{"id":"F2005L02824","name":"AD/B737/57 Amdt 3 - MLG Actuator Beam","slug":"ad-b737-57-amdt-3-mlg-actuator-beam","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37758,"registerId":"commonwealth-F2005L02824-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/57 Amdt 3 | MLG Actuator Beam | 11/2005 |\n| ----------------- | ----------------- | ------- |\n\n| Applicability: | All Model 737-100, -200,-300,-400 and -500 series aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect in accordance with the inspection requirements of Boeing Alert Service Bulletin 737-32A1314.Note 1. Boeing Alert Service Bulletin 737-32A1314 replaces Boeing Alert Service Bulletin 737-32A1224 and previous terminating action is rescinded. Further, the ultrasonic inspection techniques in Boeing Alert Service Bulletin 737-32A1314 vary depending on beam arm part number. Use of the incorrect inspection technique may result in erroneous results.Note 2. FAA AD 99-10-12 Amdt 39-11165 refers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Compliance:    | a. For undercarriage that have been inspected in accordance with Amendment 1 of this AD, inspect within 90 days (in service) or 600 landings of that inspection, whichever occurs first. Re-inspect every 90 days (in service) or 600 landings, whichever occurs first.b. For all other undercarriage, inspect prior to the accumulation of 10,000 landings or 4 years (in service) since new or overhaul, whichever occurs first. Re-inspect every 90 days (in service) or 600 landings, whichever occurs first.Note 3. The inspection interval listed here includes a calendar time in service inspection interval as well as the previously required landing cycle interval. The failure, whilst originating from a corrosion problem also is fatigue based, and there have been failures in Australia. The compliance period therefore reflects the manufacturers SB.Note 4. CASA accepts previous inspections carried out under Amendment 1 of this AD. However, all inspections subsequent to the validity of this AD must be of the revised type. |\n|                | This Amendment becomes effective on 27 October 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n\n| Background: | An Australian aircraft recently had a MLG actuator beam component fail in flight. The failure caused damage to the aileron and spoiler cables, the hydraulic lines and rear wing spar. Subsequent inspection of the remaining aircraft in the operator’s fleet found one other MLG actuator beam with significant cracks.The problem has also been reported on overseas aircraft. These aircraft had similar failures. Boeing has now released a new Service Bulletin dealing with the problem. Amendment 2, effective 12 August 1999, required use of this latest data from the manufacturer.This amendment clarifies the calendar time inspection interval as calendar time in service.Amendment 1 of this Airworthiness Directive became effective on 29 March 1999.The original issue of this Airworthiness Directive became effective on 16 May 1991. |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n15 September 2005","sortOrder":0},{"sectionNumber":"AD/B737/57 Amdt 3","sectionType":"part","heading":"AD/B737/57 Amdt 3","content":"## AD/B737/57 Amdt 3","sortOrder":1},{"sectionNumber":"MLG Actuator Beam","sectionType":"part","heading":"MLG Actuator Beam","content":"## MLG Actuator Beam","sortOrder":2},{"sectionNumber":"11/2005","sectionType":"part","heading":"11/2005","content":"## 11/2005","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD remains tightly focused on its original purpose: preventing MLG actuator beam failures on Classic 737 series aircraft. While it has been amended three times since 1991, each amendment refines the inspection methodology and intervals rather than expanding to new aircraft types or unrelated systems. The scope has not crept beyond the specific safety defect (corrosion/fatigue in actuator beams) that prompted the original directive."},"complexity_factors":["Multiple compliance pathways depending on prior inspection history (two distinct tracks in section 'Compliance')","Dual measurement systems for inspection intervals (calendar time in service AND landing cycles)","Cross-reference to external technical document (Boeing Alert Service Bulletin 737-32A1314) which is not reproduced in the AD","Nested notes (4 notes) that modify or clarify primary requirements","Amendment history references (Amendment 1, Amendment 2, original issue) that contextualize current obligations","Specific part number dependencies for inspection technique selection"],"plain_english_summary":"This AD requires operators of Boeing 737-100/200/300/400/500 (“Classic”) aircraft to carry out mandated inspections of the main landing gear actuator beam for cracks and corrosion after in‑service failures damaged flight controls and structure. It applies to affected Classic 737 fleets because corrosion and metal fatigue can cause catastrophic beam failure. The updated AD clarifies inspection intervals count only actual calendar time in service, not time spent grounded."},"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":true,"description":"This amendment changes scope by requiring inspections per Boeing Alert Service Bulletin 737‑32A1314 (replacing SB 737‑32A1224), rescinding previous terminating action, and clarifying that inspection intervals include calendar time in service as well as landing cycles. It accepts prior inspections done under Amendment 1 but requires all subsequent inspections to follow the revised SB (see Requirement; Compliance; Notes 3–4). Effective date: 27 October 2005."},"complexity_factors":["Multiple aircraft models covered (737‑100, ‑200, ‑300, ‑400, ‑500) increases fleet‑wide coordination and parts variability (Applicability).","Inspection technique varies by beam arm part number; incorrect ultrasonic method may produce erroneous results (Requirement: Boeing Alert Service Bulletin 737‑32A1314).","Two compliance categories: (a) undercarriage previously inspected under Amendment 1 with shorter re‑inspection timing, and (b) other undercarriage with pre‑service limits—creating parallel compliance paths (Compliance: a & b).","Dual interval metric: calendar time in service and landing cycles both apply, requiring mixed recordkeeping and planning (Compliance, Note 3).","Rescinds prior terminating action and replaces an earlier service bulletin, creating dependency on the latest manufacturer data (Requirement: replacement of SB 737‑32A1224).","Regulatory cross‑references to FAA AD 99‑10‑12 and reliance on Boeing service data create interagency and industry dependencies (Requirement).","CASA acceptance of previous inspections under Amendment 1 but mandate that subsequent inspections use the revised type adds administrative discretion and transition management (Compliance, Note 4).","Safety‑critical inspection outcomes (crack detection) increase liability/risk for operators if techniques are misapplied; potential need for training/equipment for ultrasonic inspections."],"plain_english_summary":"**This directive requires regular inspections of the main landing gear (MLG) actuator beam on Boeing 737‑100/200/300/400/500 aeroplanes, using Boeing Alert Service Bulletin 737‑32A1314.** It affects operators and maintenance organisations responsible for those aircraft because inspection technique varies by beam part number and must follow the revised ultrasonic methods; using the wrong technique can give erroneous results. The rule sets specific landing‑cycle and calendar‑time re‑inspection intervals and replaces earlier service‑bulletin requirements."},"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-b737-57-amdt-3-mlg-actuator-beam","history":"/api/acts/ad-b737-57-amdt-3-mlg-actuator-beam/history","analysis":"/api/acts/ad-b737-57-amdt-3-mlg-actuator-beam/analysis","conflicts":"/api/acts/ad-b737-57-amdt-3-mlg-actuator-beam/conflicts","importantCases":"/api/acts/ad-b737-57-amdt-3-mlg-actuator-beam/important-cases","documents":"/api/acts/ad-b737-57-amdt-3-mlg-actuator-beam/documents"}}