{"id":"F2006B09186","name":"AD/DHC-8/30 - Nose Wheel Steering Potentiometer Lever Stop","slug":"ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52975,"registerId":"commonwealth-F2006B09186-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-8/30 - Nose Wheel Steering Potentiometer Lever Stop","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)  \nBombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\nAD/DHC-8/30 Nose Wheel Steering Potentiometer Lever Stop 1/94\n\nApplicability: Model DHC-8 Series 100 aircraft, serial numbers 003 through 334. Requirement: Accomplish de Havilland Modification 8/1809, in accordance with de Havilland\n\nService Bulletin 8-32-99 Revision A.\n\nNote: Transport Canada AD CF-93-24 refers.\n\nCompliance: Prior to 15 May 1994.\n\nBackground: The potentiometer stops in the nose gear steering system have been found to be too short to limit excessive uncontrolled potentiometer lever movement, in the event of failure of the mechanical link between the rudder pedals and the potentiometer.\n\nFailure of the link could result in the aircraft departing the runway during take-off or landing.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive does not expand or narrow the population or remedy relative to its stated action: it mandates de Havilland Modification 8/1809 per Service Bulletin 8-32-99 Rev A for DHC-8 Series 100 aircraft serial numbers 003–334, to be completed before 15 May 1994 (Applicability, Requirement, Compliance). There is no indication in the text that the scope differs from that stated."},"complexity_factors":["Narrow applicability to a single model and to serial numbers 003–334 (Applicability).","Single, specific mandated technical action tied to a manufacturer modification and service bulletin (Requirement).","Fixed compliance deadline creates scheduling/operational constraints (Compliance).","Dependence on the manufacturer’s service bulletin for execution details creates an implementation dependency (Requirement).","Limited procedural complexity in the text—no alternative compliance pathways or exemptions stated (Requirement, Compliance)."],"plain_english_summary":"What this directive changes, mechanically:\n\n- It requires installation of a physical stop on the nose-wheel steering potentiometer lever by carrying out de Havilland Modification 8/1809, following de Havilland Service Bulletin 8-32-99 Revision A (Requirement). This changes a component of the nose-gear steering system so the potentiometer lever cannot move excessively.\n\nWho this affects:\n\n- Owners/operators and maintenance organisations responsible for Bombardier (Boeing Canada/De Havilland) DHC-8 Series 100 aircraft with serial numbers 003 through 334 (Applicability). They must arrange and pay for the modification specified (Requirement).\n\nWhy it matters and the safety mechanism:\n\n- The Safety Authority states that existing potentiometer stops are too short; if the mechanical link between rudder pedals and the potentiometer fails, unchecked potentiometer lever movement could occur and that might lead to the aircraft leaving the runway during take-off or landing (Background). The mandated stop physically limits lever movement to reduce this risk.\n\nPractical effects, incentives and trade-offs (source-grounded):\n\n- Who pays and who decides: Aircraft owners/operators bear the cost and must decide when to schedule the work. The AD prescribes the required change and directs compliance according to the manufacturer service bulletin (Requirement). \n\n- Compliance burden and timing: The modification must be completed before 15 May 1994 (Compliance). That creates a hard scheduling deadline; operators must allocate maintenance time, personnel and any necessary parts to meet it.\n\n- Implementation risk and dependence on manufacturer material: The AD requires work “in accordance with” the named service bulletin (Requirement). That makes correct execution dependent on the content, clarity and availability of the service bulletin and any parts or tooling it specifies.\n\n- Effects on operations and private choice: Operators may need to temporarily ground aircraft or reschedule flights to complete the work. The AD removes choice about whether to install the stop for affected serial numbers by the compliance date.\n\n- Concentration of costs and distribution of benefits: The AD targets a defined set of aircraft (serial numbers 003–334) (Applicability). The modification’s direct costs fall on the owners/operators of those aircraft; the safety benefit accrues to aircraft occupants and third parties exposed to runway operations (Background).\n\n- Enforcement and discretion: The directive sets a specific mandatory action and a deadline; the document itself does not provide alternative compliance routes or exemptions (Requirement, Compliance). Any variation would therefore depend on separate regulatory processes not described here.\n\nSource citations: Applicability, Requirement, Compliance, Background."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive addressing a specific mechanical defect. It has not expanded beyond its original purpose of mandating a safety modification to the nose wheel steering system."},"complexity_factors":["Single, specific technical requirement (one modification)","Narrow applicability (one aircraft model, specific serial number range)","No defined terms section","No cross-references to other legislation (only references a manufacturer service bulletin and Canadian equivalent AD)","Simple conditional structure: if you operate this specific aircraft, you must do this specific thing by this specific date","Background explanation is straightforward and technical but not legally complex"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or modifications to aircraft.\n\n**What it does:**\nOrders owners and operators of certain Bombardier DHC-8 Series 100 aircraft (specifically serial numbers 003 through 334) to install a modified part in the nose wheel steering system.\n\n**The problem:**\nThe original \"potentiometer stops\" — small physical barriers that limit how far a control lever can move — were too short. If the mechanical link between the rudder pedals and the steering system broke, the lever could swing around uncontrollably. This could cause the plane to suddenly veer off the runway during take-off or landing.\n\n**What must be done:**\nInstall \"Modification 8/1809\" following the manufacturer's instructions in Service Bulletin 8-32-99 Revision A.\n\n**Who it affects:**\nOperators of specific DHC-8-100 aircraft (a regional turboprop airliner, also known as the Dash 8).\n\n**Why it matters:**\nRunway excursions (planes leaving the runway) are serious safety events that can cause crashes, injuries, and deaths. This directive fixes a design flaw before it causes an accident.\n\n**Deadline:**\nThe fix had to be completed before 15 May 1994."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop","history":"/api/acts/ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop/history","analysis":"/api/acts/ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop/analysis","conflicts":"/api/acts/ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop/conflicts","importantCases":"/api/acts/ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop/important-cases","documents":"/api/acts/ad-dhc-8-30-nose-wheel-steering-potentiometer-lever-stop/documents"}}