engine failure after rotation

[birddog]

Does anyone have a "feel" for the drag comparison on a simulated engine failure vs a featered prop. Are we talking about a big difference or nominal. I would think it would be substantial. Anyway you could really feel the drag by pulling back the throttle to 1900 rpm. Anyone with any experence with this?
BD
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Mercedes-Benz 280 Specifications

[birddog]

Originally posted by Ernie Martin
Item 1

Yes, the manual makes it clear that in most cases of engine failure at take-off, discontinuing the takeoff is usually the best practice. It's certainly the case if there is adequate runway left to both land and stop the aircraft. Note my emphasis, since I assume that your term "runway remaining to land on" means long enough to stop.

At full gross weight, most Skymasters (certainly the normally aspirated ones) have anemic climb rates on one engine. In a one-engine-out-during-takeoff emergency, with insufficient runway available to land, it is critical to do things in the proper order and do them fast, but without mistakes. My drill is this:

a) Immediately go to best climb speed
b) Identify/verify bad engine
c) Take a second to see if the aux fuel pump fixes the engine*
d) Feather the prop of the bad engine**
e) Close cowl flaps of bad engine

After these steps, you have time to decide other things. The gear up or down is not terribly important (at 90-100 MPH drag with gear locked down is minor, and the extra drag of raising the gear may be counterproductive). Flaps can come up gradually (see item 2 below).

The asterisk on step c) is to identify this as an addition to the manual recommendation. In short, it's my idea. The aux pump may correct a failed mechanical fuel pump or a fuel vapor problem. The double asterisk on step d) is to identify this as a most critical step, because in the frenzy of an emergency it's easy to feather the wrong engine prop -- and then you're doomed. So I practice taking one extra second to absolutely, positively confirm which is the engine prop that needs feathering.

Item 2

The manual makes clear that takeoffs should be with 1/3 flaps. It reduces takeoff distance 10% and gives you a lower (better visibility) attitude on climb. Moreover, the manual also states that on a one-engine-out-during-takeoff emergency the flaps be raised gradually after feathering prop, another indication that 1/3 flaps should be used.

Ernie

P.S. On item 1, I have done both: put it down when I thought there was adequate runway left (I was wrong by 20 yards, with dire financial consequences) and kept flying (doing a go-around) on one engine when there was insufficient runway.

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[birddog]

Hey Ernie, what do you think about retarding the power lever on the suspect engine as a last check prior to feather? This might fall between C and D.
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How to roll blunts

[Ernie Martin]

Let me start with the first question, on the drag comparison on a simulated engine failure vs a featered prop. I don't quite understand what you're asking, buy I'll take a stab at it. The engine-failure simulation in your POH is after feathering. It gives you a throttle setting which corresponds, for that altitude and after adjusting for temperature, with the drag which that engine would have if it's been shut off and feathered. So, there is no difference in drag between the simulated-engine-out setting and the feathered engine.

On the second question, about retarding the power lever on the suspect engine as a last check prior to feathering, this doesn't fall between C and D -- it's the second part of B. After identifying via the gauges which is the suspect engine, you retard and advance the throttle on that engine to verify. A good reason for doing this before C is that, if one engine's gone bad, you don't want to do anything to the working engine which has even a remote possibility of creating a problem, so I don't want to change the fuel mix in the working engine.

Ernie

[J.T.Grant]

Dear Sir,
the climb rate(angle and rate) is better single or twin engine without the gear drag.You do not loose any noticeable cruise speed.No additional noise in cruise flight.
Actually allows easier cleaning and inspection of gear up locks etc.
Sold by RT Aerospace.Easily installed by your A&P. Approx $2500. Link here on the website.
Regards
James T Grant

[Ernie Martin]

Note: The J.T. Grant message immediately above contains answers to questions about the RT Aerospace gear-door removal STC, which were posed by Cjo in a message that appears on the first page of this thread.

[birddog]

Originally posted by Ernie Martin
Let me start with the first question, on the drag comparison on a simulated engine failure vs a featered prop. I don't quite understand what you're asking, buy I'll take a stab at it. The engine-failure simulation in your POH is after feathering. It gives you a throttle setting which corresponds, for that altitude and after adjusting for temperature, with the drag which that engine would have if it's been shut off and feathered. So, there is no difference in drag between the simulated-engine-out setting and the feathered engine.

On the second question, about retarding the power lever on the suspect engine as a last check prior to feathering, this doesn't fall between C and D -- it's the second part of B. After identifying via the gauges which is the suspect engine, you retard and advance the throttle on that engine to verify. A good reason for doing this before C is that, if one engine's gone bad, you don't want to do anything to the working engine which has even a remote possibility of creating a problem, so I don't want to change the fuel mix in the working engine.

Ernie

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HEALTH SHOP

[birddog]

Earnie, the simulated inopeative procedure for some reason is different than what you stated in the Riley Superskyrocket AFM.
It calls for the following:
1) Propeller control - Full High RPM
2) Throttle - Adjust for zero thrust ( per the table on alt and temp)

I felt this simulation induced considerable more drag than a feathered prop and I was wondering if this was technically correct. If so I could look forward to more than the 350 to 400 FPM we experienced. I,m not sure I can take an aircraft 50' feet in the air and abort a take-off and accuratly judge the stopping distance or how much overrun I may have.
However, you give me 50' feet and 400FPM climb and I'm out of there.
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Lovely Wendie

[Ernie Martin]

Unless Riley inaccurately (or ultra-conservatively) generated the simulated parameters, there should be the same drag. In short, you're simulating an engine out with feathered prop. Unless you've actually turned an engine off and feathered the prop (and I ssume you haven't, since you're asking these questions), how can you determine that the "simulation induced considerable more drag than a feathered prop"? Twice I've turned an engine off and feathered the prop, and there's a lot of drag. You're not only adding drag, you're also killing half the total thrust you had.

On the issue of total distance required to abort a take-off, I think a combination of a few simple tests in your own airport plus a simple calculation would permit you to get a good estimate. Next time you take-off, time how long it takes from take-off to achieving 50 feet altitude at 100 MPH (call this time T). Next time you land, try to touch down at 10 MPH or so above your normal landing speed (assume this higher-than-normal speed is S+), note the touchdown point, do aggressive braking, note the stopping point, later measure this braking distance B. To estimate total distance, first calculate gliding distance G by figuring out how far the aircraft will glide in time T at an average speed halfway between S+ and 100 MPH, and then add G and B. If your climb after take-off does not exceed 100 MPH (best single-engine speed), going for heigth rather than speed, as the POH recommends, then this total distance should be a pretty good estimate, perhaps conservative because I think T (measured at take-off) is longer than the time it would take you to put it on the runway.

But all of this may be a moot point. I hadn't noticed from the "Aircraft Type" entry on the left margin that you have a Riley Superskyrocket. That may change things. My experience is solely with (and from the outset I indicated that my comments have assumed) a standard, normally aspirated aircraft -- in Miami and the Caribbean, where high temperatures further degrades thrust. With a Riley and/or more moderate temperatures, and especially if your simulated testing shows healthy one-engine climb rates, perhaps the better solution if an engine fails at an altitude of 50 feet after take-off is indeed to keep going.

Ernie

[Paul Sharp]

Just a thought on the feathering. I noted significant drag with an engine windmilling and NOT feathered. In fact I decided that feathering the prop of the bad engine is probably the most important item even above nursing flaps up, etc.

[Ernie Martin]

Absolutely, it's by far the most important thing. As I said earlier "the gear up or down is not terribly important", it's the feathering -- or better, the feathering of the right engine -- that counts (my emphasis harks back to my concern that in the frenzy of an emergency we not feather the wrong engine).

Ernie

[Jerry De Santis]

I have read all the comments on this thread and find an important aspect no one has mentioned yet. How long is the runway being talked about? One can easily draw the conclusion that if a runway is of a minimum length for your aircraft...say 2500 feet, then after rotation if an engine out should occur, there is no way you are going to land and stop the plane safely and thus a go around is the best thing to do. To try to judge stopping distance when an engine out occurs is the wrong time to do it. That should have be decided before you started the take off.

Also, one lesson to learn here is that it is not good practice to do take offs from intersections! Always...regardless of runway length, use all the runway there is. Runway left behind you is absolutely no good! Folks..don't be shy to use all 10,000 feet of a runway that has 10,000 feet. Almost all the time I take full runway regardless of length and yes, I had sly comments from the tower people once in awhile regarding that practice but remember, they are in the tower and you are in the airplane.

Jerry
N34EC

[Ernie Martin]

Jerry, Amen.

Ernie

[birddog]

All of this has been incredable helpful and made me think through this important subject. Thanks to all for the input and a special thanks to Ernie. You are one smart dude and very interesting. Thanks.
BD P.S. I hope others will continue to share their experience and ideas on this.
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Ipad Guide

[kevin]

On the simulated feathering.

The purpose setting the power to the level recommended in the book when simulating feathering is to cause an operating engine to have the same amount of drag as a feathered engine. The power setting listed provides just enough thrust so that the engine is not dragging from windmilling, and also not providing any thrust - just like a feathered engine.

Hope that helps.

Kevin