L-1011 Flight Controls: Mach Feel and Rudder Limiter Panel (27-15)

The L-1011 Mach Feel/Rudder Limiter Panel is located on the overhead panel.

MACH FEEL

• Two Channels 
• Mach Feel Force Comparison indicator. 

RUDDER LIMITER

• Override switch to power all available hydraulic systems back to rudder. 

Typically there is also a chart of hydraulic rudder limiting for various speed conditions. 

Original Flight Hardware: Mach Trim and Rudder Limiter

The Mach Feel and Rudder Limiter panel is a combination panel located on the overhead panel of the Lockheed L-1011. All the mach feel, rudder limiter panel switches are normally latched and non is illuminated in normal operation. Mach trim becomes active the higher the mach number the aircraft flies at. At a higher mach number, the aircraft requires different trim characteristics.

The Rudder Limiter side of the panel, featured more switches in some version of the L-1011. The one shown here, only has the hydraulic override switch; others would also feature two switches for the "mechanical" rudder limiter switches at 8º and 30º rudder travel. If you look very carefully, you can actually see the drillings in the light plate for the mechanical switches.



The Mach Feel side of the panel has the following switches:

MACH FEEL SYSTEM MONITOR AND CONTROL SWITCHES ... FAIL is illuminated when monitor has detected a fault in a channel and has automatically deactivated the channel. Certain faults in a single channel may deactivate both channels. If the switch is unlatched, the OFF light will illuminate.

MACH FEEL INDICATOR ... Normal system operation is indicated when readout corresponds to aircraft mach number. Nulls to 0.73 with loss of power to indicator (as shown in the photographs here).



The RUDDER HYDRAULIC POWER LIMITER SWITCH provides monitoring automatic system and controlling rudder hydraulic pressure. When the switch is unlatched, OVRD is illuminated to indicate automatic hydraulic rudder limiting is deactivated. PUSH is illuminated together with RUDDER HYDR LMTR and FLT CONT PANELS on the master annunciator panel when rudder power channels A and C are inoperative or when full rudder power control is not available with flaps down.



Panel Location