# AD 73-12-11: Carburetor Air Box Valve

- Type: Airworthiness directive
- Status: Current
- Products: Textron 19A, 23, A23-19, B19, B23, C23 and M19A
- Effective: July 27, 1973
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1691
- Registered aircraft: 926 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/35D5C3D63F424F3B86256E0D004DEFE5.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/73-12-11

## The airworthiness directive

73-12-11 BEECH: Amdt. 39-1662 as amended by Amendment 39-1691. Applies to Models 23, B23, and C23 (Serial Numbers M-1 through M-554 and M-1095 through M-1361, except M-3); Sundowner C23 (Serial Numbers M-1362 through M-1420, M-1423, M-1425, M- 1430, M-1438, M-1439, M-1442, M-1447, and M-1453 through M-1473); Models A23-19, 19A, M-19A, and B19 (Serial Numbers MB-1 through MB-520); and Sport B19 (Serial Numbers MB- 521 through MB-585) airplanes which do not have carburetor alternate air boxes modified in accordance with Beechcraft Service Instruction 0574-241 (installation of Beech P/N 23-9011-1S, 3S, or 5S Kits).

Compliance: Required as indicated, unless already accomplished.

To prevent engine power loss caused by ingestion of pieces of failed carburetor air valves, accomplish the following:

A) Prior to further flight, except that the airplane may be ferried to the inspection location and at subsequent intervals not to exceed 25 hours' time in service, inspect the carburetor air box for the following:

1) Wear and looseness between the carburetor alternate air valve and its shaft.

2) Looseness of rivets which hold the valve plates together.

3) Looseness and wear of the cap screws which attach the valve plates to the shaft.

If any of these conditions are found, accomplish Paragraph B below.

B) Within 120 days after the effective date of this AD, remove the existing carburetor air box valve and install Beech P/N 23-9011-1S or 23-9011-3S or 23-9011-5S Kit, as applicable, in accordance with Beechcraft Service Instructions 0574-241, or later FAA-approved revision or any alternate modification approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. The repetitive inspections specified in Paragraph A may be discontinued when this modification is accomplished.

This AD Amendment 39-1662 cancels and supersedes AD 72-01-04.

Amendment 39-1662 became effective June 18, 1973.

This amendment 39-1691 becomes effective July 27, 1973, to all persons except those to whom it was made effective by letter dated July 9, 1973.

## 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 7 of 14 models: M19A, A23-19, B23, B19, 23, 19A, 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: 926 (926 by airframe model, 0 by engine model)
- Makers: Beech 926

Models with the most aircraft:

- [Beech C23](https://openairdocs.org/model/beech-c23): 456 aircraft (airframe model)
- [Beech 23](https://openairdocs.org/model/beech-23): 147 aircraft (airframe model)
- [Beech B19](https://openairdocs.org/model/beech-b19): 145 aircraft (airframe model)
- [Beech A23-19](https://openairdocs.org/model/beech-a23-19): 72 aircraft (airframe model)
- [Beech B23](https://openairdocs.org/model/beech-b23): 62 aircraft (airframe model)
- [Beech 19A](https://openairdocs.org/model/beech-19a): 41 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 8 models: https://openairdocs.org/ad/73-12-11/models.md
Every aircraft: https://openairdocs.org/ad/73-12-11/aircraft.md

Its text cites no advisory circulars or STCs.

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