EOLs
 

Hi guys & gal,

We all know that if you ask three pilots for the best sequence of control handling for a standard engine-off landing, you're likely to get four answers. So can we have some tips please.

My standard teach is. After the standard pre-exercise checks ... Establish what I call a 'steady state' descent in autorotation, (rrpm & airspeed steady, slip ball centred, wings level) ... at say 50 to 65 knots & 75% to 90% max auto rrpm for most piston types adding circa 10 knots for the smaller turbines. Depending on type, weight, air density and w/v - commence a 'progressive' cyclic flare at around 30 to 50 feet AGL. In the latter stages of the flare, progressively introduce 50% of available collective lever to reduce ROD and increase rrpm so that for a second or two both cyclic and collective are pulled to minimum achievable groundspeed and positioning for the desired landing point. As airframe approaches say 10 to 20 feet skid height - still in the tail down attitude ... forward cyclic to level the skids. Allow airframe to sink to the 'skids on' position progressively raising collective lever, co-ordinated, but 'in arrears' to the observed sink rate. As skids make contact, no further collective or cyclic movement but using yaw pedals to maintain direction if a 'run-on' landing is made. With aircraft stationary, cyclic and yaw pedals are centralised and collective lever lowered gently to minimum position.

So guys ... that's me ... lets have the options please. Dennis K.

Not sure what Elf and Safety would have to say about that Dennis. Surely far too risky? Do engines actually fail these days? Does anyone teach EOL's outside of the mil? Last real one I did was at MW in the 1980's.

Whether they fail or not, I would want to know what to do. The thought of it all going quiet and the Nr going through the floor at a couple of thousand feet with no idea what to do next would keep me on the ground.

And it's not only engine failure that results in an EOL. Gearbox malfunctions
and tail rotor failures both may lead you to EOL.

Sven

I don't think many people I know would teach the use of the collective before the flare is over and the ship levelled, unless for control of rrpm.

puntosaurus, I disagree.

I was taught a basic auto (ie first lessons) in a small piston like this:

1. Lower lever fully - rapidly and smoothly, ensure its fully down.
2. Maintain the attitude - dont let the nose drop, don't let it roll, keep it in balance.
3. Check the RRPM is restoring
4. Set the attitude for the desired speed - we used 55KT in R22 and H300 nil wind
5. Turn into wind
6. Control RRPM as required with collective, middle of the green
7. Hold your speed until the groundspeed seemed excessive
8. Flare smoothly but positively as required to lose the groundspeed you need to lose (ie back to a safe run on speed, or zero speed, depending upon terrain)
9. Hold the flare until you had lost the speed, or were concerned about a tail strike and it sinking out
10. A short pitch pull on the collective (only a couple of inches or so), at the end of the flare, to further reduce groundspeed and prevent it sinking out
11. Immediately level the ship and cushion it onto the ground with collective as required, ensuring its straight.

Oh yes.

Just tried to armchair fly the maneouvre after a glass of Rioja ... but I don't think I was taught to raise the collective during the flare ... Flare, Level, Check.

Cheers

Whirls

Flare check level cushion - 3 Riojas.

The debate could run and run ...

http://www.pprune.org/rotorheads/19323-f-c-l-f-l-c.html

3no. Riojas now consumed but still .. Flare, Level, Check :)

Cheers

Whirls

I presume you mean "decrease rpm"?

increase, momentarily, Monsieur Coriolis will explain.

whirls
i'm with epiphany, but I make it four riojas (FCLC) or seeing as how its only three particpants in the riojas then we should even it at the next logical common demoninator and consume four each.

usually only in a big wind can you get away without an initial, "check."

The aircraft levels with application of collective, not cyclic.
Give an inch or two on the lever at the end of the flare and it hangs in the air and noses over. Works nicely. Thanks to Shawn and Gordy for getting me there...

Depends what aircraft you're flying.

Not saying it's the only way, but I like and cast my vote for:

1. Establish in auto at desired speed with collective fully down.

2. At the right height (type, DA, wind etc dependent, use your good judgement...), flare.

3. When you've washed off enough speed, or the tail's getting too close to the ground, whichever comes first (ideally both at once), do a little pitch pull - short, sharp movement on the collective, maybe an inch or so.

4. Cyclic forward to adopt the landing attitude - skids level.

5. Freeze collective, keep straight with pedal, let it settle.

6. As skids reach a bee's dick above the ground (technical measurement term there), cushion on with remaining collective.

7. When the ground slide stops, lower the collective.

8. Congratulate yourself on a job well done.

To check or not to check........I think it depends on the inertia of your rotor system - the flare, check, level, cushion worked well on the Gazelle in the mil for many years and the same technique is taught on the squirrel.

However, something like an R22 is a different kettle of fish and applying 50% of the lever before you have the skids level and are cushioning will decay the Nr very rapidly (TET would love you to explain how Mr coriolis manages a slight rise - the coning effect and CAV will be massively opposed by rotor drag)

On larger mil helos the approved technique is not to check but use flare, level and cushion with the level and cushion being a coordinated movement.

Personally, on the Gazelle, I used to encourage a small amount of lever application during the initial stages of the flare to utilise the extra Nr generated to increase rotor thrust, especially on the heavy Army ones. The teaching for the check was to wait until the flare started to lose its effect and anticipate the 'sink'.

The crucial element is always to get the skids level and land straight, most EOLs are survivable if you do that - this requires forward cyclic - helicopters generally are not self-levelling:)

Ultimately everything is variable in a variable flare EOL, the flare, the check the level, and the cushion all depend on the conditions of the day and the aircraft mass and C of G, not to mention the landing area.

I'm with crab on this, specifically regarding the R22. However, I took the previous posts to suggest a slight tug on the pole, not 50%. Regardless of the amount, the R22 RRPM decays so quickly, I don't want to pull the pole any sooner than the "cushion", because there just isn't a whole lot of cushion there.:eek:

My lady Instructor at EGNH, impressed her tight control on EOLs right from the word go, at first the butterflys alway hit me with that dumping of power to simulate the problem but after a few more lessons it becames almost second nature and held no fears for me, Like wise a really good man then showed me in the 206 which amazed me as to the total lack of hurry that big rotor (cmpared with the R22/44) induced almost a calmness that the Robbies didnt, I was fortunate to have been taught to complete run ons on both C/crete and grass, and they way DK suggests is exactly as I have been shown and indeed done., being at EGNH I nearly aways had the help of the wind, still conditions made things just a tad faster until head started to control the hands.

On a check ride I ws shown by Geoff Day some additional moves but I think they were only for bigger and heavier craft not the range I fly.

But on the whole EOL do not worry me, but ask me after I have landed.!!

Peter R-B
Vfrpilotpb

I should have mentioned that the majority of my own experience teaching EOLs and those I work with has been in R22s. There's a neat part of the Robinson Safety Course presentation which shows the energy of the R22 in HP seconds, so you can see how long the height, the speed and the rotor inertia will keep you up. From memory the latter is less than 5% of the total from 2000ft and 70kt, so not much to play with. I'm sure it's a different story in other machines.

However I've never come across anyone in any machine on my profile who teaches use of collective prior to the levelling the ship, unless to control rrpm. Even rrpm control during the flare is a little moot in a real world (as opposed to training) situation. I've always thought that was a sensible rule because real world EOLs are not marked for artistic impression, only survivability. By keeping the rotational inertia till the very end you give yourself the best shot at the landing.

Now there are plenty of machines I've not flown (including the Gazelle which has a very long tail) so I can only speak from my own experience. But given that caveat, I would say that once you start teaching people to fiddle around with the collective during what is already a busy time, you're opening the door to (more) mistakes.

easy, get a piece of string with a weight on the end of it. swing it around in a circle at a constant speed, then shorten the string a little and see how it speeds up.

same as the diameter of a coning set of blades reduces.

Mr C talks about all those fangled things like - cetrifugal forces - and - sum total of masses and energy -, but really the bit of string is easy to demonstrate and happens well before any extra drag shows up.

one more red please.
tet.

TET
Your string and weight example is a demonstration of the conservation of angular momentum...not Coriolis Effect ! (or possibly the Red effect) :)

E O Ls as I was taught.
Close the throttle, full flare and lever to the bottom.
Establish 65 knots, raise the lever 2 notches on the collective indicator and establish 1,500 rpm on the engine.
Trim the flying controls. (For/aft lateral wheels in the cockpit.)
With luck the Rrpm will be at about 2 o’clock on the gauge, adjust if necessary and turn into wind and your landing point is straight ahead; if it is OK carry on. (It’s a practice.)
Pull the slow running cut out to stop the engine. (This is so the engine control cam does not open the throttle when the collective lever is pulled on landing.)
At 100ft AGL flare the aircraft to kill off most of the groundspeed.
When the ground starts to swallow you up pull full collective and slight forward cyclic to ensure the aircraft is rolling forward when it lands. (This is to stop the undercarriage splaying in a zero speed condition that would cause the tyres to roll in off their rims.)
After landing ensure the blades do not hit the cockpit roof as your lower the lever and RESTART THE ENGINE. (This is important, the droop stops were not very reliable and there was a good chance of the blades chopping into the boom.)
When everything is stabilised rotors running on the ground you realise that as your instructor was following through with both hands he actually did it all for you.
That was how I was taught on the Bristol Sycamore in 1965. Supercharged radial engine, wooden blades, trim wheels, they have it easy now.

The implication so far in this thread is that EOL technique needs to vary with type. What do the pro's suggest for the B407?