokes, which if not detected could cause loss of control of the aircraft during landing operations.\n\nAmendment 1 was raised to incorporate the revised procedures of the amended requirement document and the revised FAA AD.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nAmendment 2 was raised to remove cracked NLG and MLG yokes from service, due to an inability to determine, or to predict, crack growth on areas where stress corrosion occurs in primary structure with a single load path, (landing gear is considered to be such structure).\n\nAmendment 3 is raised to clarify that a MLG yoke or NLG yoke must now be removed from service before further flight if any cracks are detected during inspection. The previous staggered replacement time was intended to be applicable for the initial inspection only.\n\nAmendment 2 of this airworthiness directive became effective on 30 October 1995\\. Amendment 1 of this airworthiness directive became effective on 27 October 1995.\n\nThe original issue of this airworthiness directive became effective on 25 October 1995.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Amendment 3 clarified and tightened a compliance requirement (making clear that any yoke found cracked must be removed from service before further flight) but did not broaden the affected fleet, add new aircraft types, or expand the technical subject matter beyond the original intent to address stress-corrosion cracking of landing gear yokes. Earlier amendments adjusted procedures and the removal requirement; this amendment is a clarification and enforcement tightening rather than an expansion of scope."},"complexity_factors":["Short, self-contained directive (single AD with three numbered requirements).","Applicability limited to specific aircraft models and two specific part numbers with dash-number ranges (some precision required).","Cross-references to three Fairchild Service Bulletins and one FAA AD (external documents contain procedural detail).","Two-stage compliance timing: initial inspection deadline (75 hours or before replacement) and recurring intervals (2,500 hours or 12 months).","A special-case rule: replacing a yoke with an approved alternative part terminates repetitive inspections (conditional exception).","Amendment history and clarifying language (Amendments 1–3) could cause confusion about which procedures and deadlines apply unless the latest text is read carefully."],"plain_english_summary":"**What this directive does (mechanics)\n\n- This Airworthiness Directive (AD) applies to Fairchild (Swearingen) SA226 and SA227 series aeroplanes listed in the Applicability that have Ozone Industries yokes: main landing gear (MLG) yoke part number OAS5453 (dash numbers up to -19) or nose landing gear (NLG) yoke part number OAS5451 (dash numbers up to -17).\n\n- It requires operators to inspect and protect those yokes following the specified Fairchild Service Bulletins (SB 226-32-065, SB 227-32-039 or SB CC7-32-007) as revised on the dates shown in the AD.\n\n- If a crack is found in an NLG or MLG yoke, the yoke must be removed from service (replaced) before the aircraft is flown again.\n\n- Repetitive inspections must be carried out after the initial inspection: inspections at intervals not exceeding 2,500 hours time-in-service or 12 months, whichever occurs first.\n\n- Initial compliance deadline (where not already done) is within 75 hours time-in-service after 29 January 1998, or before installing a replacement landing gear yoke.\n\n- Replacing the yoke with an approved part other than the specified Ozone parts terminates (stops) the repetitive-inspection requirement for that landing gear.\n\n\nWhy the rule exists (stated purpose)\n\n- The AD’s stated purpose is to prevent failure of the nose or main landing gear caused by stress-corrosion cracks in the yokes. If such cracks are not detected and a yoke fails, it could lead to loss of control during landing operations.\n\n\nWho this affects and who pays\n\n- Affected parties: owners/operators of the specified SA226/SA227 aeroplane models that have the listed Ozone yokes fitted.\n\n- Who pays: aircraft owners/operators pay for inspections, protective work, and any replacements (parts and labour). Maintenance organisations perform the work under the applicable maintenance regulations.\n\n\nPractical effects on behaviour and choices\n\n- Operators must schedule and carry out the inspections at the prescribed initial deadline and at the ongoing intervals (2,500 hours or 12 months).\n\n- If a crack is detected, operators must ground the aircraft for that landing gear and replace the yoke before further flight.\n\n- Operators may choose to fit an approved alternative yoke part (not the listed Ozone parts); doing so removes the need for further repetitive inspections for that gear.\n\n- Maintenance workload and parts demand for replacement yokes are likely to increase for affected fleets.\n\n\nCosts, incentives, and trade-offs (implementation reality)\n\n- Direct costs: labour, inspection time (aircraft downtime), protective work specified in the Service Bulletins, and replacement parts where cracks are found or operators elect to change to a different approved yoke.\n\n- Incentives created: operators have a clear economic incentive to either comply with repetitive inspections or to invest in an approved replacement yoke that avoids future inspections (one-off capital cost vs ongoing inspection costs).\n\n- Risk and uncertainty: the AD reflects an inability to predict crack growth reliably in a single-load-path primary structure (landing gear), which drives a precautionary replacement rule when cracks are found.\n\n- Implementation burden: compliance requires following specific manufacturer Service Bulletins; this imposes a technical compliance task on approved maintenance organisations and operators.\n\n\nRegulatory and market effects\n\n- Regulatory decision-maker: the Civil Aviation Safety Authority (through the AD) sets the requirement; compliance is enforceable under the Civil Aviation Regulations framework.\n\n- Effects on private enterprise: independent maintenance organisations can perform inspections and replacements subject to certification; parts suppliers of approved alternative yokes may see increased demand.\n\n- Competition and prices: if alternative approved parts are available from a limited supplier set, operators may face concentrated parts costs; otherwise operators manage a trade-off between inspection costs and replacement-part costs.\n\n\nNotes and cross-references\n\n- The AD cross-references specific Fairchild Service Bulletins for the inspection and protection procedures and references FAA AD 96-19-05 for related action.\n\n- This amendment (Amendment 3) clarifies that any crack found requires removal from service before further flight; earlier wording had allowed a staggered replacement schedule for the initial inspection only, which this amendment corrects.\n\n\nBottom line (concise): The AD mandates regular inspection and protection of specific Ozone-manufactured landing-gear yokes on certain SA226/227 aircraft, requires immediate replacement of any cracked yoke before further flight, and allows operators to stop the inspection cycle by fitting an approved alternative yoke. The rule increases maintenance and parts costs for affected operators but reduces the risk of landing-gear failure from stress-corrosion cracking."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original directive (October 1995) required inspections and protective treatments. Amendment 2 (October 1995) expanded scope to mandate removal of cracked parts from service. Amendment 3 (January 1998) further tightened the scope by eliminating any staggered or deferred replacement timeline for cracked parts, requiring immediate grounding. The directive has evolved from a preventive maintenance schedule to an immediate-action safety mandate, significantly narrowing operational flexibility for operators."},"complexity_factors":["Multiple amendment history requiring cross-referencing (Amendments 1, 2, and 3) to understand current requirements","Specific part number ranges with dash number cutoffs (\"up to and including -19/-17\") requiring careful parts catalog verification","Dual compliance timelines: initial 75-hour window versus ongoing 2,500 hour/12-month recurring intervals","Conditional logic: \"Unless already accomplished\" and \"whichever occurs first\" qualifiers","Reference to external documents (FAA AD 96-19-05 and three specific Fairchild Service Bulletins) that are not reproduced in the text","Technical aviation terminology requiring domain knowledge (MLG/NLG, \"time in service\", \"single load path\", \"dash numbers\")"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection, corrosion protection, and recurring checks of specific Ozone landing‑gear yokes on listed Fairchild (Swearingen) SA226/SA227 models. If stress‑corrosion cracks are found the yoke must be replaced before the aircraft flies again, and inspections repeat every 2,500 flight hours or 12 months. Amendment 3 removes any grace period: cracked parts require immediate replacement to prevent catastrophic landing‑gear failure."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-swsa226-74-amdt-3-landing-gear-stress-corrosion","history":"/api/acts/ad-swsa226-74-amdt-3-landing-gear-stress-corrosion/history","analysis":"/api/acts/ad-swsa226-74-amdt-3-landing-gear-stress-corrosion/analysis","conflicts":"/api/acts/ad-swsa226-74-amdt-3-landing-gear-stress-corrosion/conflicts","importantCases":"/api/acts/ad-swsa226-74-amdt-3-landing-gear-stress-corrosion/important-cases","documents":"/api/acts/ad-swsa226-74-amdt-3-landing-gear-stress-corrosion/documents"}}