{"id":"F2017L01426","name":"AD/DHC-8/48 Amdt 3 - Provision of Separate Instrument Grounds","slug":"ad-dhc-8-48-amdt-3-provision-of-separate-instrument-grounds","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":144233,"registerId":"commonwealth-F2017L01426-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier DHC-8 Series Aeroplanes","sectionType":"part","heading":"Bombardier DHC-8 Series Aeroplanes","content":"# Bombardier DHC-8 Series Aeroplanes\n\n| AD/DHC-8/48 Amdt 3 | Provision of Separate Instrument Grounds | 23/2017 |\n| ------------------ | ---------------------------------------- | ------- |\n\n| Applicability: | Bombardier DHC-8 aircraft, Models 102, 103, 106, 201, 202, 301, 311, 314 and 315, serial numbers 3 to 472.                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Carry out de Havilland modification 8/2710 in accordance with de Havilland Alert Service Bulletin A8-34-117, as in force from time to time.Note 1: Transport Canada AD CF-97-01R2 refers.Note 2: The words “as in force from time to time” require compliance with the most recent version of the SB.                                                                                                                                                                                                                         |\n| Compliance:    | Within 30 days after the commencement date of this AD, unless previously accomplished.Note 3: Previous compliance with the requirement in AD/DHC-8/48 Amdt 2 constitutes compliance with the requirement in this AD.                                                                                                                                                                                                                                                                                                          |\n|                | This AD commences on 10 November 2017.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Background:    | Transport Canada advised that simultaneous failures of both the pilot’s and co-pilot’s Attitude and Heading Reference System have occurred due to a faulty terminal block which provides a common ground connection. The modification details the provision of separate grounds for each instrument.Amendment 3 of this AD is issued to reduce the serial number range in the applicability in accordance with the latest revision of the Canadian AD and also to reference the latest revision of the Canadian AD in Note 1. |\n\n![](image.001.png)\n\nBen Wilson  \nDelegate of the Civil Aviation Safety Authority\n\n2 November 2017","sortOrder":0},{"sectionNumber":"AD/DHC-8/48 Amdt 3","sectionType":"part","heading":"AD/DHC-8/48 Amdt 3","content":"## AD/DHC-8/48 Amdt 3","sortOrder":1},{"sectionNumber":"Provision of Separate Instrument Grounds","sectionType":"part","heading":"Provision of Separate Instrument Grounds","content":"## Provision of Separate Instrument Grounds","sortOrder":2},{"sectionNumber":"23/2017","sectionType":"part","heading":"23/2017","content":"## 23/2017","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 3 reduced the serial-number range in the AD's applicability and explicitly references the latest revision of the Canadian AD. That narrows the set of affected airframes compared to the prior amendment and requires checking the updated Canadian AD and service bulletin (Background; Applicability; Note 1)."},"complexity_factors":["Short mandatory compliance window — modification must be completed within 30 days (Compliance).","Obligation to follow external service bulletin 'as in force from time to time' creates an ongoing need to monitor revisions (Requirement; Note 2).","Applicability spans multiple models and serial numbers, requiring fleet serial-number tracking to determine affected aircraft (Applicability).","Amendment narrows serial-number range (Background) — changes to scope must be checked against prior compliance records.","Previous compliance credit reduces duplication where the modification was already done (Compliance Note 3).","Reliance on Transport Canada AD and a manufacturer bulletin ties Australian compliance to foreign regulatory and supplier documents (Requirement; Note 1).","Direct operational cost and labour burden fall on aircraft operators to arrange and perform the modification (Requirement/Compliance)."],"plain_english_summary":"This airworthiness directive requires operators of specified Bombardier DHC-8 models and serial numbers to install separate electrical grounds for each attitude and heading instrument by performing *de Havilland modification 8/2710* in accordance with *Alert Service Bulletin A8-34-117*. Compliance is required within 30 days of the AD’s commencement.\n\nTransport Canada reported that a faulty common-ground terminal block caused simultaneous pilot and co-pilot AHRS failures; Amendment 3 narrows the serial-number applicability and points to the latest Canadian AD and service bulletin."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment maintains the original purpose of the directive — mandating electrical grounding modifications to prevent dual instrument failure. Amendment 3 merely narrows the affected aircraft serial number range and updates the reference to the Canadian source directive. The scope has not expanded beyond the original safety intent."},"complexity_factors":["Short, single-purpose directive (approximately 250 words of substantive content)","Only 2 defined references (the modification number and service bulletin)","Simple conditional logic: compliance required within 30 days unless already done","Single cross-reference to Canadian aviation regulation (Transport Canada AD CF-97-01R2)","Narrow, clearly specified applicability (9 specific models, specific serial number range)","No nested exceptions or complex definitional sections","Straightforward amendment purpose (reducing serial number range from previous version)"],"plain_english_summary":"This AD mandates a safety modification on specific Bombardier DHC‑8 (Dash 8) aircraft to add separate electrical ground connections for the pilot’s and co‑pilot’s Attitude and Heading Reference Systems. It responds to findings that a shared ground can cause simultaneous AHRS failures, creating a serious in‑flight loss of primary instruments. Affected Australian operators must install kit 8/2710 per the manufacturer’s service bulletin within 30 days."},"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-8-48-amdt-3-provision-of-separate-instrument-grounds","history":"/api/acts/ad-dhc-8-48-amdt-3-provision-of-separate-instrument-grounds/history","analysis":"/api/acts/ad-dhc-8-48-amdt-3-provision-of-separate-instrument-grounds/analysis","conflicts":"/api/acts/ad-dhc-8-48-amdt-3-provision-of-separate-instrument-grounds/conflicts","importantCases":"/api/acts/ad-dhc-8-48-amdt-3-provision-of-separate-instrument-grounds/important-cases","documents":"/api/acts/ad-dhc-8-48-amdt-3-provision-of-separate-instrument-grounds/documents"}}