# AD 74-05-01: Restricted Fuel Tank Vent Lines

- Type: Airworthiness directive
- Status: Current
- Products: Textron B19, B24R and C23
- Effective: February 27, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1791
- Registered aircraft: 721 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2A350580EFB722C186256A08006E82CA.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/74-05-01

## The airworthiness directive

74-05-01 BEECH: Amend. 39-1791. Applies to Models B19 (Serial Numbers MB-606 thru MB-628); C23 (Serial Numbers M-1477 thru M-1496 and M-1501); and B24R (Serial Numbers MC-159 thru MC-192, MC-195, MC-197 and MC-198) airplanes.

Compliance: Required within 25 hours' time in service after the effective date of this AD, unless already accomplished.

To prevent engine power loss due to restricted fuel tank vent lines, accomplish the following:

A) 1. Remove the inspection plates from both lower wings outboard of the fuel tanks.

2. With the aid of a flashlight and mirror, visually inspect the fuel vent lines in both wings outboard of the fuel tanks for kinks, bends or twists.

3. Remove any kink, bend or twist observed in the fuel vent lines. If an existing fuel vent line cannot be straightened, cut the obstructed area from the fuel vent line and splice in a replacement with a P/N 262P 1/4 union. (Available from Imperial Eastman, 6300 West Howard Street, Chicago,Illinois 60648, or Beech Aircraft Company.)

4. Remove the fuel filler cap, cover the small hole in the side of the vent outlet, and blow air orally into the vent outlets to verify that the vent lines are open.

5. Check the routing of the vent lines for excessive tubing adjacent to the tank ribs at the outboard end of the tanks. Remove any excess tubing and splice the line with a P/N 262P 1/4 union.

6. Replace the fuel caps and inspection plates.

B) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

Beechcraft Service Instruction No. 0628-281 or later FAA-approved revisions cover the subject matter of this AD.

This amendment becomes effective February 27, 1974.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A1CE](https://openairdocs.org/tcds/A1CE): Textron Aviation Inc.; names 3 of 14 models: B19, B24R, C23

## 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: 721 (721 by airframe model, 0 by engine model)
- Makers: Beech 721

Models with the most aircraft:

- [Beech C23](https://openairdocs.org/model/beech-c23): 456 aircraft (airframe model)
- [Beech B19](https://openairdocs.org/model/beech-b19): 145 aircraft (airframe model)
- [Beech B24R](https://openairdocs.org/model/beech-b24r): 117 aircraft (airframe model)
- [Beech B-19 SPORT](https://openairdocs.org/model/beech-b-19-sport): 2 aircraft (airframe model)
- [Beech C 23](https://openairdocs.org/model/beech-c-23): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/74-05-01/models.md
Every aircraft: https://openairdocs.org/ad/74-05-01/aircraft.md

Its text cites no advisory circulars or STCs.

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