{"id":"F2005L03554","name":"AD/B737/257 - Bendix Main Wheel","slug":"ad-b737-257-bendix-main-wheel","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39076,"registerId":"commonwealth-F2005L03554-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/B737/257 | Bendix Main Wheel | 13/2005 |\n| ----------- | ----------------- | ------- |\n\n| Applicability: | Model 737-100 and -200 series aircraft equipped with Bendix main wheel assembly part number 2601571-1.                                                                                                                                                                                                                                                                                                                             |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 98-26-24Amdt 39-10967.Note: Bendix Service Information Letter 392 Revision 1 and Allied Signal Service Bulletin No. 737-32-026 dated 27 June 1998 including Attachment 1 dated17 January 1978 and Attachment 2 dated 27 June 1988, or later FAA approved revisions/attachments, refer.                                                                              |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of22 December 2005.                                                                                                                                                                                                                                                                                                                                        |\n|                | This Airworthiness Directive becomes effective on 22 December 2005.                                                                                                                                                                                                                                                                                                                                                                |\n| Background:    | This Directive requires replacement of certain wheel halves with improved wheel halves and inspections for corrosion, missing paint, or cracks, and repair and replacement if necessary. The actions specified by this Directive are intended to prevent failure of the wheel flanges, which could result in damage to the hydraulic systems, jammed flight controls, loss of electrical power, or other combinations of failures. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n10 November 2005","sortOrder":0},{"sectionNumber":"AD/B737/257","sectionType":"part","heading":"AD/B737/257","content":"## AD/B737/257","sortOrder":1},{"sectionNumber":"Bendix Main Wheel","sectionType":"part","heading":"Bendix Main Wheel","content":"## Bendix Main Wheel","sortOrder":2},{"sectionNumber":"13/2005","sectionType":"part","heading":"13/2005","content":"## 13/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive remains narrowly focused on replacing and inspecting specific Bendix wheel halves on 737-100/200 aircraft to prevent flange failure. There is no indication in the text that the AD broadens its original safety purpose or extends to other systems or aircraft beyond the stated applicability. The instrument cross-references FAA and manufacturer service material but does not expand the technical scope beyond the original intent described (replacement/inspection to prevent wheel flange failure)."},"complexity_factors":["Short, single‑topic directive focused on one part number and limited aircraft models (737-100/200).","Relies on external technical documents (FAA AD 98-26-24Amdt 39-10967) and multiple manufacturer service documents (Bendix Service Information Letter 392 Rev 1; Allied Signal Service Bulletin No. 737-32-026) — requires cross-referencing.","Technical actions are straightforward (inspect for corrosion/missing paint/cracks; replace certain wheel halves) rather than complex procedural conditions.","One effective date and straightforward compliance obligation (no layered conditional exemptions).","Potential complexity for implementers arises from sourcing approved replacement parts and ensuring use of the correct, possibly revised, service attachments (dependency on FAA-approved revisions)."],"plain_english_summary":"**What this instrument requires**\n\n- It applies to Boeing 737-100 and 737-200 aeroplanes that have a Bendix main wheel assembly with part number 2601571-1. (Applicability)\n\n- The directive requires operators to follow the technical actions set out in FAA Airworthiness Directive 98-26-24Amdt 39-10967 and the referenced Bendix/Allied Signal service documents. In practice that means replacing certain wheel halves with improved wheel halves, inspecting affected wheels for corrosion, missing paint, or cracks, and repairing or replacing wheels as necessary. (Requirement; Background)\n\n- The AD takes effect on 22 December 2005 and requires compliance as specified in the referenced FAA document and service information. (Compliance)\n\n**Who is affected**\n\n- Aircraft owners and operators of affected 737-100/200 aeroplanes. They are responsible for arranging the inspections, repairs and replacements.\n- Maintenance organisations and licensed engineers who perform the physical work and record compliance.\n- Parts suppliers/manufacturers who supply the improved wheel halves or repair parts referenced by the service information.\n\n**Why it matters (stated purpose and mechanical effect)**\n\n- The stated safety goal is to prevent failure of the wheel flanges. The document says flange failure could lead to damage to hydraulic systems, jammed flight controls, loss of electrical power or combinations of those failures. The required inspections and replacement of improved wheel halves are the prescribed mechanical steps to reduce that risk. (Background; Requirement)\n\n**Who pays, who decides, and what behaviour changes**\n\n- Owners/operators pay for parts, labour and any aircraft downtime required to comply. They also decide when to schedule the work within the compliance window set by the FAA AD.\n- Maintenance organisations carry out the inspections, repairs and replacements and must keep the records required for continuing airworthiness.\n- Behavioural change: affected operators must schedule inspections/replacements, source the improved wheel halves or approved repairs, and maintain compliance records. Aircraft may be temporarily out of service while work is done. (Applicability; Requirement)\n\n**Implementation mechanics and dependence on external documents**\n\n- The AD is prescriptive but does not reproduce technical procedures: it incorporates by reference the FAA AD and Bendix/Allied Signal service information. That means compliance depends on obtaining and following those external technical documents (and on later FAA‑approved revisions or attachments if applicable). (Requirement)\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: purchase of improved wheel halves or repair components, labour costs, and aircraft downtime while the work is done.\n- Incentive structure: the immediate incentive for operators is risk reduction (avoiding potential in-service failure and consequential damage). The cost is concentrated on the operators, while the safety benefit accrues to the operator, passengers/crew and the public at large.\n- Supply and timing risk: the requirement to use specific improved wheel halves or to follow manufacturer service documents creates dependence on availability of those parts and on the manufacturer’s technical data. If parts are scarce or lead times long, operators face greater downtime or must seek FAA‑approved alternatives.\n\n**Compliance burden and discretion**\n\n- The directive prescribes actions and refers to FAA/ manufacturer documents for technical detail, so regulatory discretion is limited—compliance is binary: carry out the inspections and replacements as specified (or follow FAA‑approved alternatives). The burden is operational (scheduling, parts, labour, records).\n\n**Concrete implementation risks and opportunity costs**\n\n- Opportunity cost: aircraft out of service for inspection/repair could reduce available capacity or force schedule changes for operators.\n- If replacement parts are controlled by a single manufacturer or supplier, there is potential for constrained supply and higher direct costs, which could affect independent MROs and smaller operators more than large fleets.\n\n**Source citations**\n\n- Applicability: which models and part number are covered. (Applicability)\n- Required technical actions and referenced documents: FAA AD 98-26-24Amdt 39-10967 and Bendix/Allied Signal service material. (Requirement)\n- Effective/compliance date: 22 December 2005. (Compliance)\n- Safety rationale: preventing wheel flange failure and consequent systems damage. (Background)\n\n"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive focused on a specific mechanical defect in a specific aircraft part. It has not expanded beyond its original safety purpose."},"complexity_factors":["Short, single-purpose directive (approximately 200 words of substantive content)","Only one defined applicability criterion (specific part number 2601571-1)","Heavy reliance on external documents — compliance requires cross-referencing to FAA AD 98-26-24, Bendix Service Information Letter 392 Rev 1, and Allied Signal Service Bulletin 737-32-026 with two dated attachments","No nested conditional logic or exceptions within the directive itself — all complexity is outsourced to the referenced technical documents","Single compliance date with straightforward effective date mechanism"],"plain_english_summary":"This CASA Airworthiness Directive targets Boeing 737‑100/‑200 aircraft fitted with certain Bendix main wheel assemblies, requiring replacement of specific wheel halves, inspection for corrosion, missing paint or cracks, and repair or replacement of any damaged wheels. It addresses risk of wheel‑flange failure that can lead to hydraulic damage, jammed flight controls or electrical loss. Compliance follows FAA AD 98‑26‑24 and referenced Bendix/Allied Signal service documents, effective 22 December 2005."},"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-b737-257-bendix-main-wheel","history":"/api/acts/ad-b737-257-bendix-main-wheel/history","analysis":"/api/acts/ad-b737-257-bendix-main-wheel/analysis","conflicts":"/api/acts/ad-b737-257-bendix-main-wheel/conflicts","importantCases":"/api/acts/ad-b737-257-bendix-main-wheel/important-cases","documents":"/api/acts/ad-b737-257-bendix-main-wheel/documents"}}