# AD 46-38-01: Vacuum System Tubing

- Type: Airworthiness directive
- Status: Current
- Products: Grumman American G-21 and G-21A (Army OA-9, Navy JRF-1, -2, -3, -4, -5, and -6B)
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 35 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/EFC6B94741B0851886256A38005B30C1.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/46-38-01

## The airworthiness directive

46-38-01 GRUMMAN: (Was Mandatory Note 4 of AD-654-1.) Applies to G-21 and G- 21A Aircraft.

Compliance required prior to November 1, 1946.

Reroute to vacuum system tubing in the engine compartments to prevent raw fuel from lodging in the check valve, thus deteriorating the valve and possible seeping through. The flap system storage tank should be inspected and if fuel is found it should be thoroughly flushed. The check valves in the vacuum system are to be removed and inspected for wear and deterioration. Presence of fuel in the flap system storage tank is sufficient cause for the replacement of the check valves.

(Grumman Service Bulletin No. 19 dated July 18, 1946, covers this same subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS TC 654](https://openairdocs.org/tcds/TC%20654): Frakes Aviation; names 2 of 2 models: G-21, G-21A (Army OA-9; Navy JRF-1; -2; -3; -4; -5; and -6B)

## 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: 35 (35 by airframe model, 0 by engine model)
- Makers: Grumman 35

Models with the most aircraft:

- [Grumman G-21A](https://openairdocs.org/model/grumman-g-21a): 34 aircraft (airframe model)
- [Grumman G-21](https://openairdocs.org/model/grumman-g-21): 1 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/46-38-01/models.md
Every aircraft: https://openairdocs.org/ad/46-38-01/aircraft.md

Its text cites no advisory circulars or STCs.

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