{"id":"F2006B06081","name":"AD/PC-12/18 - Flap Drive Shafts","slug":"ad-pc-12-18-flap-drive-shafts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114479,"registerId":"commonwealth-F2006B06081-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PC-12/18 - Flap Drive Shafts","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 PC-12 Series Aeroplanes\n\nAD/PC-12/18 Flap Drive Shafts 8/99\n\nApplicability: All Model PC-12 and PC-12/45 aircraft.\n\nRequirement: Action in accordance with the Accomplishment Instructions of Pilatus Service Bulletin 27-003, dated March 8, 1999.\n\nNote: Swiss FOCA AD HB 99-241 refers.\n\nCompliance: Before 12 December 1999, unless already accomplished.\n\nThis Airworthiness Directive becomes effective on 12 August 1999.\n\nBackground: Reports were received of corroded inner drive cables of the flap flexible shafts (flap drive shafts). Investigations revealed that moisture from the pressurised cabin can enter the flap drive shafts through the unsealed areas of the flap drive shaft attachments and the shaft casings. This Directive requires replacement of the flap inboard and outboard flap drive shafts with modified shafts, the installation of additional gaskets on both sides of the Power Drive Unit, and modification of support brackets.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific mechanical defect. It has not expanded beyond its original purpose of mandating flap drive shaft replacement and modification."},"complexity_factors":["Very short document — approximately 150 words","Only 1 defined term implicitly referenced (the Service Bulletin)","No cross-references to other legislation beyond a single note about a Swiss authority document","Single, unambiguous compliance requirement: follow the Service Bulletin instructions","No conditional logic, exceptions, or nested provisions","Clear applicability statement (all PC-12 and PC-12/45 models)"],"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). Think of it as a \"recall notice\" for aircraft, but legally binding.\n\n**What it does:** It requires owners and operators of Pilatus PC-12 aircraft to replace specific parts of the flap system (the mechanisms that extend and lower the wing flaps during takeoff and landing). Specifically:\n- Replace the inner flap drive shafts with modified versions\n- Install extra gaskets (seals) on the Power Drive Unit\n- Modify support brackets\n\n**Why it matters:** Moisture from the pressurised cabin was leaking into the flap drive shafts, causing corrosion in the inner cables. Corroded cables could fail, potentially causing the flaps to jam or malfunction — a serious safety risk during critical flight phases like landing.\n\n**Who must comply:** Anyone who owns or operates a Pilatus PC-12 or PC-12/45 aircraft in Australia.\n\n**Deadline:** The work had to be completed before 12 December 1999 (unless already done)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope, as stated in the document, applies to all Model PC-12 and PC-12/45 aircraft and requires the specific mechanical changes described (Applicability; Requirement; Background). The stated intent (prevent moisture ingress and resultant corrosion) aligns with the required actions; nothing in the supplied text indicates a change from that original stated scope."},"complexity_factors":["Narrow applicability — single aircraft family (PC-12 and PC-12/45) reduces regulatory breadth (Applicability).","Technical mechanical work required (shaft replacement, gasket installation, bracket modification) requires specialist maintenance skills and parts (Requirement; Background).","Compliance is tied to a manufacturer service bulletin, so correct execution depends on that document and parts supply (Requirement).","Hard compliance deadline creates scheduling and operational constraints for operators (Compliance).","Regulatory mandate leaves little operator discretion over method—must follow the Service Bulletin—reducing flexibility (Requirement).","Potential for aircraft downtime while work is performed increases logistical complexity for operators (Compliance)."],"plain_english_summary":"Mandates replacement of inboard/outboard flap drive shafts with modified shafts, installation of additional gaskets on both sides of the Power Drive Unit, and modification of support brackets on all Pilatus PC‑12 and PC‑12/45 aeroplanes to stop moisture ingress that has caused corrosion of inner drive cables. Owners/operators must comply with Pilatus Service Bulletin 27‑003 (8 Mar 1999) by 12 Dec 1999, at their cost, which may require parts, labour and aircraft downtime."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pc-12-18-flap-drive-shafts","history":"/api/acts/ad-pc-12-18-flap-drive-shafts/history","analysis":"/api/acts/ad-pc-12-18-flap-drive-shafts/analysis","conflicts":"/api/acts/ad-pc-12-18-flap-drive-shafts/conflicts","importantCases":"/api/acts/ad-pc-12-18-flap-drive-shafts/important-cases","documents":"/api/acts/ad-pc-12-18-flap-drive-shafts/documents"}}