# AD 73-19-01: Prop Auto-feathering System

- Type: Airworthiness directive
- Status: Current
- Products: Viking Air DHC-6-100, DHC-6-200 and DHC-6-300 with STC SA2608WE
- Effective: February 18, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1786
- Registered aircraft: 88 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/291F41E217CE4CD086256E0D00503E97.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/73-19-01

## The airworthiness directive

73-19-01 de HAVILLAND: Amendment 39-1709 as amended by Amendment 39-1786. Applies to de Havilland Aircraft of Canada, Ltd., Model DHC-6 aircraft Series 100 and 200, Serial Numbers 6 through 230 inclusive, incorporating propeller autofeather system installed in accordance with de Havilland Modification No. 6/1278 or Supplemental Type Certificate No. SA2608WE and Series 300 Serial Numbers 130, 210, 231 through 290 inclusive (less Serial Numbers 265, 270, 277, 281 and 283).

Compliance required within 200 hours after the effective date of this AD unless already accomplished.

To prevent inadvertent auto-feathering accomplish the following:

1. (a) Deactivate the auto-feather system by disconnecting the circuit breaker marked "PROP AUTO-FEATHER" in the panel behind the co-pilot's position.

  (b) Install placard stating "Auto-feather System Deactivated" adjacent to auto-feather select switch.

  (c) Revise Vmc speed on airspeed limitation placard above pilot's position as follows:

Series 100 (Long-Nose) "68 kts. CAS" Series 200 "68 kts. CAS" Series 300 "70 kts. CAS"

2. The accomplishment of de Havilland Modifications Nos. 6/1472 and 6/1459 as applicable or an equivalent modification approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, nullifies the applicability of this airworthiness directive.

(MOT approved Flight Manual Supplements Nos. 13, 14, and 19 pertain to and validate aircraft operations under CAR 3 or SFAR 23.) (Note: Canadian Ministry of Transport Airworthiness Directives CF-73-4 and CA-73-9 cover the same subject.)

Amendment 39-1709 was effective September 11, 1973. This Amendment 39-1786 is effective February 18, 1974.

## 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 3 of 5 models: 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/73-19-01/models.md
Every aircraft: https://openairdocs.org/ad/73-19-01/aircraft.md

## Related documents

- [STC SA2608WE](https://openairdocs.org/stc/SA2608WE): Installation of equivalent modifications to deHavilland modifications.. Golden West Airlines, Inc, Named in the applicability

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