# AD 56-20-05: Propeller Operating Limits

- Type: Airworthiness directive
- Status: Current
- Products: Boeing C54-DC, DC-4, DC3-G102, DC3-G102A, DC3-G103A and DC3-G202A
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Registered aircraft: 8 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/1FEED287953B24C4862569BC0066D520.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/56-20-05

## The airworthiness directive

56-20-05 DOUGLAS: Applies to All DC3 Series, DC-4 and C54-DC Series Aircraft Powered With Pratt & Whitney Military R-2000 and Twin Wasp D Series Engines.

Compliance required not later than December 1, 1956.

To avoid crankshaft bending failures, the following placard must be placed on the instrument panel in a conspicuous place: "Avoid Continuous Operation of the Engines between 2310 and 2510 r.p.m." The tachometers must be marked with a red radial band in the above range.

This supersedes AD 48-03-01, which applied only to DC-4 airplanes.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-618](https://openairdocs.org/tcds/A-618): The Boeing Company; names 4 of 4 models: DC3-G202A, DC3-G102A, DC3-G103A, DC3-G102
- [TCDS A-762](https://openairdocs.org/tcds/A-762): The Boeing Company; names 2 of 7 models: DC-4, 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: 8 (8 by airframe model, 0 by engine model)
- Makers: Douglas 8

Models with the most aircraft:

- [Douglas DC3-G202A](https://openairdocs.org/model/douglas-dc3-g202a): 7 aircraft (airframe model)
- [Douglas DC3-G102A](https://openairdocs.org/model/douglas-dc3-g102a): 1 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/56-20-05/models.md
Every aircraft: https://openairdocs.org/ad/56-20-05/aircraft.md

Its text cites no advisory circulars or STCs.

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