- Model
- S-51
- Data sheet
- TCDSH-2
- Product
- Aircraft · Rotorcraft
Unofficial copy of the text in the FAA’s Dynamic Regulatory System. The FAA’s own copy is the authoritative one. DRS record last changed May 30, 2024.
Copies of the files this page was built from, with their SHA-256. Retrieved October 18, 2026.
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The airworthiness directive
47-50-08 SIKORSKY: Applies to Model S-51 Helicopters.
Compliance required at each 200-hour inspection period.
Disassembly and inspection of the vertical hinge pins and bearings is a mandatory procedure and should be accomplished at each 200-hour inspection period.
The helicopters which utilize Torrington No. 4479 bearings at the vertical hinge pins are subject to replacement of these bearings at each 200-hour inspection period.
The procedure followed is explained on page 4 of Sikorsky Service Bulletin No. 7 dated August 4, 1947.
Helicopters which utilize Smith 14TR-X1 bearings at the vertical hinge pins are subject to inspection at each 200-hour interval and replacement of the bearings is not required unless the installation shows sign of serious wear or damage.
Helicopters which utilize Torrington No. 4479 bearings at the vertical hinge pins can be reworked to incorporate Smith 14TR-X1 bearings at the vertical hinge pins if desired by the owner.
(The procedure to follow for this exchange of bearings is as explained on page 2 of Sikorsky Service Bulletin No. 7 dated August 4, 1947.)
Affected TCDS · 1
The type certificate data sheets for the models this AD names, matched by model and maker.