56-20-03: Tail Rotor Hub Bolts
FAA order 56-20-03 is an airworthiness directive. The FAA's subject line: Tail Rotor Hub Bolts. 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, 47G, 47G-2, 47H-1
- 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 (865 characters)
56-20-03 BELL: Applies to All Models 47B, 47B3, 47D, 47D1, 47G, 47G2 and 47H1.
Compliance required as soon as possible but not later than October 20, 1956.
Failure of the tail rotor hub retention bolts P/N 47-641-052-1 has occurred in service. The probable cause of the bolt failures experienced to date has not been determined and this problem is currently being investigated. At the conclusion of this investigation Bell anticipates supplying a newly designed hub retention bolt as a replacement for the present bolts. In the interim it is mandatory that a service life of 300 hours be established for the subject bolt. At this time it is necessary to remove the two tail rotor retention bolts and replace them with new retention bolts of the same part number.
(Bell Mandatory Service Bulletin No. 112 dated August 8, 1956, 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/56-20-03.json · aircraft systems.