# AD 78-01-05: Electrical Failure

- Type: Airworthiness directive
- Status: Current
- Products: Viking Air DHC-6-1, DHC-6-100, DHC-6-200 and DHC-6-300
- Effective: February 9, 1978
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-3111
- Registered aircraft: 88 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/A61EE9DD0619AFA986256A38004BFF99.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/78-01-05

## The airworthiness directive

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.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A9EA](https://openairdocs.org/tcds/A9EA): De Havilland Aircraft of Canada Limited; names 4 of 5 models: DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 88 (88 by airframe model, 0 by engine model)
- Makers: Dehavilland 84, Dehavilland Acft Of Canada 4

Models with the most aircraft:

- [Dehavilland DHC-6-300](https://openairdocs.org/model/dehavilland-dhc-6-300): 59 aircraft (airframe model)
- [Dehavilland DHC-6-200](https://openairdocs.org/model/dehavilland-dhc-6-200): 19 aircraft (airframe model)
- [Dehavilland DHC-6-100](https://openairdocs.org/model/dehavilland-dhc-6-100): 6 aircraft (airframe model)
- [Dehavilland Acft Of Canada DHC 6-300](https://openairdocs.org/model/dehavilland-acft-of-canada-dhc-6-300): 4 aircraft (airframe model)

All 4 models: https://openairdocs.org/ad/78-01-05/models.md
Every aircraft: https://openairdocs.org/ad/78-01-05/aircraft.md

Its text cites no advisory circulars or STCs.

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