{"id":"F2006B11169","name":"AD/LJ60/1 Amdt 1 - Abnormal Brake Wear Condition","slug":"ad-lj60-1-amdt-1-abnormal-brake-wear-condition","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56867,"registerId":"commonwealth-F2006B11169-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LJ60/1 Amdt 1 - Abnormal Brake Wear Condition","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/LJ60/1 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nLearjet 60 Series Aeroplanes\n\nAD/LJ60/1\n\nAmdt 1\n\n  \nAbnormal Brake Wear Condition 7/2004\n\nApplicability: Model 60 aircraft, equipped with Aircraft Braking Systems (ABS) brake assembly part number 5003096-7.\n\nRequirement: 1. Measure the brake wear dimension between the housing sub-assembly and the pressure plate that is adjacent to the top pistons of the brake assembly, in accordance with ABS Service Bulletin LEAR60-32-03, dated 5 March 1998.\n\n    If the dimension is less than 0.344 inches (8.74 mm), thereafter, repeat the measurement.\n\n    b. If the dimension is equal to or greater than 0.344 inches (8.74 mm), thereafter, repeat the measurement.\n\n    c. If the dimension is equal to or greater than 0.359 inches (9.12 mm) and less than 0.464 inches (11.79 mm), perform a visual inspection to detect abnormal wear of the friction mix on the rotating discs, in accordance with the Requirement document.\n\n    (i) If the friction mix is not worn to the disc cores on either disc, thereafter, repeat the measurement.\n\n    (ii) If the friction mix is worn to the disc core on either disc, replace both rotating discs with new discs in accordance with the Requirement document. Thereafter, repeat the measurement.\n\n    d. If the dimension is greater than or equal to 0.464 inches (11.79 mm), replace the disc stack with a new disc stack, or overhaul it; in accordance with the Requirement document. Thereafter, repeat the measurement.\n\n    2. A used ABS part number 5003096-7 brake assembly shall not be installed on any aircraft, unless it has been inspected and applicable corrective actions have been performed in accordance with the requirements of this Directive.\n\nNote: FAA AD 98-16-18 Amdt 39-10694 refers.\n\nLearjet 60 Series Aeroplanes\n\nAD/LJ60/1 Amdt 1 (continued)\n\nCompliance: 1. For brakes which have accumulated more than 100 cycles since new, accomplish within 10 flight hours after the effective date of this AD, unless the initial check is already accomplished. No inspection is required for brakes with less than 100 cycles accumulated.\n\n    At intervals not to exceed 35 flight cycles.\n\n    b. At intervals not to exceed 25 flight cycles.\n\n    c. (i). Repeat at intervals not to exceed 25 flight cycles.\n\n(ii). Before further flight. Subsequent repeat inspections are to be carried out in accordance with an initial threshold and repeat interval appropriate for new brakes, i.e. begin again from part 1 of this AD\n\n    d. Before further flight. Subsequent repeat inspections are to be carried out in accordance with an initial threshold and repeat interval appropriate for new brakes, i.e. begin again from part 1 of this AD.\n\n2. As of the effective date of this Directive.\n\nThis Amendment becomes effective on 8 July 2004.\n\nBackground: This AD was raised in response to the release of an FAA AD that was issued after reports of abnormal (uneven) brake wear.\n\nThis amendment changes the compliance to reflect the compliance allowed in FAA letter of dispensation to the Danish LDD. Refer to FAA letter of dispensation, LDD 2000-099-047, dated November 12, 1998.\n\n![Signature of David Villiers Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 26 May 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 16 June 2004.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This Amendment does not materially broaden the subject matter or affected population of the original AD. It continues to target Learjet 60 aeroplanes fitted with ABS assembly part number 5003096‑7 and prescribes inspection and corrective actions for abnormal brake wear (same substantive scope). The stated change is to align compliance timing with an FAA letter of dispensation (Background), i.e. a procedural adjustment to allowed compliance intervals rather than an expansion of applicability or new types of obligations. The amendment therefore adjusts timing and aligns with FAA guidance but does not grow the AD beyond its original safety purpose."},"complexity_factors":["Single, specific applicability (one aircraft model and one ABS part number) — limits scope but focuses requirements.","Multiple numeric wear thresholds with different actions: <0.344 in, ≥0.344 in, ≥0.359–<0.464 in, and ≥0.464 in — creates branching logic (Requirement 1 a–d).","Conditional actions include both measurement repeats and different corrective actions (visual inspection, replace discs, overhaul/replace disc stack).","Varying compliance intervals tied to the measured condition (initial check within 10 flight hours for >100 cycles; repeat intervals of 35 cycles, 25 cycles, and ‘before further flight’) — non‑uniform timing increases operator decision points (Compliance).","External cross‑references: ABS Service Bulletin LEAR60‑32‑03 for measurement/inspection procedures, and FAA AD/letter of dispensation references — requires consult of other documents for full compliance (Requirement; Note; Background).","A prohibition on installing used parts unless inspected (Requirement 2) adds a procedural gate affecting supply chains and maintenance policies.","Short document length and limited number of defined terms lower complexity overall."],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Revokes the prior AD/LJ60/1 and replaces it with Amendment 1, which mandates inspections and corrective actions for certain Learjet 60 brake assemblies (ABS part number 5003096-7). (Applicability; Requirement)\n\n- Requires operators to measure a specific brake wear dimension — the gap between the brake housing sub‑assembly and the pressure plate next to the top pistons — following the procedure in ABS Service Bulletin LEAR60‑32‑03. Based on the measured dimension, the AD sets out conditional follow‑up actions: repeat measurements at specified intervals, carry out visual inspections of friction material on rotating discs, replace both rotating discs if friction is worn to the disc cores, or replace/overhaul the entire disc stack if wear exceeds a higher threshold. (Requirement 1 a–d)\n\n- Prohibits installing a used ABS assembly (part 5003096‑7) on any aircraft unless it has been inspected and any required corrective actions from this Directive have been carried out. (Requirement 2)\n\n- Sets timing for compliance: an initial check within 10 flight hours for brakes with more than 100 cycles since new (no initial check required for brakes with fewer than 100 cycles); then repeat inspections at intervals that depend on the measured wear condition (specified as not to exceed 35 flight cycles, 25 flight cycles, or “before further flight” for the most severe cases). (Compliance)\n\n- The AD notes it was raised in response to an FAA AD after reports of uneven brake wear and that this amendment aligns the compliance with an FAA letter of dispensation. (Background; Note)\n\nWhy it matters and who it affects\n\n- Who is affected: operators and maintenance organisations responsible for Learjet 60 aeroplanes that have ABS brake assembly part number 5003096‑7 installed. (Applicability)\n\n- Who pays and who decides: aircraft operators and their maintenance providers pay for inspections, labour, parts replacements and any aircraft downtime. The Civil Aviation Safety Authority (CASA), via its delegate, prescribes the mandatory inspection, corrective actions and installation prohibition. (Requirement; Compliance; signature)\n\n- Behavioural change required: operators must (1) perform the specified dimensional measurement per the service bulletin, (2) follow the conditional inspection/replacement path set out in the AD when particular measurement thresholds are reached, (3) refrain from installing used ABS assemblies unless they meet the AD’s inspection/correction requirements, and (4) schedule repeat inspections at the stated intervals. (Requirement; Compliance)\n\nStated rationale and testing it against costs and implementation issues\n\n- Rationale claimed by the instrument: the AD follows an FAA directive prompted by reports of abnormal (uneven) brake wear. This Amendment aligns compliance timing with an FAA dispensation. (Background; Note)\n\n- Direct costs and incentives: the AD imposes routine measurement costs and, where wear thresholds are reached, replacement or overhaul costs for discs or entire disc stacks. These are direct, concentrated costs on operators and maintenance providers (Requirement 1 c–d; Compliance). The prohibition on installing used ABS assemblies (Requirement 2) reduces the option to reuse lower‑cost second‑hand parts, increasing demand for new or overhauled parts.\n\n- Trade‑offs and opportunity costs: the safety objective is achieved at the cost of parts, labour and aircraft downtime. Operators must choose between earlier replacement (higher immediate costs) and the risk of further wear (safety and potentially higher future cost). The AD’s thresholds and intervals create a predictable maintenance regime but may produce additional replacements that operators would not have undertaken under looser guidance.\n\n- Implementation and compliance burden: CASA delegates the specific measurement procedure to the ABS Service Bulletin (external document). Accurate compliance depends on maintenance staff applying that bulletin correctly. The AD also cross‑references FAA material (FAA AD 98‑16‑18 and a FAA letter of dispensation), so implementers must track both CASA and FAA documents to ensure full compliance. Parts availability (new discs or overhauled disc stacks) and workshop capacity affect how quickly operators can comply with “before further flight” replacement requirements. (Requirement; Note; Background)\n\n- Effects on private choice and markets: by forbidding uninspected used assemblies, the AD reduces the market for such used parts (affecting sellers of used components) and increases demand for new or overhauled parts (affecting parts suppliers and MROs). Maintenance providers gain work from required inspections and replacements, concentrating costs on aircraft operators.\n\n- Risk of unintended consequences: if parts are scarce or lead times long, the “before further flight” replacement requirement could ground aircraft for extended periods or prompt temporary operational changes (cancellations, lease substitution, or part cannibalisation). The AD relies on a service bulletin for procedural detail; any ambiguity there would raise compliance risk.\n\nKey citations to the AD text\n\n- Applicability: Model 60 aircraft with ABS brake assembly part number 5003096‑7. (Applicability)\n- Measurement and conditional actions: Requirement 1 a–d. (Requirement)\n- Prohibition on installing used assemblies: Requirement 2. (Requirement)\n- Timing and repeat intervals: Compliance section. (Compliance)\n- Alignment with FAA actions: Note and Background. (Note; Background)\n\nBottom line (neutral): this AD imposes a targeted, conditional inspection and replacement regime for a specific Learjet 60 brake assembly part number to address reports of uneven brake wear. Operators must measure a specified dimension, follow the AD’s stepwise actions when thresholds are met, and cannot fit used assemblies without inspection and correction. The principal impacts are inspection, parts and labour costs and scheduling/availability effects for maintenance and spare parts."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose — addressing abnormal brake wear on Learjet 60 aircraft. The amendment only adjusts compliance timeframes to match an FAA dispensation letter; it does not expand applicability to new aircraft types, add unrelated systems, or broaden regulatory reach beyond the specific brake assembly (P/N 5003096-7) originally targeted."},"complexity_factors":["Nested conditional logic with 4 distinct measurement thresholds triggering different actions (0.344 in, 0.359 in, 0.464 in)","Cross-reference to external technical document (ABS Service Bulletin LEAR60-32-03) without reproducing its contents","Compliance section uses lettered sub-paragraphs (a, b, c, d) that don't align clearly with Requirement section numbering, creating parsing difficulty","Circular reference in compliance requirements — 'begin again from part 1 of this AD' sends readers back to start","Mixed units (inches and millimetres) requiring conversion verification","Reference to foreign regulatory correspondence (FAA letter of dispensation LDD 2000-099-047) for background context"],"plain_english_summary":"This AD requires owners/operators of Learjet 60s fitted with brake assembly P/N 5003096-7 to inspect and measure brake wear and take corrective action (increased monitoring, repair, overhaul or replacement) based on the measurement, and prohibits installing used assemblies unless inspected and rectified.  \n\nIt affects operators and maintenance personnel and is intended to prevent catastrophic brake failure during landing by catching abnormal wear early."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lj60-1-amdt-1-abnormal-brake-wear-condition","history":"/api/acts/ad-lj60-1-amdt-1-abnormal-brake-wear-condition/history","analysis":"/api/acts/ad-lj60-1-amdt-1-abnormal-brake-wear-condition/analysis","conflicts":"/api/acts/ad-lj60-1-amdt-1-abnormal-brake-wear-condition/conflicts","importantCases":"/api/acts/ad-lj60-1-amdt-1-abnormal-brake-wear-condition/important-cases","documents":"/api/acts/ad-lj60-1-amdt-1-abnormal-brake-wear-condition/documents"}}