{"id":"F2006B03535","name":"AD/BAe 146/88 Amdt 2 - Engine Start Electrical Circuit","slug":"ad-bae-146-88-amdt-2-engine-start-electrical-circuit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43102,"registerId":"commonwealth-F2006B03535-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/88 Amdt 2 - Engine Start Electrical Circuit","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/BAe 146/88 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CAR 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\nBritish Aerospace BAe 146 Series Aeroplanes\n\nAD/BAe 146/88\n\nAmdt 2\n\n  \nEngine Start Electrical Circuit 11/2001\n\nApplicability: Avro 146-RJ70 and BAe 146 series aeroplanes detailed in BAe Systems BAe 146 Series/Avro 146-RJ Series Mandatory Modification Service Bulletin SB.80-18- 50293A dated 18 January 2001 or Revision 1 dated 4 July 2001.\n\nBAE 146 Series 100 aeroplanes detailed in BAe Systems BAe 146 Series/Avro 146- RJ Series Mandatory Modification Service Bulletin SB.80-019-50293B dated 6 July 2001.\n\nBAE 146 Series 200 aeroplanes detailed in BAe Systems BAe 146 Series/Avro 146- RJ Series Mandatory Modification Service Bulletin SB.80-020-50293C dated 6 July 2001.\n\nRequirement: Modify the engine electrical start circuit in accordance with either BAe Systems SB.80-18-50293A, SB.80-18-50293A Revision 1, SB.80-019-50293B or SB.80-020- 50293C.\n\nNote: CAA(UK) AD 003-01-2001 refers.\n\nCompliance: Remains unchanged as “Before 20 December 2002”.\n\nThis Amendment becomes effective on 1 November 2001.\n\nBackground: Current Crew and Maintenance procedures have failed to protect the soft start resistor in the event of component failures, which could result in the resistor overheating and, in some cases, smoke and fumes entering the cabin.\n\nThe modification required by this Directive introduces a changeover contactor and protection circuit, which includes a time delay relay. This modification will isolate the start busbar should start power be supplied through the soft start resistor for more than 1.5 seconds. The circuit is also designed so that failure of the changeover contactor to energise will result in a hard start rather than a failed engine start.\n\nAmendment 1 introduced a revised Service Bulletin that provides an alternate method of compliance for modified aeroplanes.\n\nBritish Aerospace BAe 146 Series Aeroplanes\n\nAD/BAe 146/88 Amdt 2 (Continued)\n\nThis amendment increases the range of affected aeroplanes and introduces additional Modification Service Bulletins applicable to the increased range.\n\n![Signature of Eugene Paul Holzapfel, Delegate of the Civil Aviation Safety Authority.](image.002.png)  \nThe original issue of this Directive became effective on 17 May 2001. Amendment 1 became effective on 6 September 2001.\n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 25 September 2001\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 10 October 2001.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 2 expanded the scope of the original AD by increasing the range of affected aeroplanes and adding additional BAe Mandatory Modification Service Bulletins as acceptable methods of compliance. The amendment therefore broadened which BAe/Avro 146 variants and serials are covered and provided more SB documents that operators can use to comply (Applicability; Amendment description)."},"complexity_factors":["Single‑topic instrument (engine start electrical circuit) – short text focusing on one modification","Multiple aircraft models covered via cross‑references to four Service Bulletins (SB.80-18-50293A, its Revision 1, SB.80-019-50293B, SB.80-020-50293C) (cross‑references increase implementation steps)","Reference to previous ADs and amendments (revocation of Amdt 1 and note of original AD)","A defined technical trigger and protection timing (1.5 second time delay) that implementers must follow precisely (technical detail)","Compliance deadline is fixed (before 20 December 2002) and unchanged, creating time pressure for operators","Reference to foreign regulator AD (CAA(UK) AD 003-01-2001) as an informational cross‑reference","Alternative method of compliance introduced in prior amendment (Amdt 1) – conditional compliance paths"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) that requires operators of specified BAe/Avro 146 family aeroplanes to modify the engine start electrical circuit.\n- The required modification is to be carried out exactly as described in one of several BAe Mandatory Modification Service Bulletins named in the AD (SB.80-18-50293A or its Revision 1, SB.80-019-50293B, or SB.80-020-50293C) (Requirement; Applicability).\n- The modification adds a changeover contactor, a protection circuit and a time‑delay relay so that the start busbar is isolated if start power is supplied through the soft‑start resistor for more than 1.5 seconds; the circuit design also makes a failed changeover contactor result in a hard start rather than a failed engine start (Background).\n- The AD revokes the earlier AD (Amdt 1) and replaces it with this version, which expands the list of affected aeroplanes and adds additional service bulletins as acceptable compliance methods (Amdt 2; Amendment description).\n- The stated compliance deadline is unchanged: modifications had to be completed before 20 December 2002 (Compliance). The amendment becomes effective on 1 November 2001.\n\n**Who is affected**\n\n- Owners and operators of BAe 146 / Avro 146‑RJ aeroplanes specifically listed by the Service Bulletins cited in the AD (Applicability).\n- Maintenance organisations and licensed engineers who perform mandated modifications under the Service Bulletins.\n- BAe/approved parts suppliers for the specific components (changeover contactor, time‑delay relay and associated wiring/protection components).\n\n**Why it matters (stated purpose and technical effect)**\n\n- Stated purpose: existing crew and maintenance procedures had not protected the soft‑start resistor against certain component failures, creating a risk that the resistor could overheat and produce smoke/fumes into the cabin (Background).\n- The mandated change isolates the start busbar after 1.5 seconds of improper current flow through the soft‑start resistor, reducing the risk of overheating, smoke or fumes entering the cabin, and ensures that some contactor failures produce a hard start rather than a failed start (Background; Requirement).\n\n**Who pays, who decides, and what behaviour changes**\n\n- Who pays: aircraft operators pay for parts, labour and any downtime needed to carry out the modification (Requirement; Applicability).\n- Who decides/authorises work: the regulator (CASA delegate) mandates the modification; operators must follow the specified BAe Service Bulletin instructions; maintenance organisations decide scheduling and execution consistent with the SBs (Requirement; Applicability).\n- Behavioural change required: affected operators must schedule and complete the modification by the compliance date and use the specified Service Bulletin procedures rather than continuing with existing start‑circuit arrangements (Compliance; Requirement).\n\n**Costs, incentives and trade‑offs (practical effects)**\n\n- Direct costs: purchase and installation of the changeover contactor, time‑delay relay and protection components; labour and aircraft downtime. These are borne by operators (Requirement; Applicability).\n- Incentives: operators have a compliance obligation; non‑compliance risks regulatory action and continued exposure to the safety issue. Maintenance and modification workshops may receive additional business from the mandated work (Requirement; Compliance).\n- Opportunity cost: scheduling the retrofit may displace other maintenance or operational flying, potentially affecting route capacity or revenue for operators (Compliance).\n- Implementation risk: availability of parts and approved trained personnel could delay compliance; incorrect installation risks new failure modes, so work must follow the Service Bulletin precisely (Requirement; Background).\n- Substitution effects: operators nearing end‑of‑life for older aircraft may choose to retire rather than modify; small operators with tight cashflow may defer investment subject to regulatory enforcement (Applicability; Compliance).\n\n**Effects on competition, contracts and private choice**\n\n- Market for maintenance: the AD generates demand for MRO (maintenance, repair and overhaul) services and parts; authorised/experienced MROs may capture more of that work (Requirement; Applicability).\n- Prices and productivity: one‑off retrofit costs increase short‑term operating costs for affected aircraft; productivity losses occur during aircraft downtime for modification (Compliance).\n- Contract freedom: operators must follow a regulator‑mandated process (specific Service Bulletins), which narrows private choice about how to address the identified unsafe condition (Requirement). Operators cannot substitute alternative solutions unless approved by the regulator.\n\n**Compliance burden and bureaucratic discretion**\n\n- Compliance burden: defined components and procedures in the Service Bulletins create a structured but prescriptive compliance path; costs and scheduling are the primary burdens on operators (Requirement; Applicability).\n- Bureaucratic discretion: the AD specifies the approved SBs; any alternative means of compliance would require regulator approval (Requirement; Note referencing CAA(UK) AD may influence acceptable methods).\n\n**Risks of concentrated benefits or unintended consequences**\n\n- Concentrated benefits: MROs and parts suppliers obtain concentrated revenue from retrofits; BAe’s approved procedures channel work to organisations capable of performing the SB instructions (Requirement).\n- Unintended consequences: retrofit complexity could introduce new electrical failure modes if not installed correctly; small operators may retire or ground aircraft rather than absorb costs (Background; Requirement).\n\n**Source claims vs mechanical effect**\n\n- The AD states that the modification reduces risk of resistor overheating and cabin smoke/fumes (Background). Mechanically, it does this by isolating the start busbar after a 1.5 second overcurrent condition and changing contactor behaviour (Background; Requirement).\n- That safety claim implies a reduction in certain in‑flight or ground safety incidents; the AD does not quantify incident frequency or cost, so operators must weigh the retrofit cost against regulatory obligation and their internal risk assessments.\n\n"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original directive (effective May 2001) and Amendment 1 (September 2001) covered a narrower range of aircraft. Amendment 2 explicitly 'increases the range of affected aeroplanes and introduces additional Modification Service Bulletins applicable to the increased range.' The scope has expanded from the original BAe 146 coverage to include more series-specific variants (100, 200 series) and additional technical compliance pathways."},"complexity_factors":["Single, clearly defined technical requirement (modify engine start circuit)","Four specific Service Bulletins referenced for compliance, with clear applicability to different aircraft series","Simple conditional logic: if power flows through resistor >1.5 seconds, circuit isolates start busbar","Limited cross-referencing (one UK CAA AD mentioned in a note, no complex legislative interdependencies)","No defined terms section or interpretation provisions","Clear, fixed compliance deadline (Before 20 December 2002)","Background section explains technical rationale in accessible language"],"plain_english_summary":"This mandatory CASA Airworthiness Directive orders operators of BAe 146 and Avro 146‑RJ70 aircraft to modify the engine‑start electrical circuit to prevent the soft‑start resistor overheating and causing smoke or fumes in the cabin. It requires fitting a changeover contactor and a time‑delay relay that cuts power if current passes through the resistor over 1.5 seconds, allowing a hard start if the contactor fails. Compliance is required before 20 December 2002; this AD supersedes the prior amendment."},"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-146-88-amdt-2-engine-start-electrical-circuit","history":"/api/acts/ad-bae-146-88-amdt-2-engine-start-electrical-circuit/history","analysis":"/api/acts/ad-bae-146-88-amdt-2-engine-start-electrical-circuit/analysis","conflicts":"/api/acts/ad-bae-146-88-amdt-2-engine-start-electrical-circuit/conflicts","importantCases":"/api/acts/ad-bae-146-88-amdt-2-engine-start-electrical-circuit/important-cases","documents":"/api/acts/ad-bae-146-88-amdt-2-engine-start-electrical-circuit/documents"}}