{"id":"F2006B11443","name":"AD/P166/16 - Elevator Trim Drum - Inspection and Modification","slug":"ad-p166-16-elevator-trim-drum-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57383,"registerId":"commonwealth-F2006B11443-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/P166/16 - Elevator Trim Drum - Inspection and 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/P166/16 Elevator Trim Drum - Inspection and Modification 3/62\n\nApplicability: S/Nos. prior to 406. Document:  Piaggio SB P166-21. 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":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft model range. It has not expanded beyond its original purpose of ensuring airworthiness of the elevator trim drum in affected Piaggio P166 aircraft."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory content","No defined terms section — relies entirely on external references (Piaggio service bulletin)","No conditional logic or nested exceptions","Single, unambiguous applicability criterion (serial numbers prior to 406)","Simple compliance requirement ('Forthwith' — immediate action)","No cross-references to other legislation beyond the enabling regulations (Part 39)","Essentially a pointer to an external technical document rather than self-contained regulatory text"],"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 specific Piaggio P166 series aircraft to inspect and modify the **elevator trim drum** — a mechanical component that helps control the aircraft's pitch (nose up/down movement). The directive references a manufacturer's service bulletin (Piaggio SB P166-21) which contains the technical details of what needs to be done.\n\n**Who it affects:** Anyone who owns or operates a Piaggio P166 aircraft with **serial numbers prior to 406**.\n\n**When it must be done:** **Forthwith** — meaning immediately, before further flight.\n\n**Why it matters:** Airworthiness directives are issued when CASA identifies unsafe conditions in aircraft. This suggests there was a safety defect discovered in the elevator trim drum on these specific aircraft that could affect flight safety if not addressed immediately."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The supplied AD text contains no information about any prior or original instrument or a previous scope from which this AD would have changed. Based solely on the provided text, the AD sets a discrete requirement (inspection and modification of the elevator trim drum for P.166 aircraft with S/Ns prior to 406) and does not indicate that this alters or expands an earlier scope. Therefore a change from an earlier scope cannot be established from the material provided."},"complexity_factors":["Short, focused directive limited to a single component (elevator trim drum).","Clear applicability criterion using serial numbers (S/Nos. prior to 406), which narrows scope.","Immediate compliance timing (\"forthwith\") creates urgency but no phased compliance rules.","Technical implementation details are delegated to an external document (Piaggio SB P166-21), requiring consultation of that bulletin for actionable steps.","AD text lacks cost, exemption, or alternative-compliance language, reducing internal procedural complexity but increasing reliance on external guidance and operator judgement for implementation logistics."],"plain_english_summary":"This AD mandates immediate (\"forthwith\") inspection and, if required, modification of the elevator trim drum on Piaggio P.166 aeroplanes with serial numbers prior to 406, to be carried out per Piaggio Service Bulletin P166-21.  \n\nIt affects owners/operators and maintenance organisations of those aircraft; the AD sets the action and timing but gives no rationale, cost allocation, or implementation detail beyond referencing the service bulletin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-p166-16-elevator-trim-drum-inspection-and-modification","history":"/api/acts/ad-p166-16-elevator-trim-drum-inspection-and-modification/history","analysis":"/api/acts/ad-p166-16-elevator-trim-drum-inspection-and-modification/analysis","conflicts":"/api/acts/ad-p166-16-elevator-trim-drum-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-p166-16-elevator-trim-drum-inspection-and-modification/important-cases","documents":"/api/acts/ad-p166-16-elevator-trim-drum-inspection-and-modification/documents"}}