公开(公告)号：BR9007947A

公开(公告)日：1992-10-06

申请号：BR9007947

申请日：1990-12-05

Applicant: UNITED TECHNOLOGIES CORP

Inventor： SCHWARTZ ROBERT A ,  CARVALHO PAUL A ,  LAMPETER ROBERT J

IPC: B64C11/38 ,  B64C11/30

Abstract: A pitch control system has a main electronic control, a mechanical back-up control and a switching system for transferring pitch control from the electronic to the mechanical control in the event of electronic control failure. The switching system utilizes a switch for comparing the output of the electronic and mechanical control systems, the switch choosing the mechanical system if a failure occurs in the electronic control system. By utilizing the switching system, a failure of the electronic control does not permit the blades to go to feather. In certain failure modes, an enable valve or an enable solenoid locks out the switch, to ensure mechanical pitch change control.