{"id":"F2006B02400","name":"AD/AMD 50/4 - Thrust Reverser Electrical Control System","slug":"ad-amd-50-4-thrust-reverser-electrical-control-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41643,"registerId":"commonwealth-F2006B02400-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AMD 50/4 - Thrust Reverser Electrical Control System","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)  \nAMD Falcon 50 and 900 Series Aeroplanes\n\nAD/AMD 50/4 Thrust Reverser Electrical Control System 2/90\n\nApplicability: All Falcon 900 aircraft.\n\nRequirement: Action in accordance with Avions Marcel Dassault \\- Breguet. Aviation Service Bulletin AMD-BA/F900/54 R2.\n\nNote: DGAC Airworthiness Directive 89-106-008 (B) R1 also refers.\n\nCompliance: Prior to 22 May 1990.\n\nBackground: AMDBA advise that during landing with the thrust reverser doors ordered deployed, an automatic stow signal will be generated if a landing rebound occurs. This can cause abnormal loads on the door actuating linkages by allowing thrust to be applied to the doors whilst in stowage transit.\n\nThis AD requires modification of the thrust reverser electrical control system in order to maintain the doors open when ordered deployed on the ground.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument applies to all Falcon 900 aircraft and mandates a specific modification per the manufacturer's service bulletin with a fixed compliance date. The text does not indicate any expansion or narrowing of applicability or a change from an earlier stated scope within the document itself."},"complexity_factors":["Narrow applicability limited to a single aircraft type (Falcon 900).","Single, specific technical remedy required (follow a named manufacturer service bulletin).","Fixed compliance deadline imposes scheduling and logistics constraints.","Dependence on external document (service bulletin) for technical details increases operational coordination needs.","Safety-technical subject matter requires qualified maintenance personnel and parts, adding practical implementation complexity."],"plain_english_summary":"### What this instrument does\n\n- Requires a modification to the thrust reverser electrical control system on Falcon 900 aeroplanes so that the thrust reverser doors remain open when they are ordered deployed on the ground. (Requirement: \"Action in accordance with Avions Marcel Dassault - Breguet. Aviation Service Bulletin AMD-BA/F900/54 R2.\"; Background: \"This AD requires modification of the thrust reverser electrical control system in order to maintain the doors open when ordered deployed on the ground.\")\n\n### Who it affects\n\n- Applies to all Falcon 900 aircraft. (Applicability: \"All Falcon 900 aircraft.\")\n- The immediate obligations fall on the aircraft operator or owner to arrange and complete the modification before the stated compliance date. (Compliance: \"Prior to 22 May 1990.\")\n\n### Why it matters (stated purpose and mechanical effect)\n\n- Stated purpose: to stop an automatic stow signal being generated if a landing rebound occurs while the reverser doors have been ordered deployed. The automatic stow during a rebound can allow thrust to be applied to doors while they are in transit to stow, producing abnormal loads on the door actuating linkages. (Background: \"during landing with the thrust reverser doors ordered deployed, an automatic stow signal will be generated if a landing rebound occurs... This can cause abnormal loads on the door actuating linkages by allowing thrust to be applied to the doors whilst in stowage transit.\")\n- Mechanical effect: the modification changes the electrical control logic so the doors stay open when deployed on the ground, preventing the described sequence that generates abnormal loads. (Requirement: see referenced service bulletin.)\n\n### Implementation mechanics and administrative points\n\n- The AD mandates compliance with a specific manufacturer's service bulletin as the means of modification. (Requirement: \"Action in accordance with ... Service Bulletin AMD-BA/F900/54 R2.\")\n- A firm compliance date is given: the required work must be completed prior to 22 May 1990. (Compliance: \"Prior to 22 May 1990.\")\n- The AD cross-references a related foreign authority AD (DGAC Airworthiness Directive 89-106-008 (B) R1), indicating the issue has also been addressed by another regulator. (Note: \"DGAC Airworthiness Directive 89-106-008 (B) R1 also refers.\")\n\n### Practical costs, incentives and trade-offs (source-grounded)\n\n- Who pays: the operator or owner of each affected Falcon 900 must arrange for the modification (the AD imposes the duty to have the work done on applicable aircraft). (Applicability; Requirement; Compliance.)\n- Compliance burden: operators must schedule maintenance, source parts and/or technical support to perform the modification per the manufacturer's service bulletin, and take the aircraft out of service for the work until complete. (Requirement: service bulletin; Compliance date.)\n- Timing and incentives: the presence of a firm compliance date creates a clear deadline that operators must meet; operators may balance the cost and aircraft downtime against the deadline but cannot legally defer past the compliance date. (Compliance.)\n- Implementation risk and dependency: the AD relies on the manufacturer's service bulletin as the required method; successful implementation depends on the completeness and accuracy of that bulletin and availability of required parts or qualified maintenance personnel. (Requirement.)\n- Trade-offs: the measure imposes a one-off retrofit requirement and associated costs and downtime in exchange for reducing the risk of abnormal loads on reverser door linkages caused by the described mode of operation. (Background; Requirement.)\n\n### Discretion and enforcement\n\n- The AD sets a mandatory technical standard and deadline; it does not indicate discretionary alternatives within the text. (Requirement; Compliance.)\n\n### Source citations (from the instrument)\n- Applicability: \"All Falcon 900 aircraft.\"\n- Requirement: \"Action in accordance with Avions Marcel Dassault - Breguet. Aviation Service Bulletin AMD-BA/F900/54 R2.\"\n- Compliance: \"Prior to 22 May 1990.\" \n- Background: text describing the automatic stow signal, landing rebound, abnormal loads, and the modification objective.\n"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft model. It has not expanded beyond its original purpose of mandating a thrust reverser system modification."},"complexity_factors":["Single, specific aircraft type (Falcon 900 only)","One clear mechanical modification required","No defined terms section","No nested exceptions or conditional logic","Cross-reference to only one manufacturer service bulletin and one French aviation directive","Total length: approximately 150 words","Straightforward compliance deadline with no alternative methods of compliance (AMOC) described in this excerpt"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety fix ordered by Australia's aviation regulator (CASA) for a specific aircraft type.\n\n**What it does:**\nOrders owners and operators of **Falcon 900 aircraft** (a type of business jet made by French manufacturer Avions Marcel Dassault-Breguet) to modify the **thrust reverser electrical control system**.\n\n**The safety problem:**\nWhen a Falcon 900 lands and the pilot deploys the thrust reversers (those panels that flip up behind the engines to help slow the plane), there's a dangerous glitch. If the plane bounces slightly on landing (a \"landing rebound\"), the old system would automatically try to **stow (close) the reverser doors** — even while the pilot still wanted them open. If the pilot then applied engine power during this closing process, it could put massive, damaging stress on the door mechanisms.\n\n**What the fix does:**\nChanges the electrical system so that **once the reverser doors are commanded open on the ground, they stay open** — no more automatic stow signal on landing bounce.\n\n**Who must act:**\nAnyone operating a Falcon 900 aircraft in Australia.\n\n**Compliance deadline:**\nBefore 22 May 1990 (now long past — this is a historical directive).\n\n**Why it matters:**\nPrevents potential structural damage to the aircraft and reduces risk of an accident caused by malfunctioning thrust reversers during a critical phase of flight (landing)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-amd-50-4-thrust-reverser-electrical-control-system","history":"/api/acts/ad-amd-50-4-thrust-reverser-electrical-control-system/history","analysis":"/api/acts/ad-amd-50-4-thrust-reverser-electrical-control-system/analysis","conflicts":"/api/acts/ad-amd-50-4-thrust-reverser-electrical-control-system/conflicts","importantCases":"/api/acts/ad-amd-50-4-thrust-reverser-electrical-control-system/important-cases","documents":"/api/acts/ad-amd-50-4-thrust-reverser-electrical-control-system/documents"}}