47-21-08: Generator Terminal Stud Insulator

FAA order 47-21-08 is an airworthiness directive. The FAA's subject line: Generator Terminal Stud Insulator. System: electrical power.

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 (477 characters)

47-21-08	NAVION:  (Was Mandatory Note 7 of AD-782-3.)  Applies to Serial Numbers NAV-4-2 Through 411. 

To be accomplished not later than August 1, 1947. 

Short circuits have been reported caused between the generator lower terminal and the fitting on the hydraulic pump inlet hose.  To prevent such short circuits, install a self-threading insulator No. 145-54053 (or equivalent) on the generator lower terminal stud. 

(NAA Field Service Bulletin No. 18 covers this change.)

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/47-21-08.json · aircraft systems.