{"id":"F2009L03896","name":"AD/BAe 146/140 - Airbrake Lever Detent Mechanism","slug":"ad-bae-146-140-airbrake-lever-detent-mechanism","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":81220,"registerId":"commonwealth-F2009L03896-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"British Aerospace BAe 146 Series Aeropla","sectionType":"division","heading":"British Aerospace BAe 146 Series Aeroplanes","content":"### British Aerospace BAe 146 Series Aeroplanes\n\n| AD/BAe 146/140 | Airbrake Lever Detent Mechanism | 21/2009 |\n| -------------- | ------------------------------- | ------- |\n\n| Applicability: | BAE Systems (Operations) Ltd, British Aerospace plc, British Aerospace (Commercial Aircraft) Ltd, British Aerospace (Operations) Ltd, British Aerospace Regional Aircraft Ltd, British Aerospace Regional Aircraft trading as Avro International Aerospace: BAe 146 Series 100, 100A, 200 and 200A aeroplanes, serial numbers as listed in British Aerospace (Commercial Aircraft) Ltd Modification Service Bulletin SB.27-73-00889A&B, Revision 4 dated 15 June 1990.Note 1: BAe 146 Series 100A and 200A aeroplanes have been manufactured to the United States (FAA) certification standard. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | Modify the airbrake lever detent mechanism in accordance with the instructions of British Aerospace (Commercial Aircraft) Ltd Modification Service Bulletin SB.27-73-00889A&B, currently at Revision 4 dated 15 June 1990 or later revision approved by the European Aviation Safety Authority (EASA).Modification of an aeroplane, prior to the effective date of this AD, in accordance with the instructions of British Aerospace (Commercial Aircraft) Ltd Service Bulletin SB.27-73-00889A&B at original issue, Revision 1, Revision 2 or Revision 3 is an acceptable method to comply with the modification requirements of this AD.Note 2: EASA AD 2009-0206 dated 30 September 2009 refers. |\n| Compliance: | Within the next 12 months after the effective date of this AD, unless previously accomplished. |\n| | This Amendment becomes effective on 14 October 2009. |\n| Background: | The operation of the airbrake lever in the “airbrakes out” to “lift spoiler” range has been the subject of two occurrence reports. The lift spoilers on the BAe 146 and Avro 146-RJ aeroplanes have been designed to deploy on landing to provide aerodynamic braking and to dump lift to ensure that the wheel brakes can provide the necessary speed reduction.A review of the changing operational profile of the aeroplane type concluded that its proven short field performance has increasingly been exploited in recent years by a number of operators worldwide. Frequently, these short field operations are conducted from airports that are located in mountainous terrain or in close proximity to bodies of water, leaving fewer margins for error, e.g. landing long or at (too) high speed.The effects of deceleration and landing inertia loads can cause uncommanded movement of the airbrake selector lever from the “lift spoiler” position to the “airbrakes out” position, causing the lift spoilers to retract during the landing roll.This condition, if not corrected, would increase the landing distance, possibly resulting in a runway overrun and consequent injury to aeroplane occupants.On certain BAe 146 aeroplanes, without modifications HCM00889A and B or modifications HCM00889A and C incorporated, negligible force is required to move the airbrake lever back to the “airbrakes out” position. From 1988 onwards, modifications were introduced on the production line to incorporate a modified friction baulking device such that a force of 12 lbs must be applied to move the airbrake lever from the “lift spoiler” position to the “airbrakes out” position. These modifications were also made available as an optional in-service retrofit.For the reasons described above, this AD requires the modification of the airbrake lever detent mechanism. |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n9 October 2009","sortOrder":0},{"sectionNumber":"AD/BAe 146/140","sectionType":"part","heading":"AD/BAe 146/140","content":"## AD/BAe 146/140","sortOrder":1},{"sectionNumber":"Airbrake Lever Detent Mechanism","sectionType":"part","heading":"Airbrake Lever Detent Mechanism","content":"## Airbrake Lever Detent Mechanism","sortOrder":2},{"sectionNumber":"21/2009","sectionType":"part","heading":"21/2009","content":"## 21/2009","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a narrow, well-defined scope addressing a specific mechanical safety issue. The scope remains tightly focused on the airbrake lever detent mechanism modification for the specified aircraft series, consistent with the original purpose of ensuring safe aircraft operation."},"complexity_factors":["Single, specific mechanical modification required","Only 4 aircraft models affected (BAe 146 Series 100, 100A, 200, 200A)","Clear compliance pathway: follow specific service bulletin (SB.27-73-00889A&B)","Simple deadline structure: 12 months from effective date","Limited conditional logic: only one exception noted (prior modifications at earlier revisions still acceptable)","No nested definitions or extensive cross-referencing to other legislation","Background section provides clear safety rationale in plain language"],"plain_english_summary":"This CASA Airworthiness Directive mandates that owners/operators of specified BAe 146-100/100A/200/200A aircraft install a modified airbrake lever detent (requiring 12 lb of force to move) to prevent accidental slip from \"lift spoiler\" to \"airbrakes out\" during landing. The retrofit, already standard on aircraft built from 1988, must be done on affected older/retrofit-missing aircraft within 12 months to reduce landing distance, runway-overrun risk and injury."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD remains focused on its original technical purpose: correcting a mechanical vulnerability in the airbrake selector detent to prevent inadvertent retraction of lift spoilers during landing. It does not broaden the affected fleet beyond the serial numbers listed in the manufacturer’s Service Bulletin, nor does it add unrelated compliance requirements. The AD specifies an acceptable set of compliance methods (current SB Revision 4 or earlier in-service revisions already installed) and defers to EASA for approval of later revisions — procedural refinements rather than a substantive expansion of scope."},"complexity_factors":["Short instrument (single AD) with limited scope (one component: airbrake lever detent mechanism)","Low number of defined terms within the AD text","Primary cross-reference to one manufacturer Service Bulletin (SB.27-73-00889A&B) and EASA approval for later revisions","One clear compliance deadline (12 months) and an explicit acceptance of earlier in-service SB revisions","Limited conditionality: acceptable earlier modifications if installed before effective date; later revisions require EASA approval","Reference to one related EASA AD (2009-0206) but no complex nested exceptions or multiple compliance paths"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Requires modification of the airbrake lever detent mechanism on specified British Aerospace BAe 146 series aeroplanes.\n- The modification must follow the instructions in British Aerospace (Commercial Aircraft) Ltd Modification Service Bulletin SB.27-73-00889A&B, at Revision 4 (15 June 1990) or a later revision approved by the European Aviation Safety Authority (EASA).\n- If a plane was already modified before this Airworthiness Directive (AD) using the original issue or Revisions 1–3 of that Service Bulletin, that earlier work is acceptable.\n- Operators must complete the modification within 12 months of the AD’s effective date.\n\nWho is affected\n\n- Owners and operators of BAe 146 Series 100, 100A, 200 and 200A aeroplanes listed in the manufacturer’s service bulletin (specific serial numbers are identified in that bulletin).\n- Maintenance organisations and engineers who carry out structural/flight-control modifications using the cited Service Bulletin.\n\nWhy it matters (safety rationale and operational effect)\n\n- The AD responds to reports that the airbrake selector lever can move unintentionally from the \"lift spoiler\" position to the \"airbrakes out\" position during the landing roll because deceleration and inertia loads can displace the lever.\n- If lift spoilers retract unintentionally on landing, aerodynamic braking is reduced and lift is regained, increasing landing distance and raising the risk of runway overrun and injury to occupants.\n- The required modification increases the force needed to move the lever from \"lift spoiler\" to \"airbrakes out\" (production changes raised this to about 12 lbs), preventing inadvertent movement under landing loads.\n\nMechanics, incentives and practical effects (implementation-focused)\n\n- Who pays: aircraft owners/operators pay for the parts and labour to carry out the Service Bulletin modification.\n- Who decides: compliance is mandatory for the affected aircraft; the AD prescribes the method (the Service Bulletin) and accepts earlier revisions only if installed prior to the AD’s effective date. EASA approval governs acceptance of later revisions.\n- Behaviour change: operators must schedule the modification within 12 months, potentially grounding or diverting maintenance resources; maintenance providers will perform a defined retrofit rather than a design choice.\n- Costs and trade-offs: the expense is a compliance cost to operators (parts, labour, downtime). The benefit is reduced operational risk of increased landing distance. There is a limited opportunity cost where maintenance capacity is constrained.\n- Implementation risk and compliance burden: the AD relies on an existing Service Bulletin. That concentrates technical discretion with the manufacturer’s instructions and EASA’s approval of later revisions; local civil aviation authority enforces the compliance deadline.\n- Market effects: the measure imposes a one-off retrofit cost on a narrow set of aircraft; it does not change operating rules, ownership or competition between operators, nor does it create ongoing recurring charges. Maintenance providers who are approved/competent to carry out the SB may see concentrated business; operators using less complex maintenance supply chains may incur modest logistical costs.\n\nOfficial purpose-claim and testing against trade-offs\n\n- The AD’s stated purpose is to prevent inadvertent retraction of lift spoilers on landing (see Background). That purpose is achieved by mandating a manufacturer-defined mechanical change that increases detent/friction on the selector lever.\n- Trade-offs: the modification reduces a specific safety risk at the cost of retrofit expenditure and maintenance scheduling. The AD’s prescription (specific SB revision with acceptance of earlier in-service installs) narrows operator choice about how to comply but reduces regulatory uncertainty by specifying acceptable methods.\n\nReferences within the instrument\n\n- Applicability: lists the affected BAe 146 variants and serial numbers as in the manufacturer’s Service Bulletin.\n- Requirement: mandates modification in accordance with SB.27-73-00889A&B (Rev 4 or later EASA-approved revision); allows earlier SB revisions if already fitted before the AD’s effective date.\n- Compliance timeframe: within 12 months of the effective date.\n- Background: describes incident reports, operational context (increased short-field use), and the mechanical vulnerability that gives rise to the AD.\n\nOverall effect in one sentence: The AD mandates a manufacturer-prescribed retrofit to the airbrake lever detent on specified BAe 146 aircraft within 12 months to reduce the risk of inadvertent lift-spoiler retraction on landing, shifting the retrofit cost and scheduling burden to aircraft owners/operators while standardising the technical solution via an approved Service Bulletin."},"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-bae-146-140-airbrake-lever-detent-mechanism","history":"/api/acts/ad-bae-146-140-airbrake-lever-detent-mechanism/history","analysis":"/api/acts/ad-bae-146-140-airbrake-lever-detent-mechanism/analysis","conflicts":"/api/acts/ad-bae-146-140-airbrake-lever-detent-mechanism/conflicts","importantCases":"/api/acts/ad-bae-146-140-airbrake-lever-detent-mechanism/important-cases","documents":"/api/acts/ad-bae-146-140-airbrake-lever-detent-mechanism/documents"}}