{"id":"F2008L00783","name":"AD/DHC-3/37 Amdt 1 - Magneto Cannon Plug","slug":"ad-dhc-3-37-amdt-1-magneto-cannon-plug","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72858,"registerId":"commonwealth-F2008L00783-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"DHC-3 (Otter) Series Aeroplanes","sectionType":"division","heading":"DHC-3 (Otter) Series Aeroplanes","content":"### DHC-3 (Otter) Series Aeroplanes\n\n| AD/DHC-3/37 Amdt 1 | Magneto Cannon Plug | 4/2008 |\n| ------------------ | ------------------- | ------ |\n\n| Applicability: | All Model DHC-3 aeroplanes powered by radial engines incorporating a firewall magneto connector plug as described in Viking Air Limited Service Bulletin (SB) V3/0001. |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. If not previously accomplished in accordance with the original issue of this Directive, perform a visual inspection of the firewall ignition plug and receptacle for proper lock wiring and security in accordance with the Accomplishment Instructions of Bombardier Aerospace de Havilland Otter Alert Service Bulletin A3/53, Revision ‘A’ dated 30 August 2001 or later revision approved by the Chief, Continuing Airworthiness, Transport Canada. |\n| | 2. Replace any damaged parts detected during the Requirement 1 inspection. |\n| | 3. If not previously accomplished in accordance with the original issue of this Directive, incorporate Maintenance Manual PSM 1-3-2 Temporary Revision TR14, dated 24 August 2001, into the periodic inspection of the aircraft approved maintenance schedule. Once incorporated, this inspection is considered a routine task subject to normal maintenance program development and escalation. |\n| | TR14 may be removed from the Maintenance Manual when it is superseded by a normal revision to the manual. |\n| | 4. Replace the firewall magneto connector in accordance with the accomplishment instructions of Viking Air Limited SB V3/0001 dated 27 June 2007, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada. |\n| | Note: Transport Canada AD CF-2001-37R1 refers. |\n| Compliance: | For Requirement 1 - Within 3 months or 110 hours time in service after the effective date of this Directive, whichever occurs first. |\n| | For Requirement 2 - Before further flight after the Requirement 1 inspection. |\n| | For Requirement 3 - Within 3 months after the effective date of this Directive. |\n| | For Requirement 4 - Before 1 August 2008. |\n\n| | This Amendment becomes effective on 10 April 2008. |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Background: | Transport Canada has advised that a complete loss of both ignition systems occurred on a DHC-3 Otter when the lock wire hole in the ignition connector plug on the firewall broke out, allowing the plug to vibrate loose. A maintenance safety feature grounds out both magneto systems through a spring-loaded safety pin incorporated into the Cannon plug. |\n| | The original issue of this Directive required a one time inspection of the ignition connector plug to detect any discrepancies and, if necessary, their rectification. The Directive also required amendment of the Maintenance Manual. |\n| | Subsequent to the issuance of AD CF-2001-37 (AD/DHC-3/37) a complete loss of both ignition systems occurred on a DHC-2 Beaver, resulting in engine failure and subsequent forced approach and landing. Investigation by the Canadian Transportation Safety Board determined the internal failure of the magneto firewall connector resulted in both magneto “P” leads shorting to ground. A maintenance “safety” feature through a spring-loaded safety pin incorporated in the firewall connector on many DHC-2 aircraft grounds out both magneto systems when the connector is disconnected. This connector type is readily identified, when disconnected by the existence of three internal pins on the firewall and magneto harness side, one of which is shorted directly to ground.These connectors have also been installed on the DHC-3 aircraft but are no longer in production.Since no effective Instructions for Continued Airworthiness exist to ensure the safety feature of these connectors will operate correctly when disconnected, or will ensure the internal integrity of the connector while in service, this Directive is revised to mandate replacement of connectors with a different design.Viking Air Limited has developed SB V3/0001 to provide for the installation of a replacement connector, similar in design to magneto systems in service today. This modification incorporates a “straight through” type connector, ensuring magneto circuit integrity should the connection open. |\n| | The original issue of this Directive became effective on 29 November 2001. |\n\n![](image.001.png) \nDavid Punshon \nDelegate of the Civil Aviation Safety Authority\n\n13 February 2008","sortOrder":0},{"sectionNumber":"AD/DHC-3/37 Amdt 1","sectionType":"part","heading":"AD/DHC-3/37 Amdt 1","content":"## AD/DHC-3/37 Amdt 1","sortOrder":1},{"sectionNumber":"Magneto Cannon Plug","sectionType":"part","heading":"Magneto Cannon Plug","content":"## Magneto Cannon Plug","sortOrder":2},{"sectionNumber":"4/2008","sectionType":"part","heading":"4/2008","content":"## 4/2008","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. The original directive required a one‑time inspection and maintenance manual amendment; this amendment expands scope to mandate replacement of the firewall magneto connector with a straight‑through design and requires incorporation of a temporary maintenance revision, imposing affirmative modification and replacement obligations on owners/operators within set deadlines."},"complexity_factors":["Multiple distinct mandatory actions with different deadlines (visual inspection, immediate repair or replace if damaged, incorporate temporary maintenance revision, and full connector replacement by a fixed date).","Cross-references to external documents and approvals (Bombardier/Aircraft, Viking Air SB V3/0001, Transport Canada AD and Chief, Continuing Airworthiness approvals) which create inter-agency and supplier dependency.","Requirement to modify the maintenance manual temporarily (TR14) and then fold into normal maintenance program — procedural and record-keeping implications for maintenance organisations.","Operational interruption risk: damaged parts must be replaced before further flight, creating potential grounded time and scheduling impacts.","Supply/availability issue: the background notes this connector type is no longer in production, increasing procurement and modification complexity.","Regulatory discretion: later revisions of referenced service bulletins or Transport Canada approvals can change compliance detail, requiring ongoing oversight."],"plain_english_summary":"Requires owners/operators of DHC‑3 Otter radial‑engine aircraft fitted with the firewall magneto (Cannon) connector to inspect the firewall ignition plug and receptacle, repair or replace damaged parts, incorporate a temporary maintenance revision into the maintenance schedule, and install a replacement “straight‑through” connector by specified dates.\n\nOwners/operators and maintenance organisations must carry out and pay for the inspections, repairs and connector replacements within set timeframes to address the risk of a complete dual‑ignition loss."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original directive (November 2001) only required inspection and manual updates. This Amendment 1 (April 2008) significantly expands the scope to mandate complete replacement of the connector with a redesigned part, triggered by a subsequent accident in a related aircraft type (DHC-2 Beaver) that revealed the fundamental design was unsafe."},"complexity_factors":["Multiple cross-references to external documents (Bombardier Service Bulletin, Viking Air Service Bulletin, Transport Canada AD, Maintenance Manual Temporary Revision)","Staged compliance deadlines with different triggers (calendar date vs flight hours vs 'before further flight')","Technical aviation terminology requiring specialized knowledge (magneto 'P' leads, lock wiring, time in service)","Conditional logic ('if not previously accomplished') referring back to original directive issue","Note regarding Canadian regulatory reference (Transport Canada AD CF-2001-37R1)"],"plain_english_summary":"This AD orders owners/operators of DHC‑3 Otters fitted with the firewall \"Cannon\" ignition connector to inspect, repair and lock‑wire the part, update maintenance instructions, and replace the connector with a modern design (deadline 1 Aug 2008). It responds to incidents where the connector’s design could short both magnetos and cause total engine failure in flight."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-3-37-amdt-1-magneto-cannon-plug","history":"/api/acts/ad-dhc-3-37-amdt-1-magneto-cannon-plug/history","analysis":"/api/acts/ad-dhc-3-37-amdt-1-magneto-cannon-plug/analysis","conflicts":"/api/acts/ad-dhc-3-37-amdt-1-magneto-cannon-plug/conflicts","importantCases":"/api/acts/ad-dhc-3-37-amdt-1-magneto-cannon-plug/important-cases","documents":"/api/acts/ad-dhc-3-37-amdt-1-magneto-cannon-plug/documents"}}