Rudder Pressure Gauge

Rudder Pressure Gauge conversion

Bought a heavily damaged and corroded rudder pressure indicator on eBay and fully refurbished it with new GE328 5V bulbs and a new 2-inch housing. Let the photos speak for themselves. It has the standard Switec X27 stepper motor that uses its internal stop for resets.


System description

This Indicator on the copilot’s panel labeled RUDDER displays rudder hydraulic system pressure. Since the pressure transmitter for the instrument is located downstream of the rudder pressure control valve, only rudder system hydraulic pressure is shown, which does not in all cases reflect auxiliary hydraulic system pressure. The indicator should be monitored at speeds above 240 KIAS
to check that the rudder airspeed switch and rudder control valve have reduced rudder system pressure. Nominal system pressure below 260 KIAS is 3000 psi, above 260 KIAS the pressure is 2250 psi. The indicator receives 28V AC power through P7.

Boeing 707 rudder

The rudder is normally displaced hydraulically by a rudder power package receiving input signals from the pedals, trim crank and yaw damper.



The control tab moves in an anti-balance direction. Feel forces are provided by an artificial feel mechanism. The tab aerodynamic reaction is not reflected in the pedals. Rudder and tab flutter is prevented by the associated damper.


Pedals and trim knob actions are directly transmitted to the tab which operates as a control tab. Feel forces are provided by the aerodynamic reaction on the control tab.


The yaw damper eliminates dutch roll. Is inoperative without rudder boost. Its action is not reflected in the pedals.

B707 rudder angle
B707 rudder angle