# AD 68-17-06: Parking Brake

- Type: Airworthiness directive
- Status: Current
- Products: Textron 23, A23, A23-19, A23-24 and A23A
- Effective: August 27, 1968
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-641
- Registered aircraft: 476 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/B6F44FA8C0DF715E86256A080071ABBD.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/68-17-06

## The airworthiness directive

68-17-06 BEECH: Amendment 39-641. Applies to Models 23, A23 and A23A, Serial Numbers M-1 through M-1034; Model A23-19, Serial Numbers MB-1 through MB-264; Model A23-24, Serial Numbers MA-1 through MA-233.

Compliance: Required as indicated.

To prevent inadvertent engagement of parking brake, in flight, accomplish the following:

      (A) For Models 23, A23 and A23A, Serial Numbers M-555 through M-1034; Model A23-19, Serial Numbers MB-1 through MB-264; and Model A23-24, Serial Numbers MA-1 through MA-233 modify the master brake cylinders as set forth in (C) or (D).

      (B) For Models 23, A23 and A23A, Serial Numbers M-1 through M-554, inspect the left master brake cylinder. If brake cylinder Part No. 169-380006 is installed no further action is required. If brake cylinders Part No. VHR-625NL are installed modify as set forth in (C) or (D).

      (C) Remove the steel ball Part No. A134-9 from the parking brake check valve on both left and right master brake cylinders soas to disengage the parking brake and thereafter operationally check the brakes to assure proper operation; or,

      (D) Modify the left master brake cylinder in accordance with either Beech Class 1, Service Instruction 0092-220 and drill out the floor board beneath the left brake pedal in accordance with procedures set forth in the aforesaid Beech Service Instruction, or install the improved braking system provided by Beech Service Letter No. 67-12, Revision 1.

      (E) The foregoing modification must be accomplished prior to further flight except the airplane may be flown in accordance with Federal Aviation Regulation 21.197 to a base where the repair can be performed.

This amendment becomes effective August 27, 1968.

## 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 5 of 14 models: A23-24, A23, A23-19, 23, A23A

## 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: 476 (476 by airframe model, 0 by engine model)
- Makers: Beech 476

Models with the most aircraft:

- [Beech 23](https://openairdocs.org/model/beech-23): 147 aircraft (airframe model)
- [Beech A23-24](https://openairdocs.org/model/beech-a23-24): 121 aircraft (airframe model)
- [Beech A23](https://openairdocs.org/model/beech-a23): 85 aircraft (airframe model)
- [Beech A23-19](https://openairdocs.org/model/beech-a23-19): 72 aircraft (airframe model)
- [Beech A23A](https://openairdocs.org/model/beech-a23a): 51 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/68-17-06/models.md
Every aircraft: https://openairdocs.org/ad/68-17-06/aircraft.md

Its text cites no advisory circulars or STCs.

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