Autopilot 400

[Bob Cook]

GMAS

You are only telling 1/2 the story. They are two different animals..... one is a role rate (s-tec) and the 400 is a pitch/roll autpilot that has its input from the AI and DG. The S-TEC is a rate of change device that gets its input from the turn and bank.

Big difference.

I do not see 737 / DC8 autopilots being replaced with new ones, and these are far older than most 400 series autopilots. BTW mylar caps do not dry up or become leaky. The power supplies were the weak side of things and you need some good support equipment to set them up or diagnose problems with them. There are still good service people that support the 400 series autopilot and there are lots of parts around from those who have been convinced a new autopilot is necessary.

The 400 was and is a good autopilot if serviced properly. The aircraft does not need to change direction BEFORE the autopilot senses the change.

Each case is different and must be subjectively analized. If the 400 is working properly it is a damn good autopilot. I can do fully coupled approaches with mine and I have not seen a hiccup yet. Let's me more objective.

my two cents.

Bob