47-51-11: Pinion Gear and Bearings
FAA order 47-51-11 is an airworthiness directive. The FAA's subject line: Pinion Gear and Bearings. 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: other and general.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Scotts-Bell 47 Inc
- Models
- 47B, 47B3
- 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 (872 characters)
47-51-11 BELL: Applies to Model 47B Series Helicopters.
Service experience indicates that the transmission pinion gear bearing life can be extended to 100 hours of operation providing rework in accordance with Bell Service Bulletin No. 47C4 dated December 4, 1947, has been accomplished. New bearings P/N 47-820-358-1 must be installed in the upper spider assembly pinion gears and bearings P/N 47-620-357-1 must be installed in the lower stage spider assembly pinion gear at the 100-hour teardown inspection. (In order to assist in determining the service life of these bearings, it is recommended that removed bearings be tagged with any pertinent information and returned to Bell Aircraft Corp., Attention: Helicopter Division, Fort Worth, Texas.)
(Bell Service Bulletin 47C4 revised December 4, 1947, covers this same subject.)
This supersedes AD 47-41-09.
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/47-51-11.json · aircraft systems.