elevator trim switch

[Ulysse]

how is this switch supposed to work? in my plane it disables the yoke trim switch but the autopilot can still operate the elevator trim. Is this right or should the switch also disable the autopilot authority on the trim 

[PT20J]

What autopilot do you have?

[Fly Boomer]

I'm interested too.

[PT20J]

A GFC 500 works as described. I don’t believe the KAP/KFC 150 A/P will engage with the trim breaker off. Perhaps @Jake@BevanAviation has more info.

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[Jake@BevanAviation]

The KAP/KFC150 system would not be happy if trim power was removed but if it is interrupting the regulated voltage from the trim servo after the parallel to the computer it should continue to work. However, this would not conform to the install manual .  More information about the system in the aircraft is needed to determine if it is operating correctly.

[Ulysse]

13 hours ago, PT20J said:

What autopilot do you have?

GFC 500 

So the only function of the switch is to disable the yoke trim switch? 

[PT20J]

28 minutes ago, Ulysse said:

GFC 500 

So the only function of the switch is to disable the yoke trim switch? 

It is there to protect the manual electric trim circuit in case of a short somewhere.

[Ulysse]

On 3/7/2022 at 9:27 PM, PT20J said:

protect the manual electric trim

Why is it not a CB then? 

[PT20J]

40 minutes ago, Ulysse said:

Why is it not a CB then? 

The GFC 500 STC calls for a trim circuit breaker that can be manually operated. If the airplane originally had electric trim, the Mooney TRIM rocker switch is actually a circuit breaker switch, and this is often reused.