There are several things I'd like to know.
Yes, that was a foolish thing to do. You never want to wash down a hot engine taking if from 300 degrees to 75 degrees in a short period of time. It thermal shocks the metal. It IS very likely that you did damage the engine.
Plan on getting a new instructor... and being sued. That sucks.
I very much doubt the CHTs will be 300 degrees after decent and taxi. and a shut down.
You may be talking about in flight shock cooling, and that may or may not be disproven.
I think the shock cooling you are refering to is air cooling on decent. I agree there is minimal chance of doing serious damage from air cooling. Air cooling is a much slower process than water cooling. The human body operates at 98.6 degrees and is perfectly happy with an air temperature of 72. Get in 72 degree water and you will start experiencing hypothermia in a short amount of time because of the waters ability to draw heat from the body. A similar situation will occur washing a hot engine down with 70 degree water. It RAPIDLY cools down the outer metal of the engine setting up severe stress across the thickness of the metal since the metal is still very hot on the inside. These stresses can cause stress cracks and possibly brittle fracture. If you could provide the same amount of cooling to the inside of the engine that you did the outside, there would be less chance of damage, but when you only supply rapid cooling to the outside it really stresses the block of metal.
No runup or engine abnormalities that you noticed? The way you described your CFI almost going into cardiac arrest after this happened, surprises me he wasn't eager to call in a mechanic before flying it home.
During manufacturing processes the case and cylinder heads under go heat treatment much more severe that anything that can happen during usage.
This is the kind of mental that gets people killed, hate to say it. Cussing someone out because they dont want to potentially put themselves in a dangerous situation..? The "lets just do it" will end up coming back around and biting you between your cheeks if you keep this mindset up down the road. Granted, you hopefully would've found an impending issue on the ground if there had been one, but you didn't know if "everything was fine".
Normalizing is pretty much the opposite of shock cooling.
IF I were the administrator, I'd include an engine management course requirement for each CPL/CFI's training.
Yeah, been around the block and has his answer formed in his head before asking the question.
I was referring to the temps involved and the rate of change to get it done. much greater that what occurred here.
I think there's many more lessons to be learned here than that. Spraying a hot engine with water to make for an easier start is totally incorrect.
Heat treatment is very different. If a metal is extremely hard it can be brittle, too soft or elastic and it can be weak. Heat treatment is a VERY CONTROLLED process where the metal is treated to create the optium balance between the two for the application in which the metal will be used. During a heat treatment I think you will find that the stresses across the metal is very controlled to be very even so it will evenly create the desired properties through the entire piece of metal. When you have a condition where the metal is extrely hot on one side and cold on the other, undesirable stresses are created across the thickness of the metal, nothing like a heat treatment process. Furthermore, spraying down a hot engine with cold water is NOT 'what can happen during usage', not normal usage anyway. While spraying down the engine might not create a fatal crack the first time, it can weaken the metal so that it will be less resilient next time it is stressed. A simple layman example would be to bend a coat hanger in half and straighten it back out. The first time you do this you won't break the hanger, but when repeated it will eventually break. Applying abnormal stresses across metal from thermal shock can eventually have the same effect.
OMG...solid phase behavior used as an argument to counter cooling rates with dissimilar materials...lots of folks misconstrue...lots of folks on POA misconstrue...but this is bad.
