{"id":"F2006B10434","name":"AD/HS 125/153 - Thrust Reverser Secondary Locks, Microswitches and Wiring","slug":"ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116131,"registerId":"commonwealth-F2006B10434-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 125/153 - Thrust Reverser Secondary Locks, Microswitches and Wiring","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 125 Series Aeroplanes\n\nAD/HS 125/153 Thrust Reverser Secondary Locks,\n\nMicroswitches and Wiring\n\n  \n12/95\n\nApplicability: BAe 125 Series 1000A, 1000B and Hawker 1000 aircraft Pre Mod 253352 and Post Mod 253352.\n\nRequirement: Incorporate thrust reverser secondary locks microswitches and wiring in accordance with Hawker Raytheon Corporate Jets Service Bulletin SB. 78-14-3691A, B & E dated 21 June 1995.\n\nNote: CAA (UK) AD 004-06-95 refers.\n\nCompliance: Prior to 1 March 1996.\n\nBackground: The manufacturer has advised of the possibility of failure of a drive link or its attachments which may result in an inadvertent in-flight thrust reverser deployment.\n\nThis Directive requires the installation of a secondary locking feature to the thrust reversers in order to meet the certification requirements.","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 mechanical failure mode in specific aircraft models. It has not expanded beyond its original purpose of mandating thrust reverser safety modifications."},"complexity_factors":["Very short document (under 200 words)","Only 3 defined applicability categories (specific aircraft models)","Single, clear compliance requirement referencing an external technical standard","No nested exceptions or conditional logic","Straightforward deadline with no extensions or alternative compliance methods stated","Minimal cross-referencing (only one UK CAA AD mentioned in a note, and one service bulletin)"],"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 modifications to aircraft.\n\n**What it does:**\nOrders owners and operators of specific British Aerospace BAe 125 business jets to install **secondary locking mechanisms** on the thrust reversers (the parts of jet engines that help slow the plane down after landing). This includes new microswitches and wiring.\n\n**Why it matters:**\nThe manufacturer discovered a dangerous flaw: a drive link or its attachments could fail, causing a **thrust reverser to accidentally deploy during flight**. If this happens while the plane is airborne, it creates severe drag and loss of control — potentially causing a crash. The secondary locks act as a backup safety system to prevent this.\n\n**Who must comply:**\n- Owners/operators of **BAe 125 Series 1000A, 1000B and Hawker 1000 aircraft**\n- Applies whether or not the aircraft has been modified (Pre Mod 253352 and Post Mod 253352)\n\n**What must be done:**\nInstall the safety equipment exactly as specified in **Hawker Raytheon Service Bulletin SB. 78-14-3691A, B & E** (dated 21 June 1995).\n\n**Deadline:**\nAll modifications must be completed **before 1 March 1996**.\n\n**Key point:** This is not optional. Airworthiness Directives are legally binding — failure to comply means the aircraft cannot legally fly in Australian airspace."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text does not indicate any change to scope from an earlier intent. It sets out a single, clear requirement: incorporate thrust reverser secondary locks, microswitches and wiring on the specified BAe 125 / Hawker 1000 aircraft in accordance with the named service bulletin, to be completed prior to 1 March 1996 (Applicability, Requirement, Compliance, Background)."},"complexity_factors":["Reference to an external technical document (Service Bulletin SB. 78-14-3691A, B & E) that prescribes the exact modification (Requirement).","Applicability phrasing limited to specific BAe 125 Series 1000A, 1000B and Hawker 1000 aircraft with the cryptic note 'Pre Mod 253352 and Post Mod 253352' which requires operator interpretation (Applicability).","Fixed compliance deadline (prior to 1 March 1996) that concentrates implementation activity and scheduling pressure (Compliance).","Safety-critical nature of the modification (thrust reverser locking, microswitches and wiring) increases technical and implementation risk and requires competent maintenance (Background, Requirement).","Cross-reference to a foreign regulator's AD (CAA (UK) AD) which may require operators to consult multiple documents for full context (Note)."],"plain_english_summary":"This directive requires owners/operators of specified BAe 125 Series 1000A/1000B and Hawker 1000 aircraft to install a secondary thrust-reverser locking feature, microswitches and wiring per Hawker Raytheon Service Bulletin SB.78‑14‑3691A/B/E to prevent inadvertent in‑flight deployment. \n\nWork must be completed before 1 March 1996; operators bear costs, downtime and must use approved maintenance organisations to implement the safety‑critical modification."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring","history":"/api/acts/ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring/history","analysis":"/api/acts/ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring/analysis","conflicts":"/api/acts/ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring/conflicts","importantCases":"/api/acts/ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring/important-cases","documents":"/api/acts/ad-hs-125-153-thrust-reverser-secondary-locks-microswitches-and-wiring/documents"}}