A-96-144
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FAA: REVISE ADVISORY CIRCULAR 20-66 TO INCLUDE THE VIBRATORY TESTING OF COMPOSITE PROPELLER BLADES THAT HAVE BEEN PREVIOUSLY OPERATED FOR A SUBSTANTIAL NUMBER TO SERVICE HOURS, & COMPOSITE BLADES THAT HAVE BEEN ALTERED TO THE LIMITS SET FORTH IN FAA-APPROVED REPAIR MANUALS TO DETERMINE THE EXPTECTED EFFECTS OF AGE ON PROPELLER BLADE'S NATURAL FREQUENCIES & THE EXCITATION FREQUENCIES ASSOCIATED WITH PROPELLER OPERATION.
In plain language (FlightFinder summary)
The FAA is asked to update Advisory Circular 20-66 to require vibratory testing of composite propeller blades that have been in service for many hours or have been repaired to the maximum limits allowed by approved manuals, in order to assess how aging affects the blades' natural frequencies and the frequencies that can excite them during operation.
This plain-language summary is written by FlightFinder to explain the recommendation above. It is not the official wording — the verbatim NTSB text is quoted above.
Details
| Status | Closed - Acceptable Action |
|---|---|
| Mode | Aviation |
| Closed | Feb 4, 2002 |
| NTSB number | DCA95MA054 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).