# AD 47-21-07: Carburetor Air Intake Scoop Filler Strip

- 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- Superseded by: Nothing supersedes this AD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/C64D972ED65A806786256A56006E168E.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/47-21-07

## The airworthiness directive

47-21-07 NAVION: (Was Mandatory Note of AD-782-3.) Applies to Serial Numbers NAV-4-10 Through 20, 22 Through 26, 28, 29, 31 Through 49, 51, 52, 55 Through 58, 60, 63, 73, 76, 79, 82 Through 84, 88 Through 95, 99 Through 104, 106, 108, 110, 112 Through 116, 120 Through 122, 124, 125, 130, 133, 141, 151, 153, 158, 163, 171.

To be accomplished prior to August 1, 1947.

Some airplanes were delivered with a cork or rubber filler strip cemented to the upper surface of the 145-42201-71 carburetor air intake scoop where the scoop fits over the flange of the air mixing chamber. This strip may becomes dislodged and drawn into the air induction system. To prevent this, replace the filler strip with a 3 1/8-inch x 5/8-inch dural strip of 0.093- inch thickness, flush-riveted to the scoop.

(NAA Field Service Bulletin No. 15 covers this subject.)

## 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/47-21-07/models.md
Every aircraft: https://openairdocs.org/ad/47-21-07/aircraft.md

Its text cites no advisory circulars or STCs.

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