{"id":"F2006B07193","name":"AD/SWSA226/52 - Elevator Gust Lock","slug":"ad-swsa226-52-elevator-gust-lock","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48889,"registerId":"commonwealth-F2006B07193-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SWSA226/52 - Elevator Gust Lock","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)  \nFairchild (Swearingen) SA226 and SA227 Series Aeroplanes\n\nAD/SWSA226/52 Elevator Gust Lock 7/86 DM\n\nApplicability: All models SA-226 and SA-227 referenced in the Requirement Documents. Requirement: Action in accordance with:\n\n    Fairchild Aircraft Corporation S.B. 226-27-041 Revised 18 February 1986, or\n\n    2. Fairchild Aircraft Corporation S.B. 227-27-016 Revised 18 February 1986.\n\nNote: FAA AD 86-10-08 Amdt 39-5315 refers.\n\nCompliance: Prior to 31 July 1986.\n\nBackground: There have been several reports overseas of in-flight engagements of the elevator gustlock. The gustlock plunger assembly is subject to freezing or corrosion due to exposure to the environment. This condition may cause the lock to stick in the intermediate engage position and result in uncommanded in-flight engagement. This Directive provides for an alternate method of gust locking the elevator.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD maintains a narrowly targeted scope: it addresses the elevator gust-lock failure mode on the SA-226 and SA-227 models referenced and prescribes specific Service Bulletins as the remediation. The Directive does not expand its applicability beyond those models or introduce additional obligations beyond following the named SBs and meeting the compliance deadline. (Applicability; Requirement; Compliance; Background)"},"complexity_factors":["Narrow applicability: applies only to SA-226 and SA-227 models referenced in the Requirement documents (Applicability).","Prescriptive technical remedy: directs compliance specifically by reference to two Service Bulletins rather than setting performance objectives (Requirement).","Fixed compliance deadline: a single, short-term compliance date is specified (Compliance).","Dependency on external documents (Service Bulletins) for detailed technical steps (Requirement).","Safety-critical technical implementation requiring qualified maintenance actions (Background; Requirement)."],"plain_english_summary":"# What this directive does\n\nThis Airworthiness Directive (AD) requires operators of certain Fairchild (Swearingen) SA-226 and SA-227 series aeroplanes to modify how the elevator gust lock is fitted or used. It does this by mandating action “in accordance with” one of two Fairchild Service Bulletins (SB 226-27-041 or SB 227-27-016). (Requirement)\n\n# Who it affects\n\n- Owners and operators of the SA-226 and SA-227 models referenced in the Requirement documents. (Applicability)\n- Maintenance organisations and technicians who must carry out the work described in the Service Bulletins. (Requirement)\n\n# Why it matters (mechanics and safety issue)\n\nThe AD responds to reports that the elevator gust lock plunger can freeze or corrode, stick in an intermediate position and engage in flight without command. That uncommanded engagement can affect elevator control. The Directive requires implementing an alternate gust-locking method to prevent that failure mode. (Background)\n\n# Key operational requirements and timing\n\n- The AD prescribes compliance by following Fairchild Service Bulletin 226-27-041 (revised 18 February 1986) or SB 227-27-016 (revised 18 February 1986). (Requirement)\n- The work had to be completed prior to 31 July 1986. (Compliance)\n- The AD cross-references the related FAA AD (FAA AD 86-10-08). (Note)\n\n# Who pays and what choices they have\n\n- Aircraft owners/operators pay for the modification: parts, labour, and aircraft downtime required to implement the Service Bulletin instructions. (Requirement; Compliance)\n- The AD specifies the acceptable instructions (the two named Service Bulletins). That leaves limited technical choice to operators: they must follow one of the prescribed SBs rather than inventing an alternative solution. (Requirement)\n\n# Incentives, trade-offs and implementation considerations\n\n- Incentive: completing the SB work reduces the specific risk of in-flight gust-lock engagement identified in the Background. (Background)\n- Trade-off: operators incur direct financial cost and aircraft out-of-service time to get that risk reduced. (Requirement; Compliance)\n- Opportunity cost: maintenance resources (hangar time, mechanic hours) diverted to this mandated work cannot be used elsewhere during the compliance window. (Compliance)\n- Implementation risk: the safety outcome depends on correct and complete adherence to the Service Bulletin procedures. The AD enforces method choice by reference to those SBs, so deficient workmanship or partial compliance would leave the identified hazard unmitigated. (Requirement)\n- Enforcement / oversight: the AD sets the required method and deadline; oversight responsibility lies with the civil aviation authority administering ADs. The AD itself offers no alternative waiver or discretionary route in its text beyond following the specified SBs. (Requirement; Compliance)\n\n# Effects on businesses and markets\n\n- Maintenance and parts suppliers that carry out the Service Bulletin work will receive concentrated work from affected operators. (Requirement)\n- Operators face costs that are concentrated on the affected fleet; the AD does not redistribute those costs by itself. (Applicability; Requirement)\n\n# Summary statement\n\nThis AD directs operators of the named Fairchild SA-226/227 aircraft to adopt an alternate gust-lock method specified in designated Service Bulletins to address a corrosion/freezing failure mode that can cause uncommanded in-flight elevator gust-lock engagement. Operators bear the cost and scheduling burden of completing the specified work by the given compliance date; the AD prescribes the technical method to be used and therefore limits operator discretion to those SB procedures. (Applicability; Requirement; Compliance; Background)"},"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 a fix for the elevator gust lock issue."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined applicability criteria (aircraft model series)","Single requirement with two alternative compliance paths (either service bulletin)","No nested exceptions or conditional logic","No cross-references to other legislation beyond a single note about the corresponding FAA directive","Clear, unambiguous compliance deadline"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:** It requires owners and operators of Fairchild Swearingen SA-226 and SA-227 series aircraft (commonly known as Metroliner or Merlin aircraft) to modify or replace the elevator gust lock system.\n\n**The problem:** The original gust lock — a device that prevents the elevator (the moveable part of the tail that controls up/down movement) from flapping around in the wind when the plane is parked — was malfunctioning. The plunger could freeze or corrode, causing it to stick in a partially engaged position. This led to terrifying situations where the lock would engage unexpectedly during flight, potentially causing loss of control.\n\n**The fix:** Aircraft must be modified following specific service bulletins from Fairchild Aircraft Corporation (one bulletin for each aircraft series), which provide an alternate method of locking the elevator.\n\n**Who must comply:** Anyone operating these specific Fairchild aircraft models in Australia.\n\n**Why it matters:** This is a critical safety issue. An unexpected gust lock engagement during flight could prevent the pilot from controlling the aircraft's pitch, potentially leading to a crash. The compliance deadline was tight (before 31 July 1986), reflecting the urgency."}},"importantCases":[],"_links":{"self":"/api/acts/ad-swsa226-52-elevator-gust-lock","history":"/api/acts/ad-swsa226-52-elevator-gust-lock/history","analysis":"/api/acts/ad-swsa226-52-elevator-gust-lock/analysis","conflicts":"/api/acts/ad-swsa226-52-elevator-gust-lock/conflicts","importantCases":"/api/acts/ad-swsa226-52-elevator-gust-lock/important-cases","documents":"/api/acts/ad-swsa226-52-elevator-gust-lock/documents"}}