US3671139A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite blade construction
Assignee: RTX Corp
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Filing: 1970-09-11
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Granted: 1972-06-20
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Expires: 1990-09-11
Abstract
Abstract A FAN BLADE OR COMPRESSOR BLADE IS MADE UP OF A PLURALITY OF VERY THIN PLIES OF FIBERS FOR MAXIMUM STRENGTH AND THESE FIBERS ARE SUBJECT TO DAMAGE BY FOREIGN OBJECTS THAT MAY ENGAGE THE BLADES SPECIALLY ALONG ITS LEADING EDGE AND THEREBY WEAKEN THE BLADE. TO PERMIT VISUAL INSPECTION OF A BLADE TO DETERMINE THE EXTENT TO WHICH THE PLIES HAVE BEEN WORN AWAY, ONE PLY IS MADE VISIBLY DIFFERENT FROM THE OTHERS AND IS POSITIONED IN THE STACK O PLIES AT THE LIMIT POSITION TO WHICH THE BLADE SURFACE CAN BE WORN AWAY BEFORE PLACEMENT.
Inventors
- 👤 James S Plowman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:55
CPC Classifications
F; F01; F01D; F01D5/00; F01D5/12; F01D5/28; F01D5/282; F01D25/00; F01D25/007; F02; F02C; F02C7/00; F02C7/30
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |