{"id":"F2006B09084","name":"AD/DHC-3/34 Amdt 1 - Tailplane Main Rib Forward Flange and Forward Lower Flange","slug":"ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115637,"registerId":"commonwealth-F2006B09084-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-3/34 Amdt 1 - Tailplane Main Rib Forward Flange and Forward Lower Flange","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-3 (Otter) Series Aeroplanes\n\nAD/DHC-3/34\n\nAmdt 1\n\n  \n\nTailplane Main Rib Forward Flange and Forward Lower Flange\n\n  \n10/99\n\nApplicability: All Model DHC-3 aircraft.\n\nRequirement: Action in accordance with Bombardier Regional Aircraft Service Bulletin (SB) 3/46 Revision E.\n\nCompliance: Unless accomplished in the 12 months prior to 7 October 1999, before 7 October 2000; thereafter at intervals not to exceed 2 calendar years, until Modification 3/935 (SB 3/50) is incorporated.\n\nThis Amendment becomes effective on 7 October 1999.\n\nBackground: The manufacturer received reports of the tailplane centre section main rib cracking at the main rib forward and forward lower flange radii. Such cracking could lead to failure of the rib structure supporting the tailplane front attachment fitting.\n\nAmendment 1 is issued to introduce a modification which constitutes terminating action to the repetitive inspection requirements of this Directive.\n\nThe original issue of this Airworthiness Directive became effective on 17 May 1990.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment stays within the original scope of the 1990 Airworthiness Directive. It does not expand applicability to new aircraft types or introduce new safety issues. It simply adds a terminating action (the modification option) to the existing inspection regime, which is a standard evolution of airworthiness directives."},"complexity_factors":["Very short document (under 200 words)","Only 4 defined elements: applicability (aircraft model), requirement (service bulletin reference), compliance deadline, and terminating modification","Single conditional logic path: repetitive inspections OR terminating modification","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Clear, technical but straightforward aviation maintenance language","No nested exceptions or layered definitions"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of de Havilland Canada DHC‑3 Otter aircraft to inspect tailplane ribs for cracking per Bombardier SB 3/46 (Rev E) — initially by 7 Oct 2000 and then every 2 years — unless they install Mod 3/935 (SB 3/50), which permanently terminates the repetitive inspection requirement. The 1999 amendment adds that terminating modification."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 adds a terminating modification (Modification 3/935, SB 3/50) that, once incorporated, ends the repetitive two‑year inspections required by the original AD. Applicability remains all Model DHC‑3 aircraft, but the compliance pathway broadened from indefinite repetitive inspections to allow a one‑time modification to terminate the inspection cycle (Amendment 1; Applicability; Compliance)."},"complexity_factors":["Applicability to the entire DHC‑3 fleet increases administrative reach but not technical variability (Applicability).","Mandated compliance with an external technical document (Bombardier SB 3/46 Rev E) requires operators to obtain and follow the service bulletin (Requirement).","Fixed initial date plus recurring two‑year inspection interval creates ongoing scheduling and recordkeeping obligations (Compliance).","Existence of a terminating modification (Modification 3/935 / SB 3/50) creates an alternative compliance pathway and a one‑off retrofit cost/decision (Compliance; Amendment 1).","Background report of rib cracking defines the safety trigger but does not quantify inspection or repair scope, leaving technical judgement to maintenance providers (Background).","Operators bear the labour, downtime and parts costs for inspections and for installing the terminating modification (Requirement; Compliance).","Regulator discretion is limited—AD prescribes the SB and timing—so implementation detail sits with operators and maintenance organisations rather than with the regulator (Requirement; Compliance)."],"plain_english_summary":"This amendment requires all DHC‑3 (Otter) operators to inspect the tailplane main rib forward flange and forward lower flange following Bombardier Service Bulletin 3/46 Rev E. Inspections must be completed by 7 October 2000 (unless done within the prior 12 months) and then every two years until Modification 3/935 (SB 3/50) is installed as terminating action to prevent rib failure that could compromise the tailplane attachment."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange","history":"/api/acts/ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange/history","analysis":"/api/acts/ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange/analysis","conflicts":"/api/acts/ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange/conflicts","importantCases":"/api/acts/ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange/important-cases","documents":"/api/acts/ad-dhc-3-34-amdt-1-tailplane-main-rib-forward-flange-and-forward-lower-flange/documents"}}