{"id":"F2006B10918","name":"AD/JETSTREAM/49 - Engine Control - Engine Stop Circuitry","slug":"ad-jetstream-49-engine-control-engine-stop-circuitry","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56461,"registerId":"commonwealth-F2006B10918-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JETSTREAM/49 - Engine Control - Engine Stop Circuitry","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)  \nBritish Aerospace BAe 3100 (Jetstream) Series Aeroplanes\n\nAD/JETSTREAM/49 Engine Control \\- Engine Stop Circuitry 12/91 T\n\nApplicability: All Jetstream 3100 aircraft. Jetstream series 3200 aircraft with constructors numbers in the range 790 to 946 inclusive.\n\nRequirement: 1. Carry out a post flight test of the central annunciator panel in accordance with Part 1 of Jetstream SB 80-A-JA 911045.\n\n2. Remove diodes from the engine stop circuitry in accordance with Part 2 of Jetstream SB 80-A-JA 911045.\n\nCompliance: Requirement 1. On completion of the last flight of the day, and before engine shutdown, commencing 1 November 1991.\n\nRequirement 2. Within 100 hours time in service after 31 October 1991, or prior to 10 November 1991, whichever is the sooner.\n\nBackground: A diode failure in the central annunciator panel test button circuit can cause uncommanded engine shutdown when the test button is pressed.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific identified defect. It has not expanded beyond its original purpose of fixing the diode failure issue in the engine stop circuitry."},"complexity_factors":["Single, specific technical fault addressed","Only 2 compliance requirements","Clear applicability criteria (specific aircraft models and serial number range)","Simple temporal compliance deadlines","No cross-references to other legislation beyond the enabling Civil Aviation Regulations","No defined terms section","Straightforward background explanation"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or inspections on aircraft.\n\n**What it does:**\nThis directive orders fixes for a dangerous electrical fault in British Aerospace Jetstream aircraft. A faulty diode (a small electronic component) in the central warning light panel could cause engines to shut down unexpectedly when pilots press the test button.\n\n**Who it affects:**\n- All Jetstream 3100 series aircraft\n- Jetstream 3200 series aircraft with serial numbers 790 through 946\n\n**What must be done:**\n1. **Test the warning panel** after the last flight of each day (starting 1 November 1991) — pilots must check the central annunciator panel works correctly before shutting down engines\n2. **Remove faulty diodes** from the engine stop circuitry within 100 flight hours after 31 October 1991, or before 10 November 1991 (whichever comes first)\n\n**Why it matters:**\nUncommanded engine shutdown during flight is extremely dangerous. This directive prevents a situation where testing your warning lights could accidentally kill your engines."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The AD alters operational and maintenance obligations for affected aircraft compared with prior practice by imposing a daily post-flight test (Requirement 1) and mandating a hardware modification (removal of diodes) within a short compliance window (Requirement 2). The Background explains the safety trigger for these measures (diode failure causing possible uncommanded engine shutdown)."},"complexity_factors":["Limited number of discrete requirements (two actions: test and diode removal)","Clear, short compliance windows (daily from 1 Nov 1991; diode removal within 100 flight hours or by 10 Nov 1991)","Reliance on an external technical document (Jetstream SB 80-A-JA 911045) for procedural detail","Safety-critical context increases operational importance despite procedural simplicity","Applicability limited to specific aircraft models and constructor number range"],"plain_english_summary":"### What this directive does\n\nThis Airworthiness Directive (AD) applies to all British Aerospace Jetstream 3100 aeroplanes and certain Jetstream 3200 aeroplanes (constructors' numbers 790–946) (see \"Applicability\"). It requires two things: a daily operational test of the central annunciator panel and a modification to the engine stop circuitry (removal of diodes) following a manufacturer service bulletin (Jetstream SB 80-A-JA 911045) (see \"Requirement\").\n\nMechanically, the AD changes how operators must use and maintain affected aeroplanes:\n- Operators must perform a post-flight test of the central annunciator panel after the last flight of the day and before shutting the engines down (Requirement 1). The AD specifies when this test must start (from 1 November 1991).\n- Operators must remove specific diodes from the engine stop circuitry following Part 2 of the referenced service bulletin. That modification must be completed within 100 flight hours after 31 October 1991, or by 10 November 1991, whichever comes sooner (Requirement 2).\n\nOfficial rationale and how it connects to the requirements\n\nThe AD’s stated reason is that a diode failure in the central annunciator panel test-button circuit can cause an uncommanded engine shutdown when the test button is pressed (Background). The AD therefore directs a daily test (to exercise or check the annunciator panel) and a hardware change (removal of the diodes) intended to eliminate the failure mode.\n\nWho pays and who decides\n\n- Who pays: Aircraft owners/operators pay for the time taken to run the required post-flight test and for the labour, parts and shop time required to carry out the diode removal (Requirement 1 and Requirement 2).\n- Who decides/implements: The Civil Aviation Safety Authority issued the AD under Part 39–105 (header); the AD delegates the technical steps to the aircraft operator and to maintenance organisations that will carry out Jetstream SB 80-A-JA 911045 (Requirements reference the service bulletin).\n\nCompliance burden and timing\n\n- Operational burden: a test after the last flight of each day, before engine shutdown (Requirement 1). That creates a recurring time cost for night-time shutdown procedures.\n- Modification burden: a one-off hardware change within the specified short window (within 100 hours time in service after 31 October 1991, or before 10 November 1991, whichever is sooner) (Requirement 2). The modification depends on the service bulletin’s instructions (Requirement 2 references Part 2 of Jetstream SB 80-A-JA 911045).\n\nIncentives, trade-offs and practical risks\n\n- Incentives: Operators are incentivised to perform the test and make the modification within the timeframes to avoid the safety risk described (Background) and to remain legally compliant with the AD (Compliance). There is also an incentive to complete the diode removal promptly to avoid repeating the daily test long-term.\n- Trade-offs and opportunity cost: Operators must allocate staff time and maintenance resources to the daily test and the diode removal, which displaces other maintenance or operational tasks. The short calendar window for the modification concentrates that workload in a limited period (Requirement 2).\n- Implementation risk and dependence on documentation: The directive requires following the manufacturer’s service bulletin (Jetstream SB 80-A-JA 911045). That creates operational dependence on the content and availability of that bulletin (Requirement 1 and Requirement 2). Any ambiguity or supply/delivery delays for parts, or limited maintenance capacity, could extend aircraft downtime.\n\nEffects on private choice and the market for maintenance\n\n- Private operators must incur recurring and one-off maintenance activity (Requirement 1 and Requirement 2). This increases demand for maintenance labour and parts for affected aircraft during the compliance window and thereafter to implement the modification.\n- Independent maintenance providers can carry out the service-bulletin work, subject to regulatory and customer arrangements; the AD does not itself prescribe who must perform the work beyond compliance with the service bulletin (Requirements reference the SB). The AD therefore shifts costs to operators but leaves choice over accredited providers to the market.\n\nConcrete mechanisms for the stated safety aim\n\n- The daily post-flight test exercises or checks the central annunciator panel to reveal the diode failure mode before engines are shut down (Requirement 1).\n- The diode removal is a hardware change intended to remove the failure mode that could allow a test-button press to cause an uncommanded engine stop (Requirement 2 and Background).\n\nKey textual references: Applicability; Requirement 1; Requirement 2; Compliance dates; Background."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jetstream-49-engine-control-engine-stop-circuitry","history":"/api/acts/ad-jetstream-49-engine-control-engine-stop-circuitry/history","analysis":"/api/acts/ad-jetstream-49-engine-control-engine-stop-circuitry/analysis","conflicts":"/api/acts/ad-jetstream-49-engine-control-engine-stop-circuitry/conflicts","importantCases":"/api/acts/ad-jetstream-49-engine-control-engine-stop-circuitry/important-cases","documents":"/api/acts/ad-jetstream-49-engine-control-engine-stop-circuitry/documents"}}