Watch: Aircraft Engine Thrust Control System…


Thrust Management Systems

Many new cars sold today come equipped with a cruise control system. This automatic feature allows the driver to set a desired speed and then sit back and enjoy the ride. A cruise control will adjust engine power to correct for conditions such as traveling up hills and minimizes engine changes while in a cruise condition thereby enabling fuel efficiency to be increased, not to mention a reduced workload for the driver. What a concept! But will it work in an aircraft?

As a frequent flier who is often bored by the final segment of a flight on the airlines, I often find myself counting the number of audibly recognizable power changes that occur from the time the landing gear is extended to touchdown. On a recent flight I observed 24 rpm changes. By my count this was a new record. This unusual behavior on my part is a result of routinely occupying the jump seat in a Lockheed JetStar that was flown by one of Lockheed’s original test pilots.

He would pride himself in not having to make throttle adjustments during descent and approach to landing. This true aviator would have his aircraft speed and engines synchronized then deploy secondary flight controls and landing gear when needed, while continuing to fly the approach to landing never touching the throttles.

Throttle systems

Like a cruise control in an automobile, thrust management systems (TMS) in aircraft increase the efficiency and safety of flight operations. The TMS is an auto throttle/thrust director system that supplies throttle

Thrust lever

Thrust levers or power levers are found in the cockpit of aircraft, and are used by the pilot, copilot, or autopilot to control the thrustoutput of the aircraft’s engines. In multi-engine aircraft, each thrust lever displays the engine number of the engine it controls. Normally, there is one thrust lever for each engine. The thrust levers are normally found in the aircraft’s center console, or on the dashboard of smaller aircraft. For aircraft equipped with thrust reversers, the control for each thrust reverser is usually found adjacent to the corresponding engine’s thrust lever. The position of each lever can be described by the current angle indicated. This is referred to as theThrottle Lever Angle or TLA. The greater the TLA, the greater the engine thrust.

Throttle levers

The throttle lever assembly is often designed to incorporate high-pressure (HP) cock switches so that the pilot has instinctive control of the fuel supply to the engine. Microswitches are located in the throttle box so that the throttle levers actuate the switches to shut the valves when the levers are at their aft end of travel. Pushing the levers forward automatically operates the switches to open the fuel cocks, which remain open during the normal operating range of the levers. Two distinct actions are required to actuate the switches again. The throttle lever must be pulled back to its aft position and a mechanical latch operated, or a detent (hard point) overcome, to allow the lever to travel further and shut off the fuel valve.

Single Engine Thrust Control

Kavlico’s single engine thrust control unit is designed for use in single engine jet and turbo prop aircraft and allows pilots to set the aircraft’s multiple power levels. When the pilot moves the lever, the internal triplex RVDT provides redundant signals to the FADEC control to increase or decrease the power level. Detents are provided for take-off, idle, and maximum continuous cruise. Exclusive use of lightweight materials have been used for both the body and handle.

Key Product Features

    • Triplex RVDT design
    • Adjustable friction
    • Simple 4-screw mount permits rapid line replacement
    • 70,000 min. flight hours MTBF
  • Design meets FAR Part 25 and RTCS-160