{"id":"F2006B05334","name":"AD/P166/8 - Emergency Electrical Bus - Modification","slug":"ad-p166-8-emergency-electrical-bus-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45812,"registerId":"commonwealth-F2006B05334-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/P166/8 - Emergency Electrical Bus - Modification","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Piaggio P166 Series Aeroplanes\n\n \n\nAD/P166/8 Emergency Electrical Bus - Modification NK\n\nApplicability: S/Nos. prior to 409.\n\n \n\nDocument: 1. Provide two separate feeds from the main bust to the emergency bus with a common connection at the switch and separate connections at the emergency bus.\n\n \n\n2. Aeroplanes not fitted with a continuous unbroken emergency bus shall be modified by providing pitot heat, VHF, fire warning, stall warning and turn the bank indicator circuits with an additional alternative cable loop between their circuit breakers and the emergency bus.\n\n \n\nCompliance: Forthwith.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","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 electrical system vulnerability in a specific aircraft model. It has not expanded beyond its original technical scope."},"complexity_factors":["Extremely short document (under 200 words)","Only 2 substantive requirements with clear mechanical descriptions","No defined terms section — uses standard aviation terminology","No cross-references to other legislation or regulations","Simple binary applicability test (serial numbers prior to 409)","Single compliance deadline with no conditional exceptions or phased implementation"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — essentially a mandatory safety fix ordered by Australia's aviation regulator (CASA) for a specific type of aircraft.\n\n**What it does:** This directive requires urgent modifications to the electrical systems of Piaggio P166 series aeroplanes with serial numbers before 409.\n\n**The problem:** The original electrical design had a vulnerability in the \"emergency bus\" — a backup electrical circuit that keeps critical systems running if the main power fails. The existing setup had a single point of failure that could knock out essential safety equipment when pilots need it most.\n\n**The fix (two parts):**\n- **Part 1:** Install two separate power feeds from the main electrical system to the emergency bus, so if one feed fails, the other keeps working.\n- **Part 2:** For planes without a continuous emergency bus, add a backup cable loop connecting critical safety systems (pitot heat — which prevents ice buildup on speed sensors; VHF radio; fire warning; stall warning; and turn/bank indicator) directly to the emergency bus.\n\n**Who it affects:** Owners and operators of older Piaggio P166 aircraft (serial numbers 408 and below).\n\n**Why it matters:** This is a \"do it now\" safety order. The word \"Forthwith\" means compliance is immediate — no grace period. The modifications prevent total electrical failure during emergencies, keeping pilots able to communicate, detect fires, and maintain situational awareness when it counts."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The document presents a targeted amendment that applies to a defined set of aircraft (S/N prior to 409) and prescribes specific wiring modifications with immediate effect. There is no information in the supplied text indicating a change from an earlier scope or intent; the AD text itself sets the scope (Applicability) and the required actions (Document 1–2) with immediate compliance (Compliance: Forthwith)."},"complexity_factors":["Limited and specific technical scope: prescribes two wiring modifications (Document 1–2) rather than multiple regulatory requirements.","Serial-number limited applicability reduces population size but requires accurate records to determine applicability (Applicability).","Immediate compliance deadline increases scheduling and downtime pressure on owners/operators (Compliance: Forthwith).","Technical interpretation required: installers must determine whether an aeroplane already has a “continuous unbroken emergency bus,” which may be ambiguous without technical inspection (Document 2).","Implementation requires certified electrical maintenance work and potential parts sourcing; however, the AD does not create complex certification or procedural layers beyond the standard maintenance sign-off framework (AD header; Document)."],"plain_english_summary":"This AD requires immediate wiring changes to the emergency electrical bus on Piaggio P166 aeroplanes with serial numbers prior to 409: add two separate feeds to the emergency bus and, where needed, an alternate cable loop so pitot heat, VHF, fire warning, stall warning and turn‑and‑bank circuits have an additional feed.\n\nOwners/operators must arrange and pay for certificated maintenance to comply; the Civil Aviation Safety Authority issues and enforces the AD. The measure aims to increase electrical redundancy for safety‑critical systems."}},"importantCases":[],"_links":{"self":"/api/acts/ad-p166-8-emergency-electrical-bus-modification","history":"/api/acts/ad-p166-8-emergency-electrical-bus-modification/history","analysis":"/api/acts/ad-p166-8-emergency-electrical-bus-modification/analysis","conflicts":"/api/acts/ad-p166-8-emergency-electrical-bus-modification/conflicts","importantCases":"/api/acts/ad-p166-8-emergency-electrical-bus-modification/important-cases","documents":"/api/acts/ad-p166-8-emergency-electrical-bus-modification/documents"}}