{"id":"F2006B05449","name":"AD/PA-23/16 - Rudder Trim Tab Adjustment Screw P/N 18453-00 - Replacement with P/N 18453-00","slug":"ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46189,"registerId":"commonwealth-F2006B05449-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-23/16 - Rudder Trim Tab Adjustment Screw P/N 18453-00 - Replacement with P/N 18453-00","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)  Piper PA-23 (Apache and Aztec) Series Aeroplanes\n\n \n\nAD/PA-23/16  Rudder Trim Tab Adjustment Screw NK P/N 18453-00 - Replacement with P/N 18453-00\n\nApplicability: Models PA-23 and PA-23-160 with S/Nos. 23-1 to 23-1253. Document:  1. Piper SB No. 162; or\n\n2. FAA AD 58-4-3.\n\n \n\nCompliance: Forthwith.\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 focused on a single mechanical component. Airworthiness Directives are inherently narrow in scope by design — they address specific unsafe conditions in specific aircraft types. There is no evidence of scope creep; the directive precisely matches its original safety purpose."},"complexity_factors":["Extremely short document (under 200 words)","Only one substantive requirement (replace one specific part)","No defined terms section","Minimal conditional logic (simple applicability test based on model and serial number)","Single cross-reference to external documents (Piper SB and FAA AD)","No nested exceptions or complex procedural steps"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific Piper Apache and Aztec aircraft to replace a particular part on the rudder trim tab (the small adjustable surface on the tail that helps keep the plane flying straight).\n\n**What must be done:**\n- Replace the \"Rudder Trim Tab Adjustment Screw\" with part number 18453-00\n- Interestingly, the old part and new part have the *same* part number, suggesting this is likely a manufacturing standard update or material change to an identical-looking component\n\n**Who it affects:**\n- Owners/operators of Piper PA-23 and PA-23-160 aircraft with serial numbers 23-1 through 23-1253\n\n**Why it matters:**\n- Rudder trim tabs are critical for stable flight. If the adjustment screw fails, the pilot could lose proper control of the aircraft's yaw (side-to-side movement)\n- The directive cites an FAA safety directive and a Piper service bulletin, indicating this addresses a known safety defect\n- \"Forthwith\" compliance means this must be done immediately — no grace period\n\n**Key documents referenced:**\n- Piper Service Bulletin No. 162\n- FAA Airworthiness Directive 58-4-3 (originally issued in 1958, suggesting this is a long-standing safety issue)"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument itself does not indicate any change from an original scope or intent. It specifies applicability (PA-23 and PA-23-160, S/N 23-1 to 23-1253), points to two external documents for the procedure (Piper SB No. 162 or FAA AD 58-4-3), and requires compliance 'Forthwith'. The text contains no statement that alters or expands the stated applicability or mandatory nature of the action compared with what is presented in this instrument."},"complexity_factors":["Very short, tightly prescriptive text (low intrinsic complexity).","Cross-reference to external technical documents (Piper SB No. 162 or FAA AD 58-4-3) for procedure increases operational complexity.","Immediate compliance requirement ('Forthwith') increases urgency and logistical complexity for operators.","Applicability defined by specific serial-number range requires identification and record-checking for each aircraft.","Apparent ambiguity in the title (replacement with the same part number 18453-00) introduces potential interpretive uncertainty about the required action."],"plain_english_summary":"This directive mandates immediate replacement of the rudder trim-tab adjustment screw (NK part no. 18453-00) on Piper PA‑23 and PA‑23‑160 aeroplanes, serials 23‑1 through 23‑1253, using the procedures in Piper Service Bulletin No. 162 or FAA AD 58‑4‑3.  \n\nOwners/operators must arrange and pay for the part and labour; compliance is required forthwith. The instrument is brief and mandatory, and its wording (same part number cited) may create practical ambiguity requiring reference to the cited documents or issuer clarification."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00","history":"/api/acts/ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00/history","analysis":"/api/acts/ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00/analysis","conflicts":"/api/acts/ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00/conflicts","importantCases":"/api/acts/ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00/important-cases","documents":"/api/acts/ad-pa-23-16-rudder-trim-tab-adjustment-screw-p-n-18453-00-replacement-with-p-n-18453-00/documents"}}