78-01-05 De HAVILLAND: Amendment 39-3111. Applies to de Havilland of Canada DHC-6 series aircraft serial numbers 1 through 530.
Compliance required within 800 hours in service after the effective date of this AD unless already accomplished, or de Havilland Modification 6/1591 is incorporated.
To preclude the possibility of total electrical failure due to contact welding of the reverse current relay and subsequent burning of the adjacent wiring, the other reverse current relay and the battery circuit wiring, install de Havilland modification 6/1598 in accordance with de Havilland Service Bulletin No. 6/353 dated May 13, 1977, or later revision, or an equivalent approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
This amendment is effective February 9, 1978.