has two or three wires.                                 有两或三根电线。

PROXIMITY SENSOR ACTUATOR, A steel plate                邻近传感器作动器，

located on a moving component for operation of            位于一个运动部件上，用以操作邻近传感器的钢板。

proximity sensor.

PROXIMITY SWITCH, A printed circuit card for            邻近电门，

transmitting sensor signals to indicating lights and      用以将传感器信号传输给指示灯和电路的印刷电路板。

circuits.

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英汉对照民用航空词典                                  BOEING

PRSOV, SEE - PRESSURE REGULATING AND              调压和关断活门，

SHUTOFF VALVE                                       见 Pressure Regulating and Shutoff Valve．

PTU, SEE - POWER TRANSFER UNIT                    动力转换装置，

                                                    见 Power Transfer Unit．

PURGE VALVE, A valve in the pneumatic system for  除尘活门，

removal of dirt from the air cleaner.               气源系统中用以清除空气清洁器中之灰尘的活门。

PYLON, A structural component for supporting an   吊架，

engine from the wing.                               用以从机翼支撑发动机的结构件。

Q

QAD, SEE - QUICK-ATTACH-DETACH                    快速装卸，

                                                      见Quick－Attach－Detach．

QEC, SEE - QUICK ENGINE CHANGE                    快速更换发动机，