# AD 86-23-51: Transmissions

- Type: Airworthiness directive
- Status: Current
- Products: Columbia Helicopters 234
- Effective: July 20, 1987
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-5659
- Registered aircraft: 6 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/347DF62CF417C8B786256A4E004E7753.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/86-23-51

## The airworthiness directive

86-23-51 BOEING VERTOL: Amendment 39-5659. Applies to Boeing Vertol Model 234 series helicopters certificated in any category, equipped with forward rotor transmission P/N's 234D1200-2, -3, -4, -5, and -6 and/or aft rotor transmission P/N's 234D2200-3, -4, and -5.

Compliance is required as indicated, unless already accomplished.

To prevent failure of the spiral bevel ring gear/sun gear bolted joint, accomplish the following before further flight.

  (a) For both forward and aft transmissions, remove all spiral bevel ring gears, P/N's 114D1244-5 and -6 and 114D2254-5 and -6; first stage sun gears, P/N's 234D1243-1 and -2 and 234D2250-1 and -2; and spacer shim, P/N's 114D2257-1 and -2, with more than zero hours time in service. Spiral bevel ring gears, P/N's 114D1244-6 and 114D2254-6; first stage sun gears, P/N's 234D1243-2 and 234D2250-2; and spacer shim, P/N 114D2257-2, are not eligible for further service.

  (b) Install the following parts, which must be new, except for the first stage sun gear, (item (b)(2) below), which must be serviceable:

  (1) Spiral bevel ring gear, P/N 114D1244-5 or 114D2254-5;

  (2) First stage sun gear, P/N 234D1243-1 or 234D2250-1;

  (3) Spacer shim, P/N 114D2257-1; and

  (4) Associated hardware as follows:

    (i) Bolt, P/N BACB30MT6T12;

    (ii) Washer, P/N BACW10BP6P; and

    (iii) Nut, P/N BACN10TW6.

  (c) An alternate method of compliance which provides an equivalent level of safety with this AD may be used when approved by the Manager, New York Aircraft Certification Office, 181 South Franklin Avenue, Rm. 202, Valley Stream, NY 11581.

This amendment, 39-5659, becomes effective July 20, 1987, as to all persons except those persons to whom it was made immediately effective by individual telegrams issued November 14, 1986, which contained this amendment.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H9EA](https://openairdocs.org/tcds/H9EA): Columbia Helicopters Inc.; names 1 of 1 models: 234

## 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: 6 (6 by airframe model, 0 by engine model)
- Makers: Boeing-Vertol 6

Models with the most aircraft:

- [Boeing-Vertol 234](https://openairdocs.org/model/boeing-vertol-234): 6 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/86-23-51/models.md
Every aircraft: https://openairdocs.org/ad/86-23-51/aircraft.md

Its text cites no advisory circulars or STCs.

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