{"id":"F2006B03467","name":"AD/BAe 146/13 - Additional Elevator Mass Balance","slug":"ad-bae-146-13-additional-elevator-mass-balance","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43021,"registerId":"commonwealth-F2006B03467-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BAe 146/13 - Additional Elevator Mass Balance","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)  British Aerospace BAe 146 Series Aeroplanes\n\n \n\nAD/BAe 146/13 Additional Elevator Mass Balance 8/89\n\nDM\n\nApplicability: Series 100, 100A, 200 and 200A with serial numbers listed in the Requirement Document.\n\n \n\nRequirement: Action in accordance with BAe S.B. 55-7-00955D. Compliance: Prior to 30 November 1989.\n\nBackground: This modification introduces additional mass balance forward of the elevator hinge line to assist in damping control column oscillations.\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":2,"scope_assessment":{"changed":false,"description":"The AD enforces a specified modification (additional elevator mass balance) on a defined set of BAe 146 aeroplanes and sets a compliance deadline. The text is consistent with that original, stated intent (to assist damping of control column oscillations) and does not expand or narrow the described mechanical objective beyond prescribing compliance with the BAe service bulletin for the listed serial numbers. (Applicability; Requirement; Background; Compliance)"},"complexity_factors":["Narrow applicability (specific BAe 146 series and serial numbers) (Applicability)","Single, prescriptive operative requirement referencing one specific service bulletin (Requirement)","Fixed compliance deadline (Compliance)","Technical installation details are delegated to the referenced service bulletin rather than set out in the AD (Requirement)","No alternative compliance paths or exemptions specified in the AD (Requirement)"],"plain_english_summary":"This AD requires owners/operators of specified BAe 146 Series 100/100A/200/200A aeroplanes (listed by serial number) to install an additional mass forward of the elevator hinge line per British Aerospace Service Bulletin 55-7-00955D, to damp control-column oscillations. Work must be done by 30 November 1989. Operators bear parts, labour and downtime costs; the AD is prescriptive (references the single SB) and offers no cost estimates, alternatives or exemptions."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive with a single purpose. It has not expanded beyond its original intent of addressing elevator oscillation issues in specific BAe 146 aircraft."},"complexity_factors":["Very short document (under 200 words)","Only 4 defined applicability criteria (specific aircraft series and serial numbers)","Single requirement referencing an external technical standard (BAe Service Bulletin)","No nested conditional logic or exceptions","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Straightforward compliance deadline with no alternative methods or phased implementation"],"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) that requires specific repairs or modifications to aircraft.\n\n**What it does:** It orders owners and operators of certain British Aerospace BAe 146 series aircraft (models 100, 100A, 200 and 200A with specific serial numbers) to install **extra weight (mass balance)** on the front part of the elevator control surfaces.\n\n**Why it matters:** The elevator is the movable part on the tail that makes the plane pitch up and down. Without this fix, the control column (the pilot's yoke or stick) could **shake or oscillate dangerously** during flight. The extra weight helps dampen these vibrations and keeps the aircraft stable and safe to fly.\n\n**Who must comply:** Anyone operating the affected BAe 146 aircraft models listed in the referenced technical document (BAe Service Bulletin 55-7-00955D).\n\n**Deadline:** The modification had to be completed before **30 November 1989**."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-13-additional-elevator-mass-balance","history":"/api/acts/ad-bae-146-13-additional-elevator-mass-balance/history","analysis":"/api/acts/ad-bae-146-13-additional-elevator-mass-balance/analysis","conflicts":"/api/acts/ad-bae-146-13-additional-elevator-mass-balance/conflicts","importantCases":"/api/acts/ad-bae-146-13-additional-elevator-mass-balance/important-cases","documents":"/api/acts/ad-bae-146-13-additional-elevator-mass-balance/documents"}}