Engine failure best glide speed descent rate

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Re: Engine failure best glide speed descent rate

Post by Rich »

RMarkSampson wrote:
Wed Jul 24, 2019 11:39 pm
If you fly over Lake Michigan at 100 ft, it won't help the glide distance, but it does make the math easier... :D
And decision-making. Not a lot of choices to consider or time to obsess :)
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Re: Engine failure best glide speed descent rate

Post by 40flyer »

Thanks Colin! Actually I could also time it so the Badger ferry is just about half way across😎
And Mark, the only problem with that is my waterski buddy will want a tow across and that’ll increase my fuel burn 😉
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Re: Engine failure best glide speed descent rate

Post by RMarkSampson »

Decision-making might not be my strong- suit.... or maybe I'll be just a little more serious.

So I essentially do the same glide slope math when I fly over Lake Okeechobee down here in Florida when my daughter was away at college and VFR-Direct was directly over the lake. Altitude was definitely my friend. However, I normally decided to cut my risk to zero by flying down one shoreline or the other but with a route of flight over Lake Michigan you really don't have that as a viable option. Same with me going to Key West from Tampa - its simply is too far out of the way to fly over and down A1A to avoid the water crossing.

So as noted, you likely cannot cut your risk to zero in the engine-out scenario. But being prudent, you only need to reduce your risk by factoring all of the risks and mitigating the risk where you can. Importantly it is not just about your glide slope. Risk to consider and mitigate:

1. Water temperature. How long can you survive? Can you do something to extend that time.
2. Higher altitude crossing give you more time to prepare - including your passengers. So build a checklist that they can read through while you fly the plane.
3. Your ELT - have you upgraded to a Satellite-capable ELT? Can you keep it afloat if the plane submerges? (might want to remove if from its bracket in the luggage compartment so it exits the aircraft when you do)
4. Daylight and signaling rescue - you need to be findable. Consider that you may fly a daylight crossing but could be in the water into the night.
5. Mariners are your friend - look for maritime traffic and if you lose your engine in the "no land to land on zone" - head for that ship.
6. Prior to crossing - pick a location where you will go through a detailed review of all your engine instruments. If something does not look right, divert and land vice pressing over the water.
6 and a half. No alligators in Lake Michigan so I won't mention Alligator Wrestling Lessons on this list

Yes, your risk is not zero but you will put yourself in a very good position if you have considered and reduced your risk through some common sense preparations. Finally, I will mention one more "food for thought" thought: Don't land in shallow water. You really don't want to be upside down in shallow water when pushing open the canopy to exit the plane. It may not be possible though they tell us those little hammers are supposed to work. I'm not a believer. Anyway, in Florida we have lots of shallow water. My plan has always been to head to deep water so it gives me a better chance of exiting the plane when I go inverted.

Enjoy Oshkosh!
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Re: Engine failure best glide speed descent rate

Post by pietromarx »

While I understand the concern of flying over water... how often do Lycoming IO-360s (or even Austros and Theilerts) go out spontaneously?

How many engine failures have been observed during cruise flight?

There was the double Thielert engine failure on takeoff with the DA42 and the ECU power interruptions, but that wasn't during cruise flight.

With regards to cruise over water, I know of two fatal crashes with DA40s and water: one into the Pacific approaching the shore on a low IFR approach after a long day into Crescent City and another into an Arizona lake where the plane had been observed doing things they shouldn't have been doing.

I ask out of curiosity.
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Re: Engine failure best glide speed descent rate

Post by Colin »

My understanding was Lycomings were 1 in flight engine failure every 10,000 of flight time. The Technify engines were 1 in 100,000 hours (not sure what the Austro number is). Since I have two Technify engines I have moved into the math which I do not understand to figure out if both will fail at once.

Of course, I came close to that by having the plane mis-fueled, but I didn't start the engines.
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Re: Engine failure best glide speed descent rate

Post by pietromarx »

Colin wrote:
Thu Jul 25, 2019 6:19 am
My understanding was Lycomings were 1 in flight engine failure every 10,000 of flight time. The Technify engines were 1 in 100,000 hours (not sure what the Austro number is). Since I have two Technify engines I have moved into the math which I do not understand to figure out if both will fail at once.

Of course, I came close to that by having the plane mis-fueled, but I didn't start the engines.
I think it basically goes to whether you consider these occurrences random chances (e.g. roll of the die every, say, hour) or whether they're trend-based (e.g. lines crossing on a graph). My experience with predictive service in industrial applications says that it is safe to assume the latter and that -- at some point in the distant future? -- both engines will not be working at the same time. :)

More seriously, though, do sudden catastrophic total engine failures happen in cruise flight on reasonably well-maintained mid-life Lycomings, Austros, and Technifys? Yes, I know of the issues with recently manufactured and serviced engines, as well as with ones that have signs and trend indicators (metal in the wrong places, etc.). But ... on plain old normally working engines in cruise ... ?

Anyone hear of one in the last two decades? Assuming your quote on MTBF above, we should have seen at least a few.

Thanks
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Re: Engine failure best glide speed descent rate

Post by Thomas »

Back in 2002 I had an complete engine failure with an brand new (25TT) Diamond Dimona 115TTC (Rotax914S engine) at low level on a local flight. Immediate engine stop after strange sound. 90 s after the silence began I was on ground save on a field. As an active and current glider pilot I was used to outside landings ... together with the luck of an available field this saved my day. ... and the one of my mother, in the RH seat.
Finding was a faulty valve seat on cyl 1. wich I could not believe as the stop was so sudden, but that was Diamonds/Rotax explanation. Warranty case of course.
See pics and story ... sorry in german.

http://www.hergiswil.eu/HP%20Thomy%20Ak ... tseite.htm
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Re: Engine failure best glide speed descent rate

Post by 40flyer »

Great discussion! I think Mark Sampson’s checklist is a good one. I did not mention that one other concern in the back of my mind was the time on my engine. It has just shy of 2900 hrs with no maintenance other than oil changes. It is not making any metal, burns 1 qt of oil every 15-17 hrs and compression is still very good. Mike Busch says I should not do an overhaul of any kind until I get the right “signal”, otherwise I’m euthanizing a perfectly good engine. Nevertheless, mechanical things will ultimately suffer a failure of some kind, perhaps with no forewarning.
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Re: Engine failure best glide speed descent rate

Post by Colin »

One of the pilots on here had a Rotax fail on take off (vapor lock). Soon after an upgrade or AD or something.

On the Beechtalk board there seem to be fairly regular engine failures connected to cylinder issues in the Continental engines. And they seem to be saying that quality is going down, not up.

I would agree with both engines failing at once if they had the same hours on them. On my plane the right engine is 900 hours newer.
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Re: Engine failure best glide speed descent rate

Post by pietromarx »

40flyer wrote:
Thu Jul 25, 2019 9:26 pm
Great discussion! I think Mark Sampson’s checklist is a good one. I did not mention that one other concern in the back of my mind was the time on my engine. It has just shy of 2900 hrs with no maintenance other than oil changes. It is not making any metal, burns 1 qt of oil every 15-17 hrs and compression is still very good. Mike Busch says I should not do an overhaul of any kind until I get the right “signal”, otherwise I’m euthanizing a perfectly good engine. Nevertheless, mechanical things will ultimately suffer a failure of some kind, perhaps with no forewarning.
Ah! There it is. One could argue -- as Busch does -- that your engine is more reliable today than it was new, etc.
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