{"id":"F2008L01942","name":"AD/PA-23/31 Amdt 1 - Rudder Trim Tab Control Rod - Inspection","slug":"ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":74180,"registerId":"commonwealth-F2008L01942-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Piper PA-23 (Apache and Aztec) Series Ae","sectionType":"division","heading":"Piper PA-23 (Apache and Aztec) Series Aeroplanes","content":"### Piper PA-23 (Apache and Aztec) Series Aeroplanes\n\n| AD/PA-23/31 Amdt 1 | Rudder Trim Tab Control Rod - Inspection | 7/2008 |\n| ------------------ | ---------------------------------------- | ------ |\n\n| Applicability: | Models PA-23 and PA-23-160 with S/Nos. 23-1 to 23-2046.                                                                                                                                                                                                                                                                                                                                                                                                         |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect the rudder trim tab control rod in accordance with Piper SL No. 407.Note: FAA AD 63-24-03 also refers.                                                                                                                                                                                                                                                                                                                                                  |\n| Compliance:    | At intervals not exceeding 100 hours time in service.                                                                                                                                                                                                                                                                                                                                                                                                           |\n|                | This Amendment becomes effective on 3 July 2008.                                                                                                                                                                                                                                                                                                                                                                                                                |\n| Background:    | This Directive is issued to minimise the potential hazard of the rudder trim tab disconnecting from its control rod by ensuring periodic inspection of the control rod and its attachment to the trim tab.The original issue of this Directive became effective in 1963.Amendment 1 was raised to delete reference to the once-only requirement to install a roll pin in lieu of the cotter pin in the trim tab control rod, and to note the equivalent FAA AD. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n7 May 2008","sortOrder":0},{"sectionNumber":"AD/PA-23/31 Amdt 1","sectionType":"part","heading":"AD/PA-23/31 Amdt 1","content":"## AD/PA-23/31 Amdt 1","sortOrder":1},{"sectionNumber":"Rudder Trim Tab Control Rod - Inspection","sectionType":"part","heading":"Rudder Trim Tab Control Rod - Inspection","content":"## Rudder Trim Tab Control Rod - Inspection","sortOrder":2},{"sectionNumber":"7/2008","sectionType":"part","heading":"7/2008","content":"## 7/2008","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"Amendment 1 narrowed the prescriptive hardware-change element of the original directive by deleting the prior once-only requirement to install a roll pin in place of a cotter pin in the trim tab control rod. The instrument now focuses on recurring inspections (every 100 hours TIS) per Piper Service Letter No. 407. Mechanically, the scope shifted from a combined inspection-plus-mandatory-modification approach to an inspection-focused approach and formally records the equivalent FAA AD (63-24-03). This reduces the instrument's immediate modification mandate (one-off cost) while retaining ongoing compliance obligations (recurring inspection costs and maintenance workload) for owners/operators."},"complexity_factors":["Short, single-purpose directive (one required action: inspect rudder trim tab control rod).","Single compliance interval specified (every 100 hours time-in-service).","Applicability limited to specific models and serial numbers (PA-23 and PA-23-160, S/N 23-1 to 23-2046).","References an external technical document (Piper Service Letter No. 407) for inspection procedure.","Cross-reference to an equivalent foreign regulator instrument (FAA AD 63-24-03).","Amendment deletes a one-off modification requirement but otherwise leaves the inspection regime — no nested exceptions or conditional logic."],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an airworthiness directive that requires periodic inspection of the rudder trim tab control rod and its attachment on certain Piper PA-23 (Apache and Aztec) aeroplanes.  The inspections must be carried out in accordance with Piper Service Letter No. 407.\n- Inspections must be performed at intervals not exceeding 100 hours time-in-service (TIS).\n- The Directive notes the equivalent FAA airworthiness directive (FAA AD 63-24-03).\n- Amendment 1 removes a previous one-off requirement to replace a cotter pin with a roll pin in the trim tab control rod; the current requirement is the recurring inspection described above.\n- The Directive is effective from 3 July 2008 and applies to PA-23 and PA-23-160 models with serial numbers 23-1 through 23-2046.\n\n**Who is affected**\n\n- Owners and operators of Australian-registered Piper PA-23 and PA-23-160 aircraft with S/Ns 23-1 to 23-2046.  (If you operate one of these aircraft you must comply.)\n- Maintenance organisations and licensed aircraft maintenance engineers who perform required inspections and any consequent repairs.\n- The Civil Aviation Safety Authority (CASA) enforces the directive; compliance is mandatory for affected aircraft.\n\n**Why it matters (practical effects and incentives)**\n\n- Purpose claimed: to reduce the risk that the rudder trim tab could disconnect from its control rod (a potential flight-safety hazard) by ensuring routine inspection of the control rod and its attachment.\n- Who pays: aircraft owners/operators pay the cost of inspections and any follow-up repairs or replacements. Maintenance providers receive the inspection work.\n- Behavioural change: instead of a single mandatory hardware modification (which this amendment removes), operators must perform recurring inspections every 100 hours TIS and take corrective action if defects are found.\n- Trade-offs and implementation considerations:\n  - Cost structure: recurring inspection costs (labour, downtime, parts if needed) replace — or sit alongside, depending on past compliance — a one-off modification cost that was previously mandated.\n  - Risk management: recurring inspections rely on timely compliance and effective maintenance processes. Missing inspections could allow deterioration to progress between checks; conversely, a one-off hardware change tends to be a permanent mitigation.\n  - Administrative simplicity: the directive is short and prescriptive (inspect per Piper SL No. 407 at ≤100-hour intervals) but depends on an external technical document (Piper Service Letter No. 407) for the inspection procedure.\n  - Market effect: independent maintenance organisations and engineers will perform the inspections and any required repairs; owners may trade off inspection costs versus voluntary modifications.\n\n**Concrete obligations and mechanics**\n\n- Inspect the rudder trim tab control rod and its attachment in accordance with Piper Service Letter No. 407.\n- Do the inspection at intervals of no more than 100 hours time-in-service.\n- If inspection reveals wear, damage, loose attachments or other defects, the operator must have the defect corrected in accordance with approved maintenance practices before further flight (the Directive references the Service Letter for the inspection method; standard maintenance rules govern corrective action).\n\n**Background and change from earlier version**\n\n- The original directive dates from 1963. Amendment 1 (this document) deletes the earlier once-only requirement to install a roll pin instead of a cotter pin in the trim tab control rod and instead retains the periodic inspection regime. The amendment also explicitly notes the equivalent FAA AD (63-24-03).\n\n(References: Applicability, Requirement, Compliance and Background sections of AD/PA-23/31 Amdt 1; Piper Service Letter No. 407; FAA AD 63-24-03.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment narrows rather than expands scope. It removes the original requirement to install a roll pin (a one-time modification) and retains only the recurring inspection requirement. The directive remains tightly focused on the specific safety issue of rudder trim tab control rod integrity."},"complexity_factors":["Single, specific mechanical component targeted (rudder trim tab control rod)","Only one substantive requirement: inspect per manufacturer's service letter","Simple applicability criteria (two model variants, specific serial number range)","Straightforward compliance interval (100 hours time in service)","No nested exceptions, conditional logic, or extensive cross-referencing","Background section provides clear rationale without legal obfuscation","Total length: approximately 200 words of substantive content"],"plain_english_summary":"Owners/operators of Piper PA-23 and PA-23-160 aircraft (ser. no. 23‑1 to 23‑2046) must inspect the rudder trim tab control rod every 100 flight hours per Piper Service Letter No. 407. \n\nThis mandatory CASA airworthiness directive prevents loss of rudder‑trim control that could make the aircraft hazardous; the 2008 amendment removed an old one‑time roll‑pin modification and cross‑references the equivalent US safety order."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection","history":"/api/acts/ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection/history","analysis":"/api/acts/ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection/analysis","conflicts":"/api/acts/ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection/conflicts","importantCases":"/api/acts/ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection/important-cases","documents":"/api/acts/ad-pa-23-31-amdt-1-rudder-trim-tab-control-rod-inspection/documents"}}