Engine Cooling

The problem with cooling on the cirrus are the air exits on the cowling.That is why I believe his engine cooked.No matter how rich you run it it will run hot.Cirrus In my “opinion” should re-design this.The cowl has great cool air intake for cooling but too much hot air is getting trapped inside.It needs much more of an exit.Rule of thumb is to take the intake and the exits should be double the opening size in area for hot air expansion.They have close to the same intake/exit size openings.{no cowl flaps).With no obstructions on the exit openings.The baffs could be reworked to.

The problem with cooling on the cirrus are the air exits on the cowling. That is why I believe his engine cooked…Rule of thumb is to take the intake and the exits should be double the opening size…

Chris, if this refers to N142CD’s engine, I assure you that excessive temperatures from inadequate air cooling were not in evidence, either on the panel or on the exterior of the engine. Teardown of three of the cylinders at Lycon in Visalia showed evidence of overheating caused by excessively lean mixture at very high power settings. This was seen on the pistons, exhaust valves and exhaust seats. There was no indication of excessive cylinder head or barrel temperature (scorched paint, discoloration, etc), which are the components directly cooled by the airflow. CHT and EGT on the way to Hayward were 350 and about 1400 max. Rob Leach has told me that on the legs to Australia the gauge indications were the same and yet the new engine does not have any compression problems.

You are correct on the basic 1 to 2 relationship on inlet and exit area design targets, but that had no bearing on the problems we encountered. All evident air cooling indications were normal.

I have done a great deal of research on Lycoming valve and guide problems. In the process we learned that with all CHT and EGT indications normal, you can have excessive component temperatures and never know about it until something fails, at least on the Lycoming parallel valve cylinders. If you’re interested, you can look at:

Go to the sections on the new Cessna engines and all you wanted to know about Lycoming valve failures. There is a massive amount of info.

142s problem either occurred before we picked up the plane or on the way out while we operated it normally and with normal instrument panel indications. We will probably never know which scenario actually occurred.

Based on the 12 hours I spent in the cockpit in flight, and then later looking at the engine in detail, I do not believe there is inadequate air cooling in the Cirrus design.

I was unaware of the engine problem.I looked back into the archive a bit here and read up on it.I was just going by pictures I have seen of the cirrus.I have never seen one up close.Thanks for correcting me on that.I hope he gets his engine problem worked out.