56-20-05: Propeller Operating Limits
FAA order 56-20-05 is an airworthiness directive. The FAA's subject line: Propeller Operating Limits. It names Douglas DC-3: about 155 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: propeller.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- The Boeing Company
- Models
- C54-DC, DC-4, DC3-G102, DC3-G102A, DC3-G103A, DC3-G202A
- On this site
- Douglas DC-3 155 registered
Dates and paperwork
- Docket
- Unknown
- Status
- Current
- The FAA's document
- Read the order on the FAA's site
The order itself the regulatory text, as published
Show the full text (565 characters)
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. \n\n\tCompliance required not later than December 1, 1956. \n\n\tTo 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. \n\n\tThis supersedes AD 48-03-01, which applied only to DC-4 airplanes.
Related safety bulletins advice on the same designs, not orders
2014-11-24NM-15-03 · Flight Controls
2008-06-12NM-08-28 · Landing Gear: DC-3 Tail Wheel Fork Check
Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 6, 2026. Connections as data: /graph/directive/56-20-05.json · aircraft systems.