{"id":"F2006B05331","name":"AD/P166/5 - Engine Nacelle - Drainage Modification","slug":"ad-p166-5-engine-nacelle-drainage-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45802,"registerId":"commonwealth-F2006B05331-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/P166/5 - Engine Nacelle - Drainage 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/P166/5 Engine Nacelle - Drainage Modification NK\n\nApplicability: All models.\n\n \n\nRequirement: Provide adequate drainage facilities for all sections of the lower nacelles. Compliance:              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\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific technical issue on a specific aircraft type. It has not expanded beyond its original purpose."},"complexity_factors":["Extremely short document (under 150 words)","No defined terms section","No cross-references to other legislation or regulations","Single, unambiguous requirement with no conditions or exceptions","No procedural steps or alternative compliance methods specified","Plain language directive ('Provide adequate drainage facilities') with minimal technical specification"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of **Piaggio P166 series aircraft** (a type of twin-engine propeller plane) to modify the engine nacelles (the housings around the engines) to ensure they have **proper drainage**. This prevents water, fuel, or other fluids from pooling in the lower sections of the engine housing, which could cause corrosion, fire hazards, or structural damage.\n\n**Who it affects:** Anyone who owns, operates, or maintains a Piaggio P166 aircraft in Australia.\n\n**When it must be done:** **Immediately** (\"Forthwith\"). There is no grace period — the modification must be carried out as soon as practically possible.\n\n**Why it matters:** Pooling fluids in engine nacelles can lead to serious safety risks including engine failure, in-flight fire, or loss of structural integrity. This directive is a reactive safety measure, likely issued after an incident or inspection revealed a design flaw."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument itself states applicability as \"All models\" and mandates an immediate requirement. The provided text does not indicate any change to a prior scope or differentiate between models; therefore there is no evidence in this text that the scope has changed from any earlier intent."},"complexity_factors":["Broad applicability: applies to \"All models\" of Piaggio P166 series (lowers complexity of identifying covered aircraft but raises uniform application needs).","Vague outcome requirement: uses the term \"adequate drainage facilities\" without technical detail, creating interpretive discretion for implementers and approving authorities.","Immediate compliance: \"Forthwith\" imposes urgency that can complicate scheduling and logistics for owners/operators and maintenance providers.","Lack of prescribed method or reference documents: no installation drawings, standards, or procedures are included in the supplied text, requiring additional engineering/maintenance decisions.","Concentrated compliance burden: costs and implementation choices fall to individual owners/operators and their contractors, rather than being centrally specified."],"plain_english_summary":"This AD requiring Piaggio P166 owners/operators to \"provide adequate drainage facilities for all sections of the lower nacelles\" takes immediate effect. It imposes an outcome-based, safety-driven obligation on every P166 operator and their maintenance/engineering providers, leaving the technical method and approvals to those parties — so owners bear prompt compliance cost, scheduling impact and any necessary engineering substantiation."}},"importantCases":[],"_links":{"self":"/api/acts/ad-p166-5-engine-nacelle-drainage-modification","history":"/api/acts/ad-p166-5-engine-nacelle-drainage-modification/history","analysis":"/api/acts/ad-p166-5-engine-nacelle-drainage-modification/analysis","conflicts":"/api/acts/ad-p166-5-engine-nacelle-drainage-modification/conflicts","importantCases":"/api/acts/ad-p166-5-engine-nacelle-drainage-modification/important-cases","documents":"/api/acts/ad-p166-5-engine-nacelle-drainage-modification/documents"}}