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Student Pilot · Posted: Tue Aug 26, 2003 8:24 am Post subject: Shock cooling

How would flying around on a low power setting for 5 minutes till the engine cools right down then shutting it down and stopping the prop (only starting after landing then warming up as normal) be any different to shuting down in cold weather after flying? Do you folk from the colder climes put engine plugs and cover on after flying? Do you put engine heaters on after flying to keep things warm for a while? if so how long and what temp do you take them off and what is the ambient Temp?
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diggler · Joined: 27 Jun 2002 Posts: 1932

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SuperCub MD · Posted: Tue Aug 26, 2003 2:05 pm Post subject:

We used to always shut down and feather each engine at least once per flight when ME training, even in the dead cold of winter. We tried to get the guys to cool them down slow first, and warm them back up slow after restart, but these were renters... I know it's not good for them, but I can't really remember these planes having any more cylinder problems than any other rental type planes that were not subjected to this.

When it comes to the shock cooling debate, I always ask what about flying through a big rainstorm? Nothing can be worse than getting those heads nice and hot, than throwing cold water on them. Even shutting them down dead from full power and gliding in could not achieve the fast cool down the water will.

Being very gentle with the throttle whenever possible is the way to go though. Back in the good old days when more large piston twins were working corporate and charter, the planes that would get the engines consistently to TBO without problems were the ones that were flown by the pilots that were the easiest on the throttles.

Is it true that some CFI's don't give primary students simulated engine failures anymore? I thought that was even in the PTS?

There was once a CFI who loved to pull the throttle back on his students, did it all the time. He was flying with a particularly grumpy student who didn't apreciate this extra training. So when the CFI pull the throttle on him one to many times, the student shut the engine off with the mags, pull the key out of the switch, and threw it out the window. Than he said to his instructor, "There a-hole, now YOU find a place to land the SOB!"

steve · Posted: Tue Aug 26, 2003 2:26 pm Post subject:

Boz,

"Emergency landings" are still in the PTS - power to idle.

180 degree power off accuracy landing has been put back into the commercial PTS. You must land withing 200 ft beyond the "spot". It is a great manuver and I think will help pilots a lot.

sj

CaptFox · Posted: Tue Aug 26, 2003 5:32 pm Post subject:

diggler · Joined: 27 Jun 2002 Posts: 1932

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StewartB · Posted: Tue Aug 26, 2003 5:58 pm Post subject:

You could make an argument that water interferes with the efficiency of heat transfer in an air-cooled engine. I've never noticed any difference whether it's raining or not. I do see differences based on air temp. If everybody is really concerned with shock cooling, get a digital gauge and watch your CHT's. Descents aren't as bad as you think, if you keep some power on, but watch when you turn off the motor. The manufacturers have always said if you could just start an engine and let it scream for 2000 hours, they'd all make TBO. It's the starting and stopping that kills engines.
SB

Cubus Maximus · Joined: 02 Mar 2002 Posts: 4344

RE the ME feathering: My first twin instruction was in an old Baron without accumulators. Feathered the right engine and couldn't get it started again - crank, crank, crank, nothing...(drained the battery - old generator wires)

Finally got it going on final for 23 after it had a long time to cool down and build up the battery again. My left leg got a nice workout anyway.

Brad

Aviator · Joined: 17 Jun 2002 Posts: 734 Location: Canada (Legally)

mvivion · Posted: Mon Sep 01, 2003 5:50 pm Post subject:

I love it!!

As to the shock cooling debate, I think it's like a lot of things, as noted before on this thread:

Keep the changes at least a little gradual, and there simply won't be any problems. It's the guy who goes through a long cooling period, then shoves full power on with a lot of choke in the cylinders who may have some problems. Same reason we warm up a bit prior to launch, and it's cylinder head temp I worry about in that case.

As to cooling after flight in severe cold: No, we don't do anything special. If you are at -40 and land, with an expected departure in an hour or so, put the engine cover on. That's it. If the plane is done for the day, it's going to get to ambient temperature pretty quick anyway, and whether it does so in ten minutes or two hours isn't a big deal.

Personally, I think all the hype about shock cooling is just that: hype.

But shoving a fistful of throttle onto a cold engine can't be good, in my book.

Mike V

SuperCub MD · Posted: Mon Sep 01, 2003 9:17 pm Post subject: Re: Shock cooling

PA12driver · Joined: 12 Feb 2002 Posts: 1838 Location: Battle Ground, WA

Some more opinion;

I have personally run 2 0-320's to 2000+ hours on cubs. I have for sure done a few "dead stick" landings. But I am real careful to get the oil temp off the peg and to see a couple hundred on the CHT before take-off I also use "cowl plugs" even on "summer days" it is amazing how it evens out the heat and slows the heat loss while shut down for and hour or so.

As SOP I try to keep the power up to at least 1700 while flying around looking for the place I am going to Land. I also use Full flaps, keep the pattern short and I try to keep the idling to a minimum.

I think that all of us that own our own planes, (and maintain them) will tend to take much better care of them? (Different operating habits are another reason a/c partnerships don't work very well)

It is my suggestion that new owners/operators spend some time talking to "long time" operators of the same make/model of plane, to get some suggestions on how to get the best longevity out of their pride and joy.

As for Twin Training: There is nothing like the real thing to get your attention! I believe it is worth it to shut the motor down! feather and do the landings on one! I got my multi in my 'own' twin baron and with the aid of a Great Navy test pilot with lots of Baron time, we did engine failure on takeoff "after rotation" (done at altitude) trust me the critical engine becomes a real event!

Tim (sorry for the long post)

Fortysix12 · Supercub.org Supporter VI Joined: 09 Apr 2003 Posts: 2120

Probably not. Now a C 340 out of 19000 full cruise power to idle would problably break something. On the deadstick landing thing, on our way to sentimental journey this summer I watched my brother in law dead stick his pa 12 from 4 miles and 3500 ft agl onto a paved runway with my 13 year old son on board. And it wasn't for practice. He did it flawlessly. Two years at comair paidoff. He nailed best glide and didn't waver. Why a dead stick ? The idiot that restored his rig ran the rubber fuel lines up almost as high as the tank between the fus and wing. He had 10 gallons on board when we refueled. What caused the fuel starvation was that he banked left and then right breaking the siphon effect. Some day around a camp fire I'll give more detail.

Fortysix12 · Supercub.org Supporter VI Joined: 09 Apr 2003 Posts: 2120

Probably not. Now a C 340 out of 19000 full cruise power to idle would problably break something. On the deadstick landing thing, on our way to sentimental journey this summer I watched my brother in law dead stick his pa 12 from 4 miles and 3500 ft agl onto a paved runway with my 13 year old son on board. And it wasn't for practice. He did it flawlessly. Two years at comair paidoff. He nailed best glide and didn't waver. Why a dead stick ? The idiot that restored his rig ran the rubber fuel lines up almost as high as the tank between the fus and wing. He had 10 gallons on board when we refueled. What caused the fuel starvation was that he banked left and then right breaking the siphon effect. Some day around a camp fire I'll give more detail.

Fortysix12 · Supercub.org Supporter VI Joined: 09 Apr 2003 Posts: 2120

Probably not. Now a C 340 out of 19000 full cruise power to idle would problably break something. On the deadstick landing thing, on our way to sentimental journey this summer I watched my brother in law dead stick his pa 12 from 4 miles and 3500 ft agl onto a paved runway with my 13 year old son on board. And it wasn't for practice. He did it flawlessly. Two years at comair paidoff. He nailed best glide and didn't waver. Why a dead stick ? The idiot that restored his rig ran the rubber fuel lines up almost as high as the tank between the fus and wing. He had 10 gallons on board when we refueled. What caused the fuel starvation was that he banked left and then right breaking the siphon effect. Some day around a camp fire I'll give more detail.

flagold · Joined: 13 Nov 2002 Posts: 429

Dead stick I believe refers to the old' wooden prop (stick) standing still...

sj

Steve -- it may also refer to the clothespin method they used to control the old rotary engines. The engine was always set full throttle, and the only way to control speed was with a clothespin type ignition breaker. No power, and you had a "dead stick." I have an original 1917 Army flying manual somewhere, I'll see if they were even using the term at that time when I get back.

MM

S2D · Posted: Sat Sep 06, 2003 7:05 pm Post subject:

Just a note to people that double post. I just figured out the other day after I double posted that there is a blue X in the top right corner of the post that you can use to delete your last post thus getting rid of one of your double posts. (I don't know what you do when you triple post).

rrb · Joined: 24 Aug 2003 Posts: 475

regarding the note about multiple posts-- the poster can delete any post that he has made. To do so the poster should click to edit the post and on the edit screen there is a check box to delete the post. place a check in the box and click submit. You'll be prompted to if you want to delete the post. Click yes or ok or what ever it takes to continue.

S2D · Posted: Sat Sep 06, 2003 10:42 pm Post subject:

I don't think its there after someone else has posted after you. At least I can't find out how to delete my post above now that you posted after me.
But it is still on this one. The x in the corner is just a shortcut. Only I can see it until someone posts after me.

Student Pilot · Posted: Sun Sep 07, 2003 10:40 am Post subject: Shock Cooling

Run a 720 Lyc on the Fletcher, these engines do 2000 hours between overhaul. On fertilizing AG work there is a take off every 5 to 8 minutes at full power for about 3 min then criuse for a couple then throttle off to land. Land with power off, turn around, fill in 10 seconds, then take off full power again. If the cylinders have done less than a total of 4000 or 5000 hours then they usually go full life. Mostly do around 1000 hours a years with this sort of work, you would think if shock cooling was a problem there would be more trouble on this type of operation. I will admit the same pilot and no throttle bashing does make a difference.
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