Some discussion came up in another thread about "shock" cooling of engines in descending and slowing for the pattern from cruise altitude and speed.
The best information I've seen about this is in this Avweb article. The bottom line (literally!):
"If shock cooling were a definite hazard, your engine should fall apart when you bring the mixture into idle cutoff at the end of a flight. CHTs fall at a rate of 100?F/min or more in the first seconds of shutdown?triple the rate that starts the typical "shock cooling" annunciator blinking. Does anyone complain that repeated shutdowns are causing head cracking? Of course not.
Then why are we worried about pulling the throttle back?"
I'm thinking corrosion caused by underused engines is a lot more damaging than pulling power.
The best information I've seen about this is in this Avweb article. The bottom line (literally!):
"If shock cooling were a definite hazard, your engine should fall apart when you bring the mixture into idle cutoff at the end of a flight. CHTs fall at a rate of 100?F/min or more in the first seconds of shutdown?triple the rate that starts the typical "shock cooling" annunciator blinking. Does anyone complain that repeated shutdowns are causing head cracking? Of course not.
Then why are we worried about pulling the throttle back?"
I'm thinking corrosion caused by underused engines is a lot more damaging than pulling power.