{"id":"F2006B09085","name":"AD/DHC-3/35 - Electrical System","slug":"ad-dhc-3-35-electrical-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115638,"registerId":"commonwealth-F2006B09085-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-3/35 - Electrical System","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-3/35 Electrical System 12/98\n\nApplicability: DHC-3 Otter aircraft that have been modified in accordance with FAA Supplemental Type Certificate (STC) No SA3777NM “Installation of Pratt and Whitney PT6A-135 engine, Hartzell HC-B3TN-3C/T10282 constant speed propeller and other associated changes”.\n\nRequirement: Modify the auxiliary bus system and replace the voltage regulator together with the voltage-ammeter gauge. The modification and replacements are to be carried out in accordance with A.M. Lutton Electrical Systems Schematic Drawing No 20075 Sheets 1 (Revision G), 2 (Revision E), and 3 (Revision E), all dated 15 May 1998, which are referenced in A.M. Lutton Service Information Letter No SA-SIL-98-11-03 Revision A dated 15 May 1998.\n\nNote: FAA AD 98-18-08 Amdt 10724 refers.\n\nCompliance: Prior to 5 November 1999.\n\nThis Airworthiness Directive becomes effective on 5 November 1998.\n\nBackground: The FAA has determined that the design of electrical system modifications introduced as part of STC SA3777NM was inadequate. This Directive requires modifications to the electrical system which are intended to prevent electrical system failure.\n\nElectrical system failure could result in the loss of engine instruments or possible electrical fire in cockpit.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It targets a specific safety defect in a specific engine modification (STC SA3777NM) on a specific aircraft type (DHC-3 Otter). The directive has not expanded beyond its original purpose of correcting an identified electrical system design flaw."},"complexity_factors":["Single, discrete technical requirement with clear applicability criteria","Only 3 defined technical references (drawing sheets and service letter)","No nested exceptions or conditional logic — applies to all affected aircraft without variation","Straightforward compliance deadline with no phased or alternative compliance paths","Cross-reference to one related FAA AD (98-18-08) for context only, not for substantive requirements","Short document (under 300 words) with single operational requirement"],"plain_english_summary":"This CASA Airworthiness Directive legally requires owners/operators of DHC‑3 Otter aircraft modified with Pratt & Whitney PT6A‑135 under FAA STC SA3777NM to correct unsafe electrical work. It mandates changes to the auxiliary bus, voltage regulator, and voltage‑ammeter per specified A.M. Lutton drawings and service letter to eliminate risk of cockpit electrical failure and fire.\n\nCompliance was required by 5 November 1999; aircraft not modified as directed are not airworthy in Australia."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Scope remains focused on aircraft modified under STC SA3777NM and prescribes a one‑time corrective modification per the referenced drawings and service letter. The Directive implements the FAA‑identified remedy without expanding applicability or adding recurring obligations beyond the mandated modification and the set compliance deadline (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow applicability: only DHC‑3 Otter aircraft modified under FAA STC No. SA3777NM (Applicability).","Technical hardware changes: modification of auxiliary bus and replacement of voltage regulator and voltage‑ammeter gauge require technical installation (Requirement).","Strict documentary compliance: work must follow specific A.M. Lutton schematic drawings (Sheets 1–3, listed revisions and date) and a named Service Information Letter (Requirement).","Regulatory cross‑referencing: the AD cites FAA AD 98‑18‑08, increasing the need to reconcile foreign and domestic directives (Note).","Fixed deadline: a single compliance date (prior to 5 Nov 1999) creates scheduling pressure and potential aircraft downtime (Compliance).","Safety criticality: non‑compliance risks loss of engine instruments or possible cockpit electrical fire, raising liability and maintenance scrutiny (Background).","Implementation burden: work likely requires qualified maintenance personnel, correct parts and access to the specified drawings, imposing direct costs on owners/operators (Requirement/Compliance)."],"plain_english_summary":"This Directive requires owners/operators of DHC‑3 Otter aeroplanes modified under FAA STC No. SA3777NM to modify the auxiliary electrical bus and replace the voltage regulator and voltage‑ammeter gauge, following specified A.M. Lutton drawings and a service letter. It sets a fixed compliance date (before 5 Nov 1999). The FAA identified the earlier design as inadequate; the change is intended to prevent loss of engine instruments or a cockpit electrical fire. Owners/operators pay for and arrange the work to the referenced technical instructions."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-3-35-electrical-system","history":"/api/acts/ad-dhc-3-35-electrical-system/history","analysis":"/api/acts/ad-dhc-3-35-electrical-system/analysis","conflicts":"/api/acts/ad-dhc-3-35-electrical-system/conflicts","importantCases":"/api/acts/ad-dhc-3-35-electrical-system/important-cases","documents":"/api/acts/ad-dhc-3-35-electrical-system/documents"}}