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07-02-2013, 05:32 AM
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Join Date: May 2007
Location: St. Helens OR
Posts: 429
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Stopping your engine in flight
Last month I finally climbed up over the airport a few thousand feet and pulled the mixture to cut-off position. I then slowed the plane down just to the edge of stall to get the prop to stop. I then increase speed to 90 mph and glided in to land. Yesterday I climbed up to 8000' and pulled the mixture back. I was 10 miles out from my airport and by the time the altimeter hit 2000' I knew that making the field would be no problem. I figured I could get a mile for every thousand feet of altitude, wind does need to be factored in, but actually doing it was a great learning experience. I figured that putting the plane in a dive would make the prop start windmilling again to start up, it wasn't the case, but I only got up to 135 mph. I can't really think of any reason why there would be harm to the engine but I thought I would ask if there is anything I should be aware of before doing this again. Maybe shock cooling?
Randy
8A
0-360
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07-02-2013, 06:04 AM
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Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,136
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To each his own, not my idea of good risk management.
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07-02-2013, 06:23 AM
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Join Date: Jan 2005
Location: Richmond, VA
Posts: 696
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Quote:
Originally Posted by Pat Stewart
To each his own, not my idea of good risk management.
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Interesting. Why don't you think it isn't good risk management?
I was thinking just the opposite. Here's a chance to see how your plane actually flies when the prop stops and learn from the experience. Restarting, if necessary, is not a 100% certainty, but pretty close to it. Add to this, the OP started above his airport where a dead stick landing was always an option before he moved off and glided back it. In my opinion, every pilot should be able to manage a dead stick landing. It can reasonably happen and the only way to prepare is to practice for it. I think the OP was doing exactly this.
It seems wise to me to prepare for the range of events you might encounter flying and to do so incrementally so you don't get in over your head.
What are the odds of the unprepared pilot dealing with a seized engine 10 miles out from an airport compared to Randy's odds? If I was the GIB, I'd rather be flying with Randy (or another pilot I know who does this).
__________________
Don Alexander
Virginia
RV-9A 257SW Purchase Flying - O-320, Dynon D100
RV-9A 702DA (reserved) Finish Kit IOX-340
www.propjock.com
Last edited by Don : 07-02-2013 at 06:23 AM.
Reason: Typo
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07-02-2013, 06:24 AM
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Join Date: Jan 2007
Location: Stuart, FL /Hartford, CT/Virgin Gorda,BVI
Posts: 3,122
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what you are doing is standard procedure in a ximango motor glider that i used to fly. it took a lot of speed to get the motor turning over but viola she came to life. sounds like you need to get some real glider time. a glider add on is easy to do. glide on!

__________________
TURBO YES =VAF= Payed Jan2019
Ed D'Arcy
RV6-A 5,200+ hrs, R-44 1,600 hrs, Helicycle 320 hrs, gyro sold,35,000 miles flown in 2015 
Stuart, Fl / S WINDSOR,Ct / Virgin Gorda, BVI - under major repair from hurricane damage
VAF #840 EAA AOPA FAC FABA QB SPA
addicted pickle ball player
https://i.postimg.cc/tn3h4svg/IMG-3101.jpg
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07-02-2013, 06:24 AM
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Join Date: Oct 2008
Location: Utah
Posts: 8,151
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Congrats on first dead stick landing
Interesting first feelings Randy, isn't it? Adrenalin rush and excitement after touch down. Good add-on to your bag of flight experience. You will find a lot of theories about shock cooling but I wouldn't worry about it. Keep mastering those dead stick landings it makes you better pilot and keeps out of boredom 
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07-02-2013, 06:30 AM
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Join Date: May 2006
Location: Houston
Posts: 2,012
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Quote:
Originally Posted by Pat Stewart
To each his own, not my idea of good risk management.
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I disagree totally. You have to know what's going to happen when and if the engine quits. This is totally right for testing your airplane. Done over a good landing site, absolutely.
And what about your engine's response to lack of fuel in a tank or the boost pumps? Run a tank dry and see how easily it restarts. Basic test flight procedures.
As for shock cooling, I wouldn't and don't worry (-320, 360, 540 series). What happens when you fly though rain?
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07-02-2013, 07:01 AM
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Join Date: Oct 2007
Location: Aptos, CA (previously Reno, 21 years!)
Posts: 247
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Once you stop the propeller you have to assume you are in a real dead stick. If you stop the prop you have to assume there is a chance the starter will not engage (due to failure) to start the engine.
There are a number of ways this could happen unexpectedly in flight... Such as, what happens if you are practicing stalls and the engine quits in the stall entry and the prop stops? OK, recover from the stall, fly the plane and start the engine. What happens if the starter had it's last start at the beginning of the flight that day, and now does not work? Or if you were slow on your fuel selector management, run a tank dry, and you get slow while messing with the tank selector and the prop stops before you get the engine running again and then the starter poops out. OK, it can happen I guess. So there you are with prop stopped and no starter. Here is a last ditch possibility and I had this demonstrated to me by my primary flight instructor. Once your emergency field is made and you are flying toward it, a last ditch effort to get the prop turning is to speed up to 115 kts or so then pull about 2G positive to recover from the dive. As I recall, the gyroscopic precession of the 2G pull up acting 90 degrees to the prop will get the prop to swing just enough for the air to then force the prop to windmill again. Mixture rich... and back to powered flight (hopefully). This was demonstrated to me in a C-172 with a 180HP engine and fixed pitch climb prop (fine pitch). Constant speed props may be different enough to make a big difference on suitability for this maneuver and the airframe difference would be a big variable as well.
Please, no one try this without a really good idea of what you are doing or a CFI who is current and qualified on the engine and prop and knows what he/she is doing if you are not used to the training and flight test environment where this sort of thing is typical. My comment is only based on my memory and this was 24 years ago. A good plan and brief along with a qualified CFI who is current will go a long way though. Always have a few outs and backup plans in case someone else out there does something stupid. I think experiencing things like this or at least contemplating them are what makes "true" experience and it's valuable as long as it is approached properly (I assume you pre briefed and thought it all out with contingencies before you conducted your experiment, and I'm sure you learned a lot from it including the riskiness of risk!)
I have no comment on the engine implications in this case aside from my experience in being a CFI in certified light twin training years ago with 0-360's and 0-540's and constant speed props. I would simulate engine failures in flight by shutting off the fuel selector and we would run around for 10 to 15 minutes at a time training on OEI flight. The longer you cold soak an engine in flight with the prop stopped the harder it is to start. But even a cold soaked engine would start well on a Beech Duchess with prop accumulators what would unfeather and swing the prop enough to windmill it. Once it was windmilling we could easily start it with mixture, unlike other light twins with starters only (the starter would not get the motor windmilling on those as the prop was still feathered until the engine was running).
Last edited by Eddie P : 07-02-2013 at 07:15 AM.
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07-02-2013, 07:04 AM
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Join Date: Mar 2005
Posts: 5,685
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I'm with you Pat
If the engine quits unexpectedly I will put it on the ground if I cannot get it to restart - there is no mystery there. It is an airplane after all and it will glide. Having done it a few of times for real I can assure you that the the most pressing requirement is not flying the plane - that is instinctive. The need is to have a procedure to go through to attempt a restart - In all my cases this was accomplished by switching tanks and turning on the aux (boost) pump while the propeller is windmilling. I had one case where the engine lost its oil and any power being produced was a mystery but it seized completely on the landing rollout at Chino.
The greatest value in this thread is that the tester verified that some RV will glide and that he was unable to achieve a restart even though he tried. My goodness we have pilots that are learning to fly in the RVs they built and others fretting over flap use in landing. Even implying that all REAL PILOTS should shut down their engine and attempt a dead stick landing as good risk management is incredible. If they took this seriously we would have RV's down all over the place. If you want to do it, that is your business but to suggest that it is something that everyone should do is irresponsible I believe.
As far as the initial question is concerned - if shock cooling is a problem, it would certainly seem to apply in this scenario.
Bob Axsom
Last edited by Bob Axsom : 07-02-2013 at 07:18 AM.
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07-02-2013, 07:44 AM
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Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,147
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I did this a couple weeks ago in the 172 (IO360 FP), I had to get the airspeed back up to almost 140 before the prop would start windmilling again, that produces a rather alarming down-angle if you aren't ready for it.
As for shock cooling the engine, if you're going to do this just be smart about it. I reduced power incrementally to idle over a few minutes to let the CHT's come down smoothly and at a reasonable rate before killing the engine, likewise on the restart you don't want to go to full power immediately unless you're out of altitude. When I did it, I was returning from a cross-country and pulled the mixture at 12,500' and about 6 miles out, and the restart was around 5000' at idle power for the rest of the spiral descent to my runway. Be prepared for a failed restart, it can happen for a variety of reasons. Put yourself in a place where it can be an interesting story to tell, rather than an insurance seminar.
This is one of those things that I believe will make you a better pilot - if you understand the physics of what you're doing and the risk management skills are there. It's definitely not for all pilots and would result in a bunch of accidents like Bob said if we asked all pilots to do it. I know several pilots that are barely competent enough to find the mixture knob, let alone know what it does - those guys have no business getting outside of well-charted territory.
__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid 
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
Last edited by airguy : 07-02-2013 at 07:49 AM.
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07-02-2013, 07:58 AM
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Join Date: Jun 2011
Location: Fredericksburg, VA
Posts: 312
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Risk vs Reward
I'm firmly in the camp who thinks practicing real emergencies is too much risk for too little reward. Although you may be within gliding distance of your home airport, what happens if the runway fouls when you are on short final or there's some other need to make a go around? I am also a glider pilot, but I wouldn't consider shutting down an airplane motor in flight. If I'm on short final in a glider and the runway fouls, I close the spoilers and the immediate reduction in drag gives me options. How long would it take you to make a go around from an intentional dead stick landing?
Other than learning what airspeed it takes to stop the propeller, I don't see what is to be gained from this experiment. A windmilling prop produces more drag than a stopped one does, even with the engine at idle. If you have the skills to land the airplane with a windmilling prop, then you can apply those same skills to land if the engine ever quits for real.
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Rob K
RV-8 N884RA under construction
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