{"id":"F2006B09047","name":"AD/DHC-2/29 - Elevator Mass Balance Weight","slug":"ad-dhc-2-29-elevator-mass-balance-weight","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52765,"registerId":"commonwealth-F2006B09047-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-2/29 - Elevator Mass Balance Weight","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)  \nDHC-2 (Beaver) Series Aeroplanes\n\nAD/DHC-2/29 Elevator Mass Balance Weight 9/97\n\nApplicability: All de Havilland DHC-2 MK I and MK II Beaver aircraft, and all DHC-2 MK III Turbo Beaver aircraft.\n\nRequirement: a. For all MK I and MK II Beaver aircraft:\n\nInspect the elevator tip rib for corrosion and install Modification 2/1540 in accordance with instructions contained in de Havilland Service Bulletin 2/50 (Installation of Access Cover and Special Inspection of the Elevator Mass Balance Weight for Separation).\n\nb. For all MK III Turbo Beaver aircraft:\n\nInspect the elevator tip rib for corrosion and install Modification T2/2079 in accordance with instructions contained in de Havilland Service Bulletin TB/58 (Installation of Access Cover and Special Inspection of the Elevator Mass Balance Weight for Separation).\n\nNote: Transport Canada AD CF-97-06 refers.\n\nCompliance: Before 31 January 1998; thereafter at intervals not to exceed 5 years. This airworthiness directive becomes effective on 14 August 1997.\n\nBackground: Field reports were received of the elevator tip rib corroding underneath the mass balance weights. This corrosion could lead to a loss of the balance weight in flight, and possible flight control difficulties.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope matches its stated safety purpose: it applies specifically to the named DHC-2 models and mandates inspection and modification per the cited Service Bulletins. There is no indication in the text that the applicability or obligations were expanded or narrowed from the instrument's stated requirement."},"complexity_factors":["Limited aircraft scope (only DHC-2 MK I, MK II and MK III Turbo) reduces breadth of applicability (Applicability).","Technical nature: corrosion inspection and fitting of access cover/modification require maintenance skills and possible part procurement (Requirement).","Dependency on manufacturer Service Bulletins for procedural detail increases reliance on external documents (Requirement references SB 2/50 and TB/58).","Recurring compliance: initial deadline plus mandatory 5-year repeat interval adds ongoing maintenance burden (Compliance).","Safety-critical consequence (loss of mass-balance weight) mandates compliance but offers little regulator discretion beyond the AD text (Background)."],"plain_english_summary":"Requires owners/operators of de Havilland DHC-2 Beaver (MK I, MK II and MK III Turbo) aircraft to inspect the elevator tip rib for corrosion and install a specified access-cover modification and mass-balance inspection per de Havilland Service Bulletins. The aim, as stated, is to prevent in-flight separation of elevator mass-balance weights. Compliance was required before 31 January 1998 and then at intervals not exceeding five years; the directive became effective 14 August 1997. Costs and work are borne by aircraft owners/operators."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of preventing elevator balance weight separation due to corrosion."},"complexity_factors":["Very short document (under 300 words)","Only 2 defined applicability categories (MK I/II vs MK III)","Simple binary structure (inspection + modification for each aircraft type)","Single cross-reference to Canadian aviation authority (Transport Canada)","Clear compliance deadline with straightforward recurring interval (5 years)","No nested exceptions or conditional logic","Plain language background explanation included"],"plain_english_summary":"Owners/operators of de Havilland DHC‑2 Beaver aircraft in Australia must inspect elevators for corrosion and fit a specified modification kit adding an access cover to check the mass‑balance weight. Initial inspection was required by 31 Jan 1998 and repeats every five years. The AD responds to corrosion found under balance weights; if a weight detaches in flight it can cause loss of control, so the measures prevent accidents by enabling detection and repair."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-2-29-elevator-mass-balance-weight","history":"/api/acts/ad-dhc-2-29-elevator-mass-balance-weight/history","analysis":"/api/acts/ad-dhc-2-29-elevator-mass-balance-weight/analysis","conflicts":"/api/acts/ad-dhc-2-29-elevator-mass-balance-weight/conflicts","importantCases":"/api/acts/ad-dhc-2-29-elevator-mass-balance-weight/important-cases","documents":"/api/acts/ad-dhc-2-29-elevator-mass-balance-weight/documents"}}