{"id":"F2006B09152","name":"AD/DHC-6/64 - Elevator Pushrod Ball Ends","slug":"ad-dhc-6-64-elevator-pushrod-ball-ends","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52836,"registerId":"commonwealth-F2006B09152-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/64 - Elevator Pushrod Ball Ends","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)  DHC-6 (Twin Otter) Series Aeroplanes\n\n \n\nAD/DHC-6/64 Elevator Pushrod Ball Ends 7/90\n\nApplicability: All models.\n\n \n\nRequirement: Remove the pushrods (P/N C6CF 1466-1 or C6CF 1141-1) from the aircraft. Remove the rod ends from both ends of the pushrod and inspect for corrosion, damage, freedom of rotation and cracks, in accordance with Transport Canada Emergency AD CF-90-10.\n\n \n\nCompliance: Within the next 25 hours time in service or five days, whichever occurs first, after 14 May 1990, unless accomplished within the previous 21 days.\n\n \n\nBackground: Fatigue failure of an elevator pushrod ball end has occurred in service. It is suspected that the cause may have been related to seizure of the ball and/or bending or misalignment.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope as written applies to all DHC-6 models and specifies the affected part numbers and the inspection requirement within a defined short compliance window. The instrument text does not indicate any change from its original stated scope: it mandates removal and inspection of the named pushrods and rod ends in accordance with the referenced Transport Canada Emergency AD, within the stated timeframe (Applicability; Requirement; Compliance)."},"complexity_factors":["Specific part-number identification (P/N C6CF 1466-1 or C6CF 1141-1) requires accurate parts tracking and confirmation (Requirement).","Short mandatory compliance window (25 hours TIS or five days) concentrates scheduling and operational impact (Compliance).","Physical inspection tasks: removal of pushrods and rod ends and inspection for corrosion, damage, freedom of rotation and cracks require qualified personnel and clear inspection criteria (Requirement).","Cross-reference to an external regulatory document (Transport Canada Emergency AD CF-90-10) creates dependency on another regulator’s procedures and access to that document (Requirement).","Potential downstream tasks if defects are found (repair/replacement) increase unpredictability of cost and downtime (Requirement; Background)."],"plain_english_summary":"What this instrument does (mechanically)\n\n- This airworthiness directive orders that specific elevator pushrods installed on DHC-6 (Twin Otter) aeroplanes be removed from the aircraft and that the rod ends at both ends of each pushrod be taken off and inspected for corrosion, damage, freedom of rotation and cracks. The action must be done in accordance with Transport Canada Emergency AD CF-90-10. (Requirement)\n\nWho it applies to\n\n- It applies to all models of the DHC-6 (Twin Otter) series aeroplanes and specifically identifies pushrods with part numbers C6CF 1466-1 or C6CF 1141-1. (Applicability; Requirement)\n\nWhen it must be done\n\n- Operators must complete the removal and inspection within the next 25 hours time in service or five days, whichever comes first, after 14 May 1990, unless the same work was already done within the previous 21 days. (Compliance)\n\nWhy the directive was issued (stated reason and an operational test)\n\n- The directive states that a fatigue failure of an elevator pushrod ball end has occurred in service and that the suspected causes include seizure of the ball and/or bending or misalignment. That is the stated safety concern prompting the inspection requirement. (Background)\n\nWho pays, who decides, and what behaviour changes\n\n- Aircraft owners or operators bear the direct costs and operational disruption of removing the pushrods, removing the rod ends, performing inspections, and any subsequent repairs or replacements discovered by the inspection. (Requirement; Compliance)\n- The Civil Aviation Safety Authority (as the issuing authority on the document header) prescribes the action by issuing this directive; the inspection is to be performed in accordance with the referenced Transport Canada Emergency AD. (Header; Requirement)\n- The required behaviour change is that operators must take affected aircraft out of service for the short interval necessary to remove and inspect the rod ends within the prescribed 25 flight hours or five days window, unless already compliant within 21 days. (Requirement; Compliance)\n\nCompliance burden, decision points and implementation risk\n\n- The directive creates a short, mandatory compliance window (25 flight hours or five days) which concentrates the workload and may cause short-term scheduling or availability impacts for operators. (Compliance)\n- The inspection references an external document (Transport Canada Emergency AD CF-90-10), so operators must obtain and follow that document to meet the directive’s technical inspection standard. This cross-reference creates an implementation dependency on another regulator’s prescribed procedures. (Requirement)\n- The work requires identification of particular part numbers and a physical inspection for corrosion, damage, freedom of rotation and cracks; this requires qualified personnel and may reveal parts that need repair or replacement, generating further cost and downtime. (Requirement)\n\nTrade-offs and incentives\n\n- The directive imposes immediate compliance costs on operators in exchange for reducing the risk of in-service elevator pushrod failure. Operators have an incentive to comply promptly to restore legal airworthiness and avoid in-service failure. The directive does not prescribe who pays for replacement parts or labour beyond the requirement that the inspection be completed; in practice, owners/operators will incur those costs. (Requirement; Compliance)\n\nNotes on scope and authority citations\n\n- The directive applies to all DHC-6 models and names the affected part numbers, so its scope is limited to those parts on those aircraft. The legal authority is expressed through its placement as an airworthiness directive issued under the Commonwealth/Civil Aviation Safety Authority heading. (Applicability; Requirement; Header)\n\nSource citations: Applicability; Requirement; Compliance; Background."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive addressing a specific mechanical failure mode. It has not expanded beyond its original purpose of mandating inspection/replacement of elevator pushrod ball ends on DHC-6 aircraft."},"complexity_factors":["Single, discrete safety requirement with no conditional branches or exceptions","Only 2 part numbers specified; no extensive defined terms section","Cross-reference limited to one external document (Canadian AD CF-90-10)","Compliance timeframe uses simple 'whichever occurs first' logic with clear date anchoring","No nested subsections, penalty clauses, or administrative procedures embedded in text"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of **DHC-6 Twin Otter aircraft** (all models) to urgently inspect the elevator pushrods — the mechanical linkages that control the plane's pitch (up/down movement). Specifically, they must:\n- Remove the pushrods (parts numbered C6CF 1466-1 or C6CF 1141-1)\n- Detach the rod ends (ball ends) from both sides\n- Check for corrosion, damage, stiffness, and cracks\n- Follow the inspection procedure set out in a Canadian emergency directive (Transport Canada Emergency AD CF-90-10)\n\n**Who it affects:**\nAnyone who owns, operates, or maintains DHC-6 Twin Otter aircraft in Australia.\n\n**Why it matters:**\nA fatigue failure (metal cracking from repeated stress) had already occurred on one of these parts in actual flight service. If the ball end seizes or breaks, the pilot could lose control of the elevator — potentially causing a crash. The directive is urgent: compliance required within **25 flight hours or 5 days** (whichever comes first) after 14 May 1990, unless the inspection was already done in the previous 3 weeks.\n\n**Key point:** This is a time-critical safety mandate, not optional guidance. Non-compliance grounds the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-64-elevator-pushrod-ball-ends","history":"/api/acts/ad-dhc-6-64-elevator-pushrod-ball-ends/history","analysis":"/api/acts/ad-dhc-6-64-elevator-pushrod-ball-ends/analysis","conflicts":"/api/acts/ad-dhc-6-64-elevator-pushrod-ball-ends/conflicts","importantCases":"/api/acts/ad-dhc-6-64-elevator-pushrod-ball-ends/important-cases","documents":"/api/acts/ad-dhc-6-64-elevator-pushrod-ball-ends/documents"}}