{"id":"F2006B09299","name":"AD/DO-27/4 - Flap Control Lever - Modification","slug":"ad-do-27-4-flap-control-lever-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53384,"registerId":"commonwealth-F2006B09299-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DO-27/4 - Flap Control Lever - Modification","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)  Dornier DO-27 Series Aeroplanes\n\n \n\nAD/DO-27/4 Flap Control Lever - Modification 5/64\n\nApplicability: All DO-27 fitted with flap actuating levers without control grip. Document:  Dornier TB No. 27-18.\n\nCompliance: Before 1 September 1971.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The supplied text contains a single, focused requirement: modify the flap control lever on DO-27 aircraft that lack a control grip, using Dornier TB No. 27-18, and complete the work before 1 September 1971 (title; Applicability; Document; Compliance). The excerpt does not indicate any amendment or narrowing/expansion of that original scope."},"complexity_factors":["Narrow applicability focused on DO-27 aircraft fitted with flap actuating levers without a control grip (Applicability) — reduces breadth of affected parties.","Short, fixed compliance instruction with a historic deadline (Compliance) — simple in form but potentially urgent for operators at the time.","Execution detail delegated to an external technical bulletin (Document: Dornier TB No. 27-18) — increases implementation complexity because the AD text itself lacks procedure, parts list and labour estimates.","No enforcement, exemption, or penalty language present in the supplied excerpt (Compliance) — implementers must rely on broader regulatory framework for consequences, adding interpretive steps.","Dependence on access to technical documentation and availability of parts/qualified maintenance resources — practical complexity not described in the AD itself."],"plain_english_summary":"### What this directive does\n\nThis airworthiness directive (AD/DO-27/4) requires a modification to the flap control lever on certain Dornier DO-27 aeroplanes. Mechanically, it targets DO-27 aircraft that have flap actuating levers without a control grip and directs that those levers be modified (the title and applicability identify the target and change: \"Flap Control Lever - Modification\"; \"Applicability: All DO-27 fitted with flap actuating levers without control grip\"). The text refers operators to a specific technical instruction for how to carry out the work (\"Document: Dornier TB No. 27-18\").\n\n### Who this affects\n\n- Aircraft owners and operators of Dornier DO-27 aeroplanes that have flap actuating levers without a control grip (Applicability).  \n- Maintenance organisations or engineers who must perform the modification according to the referenced technical bulletin (Document: Dornier TB No. 27-18).\n\n### Timing and formal source\n\n- The directive sets a mandatory compliance deadline: before 1 September 1971 (Compliance).  \n- It is presented under the Commonwealth of Australia (Civil Aviation Regulations 1998), Part 39 / Civil Aviation Safety Authority heading in the supplied text.\n\n### How it works, practically\n\n- The AD identifies the affected aircraft by configuration and requires a specified modification to those aircraft (Applicability; title).  \n- It tells operators to use Dornier Technical Bulletin No. 27-18 as the procedural document for the modification (Document).  \n- It imposes a fixed deadline by which the work must be completed (Compliance).\n\n### Costs, incentives and trade-offs (text‑based)\n\n- Who pays: The supplied text does not state funding arrangements; under the instruction’s mechanics, the immediate economic burden falls on the aircraft owner/operator because they are required to carry out the modification (Applicability; Compliance).  \n- Incentives: Owners face an incentive to schedule the work before the date specified to meet the AD. The directive itself does not state enforcement measures or alternative compliance options in the supplied text (Compliance).  \n- Opportunity cost and downtime: Implementing the modification will require maintenance time and resources; the AD points users to a technical bulletin for the method and thus creates a dependency on that document for parts, labour estimates and procedures (Document: Dornier TB No. 27-18).  \n- Compliance burden and implementation risk: The supplied text is brief and relies on the external technical bulletin for execution details, which means operators must obtain and follow that bulletin to understand exact parts, tools and labour required (Document). If the bulletin or parts are hard to obtain, implementing the AD may be delayed or require logistical effort.  \n\n### Discretion and enforcement (as provided)\n\n- The AD is presented as an instruction under the Commonwealth/Part 39 heading in the supplied text; it sets a mandatory task and deadline but does not include penalties, exemptions, or enforcement mechanics in the excerpt provided (heading; Compliance).  \n\n### Substitution effects and market impact (text‑based observation)\n\n- The directive obliges affected operators to alter aircraft configuration; this will create demand for the modification procedure, parts and qualified maintenance labour (Document). The supplied text does not specify who supplies parts or whether multiple suppliers can perform the work.\n\n### What the directive does not say (in this excerpt)\n\n- The text does not state the specific safety rationale, the exact modification steps, parts list, cost estimates, enforcement measures, or whether temporary operating limitations are allowed pending modification. Those details would be expected to appear in the referenced Dornier TB No. 27-18 or in fuller AD paperwork (Document; Compliance)."},"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1964 (5/64) with a specific technical purpose. It has not expanded beyond its original intent of mandating a specific safety modification to flap control levers on one aircraft type."},"complexity_factors":["Extremely short document — only 4 substantive lines","No defined terms section","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Simple conditional logic: applies to 'All DO-27 fitted with flap actuating levers without control grip'","Single compliance requirement with fixed deadline","No exceptions, exemptions, or nested conditions"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\n- Requires owners and operators of **Dornier DO-27 series aeroplanes** to modify the flap control lever on their aircraft.\n- Specifically targets planes fitted with flap actuating levers that **lack a control grip** (a handle or grip on the lever used to operate the flaps — the movable surfaces on wings that help with takeoff and landing).\n\n**Who it affects:**\n- Anyone who owns or operates a Dornier DO-27 aircraft in Australia that has the specified type of flap lever.\n\n**What must be done:**\n- The modification must be carried out following **Dornier Technical Bulletin No. 27-18** (the manufacturer's official instructions for this fix).\n- **Deadline:** Before 1 September 1971.\n\n**Why it matters:**\n- Flap levers without proper grips could pose a safety risk — perhaps slipping from the pilot's hand during critical flight phases like landing. This directive ensures all affected aircraft were modified to meet safer design standards."}},"importantCases":[],"_links":{"self":"/api/acts/ad-do-27-4-flap-control-lever-modification","history":"/api/acts/ad-do-27-4-flap-control-lever-modification/history","analysis":"/api/acts/ad-do-27-4-flap-control-lever-modification/analysis","conflicts":"/api/acts/ad-do-27-4-flap-control-lever-modification/conflicts","importantCases":"/api/acts/ad-do-27-4-flap-control-lever-modification/important-cases","documents":"/api/acts/ad-do-27-4-flap-control-lever-modification/documents"}}