# AD 48-51-01: Control Wheel Shaft Inspection

- Type: Airworthiness directive
- Status: Current
- Products: Textron Army AT-11, C18S and D17S
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 137 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9320CB847161CFF586256A1C0072D610.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/48-51-01

## The airworthiness directive

48-51-01 BEECH: Applies to AT-11, C18S, D17S Airplanes Equipped With Beech Half-Circle Type Control Wheels.

To be accomplished as soon as possible, but not later than March 1, 1949.

To preclude the possibility of failure of the control column wheel shaft due to too great a counterbore depth in the shaft, the following inspection should be accomplished: (Bow-tie type control wheels attached to the control shaft by three bolts through a flange on the shaft are satisfactory and need not be inspected).

  (1) Drill a 3/8-inch hole in the center of the hub of the control wheels. Do not allow the drill to go more than 1 inch into the hub or the pin securing the wheel will be damaged.

  (2) Place a narrow scale or straight wire through the 3/8-inch hole and obtain the distance from the bottom of the counterbore (not the peak of the counterbore cone) to the face of the hub.

  (3) Insert a small hook scale or bent wire in the hole and obtain the distance from the end of the shaft to the face of the hub.

  (4) Subtract the distance obtained in step No. 3 from the distance obtained in step No. 2 to obtain the depth of the counterbore in the end of the shaft. If this distance is over 1 7/16 inches, the shaft must be replaced. All shafts having a counterbore less than 1 7/16 inches deep are satisfactory.

(Beech Service Bulletin No. C-18-9 dated November 22, 1948, covers this same subject.)

## Affected data sheets (3) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-2-582](https://openairdocs.org/tcds/A-2-582): Textron Aviation Inc.; names 1 of 2 models: Army AT-11
- [TCDS A-649](https://openairdocs.org/tcds/A-649): Textron Aviation Inc.; names 1 of 2 models: D17S
- [TCDS A-757](https://openairdocs.org/tcds/A-757): Textron Aviation Inc.; names 1 of 1 models: C18S

## 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: 137 (137 by airframe model, 0 by engine model)
- Makers: Beech 137

Models with the most aircraft:

- [Beech D17S](https://openairdocs.org/model/beech-d17s): 124 aircraft (airframe model)
- [Beech C18S](https://openairdocs.org/model/beech-c18s): 13 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/48-51-01/models.md
Every aircraft: https://openairdocs.org/ad/48-51-01/aircraft.md

Its text cites no advisory circulars or STCs.

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