# AD 47-51-12: Carburetor Airscoop

- Type: Airworthiness directive
- Status: Current
- Products: Boeing DC3C-R-1830-90C, DC3C-S1C3G and DC3C-S4C4G
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Registered aircraft: 45 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/00DA1E12126AA0E5862569BC004FAB35.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/47-51-12

## The airworthiness directive

47-51-12 DOUGLAS: Applies to All converted C-47 Series Aircraft With Ram Non-ram (Hydraulic) Type Carburetor Airscoop.

To be accomplished not later than March 1, 1948.

Compliance with the following items is necessary to preclude carburetor icing:

1. The carburetor alcohol system must be used.

2. The accessory cowling and engine fire seal must maintain not more than 1/4-inch clearance of the collector ring.

3. The cable system for operation of the hot air door must be rigged to 30 pounds tension.

(Part B of Douglas Service Bulletin DC-3 No. 251 dated April 15, 1947, covers this same subject. Part A of the same Bulletin is not mandatory, but optional compliance may be accomplished when parts are available.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-669](https://openairdocs.org/tcds/A-669): The Boeing Company; names 3 of 10 models: DC3C-S4C4G, DC3C-R-1830-90C, DC3C-S1C3G

## 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: 45 (45 by airframe model, 0 by engine model)
- Makers: Douglas 45

Models with the most aircraft:

- [Douglas DC3C-S1C3G](https://openairdocs.org/model/douglas-dc3c-s1c3g): 30 aircraft (airframe model)
- [Douglas DC3C-R-1830-90C](https://openairdocs.org/model/douglas-dc3c-r-1830-90c): 10 aircraft (airframe model)
- [Douglas DC3C-S4C4G](https://openairdocs.org/model/douglas-dc3c-s4c4g): 5 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/47-51-12/models.md
Every aircraft: https://openairdocs.org/ad/47-51-12/aircraft.md

Its text cites no advisory circulars or STCs.

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