# AD 93-17-12: Main Rotor Transmission Lower Planetary Spider

- Type: Airworthiness directive
- Status: Current
- Products: Bell Helicopter Textron 204B, 205A, 205A-1, 205B, 212 and 412
- Effective: July 29, 1994
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-8683
- Docket: 92-ASW-49
- Registered aircraft: 137 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9456C8849308C7AE86256A4D007221B7.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/93-17-12

## The airworthiness directive

93-17-12 BELL HELICOPTER TEXTRON, INC. (BHTI): Amendment 39-8683. Docket No. 92-ASW-49. Supersedes AD 92-11-07, Amendment 39-8257.

Applicability: Model 204B, 205A, 205A-1, 205B, 212, and 412 helicopters, with main rotor transmission lower planetary spider (spider), part number (P/N) 204-040-785-003, installed, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent fatigue failure of the spider, which could result in failure of the main transmission and subsequent loss of control of the helicopter, accomplish the following:

  (a) Within the next 600 hours' time-in-service (TIS) after the effective date of this AD, unless previously accomplished within the last 2,500 hours' TIS, and thereafter at intervals not to exceed 3,100 hours' TIS from the last magnetic particle inspection (MPI), remove the spider and perform an MPI for cracks in accordance with the pertinent BHTI maintenance, repair, and overhaul manuals.

  (b) Replace any cracked spider with an airworthy part prior to further flight.

  (c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used when approved by the Manager, Rotorcraft Certification Office, FAA, Rotorcraft Directorate. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.

NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, Rotorcraft Certification Office.

  (d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished.

  (e) This amendment becomes effective on July 29, 1994.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H1SW](https://openairdocs.org/tcds/H1SW): Bell Textron Inc.; names 4 of 5 models: 205A, 205B, 204B, 205A-1
- [TCDS H4SW](https://openairdocs.org/tcds/H4SW): Bell Textron Inc.; names 2 of 4 models: 212, 412

## 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: Bell 129, Bell Helicopter Textron 6, Bell/Southwest Florida Aviatio 2

Models with the most aircraft:

- [Bell 205A-1](https://openairdocs.org/model/bell-205a-1): 56 aircraft (airframe model)
- [Bell 212](https://openairdocs.org/model/bell-212): 54 aircraft (airframe model)
- [Bell 412](https://openairdocs.org/model/bell-412): 11 aircraft (airframe model)
- [Bell 204-B](https://openairdocs.org/model/bell-204-b): 7 aircraft (airframe model)
- [Bell Helicopter Textron 212](https://openairdocs.org/model/bell-helicopter-textron-212): 5 aircraft (airframe model)
- [Bell/Southwest Florida Aviatio 205 A1](https://openairdocs.org/model/bell-southwest-florida-aviatio-205-a1): 2 aircraft (airframe model)
- [Bell 205B](https://openairdocs.org/model/bell-205b): 1 aircraft (airframe model)
- [Bell Helicopter Textron 205A-1](https://openairdocs.org/model/bell-helicopter-textron-205a-1): 1 aircraft (airframe model)

All 8 models: https://openairdocs.org/ad/93-17-12/models.md
Every aircraft: https://openairdocs.org/ad/93-17-12/aircraft.md

Its text cites no advisory circulars or STCs.

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