51-29-01: Tail Rotor Gearbox Shaft
FAA order 51-29-01 is an airworthiness directive. The FAA's subject line: Tail Rotor Gearbox Shaft. It names Bell 47: about 478 aircraft on the U.S. register today, though an order usually covers particular versions or serial numbers rather than every one. System: rotorcraft systems.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Scotts-Bell 47 Inc
- Models
- 47B, 47B3, 47D, 47D1
- On this site
- Bell 47 478 registered
Dates and paperwork
- Docket
- Unknown
- Status
- Current
- The FAA's document
- Read the order on the FAA's site
The order itself the regulatory text, as published
Show the full text (629 characters)
51-29-01 BELL: Applies to All Models 47B, 47B3, 47D, 47D1 Helicopters.
Compliance required as indicated.
1. Replace the tail rotor gearbox shaft, P/N 47-645-028-1 or 47-645-051-1, when it has accumulated 900 hours of operation.
2. Any shaft having already accumulated 900 hours of operation must be replaced by February 1, 1952. In the interim, conduct the following inspection after every 25 hours of operation: Remove tail rotor and inspect attachment bolt hole for cracks. Replace the shaft if a crack is found, or the hole is elongated over 0.010 inch.
(Bell Service Bulletin No. 83 covers this same subject.)
Related safety bulletins advice on the same designs, not orders
2001-02-09SW-01-13 ·
Source: FAA Dynamic Regulatory System, airworthiness directives. The FAA's document is the authority; the register counts are this site's, from the FAA register of November 6, 2026. Connections as data: /graph/directive/51-29-01.json · aircraft systems.