Document ID: chunk:federal_register_of_legislation:F2008L00784:body:0:p2
Version: federal_register_of_legislation:F2008L00784
Segment Type: other
Provision Reference: 
Character Range: 2935–5173

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.  The DHC-2 System is similar in design.

             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.

             Subsequent to the issuance of AD CF-2001-36 (AD/DHC-2/32) 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 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 amended to mandate replacement of connectors with a different design.

             Viking Air Limited has developed SB V2/0001 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.
             The original issue of this Directive became effective on 29 November 2001.

David Punshon
Delegate of the Civil Aviation Safety Authority

13 February 2008