{"id":"F2006B02659","name":"AD/B727/137 Amdt 1 - Brake Wear Limit","slug":"ad-b727-137-amdt-1-brake-wear-limit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41975,"registerId":"commonwealth-F2006B02659-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/137 Amdt 1 - Brake Wear Limit","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)  \nBoeing 727 Series Aeroplanes\n\nAD/B727/137\n\nAmdt 1\n\n  \nBrake Wear Limit 11/92\n\nApplicability: Model 727 series, equipped with brake part numbers identified in Tables 1 and 2 of the Requirement Document, and BF Goodrich brake P/N 2-873.\n\nRequirement: Action IAW the technical requirements of FAA AD 92-12-08 Amdt 39-8269. Compliance: As specified in the Requirement Document with a revised effective date of 15\n\nOctober 1992 for Australian registered aircraft.\n\nBackground: An investigation by the FAA of a runway excursion by a transport category aircraft following a rejected takeoff, has revealed that the majority of brake assemblies were near the current maximum wear limit and unable to absorb the required energy. This Directive required new maximum brake wear limits. Amendment 1 is issued to reflect the requirements of FAA AD 92-12-08 which lists certain additional landing gear brakes.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"Yes. Amendment 1 expands the scope by adding additional landing-gear brake part numbers to the list of affected assemblies, as it adopts the additional brakes listed in FAA AD 92-12-08. The Directive therefore applies to more brake assemblies than the original issue did. (Background)"},"complexity_factors":["Cross-reference to an external FAA airworthiness directive (FAA AD 92-12-08 Amdt 39-8269) rather than containing full technical steps in the instrument itself (Requirement).","Reliance on a separate Requirement Document that contains Tables 1 and 2 listing precise brake part numbers and specific compliance instructions (Applicability; Requirement).","Technical subject-matter (brake wear limits, energy absorption) requires specialised maintenance knowledge to assess and implement.","Need for operators to identify affected aircraft by matching part numbers, which is an administrative and technical task (Applicability).","Amendment expands the parts list (additional landing-gear brakes), increasing the set of affected aircraft and potential scope of compliance work (Background).","Defined effective compliance date for Australian-registered aircraft creates scheduling and operational timing constraints (Compliance)."],"plain_english_summary":"# What this directive does\n\n- This Airworthiness Directive updates the allowable brake wear limits for certain Boeing 727 aeroplanes and requires operators to follow specific technical steps to comply. (Requirement; Compliance)\n- It applies only to Model 727 aircraft that are fitted with the brake part numbers listed in Tables 1 and 2 of the Requirement Document and BF Goodrich brake P/N 2-873. (Applicability)\n- The technical actions to be taken are to be done in accordance with FAA AD 92-12-08 Amdt 39-8269; the Australian compliance timing is set out in the Requirement Document with an effective date of 15 October 1992 for Australian-registered aircraft. (Requirement; Compliance)\n\n# Why the rule was made (official rationale)\n\n- The stated basis is an FAA investigation of a runway excursion following a rejected takeoff, which found many brake assemblies were near the then-current maximum wear limit and could not absorb the required energy. The Directive therefore imposes new maximum brake wear limits. (Background)\n- Amendment 1 broadens the list of affected brake assemblies by adopting additional landing-gear brake part numbers identified in the FAA AD. (Background)\n\n# How it works in practice (who pays, who decides, what must change)\n\n- Who it affects: operators and owners of Australian-registered Boeing 727s that have the specified brake part numbers fitted. They must check whether their aeroplanes have those part numbers and then follow the technical measures prescribed. (Applicability; Requirement)\n- Who pays: the aircraft operators/owners pay for inspections, measurements, any rework or replacement of brake assemblies needed to meet the new maximum wear limits, and any related labour and downtime. (Applicability; Requirement)\n- What decisions are required: operators must (a) identify affected aeroplanes by checking brake part numbers listed in the Requirement Document, and (b) carry out the inspections and corrective work set out in FAA AD 92-12-08 as adopted here. Compliance timing is governed by the Requirement Document (effective 15 October 1992 for Australian aircraft). (Applicability; Requirement; Compliance)\n\n# Trade-offs, incentives and implementation issues to note\n\n- Safety objective vs operating cost: The Directive aims to reduce the risk of brake failure during high-energy events by lowering maximum wear limits (Background). Meeting that objective can raise direct maintenance costs and cause scheduling impacts for operators who must inspect or replace assemblies (Requirement; Compliance).\n- Compliance burden and administrative work: The rule relies on an external FAA AD and a separate Requirement Document that lists affected part numbers and compliance steps. Operators must cross-reference those documents and verify part numbers in Tables 1 and 2 of the Requirement Document. That cross-referencing creates an administrative compliance task beyond routine maintenance. (Applicability; Requirement)\n- Implementation risk: Effective implementation depends on (a) correctly identifying whether a given aeroplane uses one of the listed brake P/Ns, and (b) following the technical requirements exactly as set out in the FAA AD and Requirement Document. Misidentification or incomplete application of the required actions could leave brakes out of compliance with the new limits. (Applicability; Requirement)\n- Effects on third parties: Maintenance providers who perform the inspections or replacements will need to follow the technical instructions in the FAA AD and Requirement Document; operators relying on independent maintenance organisations must reflect the Directive in maintenance contracts and scheduling. (Requirement)\n\n# Summary of concrete mechanics\n\n- The Directive (as amended) imposes new maximum wear limits for certain brake assemblies on Boeing 727 series aeroplanes (Requirement; Background).\n- It does so by adopting the technical requirements of FAA AD 92-12-08 Amdt 39-8269 and by specifying compliance timing in the Requirement Document for Australian-registered aircraft (Requirement; Compliance).\n- Amendment 1 expands the list of affected brake part numbers to include additional landing-gear brakes listed in the FAA AD. (Background)\n\n(Section citations in parentheses: Applicability, Requirement, Compliance, Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment performs exactly the function intended for Airworthiness Directives: it updates technical requirements to address newly identified safety risks. The addition of extra brake models in Amendment 1 is a routine technical expansion consistent with the original purpose of ensuring brake safety, not a scope creep."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined elements: specific brake part numbers and aircraft model","Single compliance action with reference to external FAA technical document","No nested conditions or exceptions","Linear structure: applicability → requirement → compliance → background","Amendment 1 is a simple expansion of scope (adding brake models) rather than structural change"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on aircraft.\n\n**What it does:**\nThis directive orders owners and operators of **Boeing 727 series aircraft** to follow new, stricter limits on how worn their brakes can be before replacement. It applies to specific brake part numbers listed in technical tables.\n\n**Why it matters:**\nAfter a runway incident where a plane ran off the runway during an aborted takeoff, investigators discovered the brakes were too worn to stop the aircraft safely. The brakes were technically within the old \"legal\" wear limits but couldn't absorb enough energy to stop the plane in an emergency. This directive tightens those limits to prevent similar accidents.\n\n**Who must comply:**\n- Operators of Australian-registered Boeing 727s with specific brake models (including BF Goodrich brake part number 2-873)\n- Compliance deadline: 15 October 1992\n\n**What action is required:**\nOperators must follow the technical requirements set out in a US Federal Aviation Administration (FAA) directive (AD 92-12-08), which this Australian directive adopts and updates. \"Amendment 1\" adds extra brake models to the original requirement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-137-amdt-1-brake-wear-limit","history":"/api/acts/ad-b727-137-amdt-1-brake-wear-limit/history","analysis":"/api/acts/ad-b727-137-amdt-1-brake-wear-limit/analysis","conflicts":"/api/acts/ad-b727-137-amdt-1-brake-wear-limit/conflicts","importantCases":"/api/acts/ad-b727-137-amdt-1-brake-wear-limit/important-cases","documents":"/api/acts/ad-b727-137-amdt-1-brake-wear-limit/documents"}}