Century IIB switches

[MooneyBob]

I didn't use the autopilot in my M20J so far and I didn't have a opportunity to test it. Today I have tried to get familiar with it on the ground. I didn't even turn master on. I have noticed that two rocker switches for AP On/Off and Heading On/Off feel weird. They don't " click". They didn't give me any resistance when I pushed it to On position and they just return to the position before I pressed them. Both of them behave the same. They are similar in shape as the light and other switches on the panel but they don't feel right.

Can anybody advise?

Thanks

Bob

[ElkoRandy20J]

Bob,

I have a 79J, with Century. Not sure of the exact model but that is the way they feel on my unit. After the momentary push, a light will tell you the ' mode '. No mechanical feel at all. Must be electronic. My manuals are at the airport/hanger. Let me know if you need something scanned or whatever.

Randy

[MooneyBob]

Thanks. I have downloaded the manual and the operation looks pretty straight forward. However I have never used it so I didn't know about the switches. I will test it on my next flight.

[jetdriven]

They are electrically held in the on position by a coil inside the console. If the autopilot is not powered they won't latch on.

Test it on the ground first. Run engine and make sure horizon is level. Center heading bug and roll knob. Select heading mode on the radio coupler. Engage on button and command roll knob left and right. Yoke should move left and right to respond to roll knob. Engage heading mode. Roll knob Is now out of the circuit and it should command left and right turns with the heading bug displaced left and right. You should be able to override the clutch in the servo with manual yoke control both left and right. The trim button pushed down should interrupt the roll servo, and the yoke a/p disconnect button, the off button, and the circuit breaker for the autopilot should all turn the autopilot off. Verify this.

Go up to 2000', set the radio coupler to "heading" and the roll knob centered. Engage the "on" button. The switch should latch down and the roll knob should command 30 degrees left or right with full knob deflection. Heading bug and nav needle deflection is ignored.

Now center the heading bug and engage heading button. It should latch down. Airplane should bank a max of ~22 degrees and turn to the heading. Center a VOR with a "to" indication going to the station and heading bug centers. Engage LOC mode. Autopilot should track needle. Displace the OBS ten degrees and set the heading bug to the OBS selected course. The autopilot should turn 20-45 degrees towards needs and intercept the course.

A wandering autopilot or wing rocking in heading mode can be adjusted out with the gain pots behind the console cover.

[MooneyBob]

They are electrically held in the on position by a coil inside the console. If the autopilot is not powered they won't latch on.

Test it on the ground first. Run engine and make sure horizon is level. Center heading bug and roll knob. Select heading mode on the radio coupler. Engage on button and command roll knob left and right. Yoke should move left and right to respond to roll knob. Engage heading mode. Roll knob Is now out of the circuit and it should command left and right turns with the heading bug displaced left and right. You should be able to override the clutch in the servo with manual yoke control both left and right. The trim button pushed down should interrupt the roll servo, and the yoke a/p disconnect button, the off button, and the circuit breaker for the autopilot should all turn the autopilot off. Verify this.

Go up to 2000', set the radio coupler to "heading" and the roll knob centered. Engage the "on" button. The switch should latch down and the roll knob should command 30 degrees left or right with full knob deflection. Heading bug and nav needle deflection is ignored.

Now center the heading bug and engage heading button. It should latch down. Airplane should bank a max of ~22 degrees and turn to the heading. Center a VOR with a "to" indication going to the station and heading bug centers. Engage LOC mode. Autopilot should track needle. Displace the OBS ten degrees and set the heading bug to the OBS selected course. The autopilot should turn 20-45 degrees towards needs and intercept the course.

A wandering autopilot or wing rocking in heading mode can be adjusted out with the gain pots behind the console cover.

Byron,

That's how every manual should be written. Very well explained. Thank you very much. I can't wait to test it.

I think previous owner mentioned a wandering autopilot. Do you know by any chance where I can find the adjustment procedure description?

Thanks

[MooneyBob]

They are electrically held in the on position by a coil inside the console. If the autopilot is not powered they won't latch on.

Test it on the ground first. Run engine and make sure horizon is level. Center heading bug and roll knob. Select heading mode on the radio coupler. Engage on button and command roll knob left and right. Yoke should move left and right to respond to roll knob. Engage heading mode. Roll knob Is now out of the circuit and it should command left and right turns with the heading bug displaced left and right. You should be able to override the clutch in the servo with manual yoke control both left and right. The trim button pushed down should interrupt the roll servo, and the yoke a/p disconnect button, the off button, and the circuit breaker for the autopilot should all turn the autopilot off. Verify this.

Go up to 2000', set the radio coupler to "heading" and the roll knob centered. Engage the "on" button. The switch should latch down and the roll knob should command 30 degrees left or right with full knob deflection. Heading bug and nav needle deflection is ignored.

Now center the heading bug and engage heading button. It should latch down. Airplane should bank a max of ~22 degrees and turn to the heading. Center a VOR with a "to" indication going to the station and heading bug centers. Engage LOC mode. Autopilot should track needle. Displace the OBS ten degrees and set the heading bug to the OBS selected course. The autopilot should turn 20-45 degrees towards needs and intercept the course.

A wandering autopilot or wing rocking in heading mode can be adjusted out with the gain pots behind the console cover.

I have found a good manual where the adjustment procedures are explained.

[OR75]

You can google search the century IIB service manual and the procedure is described in one of the chapter. It involves having access to the back of the coupler ( need to remove dashboard)

The adjustment is done by removing the front of the console ( use Allen wrench to remove the knob). And use a small screwdriver to make adjustments.

If you cannot locate the manual, let me know and I can email you the pages

[OR75]

on the initial topic:

a key requirement for an autopilot to be approved is the need for manual overide .

if the button where to "click" , the click mechanism would break each time the AP is overiden.

the buttons are held magnetically . the overide results in overcoming the magnetic force that is keeping the buttons engaged.

[MooneyBob]

on the initial topic:

a key requirement for an autopilot to be approved is the need for manual overide .

if the button where to "click" , the click mechanism would break each time the AP is overiden.

the buttons are held magnetically . the overide results in overcoming the magnetic force that is keeping the buttons engaged.

That makes perfect sense now. I have downloaded the manual. Thank you.