Shock cooling - and related damage. is it a myth?

bflynn said:
So what I heard through the article and the thread is that shock cooling is a myth. Does that mean it really is OK to spray down the engine with cold water when I'm through flying? :D
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only do it every 2000 hrs that way no one will have to ever argue about when to OH
 
Loads of info over on BT and they are declare this total myth. And lots of information supporting the conclusion.

Go fly your plane - plenty other things need your attention over this topic.
 
GLMS_NC said:
Loads of info over on BT and they are declare this total myth. And lots of information supporting the conclusion.

Go fly your plane - plenty other things need your attention over this topic.
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In my not so humble opinion it depends on the engine, installation and operation. Run a boosted engine at 75% power at high altitude then while descending pull to idle and see what happens. An old mechanic in a part 135 op said that is one way to crack heads.
 
We all get older every day, and therefore know more?
 
Clark1961 said:
In my not so humble opinion it depends on the engine, installation and operation. Run a boosted engine at 75% power at high altitude then while descending pull to idle and see what happens. An old mechanic in a part 135 op said that is one way to crack heads.
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Agreed, and add some cold rain with the cold air as you descend, I definitely can see it happening.
 
Some of you guys must have flown with engine monitors. Have you personally observed “shock cooling?” I don’t fly as high as some of you but I always fly at high power settings and have never seen temps drop enough to be concerned, including after land and taxiing to parking in winter. If guys are worried about thermal shock they should worry about engine starts and shut downs. Those are where I see the most rapid changes in temperatures. Listen to your engine after you turn it off. Snap, crackle, pop.
 
timwinters said:
Oh, and then, one night, as dad was walking away shaking his head because his 5hp tiller motor was scattered across the shop, he mumbled "son, sometimes I think the best part of you ran down your mother's leg."

I was like a sophomore in high school before it dawned on me exactly WTF he said!!
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I have a godfather who calls one of his boys (who is now a grown man) "bum load".
 
Stewartb said:
Some of you guys must have flown with engine monitors. Have you personally observed “shock cooling?” I don’t fly as high as some of you but I always fly at high power settings and have never seen temps drop enough to be concerned, including after land and taxiing to parking in winter. If guys are worried about thermal shock they should worry about engine starts and shut downs. Those are where I see the most rapid changes in temperatures. Listen to your engine after you turn it off. Snap, crackle, pop.
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I have seen JPI alarm set at 60 degrees come off a few times during high speed spiralling descent, but never during normal ops

Sent from my SM-G935V using Tapatalk
 
Checkout_my_Six said:
unless.....they're stupid. o_O
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life-is-hard-its-harder-if-youre-stupid-john-wayne.jpg


I keep this in my office.
 
WannFly said:
I am not an A&P, so when I call one having far less mechanical knowledge than another A&P ... donno.. what do you want to call it? clearly there is a camp here that doesn't like Mike and what he preaches. I do not have enough knowledge to know who is right and who is wrong.
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My two cents for what it's worth (clearly not much to many on here reference this it seems) is that he does a good job explaining the maintaining and operating aspects of airplanes. No way, in my opinion, AOPA and EAA would constantly lean on him just because he draws a crowd. No, he nor any human, walks on water or is above ever being wrong about something in his life. I do understand that an aeronautical engineer type person would find him as over simplifying sometimes but that is what normal (stupid people like myself) need sometimes.

After watching one of his old webinars I reached out to him about a minor issue my shop said they'd have to explore. I didn't want exploring, I wanted fixing. He, without hesitation, told me exactly what to tell them to do based on a brief description. Fixed perfectly for a minimum amount of money. This was just him being knowledgeable and nice. I am not a member of his Savvy maintenance management (he didn't ask or care before helping me). I do however use his free site to download and monitor the data from my engine monitor.

Reference his advice on leaning vs the Ada guys: it appears they are ending at the same point. LOP will reduce the internal cylinder pressure and lower CHT's. Those two along with reducing the fuel being used are the benefits of running LOP that people are seeking. He simply advocates not slowly leaning to peak each time to get to the desired LOP setting. That is purposely putting your engine in the highest ICP zone for an extended period of time...all be it briefly. So he suggests a big mixture pull to get out of the danger zone quickly and then fine tuning using fuel flow and CHT's. I'm far from an expert on anything but it seems sound to me. For those that have committed to ROP, I'd still operate it the way he and APS suggests as opposed to the POH which many times puts you directly in the worst spot to operate your engine.

While I'm busy patting him on the back, I'd be remiss not to bring up the fact that he (along with TTCF, COPA and a couple others) earlier this year took on Continental after their MSB and requesting the FAA to turn it into an AD that would cost most continental owners a bunch of money for no good reason and won. While I agree he didn't go into it alone but he was there fighting for us every step of the way and communicating it well.

Taking cover now. :)
 
As many have stated, it is something that has been discussed for years (decades).Personally, I’ve always flown like it can cause issues. Being turbo’d, not sure if it’s helped, but I’m always managing the power, RPM, and airspeed on decent while watching temps. One of those things like - does it make the engine feel better, or the Pilot
 
Tell the owner of the turbo 206 skydiving plane it doesn't exist. A new pilot dropped a load of jumpers at 21,000 then pulled the power back and went down as fast as possible. Engine was trashed.
 
Paulie said:
Tell the owner of the turbo 206 skydiving plane it doesn't exist. A new pilot dropped a load of jumpers at 21,000 then pulled the power back and went down as fast as possible. Engine was trashed.
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Specifically attributed to shock cooling?

If so, curious how this was proven and who determine it as the root cause.
 
Paulie said:
Tell the owner of the turbo 206 skydiving plane it doesn't exist. A new pilot dropped a load of jumpers at 21,000 then pulled the power back and went down as fast as possible. Engine was trashed.
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The AJ1A has cooling issues for sure. So I’m sure it was hot at FL210 and then suddenly cooled.
 
Paulie said:
Tell the owner of the turbo 206 skydiving plane it doesn't exist. A new pilot dropped a load of jumpers at 21,000 then pulled the power back and went down as fast as possible. Engine was trashed.
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Was the prop driving the engine during the descent..??
 
Don't know I exited the plane before it landed. DZ owner was not very happy, the pilot was a new hire, didn't last long. Turbines are the best thing that has happened to jump operations. There was or still is a FedEx pilot that had a king air that toured the country, he'd be taking off with the next load before the previous load of jumpers landed. Don't know the dash number of his PT6s but it was something less than 10 minutes to 13,500. Quite a shock for a jumper used to 182s and Beech 18s. My old drop zone had a Beaver that was a cool plane but took forever to get to altitude.
 
Paulie said:
Don't know I exited the plane before it landed. DZ owner was not very happy, the pilot was a new hire, didn't last long. Turbines are the best thing that has happened to jump operations. There was or still is a FedEx pilot that had a king air that toured the country, he'd be taking off with the next load before the previous load of jumpers landed. Don't know the dash number of his PT6s but it was something less than 10 minutes to 13,500. Quite a shock for a jumper used to 182s and Beech 18s. My old drop zone had a Beaver that was a cool plane but took forever to get to altitude.
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I liked the twin otter better than the king air for jump ops. The king air had a very narrow configuration requirement for safe exit. In fact the one I was flying had a couple of fatalities in its history where jumpers hit the tail because the pilot wasn’t on profile when the green light was turned on.
 
Tarheelpilot said:
I liked the twin otter better than the king air for jump ops. The king air had a very narrow configuration requirement for safe exit. In fact the one I was flying had a couple of fatalities in its history where jumpers hit the tail because the pilot wasn’t on profile when the green light was turned on.
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Agree, otter door much nicer. The beaver had a huge doorway but just a snap on fabric door that always came open. The people on the rear bench would freeze for the 45 minutes it took to get to 12,5. Saw that ratty beaver on the cover of sport aviation years later, someone bought it and turned it into a beauty.
 
hindsight2020 said:
...but density drops off nonlinearly with altitude, temperature barely does so linearly. IOW, cooling environmentals of air cooled piston engines actually degrade with altitude. it is also why turbo installations do so poorly in pistons in the aggregate. Mass Flow Rate, not temperature, is the driver of cooling capacity in this context.
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Huh?? Put that in English and I may agree or disagree.

You seem to be intentionally confusing the answer with very odd verbiage.

Not sure if your point is correct or not from that very odd post.
 
The engine heats up on the way up with denser air. It gets high and it has to cool with less dense air. So it doesn't cool as well as it heats up. Its a concept that sometimes comes into play. The turbo thing is the turbo makes dense air for heating even when up high. But the cooling capacity up high is less because of less dense air.
 
Skid said:
I am also curious at what rate the engine actually does cool on shut down. One would think that the airflow would aid in this, but an engine not developing power even though stationary cools quicker based on the article.

“In fact, the real shock cooling comes at the end of the flight when you pull the mixture to idle cutoff and the CHTs drop at more than 100 degrees per minute right away—yet every engine goes through that sort of shock cooling and manages to survive it.”

That seems hard to argue if true.
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But the parts of the engine aren't moving when that happens.
 
coloradobluesky said:
The engine heats up on the way up with denser air. It gets high and it has to cool with less dense air. So it doesn't cool as well as it heats up. Its a concept that sometimes comes into play. The turbo thing is the turbo makes dense air for heating even when up high. But the cooling capacity up high is less because of less dense air.
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Is that one for me? Not sure since you didnt quote.
 
Kritchlow said:
Huh?? Put that in English and I may agree or disagree.

You seem to be intentionally confusing the answer with very odd verbiage.

Not sure if your point is correct or not from that very odd post.
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Odd verbiage? Maybe people need to pick up a book every once in a while and dispense with the American anti-intellectual position that anything that's not written to the syntax level of a Burger King menu is all of a sudden "too many Sunday words" and thus feigned, or an attempt to belittle.

I'm just saying what I mean in the way I'm accustomed to, and not merely attempting to be pompous in order to gaslight, like you seem to imply. I'm not going to apologize for having a higher vocabulary bar than most American pedestrians.

I'll try again for you. Air is denser at lower altitude. Cooling of air-cooled engines does not occur primarily because of temperature of the air, it cools primarily by the mass per volume per unit of time of colder-than-the-engine air molecules that touch the engine and then depart it. Therefore, and counter to your understanding of this process, the fact air is colder at altitude is not relevant.

This means more molecules per volume per time are passing through your engine's cooling ducts at lower altitude: this is called 'mass flow rate' in "pompous people" school. So, even though this low-altitude air is much warmer than air at the top of the atmosphere, it is so dense that it removes more heat away from the engine than the super duper (how's that for a simpleton term) cold but low-density air at high-altitude. Thence lower mass flow rate at higher altitude. You follow now, or am I still grammatically obfuscating to you?
 
hindsight2020 said:
Odd verbiage? Maybe people need to pick up a book every once in a while and dispense with the American anti-intellectual position that anything that's not written to the syntax level of a Burger King menu is all of a sudden "too many Sunday words" and thus feigned, or an attempt to belittle.

I'm just saying what I mean in the way I'm accustomed to, and not merely attempting to be pompous in order to gaslight, like you seem to imply. I'm not going to apologize for having a higher vocabulary bar than most American pedestrians.

I'll try again for you. Air is denser at lower altitude. Cooling of air-cooled engines does not occur primarily because of temperature of the air, it cools primarily by the mass per volume per unit of time of colder-than-the-engine air molecules that touch the engine and then depart it. Therefore, and counter to your understanding of this process, the fact air is colder at altitude is not relevant.

This means more molecules per volume per time are passing through your engine's cooling ducts at lower altitude: this is called 'mass flow rate' in "pompous people" school. So, even though this low-altitude air is much warmer than air at the top of the atmosphere, it is so dense that it removes more heat away from the engine than the super duper (how's that for a simpleton term) cold but low-density air at high-altitude. Thence lower mass flow rate at higher altitude. You follow now, or am I still grammatically obfuscating to you?
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Whatever. I’m a highly educated person, but when I come to an Internet forum I find it silly to decipher some silly ass post from a supposed scientist.

What you said may or may not have been factual, but in my leisure time I’m not going to try and make sense of your silly jargon.
 
Kritchlow said:
Whatever. I’m a highly educated person, but when I come to an Internet forum I find it silly to decipher some silly ass post from a supposed scientist.

What you said may or may not have been factual, but in my leisure time I’m not going to try and make sense of your silly jargon.
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The post you objected to was perfectly clear. Perhaps you didn’t want to take the time to comprehend it or perhaps you are incapable of understanding it. Your loss, not his.
 
Clark1961 said:
The post you objected to was perfectly clear. Perhaps you didn’t want to take the time to comprehend it or perhaps you are incapable of understanding it. Your loss, not his.
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Okay. You and I have agreed on very few things.
This is yet another.
 
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