51-22-01: Gear Shaft Replacement
FAA order 51-22-01 is an airworthiness directive. The FAA's subject line: Gear Shaft Replacement. System: other and general.
What it applies to as the FAA lists it
- Kind of product
- Aircraft
- Makes
- Sikorsky Aircraft Corporation
- Models
- S-51
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 (647 characters)
51-22-01 SIKORSKY: Applies to All Model S-51 Helicopters.
Compliance required within the next 25 hours of operation, but not later than November 1, 1951.
Due to the reported failures of Gear Shaft (Generator Drive-Tail Drive Transmission System) P/N S-10-35-1004, all shafts in service shall be replaced by shafts which have been jig drilled (i.e., the taper pin hole is located squarely with respect to the splines) and which have been stoned and polished to deburr and remove any sharp radii where the taper pin hole intersects the splines.
(Sikorsky Service Information Circular No. 172, dated August 30, 1951, covers this same subject.)
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/51-22-01.json · aircraft systems.