# AD 46-39-04: Fuel Tank Selector and Crossfeed Valves

- Type: Airworthiness directive
- Status: Current
- Products: Boeing C54-DC, C54A-DC, C54B-DC, C54D-DC, C54E-DC and C54G-DC
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Registered aircraft: 4 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/25D8D4FCC5CCAC768625683300501816.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/46-39-04

## The airworthiness directive

46-39-04 DOUGLAS: (Was Mandatory Note 7 of AD-762-7.) Applies to C-54 Series Aircraft.

To be accomplished not later than November 15, 1946.

Instances of valve freezing, due to ice forming in the detent chamber, have been reported on fuel tank selector and crossfeed valves. To prevent valve freezing, the Parker and Hydro Aire valves must be reworked by filling the detent chamber with Dow Corning compound No. 4 and installing a washer to retain the compound and to act as a water shield.

(Douglas Drawings 4331597 and 2331524 cover this same subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-762](https://openairdocs.org/tcds/A-762): The Boeing Company; names 6 of 7 models: C54E-DC, C54G-DC, C54B-DC, C54A-DC, C54D-DC, C54-DC

## 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: 4 (4 by airframe model, 0 by engine model)
- Makers: Douglas 4

Models with the most aircraft:

- [Douglas C54D-DC](https://openairdocs.org/model/douglas-c54d-dc): 2 aircraft (airframe model)
- [Douglas C54E-DC](https://openairdocs.org/model/douglas-c54e-dc): 1 aircraft (airframe model)
- [Douglas C54G-DC](https://openairdocs.org/model/douglas-c54g-dc): 1 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/46-39-04/models.md
Every aircraft: https://openairdocs.org/ad/46-39-04/aircraft.md

Its text cites no advisory circulars or STCs.

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