{"id":"F2006B06148","name":"AD/PC-6/44 - Horizontal Stabiliser Trim Actuator","slug":"ad-pc-6-44-horizontal-stabiliser-trim-actuator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46946,"registerId":"commonwealth-F2006B06148-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PC-6/44 - Horizontal Stabiliser Trim Actuator","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPilatus Porter PC-6 Series Aeroplanes\n\nAD/PC-6/44 Horizontal Stabiliser Trim Actuator 12/99 TX\n\nApplicability: All PC-6 aircraft fitted with horizontal stabiliser trim actuator Pilatus P/N 978.73.18.101 or 978.73.18.102 or 978.73.18.103.\n\nRequirement: Inspect in accordance with the requirements of Pilatus Service Bulletin PC-6 No 178 dated 29 Sept 1999.\n\nNote: Swiss FOCA AD HB 99-507 refers.\n\nCompliance: For aircraft with more than 2000 landings or more than 500 hours TIS if the number of landings has not been recorded, inspect before further flight.\n\nFor all other aircraft, inspect at the next 100 hourly inspection.\n\nThis Airworthiness Directive becomes effective on 11 October 1999.\n\nBackground: The Swiss Airworthiness Directive was written after the FOCA received a report of a lower lug of the electrical horizontal stabiliser trim actuator was found cracked and with a lug segment missing. The cause is suspected to be loosening of the staked bearing causing excessive wear and hence failure of the lower lug.","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 type. It has not expanded beyond its original purpose of mandating inspections for a known failure mode."},"complexity_factors":["Very short document (under 300 words)","Only 3 specific part numbers trigger applicability","Simple binary compliance trigger (landing count/hours vs. everything else)","Single cross-reference to Swiss authority document (informational only)","No defined terms section, no nested conditions, no exceptions"],"plain_english_summary":"This AD mandates inspections of Pilatus Porter PC-6 aircraft fitted with specific horizontal stabiliser trim-actuator parts. High‑use aircraft (over 2,000 landings or 500+ hours if landings untracked) must be inspected before next flight; others at the next 100‑hour check. The action responds to a cracked/missing lower lug likely from bearing wear that could cause loss of pitch control. Australian owners/operators must comply following the Pilatus service bulletin."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope aligns with its stated intent: it targets PC‑6 aircraft fitted with the listed actuator part numbers and requires inspections per the service bulletin. There is no expansion beyond those fitted with the specified parts (Applicability; Requirement)."},"complexity_factors":["Targeted applicability limited to PC‑6 aircraft fitted with three specific actuator part numbers (Applicability).","Mandates inspection per an external document (Pilatus Service Bulletin PC‑6 No 178), creating reliance on vendor guidance (Requirement).","Two alternative compliance triggers: a mandatory before‑flight inspection for aircraft >2,000 landings or >500 hours TIS where landings are unrecorded, and scheduling at the next 100‑hour inspection for others (Compliance).","Operational impact and immediate compliance risk for aircraft meeting the higher‑use threshold — potential grounding until inspection is completed (Compliance).","Root‑cause statement limits scope to a specific failure mode (cracked/missing lower lug suspected from staked bearing loosening) rather than broader airframe issues (Background).","Effective date creates a hard start for compliance obligations (This Airworthiness Directive becomes effective on 11 October 1999)."],"plain_english_summary":"This Airworthiness Directive requires Pilatus PC‑6 operators whose aircraft are fitted with horizontal stabiliser trim actuators P/N 978.73.18.101, .102 or .103 to carry out inspections in accordance with Pilatus Service Bulletin PC‑6 No 178. For aircraft with more than 2,000 landings or more than 500 hours TIS (if landings not recorded) the inspection must be done before further flight; others at the next 100‑hour inspection. The AD was issued after a report of a cracked/missing lower lug suspected to result from bearing loosening and wear."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pc-6-44-horizontal-stabiliser-trim-actuator","history":"/api/acts/ad-pc-6-44-horizontal-stabiliser-trim-actuator/history","analysis":"/api/acts/ad-pc-6-44-horizontal-stabiliser-trim-actuator/analysis","conflicts":"/api/acts/ad-pc-6-44-horizontal-stabiliser-trim-actuator/conflicts","importantCases":"/api/acts/ad-pc-6-44-horizontal-stabiliser-trim-actuator/important-cases","documents":"/api/acts/ad-pc-6-44-horizontal-stabiliser-trim-actuator/documents"}}