Savin' the Prop

[cncpc]

I don't think it's good for piston engine to shut it down in the air in the 1st place, it could shock cool, you probably aren't going to have time to get a cold engine started on short final while you are flying a plane at the same time.

I am interested in this subject and am wondering how long it takes a small piston engine to cool down to the point it is difficult to restart it.

Can you elaborate on this opinion you have?

This idiot obviously was very fortunate not to have killed himself wouldn't you say Jake?

https://www.youtube.com/watch?v=bQWXMLtR-LA

He was some fella, that idiot.

[cncpc]

This subject and the opinions about the subject shows just how important it is for those who are new to aviation making sure they research the subject and not assume all posters know what they are talking about.

Learn first, then know everything. Not the other way around.

Still learning here.

[C.W.E.]

Everyone should have a benchmark for what they want to be.

Bob Hoover was my benchmark and even if I made it to half his flying skills level I would have been very happy.

In person he was so unassuming and soft spoken you would have never even dreamed he could fly like he did.

Looking back on my life in aviation having admired and known Bob it gives me pleasure to think about how lucky I was to have known him.

My other hero was Ernest K. Gann and I was fortunate to have gotten to know him personally and been invited to his home to talk about flying.

In my opinion he was the best story writer about aviation we ever had.

[switchflicker]

I’m curious... is there something to stop you restarting the shut-down engine if you need to go around?

I don't think it's good for piston engine to shut it down in the air in the 1st place, it could shock cool, you probably aren't going to have time to get a cold engine started on short final while you are flying a plane at the same time.

I'm kinda thinking that if I was to be required to grind my engine nacelle and all the associated plumbing within onto a cement surface, the one thing I'd really like is a stone cold engine. I'd like it to be totally without fuel in it too if I could.
But that's just me.

[PilotDAR]

I don't think it's good for piston engine to shut it down in the air in the 1st place, it could shock cool, you probably aren't going to have time to get a cold engine started on short final while you are flying a plane at the same time.

Shock cooling is a risk to cylinder health when rapidly going from high power settings to idle, particularly if a speed increase at idle is an element of that. So climb with full power, then suddenly close the throttle and dive creates a risk of cylinder damage. Smacking a running engine/propeller into the ground creates a certainty of much more expensive damage. I'd rather the risk of cracking a cylinder or two, than the certainty of a prop and everything which turns in the engine being ruined.

While we're at it, the "cold" of shock cooled is not the same as the cold of 'been sitting at -25C for a week. Aircooled cylinders will cool quite quickly when the heat is taken away. That won't prevent them from turning over well enough for a quick restart. The engine case, on the other hand, is not specifically cooled, and will hold heat nicely for a long time. Restart will not be a problem at any point during a glide which any light GA airplane can achieve.

But, as said, if you the pilot cannot satisfy yourself that your landing path is sufficiently clear and will remain so, to conduct an abnormal condition landing, you're doing it wrong! If a meteor smacks a hold in the runway right in front of you, and you wreck the plane because of that, the insurance will pay (except for the gear malfunction itself, see the September COPA magazine).

[J31]

I don't think it's good for piston engine to shut it down in the air in the 1st place, it could shock cool, you probably aren't going to have time to get a cold engine started on short final while you are flying a plane at the same time.

I am interested in this subject and am wondering how long it takes a small piston engine to cool down to the point it is difficult to restart it.

Can you elaborate on this opinion you have?

This idiot obviously was very fortunate not to have killed himself wouldn't you say Jake?

https://www.youtube.com/watch?v=bQWXMLtR-LA

While not shut down in flight....TSIO520 shut down on the ground in -45 and a 30 kt wind I could not move the propeller after 3 minutes.

[C.W.E.]

While not shut down in flight....TSIO520 shut down on the ground in -45 and a 30 kt wind I could not move the propeller after 3 minutes.

We solved that problem by putting the padded engine tents on as soon as we got out of the airplane, and if electric power power was avaliable we plugged in the electric car heaters we had with us.

That kept the engines warm enough to start all night.

By the way we also had light weight wing covers to keep the wings and tail plane uncontaminated by frost or snow.

If we did not have electric power then we had to get up early in the morning and pre. heat with the Herman Nelson.

[jakeandelwood]

I don't think it's good for piston engine to shut it down in the air in the 1st place, it could shock cool, you probably aren't going to have time to get a cold engine started on short final while you are flying a plane at the same time.

I am interested in this subject and am wondering how long it takes a small piston engine to cool down to the point it is difficult to restart it.

Can you elaborate on this opinion you have?

This idiot obviously was very fortunate not to have killed himself wouldn't you say Jake?

https://www.youtube.com/watch?v=bQWXMLtR-LA

While not shut down in flight....TSIO520 shut down on the ground in -45 and a 30 kt wind I could not move the propeller after 3 minutes.

Go poor a cold bucket of water on your hot car engine and see what happens.

[C.W.E.]

Go poor a cold bucket of water on your hot car engine and see what happens.

Jake I have many thousands of hours flying all types of airplanes in the high arctic in the winter, and I think I understand the effects of very low temperatures on not only engines both piston and turbine but the effects on the airframe as well.

How much experience do you have flying at very low temperatures?

[cncpc]

I am interested in this subject and am wondering how long it takes a small piston engine to cool down to the point it is difficult to restart it.

Can you elaborate on this opinion you have?

This idiot obviously was very fortunate not to have killed himself wouldn't you say Jake?

https://www.youtube.com/watch?v=bQWXMLtR-LA

While not shut down in flight....TSIO520 shut down on the ground in -45 and a 30 kt wind I could not move the propeller after 3 minutes.

Go poor a cold bucket of water on your hot car engine and see what happens.

Jake, are you a pilot?

[shimmydampner]

Go poor a cold bucket of water on your hot car engine and see what happens.

Surely you're not suggesting that the effect of heat loss by air cooling is the same as by "a bucket of cold water"?

Jake, from now on don't put your room temperature beers in the fridge. Instead put them in a cooler of ice water. You can thank me later for this life changing advice. Throw in some salt and you'll think I'm your god!

[PilotDAR]

Go poor a cold bucket of water on your hot car engine and see what happens.

So now we're discussing what happens when you pour water on a liquid cooled engine?

[Old Dog Flying]

The same situation occurred while demonstrating a Rockwell 112TCA. Tower confirmed nose wheel only partially down, rescue equipment called out. Shut down the engine on short final, held the nose off and as speed decayed I felt a thump and waited for the bottom cowling to scrape the runway.

Surprize, the nose gear had secured and no damage to a beautiful aircraft. The nose gear springs were stretched too far to lock the gear down and when air pressure decreased we rolled out safely.

The springs were replaced and the customer came back a week later and bought the plane.

Do what is necessary to reuse the plane another day...there is no one answer to every situation

Barney

[FADEC]

So far as not being able to go around; that is the situation in a four engine airplane with two out, or a three engine with two out.
The commit point is 500 feet; after that, no go around.

How many have ever shut down an engine in flight and stopped the prop? In a 172 with either a Continental or Lycoming, you have to slow pretty close to stall.

On a long runway, one would have plenty of time to do it IF one can fly with either hand, which any real pilot should be able to do.

Any Airline Captain will have flown both seats; either hand. An Airline F/O likely flew left seat previously. Any Instructor should have both hands experience.

As for the Lake taxiing into the hangar; all Lakes have metal props, unless they have the MT Reversible STC prop.

[lownslow]

Go poor a cold bucket of water on your hot car engine and see what happens.

Nothing.

I drive through puddles all the time (the bigger the better - I'm basically a giant kid) and have yet to have any shock cooling issues. Even if I did it likely wouldn't be catastrophic, I assume the worst I could do would be a slow leak from a crack in a cooling jacket. Annoying, yes, but not a deal breaker.

Someone smarter than me could chime in on what 'shock cooling' actually does to an air cooled airplane engine, but I suspect it's more an issue of accelerated wear than the catastrophic explosion your instructor taught you to fear.

[jakeandelwood]

Go poor a cold bucket of water on your hot car engine and see what happens.

Nothing.

I drive through puddles all the time (the bigger the better - I'm basically a giant kid) and have yet to have any shock cooling issues. Even if I did it likely wouldn't be catastrophic, I assume the worst I could do would be a slow leak from a crack in a cooling jacket. Annoying, yes, but not a deal breaker.

Someone smarter than me could chime in on what 'shock cooling' actually does to an air cooled airplane engine, but I suspect it's more an issue of accelerated wear than the catastrophic explosion your instructor taught you to fear.

Yes, a cracked "cooling jacket" no big deal, those are easily replaced on a liquid cooled engine.

[cncpc]

How many have ever shut down an engine in flight and stopped the prop? In a 172 with either a Continental or Lycoming, you have to slow pretty close to stall.

I have. Several dozen times, one of them unintentionally on a sharp pull up from a forced approach in which a truck drove onto the intended landing area, crash zone. You don't have to stall, but yes, it is a low speed. Once you have it stopped, then you can increase speed a bit without it windmilling. A fair bit, actually. If you do a restart as part of the demo, it windmills very quickly once the starter gets it moving, and from there fires right up.

I think it bears saying that for a single with a nose gear problem, you can actually plant the mains and then shut down. So you have a pretty good indication then that a go round isn't necessary. Main gear bad, nose gear good, on a single its kind of your choice. If you think you can hold it straight, and the nose gear will hold up, maybe keep it running. But I'd shut it down once the nose wheel was planted anyway. You don't need it anymore, and you're ready for the worst case scenario.

All of this is pretty easy peasy if you think it through.

[C.W.E.]

Someone smarter than me could chime in on what 'shock cooling' actually does to an air cooled airplane engine, but I suspect it's more an issue of accelerated wear than the catastrophic explosion your instructor taught you to fear.

I have no idea if I am smarter than you but a lot depends on the airplane and engine you are flying.

Somewhere in my " stuff " I still have the engine handling manual for the R4D-8 with the Wright R1820 engines, the warnings about thermal shocking is quite interesting.

Bottom line it can get really expensive and unsafe if you do not control thermal shocking the engine.

[goingnowherefast]

Shock cooling is a real thing, if you knew how most cylinders were made and you'd understand why. However shutting an engine off at low airspeed after a gentle descent isn't going to do anything. Even a cracked cylinder isn't going to kill you. Just won't run quite right afterwards and the owner won't be happy if he finds you've abused it.

Run the engine hard, a bit too lean at Vx for a while, get it good and toasty, then do an idle Vne dive. That'll be real tough on it. Every engine and installation is different too. Mooney vs 172, might be the same engine, but cowled differently. Put turbos on to push up engine temperature and it's a different animal again. Radials with the huge frontal area, different again.

If my gear won't go down on a piston, I'm not too concerned with shock cooling on the rollout (slide-out?) if the engine is off. More concerned with aircraft control, potential gear collapse, fuel leaks, fire, etc.

[jakeandelwood]

I just talked to my insurance company about this. They don't care what you do really, they are just hoping no one gets hurt in the end and you don't compound the emergency. Ff you need a prop or engine teardown or whatever damage is done in the accident they will pay, your rates may go up if you start having numerous at fault claims. Insurance rates are mainly based on pilot experience and type of aircraft. I can see with the ridiculous parts prices how damage costs can easily exceed hull value, best be saving that 2 blade prop then.