{"id":"F2006B03494","name":"AD/BAe 146/43 - N2 Limitations for Anti-Ice Selection - Placard","slug":"ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43048,"registerId":"commonwealth-F2006B03494-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/43 - N2 Limitations for Anti-Ice Selection - Placard","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 146 Series Aeroplanes\n\nAD/BAe 146/43 N2 Limitations for Anti-Ice Selection \\- Placard 5/92\n\nApplicability: All BAe146 series aeroplanes specified in the Requirement Document.\n\nRequirement: Action in accordance with British Aerospace Mandatory Service Bulletin # SB.11-97- 01285A.\n\nCompliance: Prior to 31 September 1992.\n\nBackground: There have been incidents of engine N1/N2 mismatch resulting in engine roll back which cannot be restored within TGT limits when operating above FL250 with engine Anti-Ice on and after selecting airframe Anti-Ice on. In addition to introducing a placard giving a flight level and RPM limitation, wiring changes are introduced to inhibit the thrust lever actuated airbrake auto-retract function to enable the airbrake to be operated at high altitude to assist in descent when the thrust levers are forward in compliance with the placard requirements.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":3414},"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This directive addresses a specific safety issue (engine rollback at altitude) with targeted fixes. No evidence of scope expansion beyond the original airworthiness concern."},"complexity_factors":["Requires understanding of aviation-specific terminology (N1, N2, TGT, FL250, Anti-Ice systems)","References external technical document (Mandatory Service Bulletin) without reproducing its contents","Dual implementation requirements (placard installation and wiring modification)","Contains technical conditional logic (operation above FL250 with specific anti-ice configurations)"],"plain_english_summary":"**What this does:** This is a safety order requiring operators of BAe 146 aircraft to fix a dangerous engine problem. **The issue:** When flying above 25,000 feet with engine anti-ice systems active, turning on airframe anti-ice can cause engines to lose power (rollback) in a way that cannot be recovered without overheating the engine. **The fix:** Operators must follow a specific British Aerospace service bulletin that requires (1) installing a cockpit placard with flight level and engine speed (N2) limits when using anti-ice, and (2) modifying wiring to prevent airbrakes from automatically retracting when thrust levers are pushed forward. This allows pilots to use airbrakes to descend while keeping thrust forward to maintain engine power within the new limits. **Who it affects:** All British Aerospace BAe 146 series aircraft. **Compliance:** Required before the deadline specified in the directive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard","history":"/api/acts/ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard/history","analysis":"/api/acts/ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard/analysis","conflicts":"/api/acts/ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard/conflicts","importantCases":"/api/acts/ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard/important-cases","documents":"/api/acts/ad-bae-146-43-n2-limitations-for-anti-ice-selection-placard/documents"}}