On Thursday, September 6, 2018 at 5:03:42 PM UTC-5, wrote:
Hey, gang,

Soon we will be putting an overhauled engine on our Pawnee, and I am wondering if anyone has had experience with or has comments on engine monitoring systems on towplanes.

I am thinking a basic system with all 6 cylinders CHT (and EGT?) monitored, a shock cooling warning system, and data logging. Would monitoring other parameters be useful, also? If so, what parameters (adding sensors adds up $$$)?

Is such a system useful and helpful for our type of flight duty cycle (e.g., towing)? Do the shock cooling warning systems work for our very unique type of operations (I guess they are just an alarm if the rate of CHT drop exceeds a set value?)? Is the data logging useful for monitoring/predicting engine health and life? Am I overthinking/overkilling this issue?????

Thanks,
Jim

I've been using a recording engine monitor for the dozen years that I've owned an airplane -- it's invaluable in understanding how to operate the engine safely and in looking back on flights where one suspects that "something" may have happened.

Some tips I got from Ed Kollin...
- "Shock cooling" does not happen. "Shock heating" happens often (when pilots take off at full power without taking a few minutes to at least get the oil temperature above 100 degrees (an engine monitor will tell you exactly where itis)
- CHT are optimally between about 380 and 320 dF. Aluminum begins to deform above about 400 dF; in my own experience, rings can lose their temper and become brittle and later break above about 430 df.

My own experience is that CHT is extremely helpful in operating an engine for maximum longevity. I have mine alarmed at 400dF.

Oil temperature is important to understand whether the engine is adequately warmed up before takeoff.

Carb temp is useful in understanding risk of carb ice.

I like to run LOP in cruise for economy at low power (65%) but high-power, ROP operation only makes the oil dirty. It's good for the engine.