{"id":"F2006B09151","name":"AD/DHC-6/63 - Gust Lock Assembly","slug":"ad-dhc-6-63-gust-lock-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115718,"registerId":"commonwealth-F2006B09151-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/63 - Gust Lock Assembly","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-6/63 Gust Lock Assembly 3/90 DM\n\nApplicability: S/Nos 1 to 690, 692, 693, 695 and 696. Requirement:  Action in accordance with Boeing Canada SB 6/508.\n\nNote: Canadian AD CF-90-01 refers.\n\n \n\nCompliance: Prior to 31 July 1990.\n\n \n\nBackground: Three instances have been reported where aircraft took off with pre-mod 6/1676 gust locks still engaged.\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 addressing a specific mechanical issue on specific aircraft. It has not expanded beyond its original purpose of mandating a gust lock modification."},"complexity_factors":["Very short document (approximately 150 words)","Only 1 defined applicability criterion (specific serial numbers)","Single, clear compliance requirement (follow Boeing Canada SB 6/508)","No nested exceptions or conditional logic","No cross-references to other legislation beyond a single note referencing Canadian AD CF-90-01","Straightforward deadline (single date, no phased compliance)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) for specific de Havilland Canada DHC-6 Twin Otter aircraft.\n\n**What it does:**\n- Requires owners/operators of certain Twin Otter planes (serial numbers 1–690, 692, 693, 695, and 696) to take specific safety action regarding the **gust lock assembly** — a device that locks an aircraft's control surfaces (like ailerons, elevators, and rudder) while the plane is parked to prevent wind damage.\n\n**The safety problem:**\n- Three incidents were reported where aircraft took off with the gust locks still engaged. This is extremely dangerous because locked controls prevent the pilot from steering the aircraft during takeoff.\n\n**What must be done:**\n- Follow the instructions in **Boeing Canada Service Bulletin 6/508** (a manufacturer-issued technical notice describing the required modification or inspection).\n\n**Who it affects:**\n- Operators of specific DHC-6 Twin Otter aircraft with the affected serial numbers.\n\n**Deadline:**\n- Compliance required before 31 July 1990.\n\n**Why it matters:**\n- Prevents catastrophic accidents caused by attempting flight with locked flight controls. The directive mandates a fix to ensure gust locks cannot be left engaged during takeoff."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive, as presented, sets a targeted requirement addressing gust-lock incidents for a defined set of DHC-6 serial numbers and requires action per Boeing Canada SB 6/508 by a fixed date. Nothing in the text indicates a change of scope from that stated purpose; the instrument appears to implement that narrowly defined corrective action."},"complexity_factors":["Narrow, specific applicability by serial number (reduces scope complexity)","Cross-reference to an external technical document (Boeing Canada SB 6/508) that contains the procedural detail","Mandatory fixed compliance deadline (scheduling pressure for operators and MROs)","Safety-critical hardware context (gust lock assembly) increases operational consequences of non-compliance","Reference to a pre-mod configuration (pre-mod 6/1676) which may require operators to determine aircraft modification status"],"plain_english_summary":"The Civil Aviation Safety Authority requires certain DHC‑6 (Twin Otter) aeroplanes (serials 1–690, 692, 693, 695, 696) to be inspected and modified per Boeing Canada Service Bulletin 6/508 before 31 July 1990 to prevent takeoff with a gust lock engaged. It affects owners/operators and maintenance organisations, who must schedule, pay for and carry out the mandated work to meet the safety deadline and avoid regulatory non‑compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-63-gust-lock-assembly","history":"/api/acts/ad-dhc-6-63-gust-lock-assembly/history","analysis":"/api/acts/ad-dhc-6-63-gust-lock-assembly/analysis","conflicts":"/api/acts/ad-dhc-6-63-gust-lock-assembly/conflicts","importantCases":"/api/acts/ad-dhc-6-63-gust-lock-assembly/important-cases","documents":"/api/acts/ad-dhc-6-63-gust-lock-assembly/documents"}}