737NG CPC
 

Hello,

I’m just wondering if anyone knows at what stage of flight do the CPCs switch over on a 737NG? Is it on touchdown, engine start up etc…

I’ve tried to find it in Boeing notes but all it states is that they changeover each flight 🤷🏻‍♂️

I don't think I've ever seen it written anywhere. Best guess would be on landing as it would take inputs from air/ground sensors. If not, after engine shutdown would be my guess.

Nipper1980,

The active CPC changes for every flight (or when there is an autofail event) via the air/ground logic from the proximity switch electronics unit (PSEU). Ref B737-600/700/800/900 AMM CH 32-30-00 Pg 14.

Rgds McHale.