# AD 47-21-08: Generator Terminal Stud Insulator

- Type: Airworthiness directive
- Status: Current
- Products: Sierra Hotel Aero Navion (Army L-17A)
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 373 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/59C3BCCFA33BA9D286256A56006E1B0B.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/47-21-08

## The airworthiness directive

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.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-782](https://openairdocs.org/tcds/A-782): Sierra Hotel Aero Inc.; names 1 of 8 models: Navion (Army L-17A)

## 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: 373 (373 by airframe model, 0 by engine model)
- Makers: North American 203, Ryan 170

Models with the most aircraft:

- [North American NAVION](https://openairdocs.org/model/north-american-navion): 203 aircraft (airframe model)
- [Ryan NAVION](https://openairdocs.org/model/ryan-navion): 170 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/47-21-08/models.md
Every aircraft: https://openairdocs.org/ad/47-21-08/aircraft.md

Its text cites no advisory circulars or STCs.

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