allendc

I am trying to find out the control authority the 737NG autopilot has in the roll and pitch axis. I understand authority may be limited in some situations, so what I am looking for is the maximum authority.

Thanks

David
www.737FlightSim.com

QAVION

Seems like these values are going to be a little more elusive than I had previously thought, David, but I did manage to find the following statement in the 737 Maintenance Manual. Whether the 9 degree limit is an absolute maximum, I can't say however.

"Elevator Authority and Command:

If the autopilot is in the pitch go-around (G/A) mode, the authority is 9 degrees. If the autopilot is not in the pitch go-around mode, then the autopilot uses these signals to calculate elevator authority:

#Total air pressure
#Static air pressure
#Stabilizer position

If the flaps are between 0 and 7 degrees, the authority is limited to 3 degrees."

Of course, the Stab Trim system will add significantly to the total pitch authority.

Rgds.
Q.

P.S. By the way, will the autopilot in your simulator be controlling pitch by both trim and elevator movement? (Can't say I've seen a desktop sim A/P operate the elevator before, but rather, through a high speed trimming system... presumably for simplicity).

allendc

Hi Q
Thanks for the information. Boeing has sure hidden any information on 737NG autopilot authority.

As far as the simulator controlling pitch I am trying to get a handle on how the real autopilot operates, so I can emulate it's operation properly.

Thanks again

David