A-92-121
NTSB Safety Recommendation — Aviation
Recommendation text
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: CONDUCT A DESIGN REVIEW OF SERVO VALVES MANUFACTURED BY PARKER HANNIFIN HAVING A DESIGN SIMILAR TO THE B-737 RUDDER POWER CONTROL UNIT SERVO VALVE THAT CONTROL ESSENTIAL FLIGHT CONTROL HYDRAULIC POWER CONTROL UNITS ON TRANSPORT-CATEGORY AIRPLANES CERTIFIED BY THE FEDERAL AVIATION ADMINISTRATION TO DETERMINE THAT THE DESIGN IS NOT SUSCEPTIBLE TO INDUCING FLIGHT CONTROL MALFUNCTIONS OR REVERSALS DUE TO OVERTRAVEL OF THE SERVO SLIDES.
In plain language (FlightFinder summary)
The National Transportation Safety Board asks the Federal Aviation Administration to review the design of servo valves made by Parker Hannifin that are similar to the one in the Boeing 737 rudder power control unit, to ensure they are not prone to causing flight control malfunctions or reversals from servo slide overtravel.
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 | Jun 10, 1993 |
| NTSB number | DCA91MA023 |
| Addressees | FAA |
External links
NTSB safety recommendations are advisory; addressees are not legally required to adopt them. Source: NTSB CAROL (public domain).