I confirmed in BOB that I have engine/prop management set to "auto", so I have to figure that's not it.
I don't know much about Auto Engine Management settings. I narrow my eyes, snarl, and bare my fangs at such cheats!
When Ken (blue six) made the Flight Models, and I calibrated the Spitfire gauges (my modifications, not stock issue) we used Manual Engine Management.
Which is the realistic Setting.
I did not calibrate all aircraft RPM gauges. I did cal the Spitfire RPM gauge righteous and true.
If you are flying an RAF aircraft with a "bowl, float with linked to needle fuel injector, carburetor" then your RPMs may go crazy
when you are not flying fairly straight and level.
When you lift up or down the float in the carburetor bowl,
or turn hard and the fuel sloshes around the bowl, while the float-fuel injector linkage does flip-flops!!!
I expect that the Merlin engine will COUGH ! Sputter!! when starved from fuel.
The RPM gauge needle should shake about when the engine fails to be fed fuel.
Holy Hell! My wife is burning rice in a pot on the stove! The old fashioned Filipina way! That's OK, I previously disconnected the BEEP!BEEP!BEEP! smoke alarm.
Crap. I buy her a perfectly good TIGER rice cooker made in China, but she don't like to use it.
Emergency over. I threw a crumpled up Budweiser beer can at her to wake her up,
after I turned off the stove ignition source!
"And turn down that goddammed Filipino Channel! It's drowning out my Bob Dylan!"
I am old enough to remember, and try to clean.. Float & Bowl Carburetors for cars.
OK for cars, but for air craft, cylinder fuel injection is the way to go!