Components

Question 1

What is the Elevator Feel System? 9.20.6

Answer 1


The elevator feel system uses the elevator feel computer to provide simulated aerodynamic forces using airspeed (from the elevator pitot system) and stabilizer position.

Feel is transmitted to the control columns by the elevator feel and centering unit. To operate the feel system the elevator feel computer uses either hydraulic system A or B pressure, whichever is higher. 
When either hydraulic system or elevator feel pitot system fail, excessive differential pressure is sensed in the elevator feel computer, and the FEEL DIFF PRESS light illuminates

Question 2

What is the Speed Trim System? 9.20.9 


Answer 2

The speed trim system is designed to improve flight characteristics during operations with a low gross weight, aft CG, high thrust.

It monitors inputs of

• stabilizer position,
• thrust lever position, 

• airspeed, and
• vertical speed

and then trims the stabilizer using the autopilot stabilizer system. Operates most frequently during takeoff and go-arounds.

Question 3

Conditions for speed trim operations:

Answer 3

• Flaps up or down 

• Airspeed 100 – 300 KIAS 

• 10 seconds after takeoff 

• 5 seconds following release of trim switches 

• N1 above 60% 

• Autopilot not engaged 

• Sensing of a trim requirement 


Question 4

What is Mach Trim? 9.20.6 


Answer 4

Above Mach .615, the Mach trim system automatically adjusts the elevators with respect to the stabilizer as speed increases.

The Mach trim actuator repositions the elevator feel and centering unit, which adjusts the control column neutral position.