47-21-10: Propeller Guide Pin Dowel
FAA order 47-21-10 is an airworthiness directive. The FAA's subject line: Propeller Guide Pin Dowel. System: propeller.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Sierra Hotel Aero, Inc.
- Models
- Navion (Army L-17A)
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 (518 characters)
47-21-10 NAVION: (Was Mandatory Note 9 of AD-782-3.) Applies to Serial Numbers NAV-4-2 Through HAV-4-1010 Which Incorporate Hartzell HC-12X20-1 Propellers.
To be accomplished not later than September 1, 1947.
The propeller control piston guide pins, Hartzell P/N A-11, require additional safetying in order to prevent loosening and subsequent loss of engine oil. This is accomplished by the installation of a 3/32-inch steel dowel through the guide pin.
(NAA Field Service Bulletin No. 30 covers this rework.)
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/47-21-10.json · aircraft systems.