R-22 POH question

[gary-mike]

Reading through my shiny new R-22 POH,, I had to raise an eyebrow. Under the EP section, it says for power failure between 8-500 ft imiediatly lower the collective to maintain rotor RPM. Ok, I can see that at 500' AGL, even 100', but does rotor RPM really bleed off that quick to where you would want to do that at 8' AGL? I expected for a height that low you would apply rudder and let her settle softly.

 

I'm sure this bag-o-books will raise some more questions from me, thanks for your patience and support. I'm sure it will all come together for me, probably more when I can try to apply it.

[Shaun]

I'm curious to hear from anyone who has actually practiced a high hover auto in a 22.

 

In other aircraft you lower the collective proportional to your height above the ground.

 

Completely made up figures, say at 8 feet lower it half an inch, at 20 maybe one inch, etc. until the height where it's best to floor it.

[rotorwashed]

Reading through my shiny new R-22 POH,, I had to raise an eyebrow. Under the EP section, it says for power failure between 8-500 ft imiediatly lower the collective to maintain rotor RPM. Ok, I can see that at 500' AGL, even 100', but does rotor RPM really bleed off that quick to where you would want to do that at 8' AGL? I expected for a height that low you would apply rudder and let her settle softly.

 

I'm sure this bag-o-books will raise some more questions from me, thanks for your patience and support. I'm sure it will all come together for me, probably more when I can try to apply it.

 

one time i started getting distracted while in a hover dealing with the radio, looking for traffic, etc. my hover slowly crept up to about 8 or 9 ft without me realizing it. My instructor goes "hey whats that noise?, do you hear that?" and rolled my throttle off. i didnt drop collective, just let it settle a little more than a usual hover auto, started the pull to slow the fall, and quickly ran out of inertia to cushion the touchdown with still another foot or two to go. we dropped fairly hard, but it was remarkably tame considering the circumstances. that was about the absolute max i would consider being a safe controlled hover auto (without damaging the ship). after seeing a hover auto from that height, you better believe ill pay attention to my hover height. theres no reason to ever be in an 8 foot hover or higher in an r22. any higher than 8 or 9 feet and you would need to lower collective somewhat to preserve the inertia.

 

so in short, yes it most definitely bleeds off that quickly, compliments of a low inertia rotor system.

 

theres a pretty widely spread example of a huey being able to cut the throttle while sitting on the ground, pick up into a hover, turn a 180 hover turn, and set back down in a slow and controlled fashion with rpm's to spare. needless to say, an r22 ain't no huey!

[lelebebbel]

The HV curve shows 10ft skid height as the maximum hover height from which a safe landing can be made in case of an engine failure

IIRC, this is something that is actually tested during certification, and the collective can not be lowered for this test.

 

I don't call it "hover auto" - there is no autorotation involved, the rotor is just winding down driven by its inertia.

Edited March 1, 2011 by lelebebbel

[Rogue]

Ditto that, Engine failure at hover.

 

I've seen similar experiences as rotorwashed with the Bell 47. Heck one time we flew past our intended landing point, shut engine off, backed up, did a 180 and put her down.

[Trans Lift]

I have practiced engine failures in the hover from about 30ft in a 44, since that is where I spend most of my time at work. Different ball game to a 22 I know but still a lot of pucker factor involved. You really had to lower that collective and then pull it hard right at the end. Worked very well and we touched down nicely.

[gary-mike]

Thanks everyone for sharing your experiences and wisdom. I went on to read that at 8' AGL is also where you push the nose over to level out and start raising the collective. And that anything below 8' apply right pedal as required and allow the aircraft to settle.

 

I guess they just need to set a limit somewhere and ensure that all altitudes are covered. Either way anything below 1-200' I would probably have to replace the seat cushion, or at least clean it real good. I guess time will tell.

[Turner]

Hey Trans Lift, what kind of airspeed did you get up to from a 30ft hover?

[Trans Lift]

Hey Trans Lift, what kind of airspeed did you get up to from a 30ft hover?

 

Ahhh,I think I had 1/2KT drift forward. It drops like a rock!

[Trans Lift]

I went on to read that at 8' AGL is also where you push the nose over to level out and start raising the collective. And that anything below 8' apply right pedal as required and allow the aircraft to settle.

 

I presume the first part where you mention pushing the nose over is more for when you are leveling out after a flare from an autorotation.

From a stationary hover you will not be flaring but applying right pedal, keeping the aircraft level (or a very slight nose low attitude) and cushioning with the collective.

[rotorwashed]

a good tip for hover autos is to just barely give it some forward cyclic while you settle. itll transfer some of that downward energy into forward motion and make your hover autos quite a bit smoother.

 

that being said, dont even try doing that until you have a few hover autos under your belt, and be sure to let you instructor know what your doing.

[gary-mike]

I presume the first part where you mention pushing the nose over is more for when you are leveling out after a flare from an autorotation.

From a stationary hover you will not be flaring but applying right pedal, keeping the aircraft level (or a very slight nose low attitude) and cushioning with the collective.

 

Yes sir, you are correct. I didn't mention that I had taken that info from 2 different EP's. I just knew in my head that pushing the collective down at 8' didn't sound right. It makes more sense to me now, it just made me say WTF when I was reading the engine failure from 8-500' AGL.

[Trans Lift]

Yeah you definitely don't need to lower the collective from anything under a 10ft hover. If it happens in real life, you would be on the ground before you know it anyway. It is just important to keep it as level as possible.

When I did some recurrency training in the 44 last October or so, we were practicing tail rotor failure in the hover. He didn't want me to land it, just keep it over the spot while we were spinning around pretty fast about 5-6 times. Now that was fun. Trying to keep the aircraft over the same spot and level is certainly challenging after the first 2 spins!

[r22butters]

In the EP for "below 8 feet" you are either in a hover or hover taxiing, not really enough time to lower the collective.

 

With the EP for "between 8 and 500 feet" you are more likely on the takeoff run, therefore lowering the collective makes a little more sense.

[sactown77]

I've practiced hover autos at 20 feet in an R22. Yes, definitely lower the collective then pull to cushion.

[gruberwaite]

When you have an engine failure between 8' and 500' you are usually in a takeoff configuration. That being the case you also should have passed through ETL and have a significant forward airspeed. When you come back on the cyclic this will increase your rotor RPM which would require you to lower the collective to "catch the build". If you are hovering over 8' then you will just have to use your judgment, based on your actual altitude, to determine how much to lower the collective if any.