Engine management for commercial maneuvers

[Nico1]

I was wondering what the best practices were for managing engine temps when practicing commercial maneuvers? For example, practicing power-off 180's I always keep an eye on the rate of cooling of CHT's (CLD on JPI) and find myself having to add power to prevent it rising too much (40 + over). Are there any tips/tricks to avoiding sudden cooling of the engine?

On the flip side, a maneuver like chandelles increase the CHT quite a bit. Is the trick just doing a few maneuvers, then flying level to cool and repeat? 

Would love to use my plane to get my commercial but don't want to generate unnecessary wear so wonder what the best practices are. Thanks!

[Marc_B]

@Nico1 you’ll find a lot of threads on commercial maneuvers if you google search “commercial maneuvers site:mooneyspace.com”

I took the GATTs course out in Kansas for my commercial instruction. Was worried about the engine management before as I wasn’t familiar, but didn’t think it turned out to not be an issue at all. I kept cowl flaps open for most of the maneuvers, but closed on spiral descents. Once you figure out your power settings for the speed you want for maneuvers it’s pretty straightforward.

For me, gaining the proficiency with my own aircraft was just as (probably more) important as getting the rating. 

[KSMooniac]

Shock cooling is a myth, so don't worry about it.

Think what happens when flying into a rain shower as a thought experiment.

Sent from my motorola edge plus 2023 using Tapatalk

[Vance Harral]

I also fly a 1976 Mooney M20F, which we bought 20 years ago in a partnership, and have put nearly 2000 hours on the engine with no trouble.  It's not a flight school trainer, but it's been used by several of the partners to train for and obtain commercial certificates, across all seasons of the year, and we continue to fly the commercial maneuvers for proficiency on a regular basis.

Bottom line: you're way overthinking this, don't worry so much about it.  Specifically do not worry about rates of heating or cooling.  It's just not a thing for this engine, in the flight regime where normally aspirated piston singles fly.

If you're repeatedly flying a large number of high-power/low airspeed maneuvers in the heat of summer (power on stalls, chandelles), check the CHT every few minutes.  If they get over 380, sure, you can level off at cruise speed and open the cowl flaps a few minutes.  But that's it.  Otherwise, you're not going to hurt your engine with any of the commercial maneuvers.

19 hours ago, Nico1 said:

but don't want to generate unnecessary wear

You're generating more wear with a single startup/taxi/takeoff/climbout sequence than you do in hours of commercial maneuver training.

[A64Pilot]

Shock cooling isn't a Myth, but it’s not normally an issue at the temps we fly at assuming we don’t get stupid and fly at 500F cyl head temp because the book says we can. It’s not so much the temps but the contraction of the metal from being rapidly cooled, it’s at high temps, and very cold air. It was much more of an issue for highly Supercharged round motors at very high altitudes and very cold temps. It’s not going to seize a motor but if operated that way repeatedly it will increase cylinder wear.

As far as rain cooling, watch your cyl head temp as you enter rain, I’ve watched and seen very little difference, but I’ve not gotten into torrential rain for years, perhaps in true torrential rain I would.

I did my Commercial in M20AT’s back in 89, I don’t remember engine temps being an issue, surely we get hotter in a normal climb?

[EricJ]

A good example of whether shock cooling is an issue or not is that the C182s and C172s, etc., that are used as jump airplanes fly WOT climbing, often overloaded, to some high altitude, throw everybody out, and then dive as fast as they can with the power completely off so they can go pick up the next batch.   Many of those operators do so with no unusual maintenance issues on the engines.     I knew of one such operator that was getting the occassional cracked cylinder and was blaming it on the "shock cooling", but I later learned that over-torquing spark plugs is more likely to cause that than thermal cycling.    The existence of operators that did not have that problem seemed to me to indicate that the thermal cycling wasn't really an issue.     As many point out, shutting down an engine, descending, engine out training, flying through rain, etc., etc., all cause rapid cooling.   Twin engined airplanes used for training, or even just a BFR or something, get engines completely shut down in cruise, sometimes multiple times, routinely.   Doesn't seem to be an issue.