{"id":"F2006B10947","name":"AD/JETSTREAM/77 - Stall Warning - Removal of Ground Inhibit Switch","slug":"ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56512,"registerId":"commonwealth-F2006B10947-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JETSTREAM/77 - Stall Warning - Removal of Ground Inhibit Switch","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/77 Stall Warning \\- Removal of Ground Inhibit Switch\n\n  \n4/98\n\nApplicability: All BAe Regional Aircraft Jetstream 3100 and 3200 Series aircraft with Modification JM7813A (SB 27-JM7813A) or Modification JM7813B embodied.\n\nRequirement: Unless previously accomplished, remove the ground inhibit function of the stall warning system in accordance with BAe Alert Service Bulletin 27-A-JM7847.\n\nNote: CAA UK AD 003-12-97 refers.\n\nCompliance: No later than 26 June 1998.\n\nThis airworthiness directive becomes effective on 26 March 1998.\n\nBackground: Modification JM7813 installed a ground inhibit relay and ground test relay to prevent the operation of the stall warning system until the aircraft has been airborne for at least three seconds. Investigation by BAe has shown that a failure of the ground test relay in the energised position would cause a failure in the stall warning system with no indication to the crew of the malfunction.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The AD reverses the operational effect of the earlier Modification JM7813 by requiring removal of the ground-inhibit feature. It therefore changes the original modification's scope for affected Jetstream aircraft (those with JM7813A/B) by rescinding a function that had prevented stall warnings on the ground when the inhibit was active; the AD targets only those modified aircraft and imposes a retrofit obligation with a fixed deadline."},"complexity_factors":["Narrow applicability: only Jetstream 3100/3200 airframes fitted with Modification JM7813A or JM7813B are affected (Applicability).","Single prescriptive action: removal of the ground-inhibit function must follow BAe Alert Service Bulletin 27-A-JM7847 (Requirement).","Safety-critical system interaction: the stall-warning, ground-inhibit relay and ground-test relay interaction is the safety trigger for the directive (Background).","Fixed compliance timeline: effective date (26 March 1998) and mandatory completion date (26 June 1998) create scheduling pressure for operators (Compliance).","Operational cost and downtime fall to aircraft operators who must arrange the work and incorporate it into maintenance programs (Requirement).","Inter-jurisdictional reference: note to CAA UK AD 003-12-97 indicates alignment with foreign airworthiness action (Note)."],"plain_english_summary":"This directive requires operators of BAe Jetstream 3100 and 3200 aircraft fitted with Modification JM7813A or JM7813B to remove the stall-warning ground-inhibit function by following BAe Alert Service Bulletin 27-A-JM7847, completed by 26 June 1998. CASA made the directive effective 26 March 1998. The change undoes an earlier modification that delayed stall warnings on the ground because a relay failure could disable the system without crew indication. Operators pay for and schedule the maintenance to comply. (Requirement; Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific technical defect identified in a particular aircraft modification. It has not expanded beyond its original purpose of mandating removal of a faulty ground inhibit function."},"complexity_factors":["Very short document (under 200 words)","Single, specific technical requirement with clear reference to manufacturer service bulletin","Limited applicability (only two specific aircraft series with specific modifications)","No defined terms section — uses standard aviation terminology","No conditional logic or nested exceptions","Single compliance deadline with no alternative methods or phased implementation","Straightforward background explanation without cross-references to other legislation (only notes related UK authority directive)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of BAe Jetstream 3100/3200 aircraft with Modification JM7813A/B to remove the ground‑inhibit feature from the stall‑warning system per Service Bulletin 27‑A‑JM7847 by 26 June 1998. The inhibit could silence stall warnings if a relay failed, leaving crews unaware of impending stalls — a critical safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch","history":"/api/acts/ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch/history","analysis":"/api/acts/ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch/analysis","conflicts":"/api/acts/ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch/conflicts","importantCases":"/api/acts/ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch/important-cases","documents":"/api/acts/ad-jetstream-77-stall-warning-removal-of-ground-inhibit-switch/documents"}}