Falling through the flare during auto

[Airhead]

So I had some strange autos today and I thought I would throw a line out on this forum to see if the pro's had any thoughts on this. Entry and descent were normal but once the ship was level at around 40-30 feet AGL, at the normal point the vertical descending motion is gone, we were still heading down towards the runway. The words that come to mind are falling through the flare. As the actual flare was pulled we were still sinking a little bit. Not the level, or even an upwards path, that is expected during the flare. This perceived downward velocity was apparent enough that I rolled on throttle early, ended the auto, and took off. My instructor also noticed what has happening and said that he was about to take the controls when I aborted. We did another auto and it was the same.

 

Background information:

 

R-22 Beta II

Newer blades with the larger faired tip weights

7-10 Kts headwind, very close to a direct headwind

7 degrees Celcius

840 ft MSL

Entry speed 75kts and 500 feet AGL

Auto "cruising speed" was 60-65kts and RPM in or near the green

No turns

Paved runway surface

Power recovery intended

Me: 100 hours all in the R-22

 

My instructor was a little baffled, surprised, and concerned. His best explanation was that due to the newer and more efficient rotor blades that the collective check during entry was too much. I was making small adjustments at about 100ft AGL and he thinks that somewhere in those adjustments we were not optimal. This somehow caused us to sink at the point where we were used to leveling off and made the flare less effective than what we were used to. This result was significant enough to set alarms off in our heads and we bailed on the auto. He said he was going to ask around to see what the other instructors thought or had experienced in that aircraft.

 

I am not convinced that in the green parameters, or very very close to what is recommended, was the root cause. I wasn't all over the place and chasing to keep IAS and RPM in spec. It was a matter of less than 5 kts and 2-3% rotor rpm that I was adjusting. The newer and higher inertia blades, in my limited experience, are more efficient during the flare and require a little slower and longer flare. If anything, small control chasing at the bottom of the maneuver would be negated by this efficiency.

 

This wasn't my first auto in that aircraft nor my last.

 

Your thoughts?

[Gomer Pylot]

Every autorotation is different. No two are the same, ever. The wind, DA, and pilot technique constantly change. You have to adjust your technique to make the aircraft do what you want it to do, when you want it. Teaching the use of the same parameters every time, to a power recovery, will not, can not, teach anyone how to make a successful touchdown auto with power failure. All it can do is teach how to arrive at the crash in a possibly survivable condition. The only way to teach successful autos is to do them to the ground with power off, repeatedly. That doesn't happen in most flight schools, nor in most commercial checkrides. During my more than 40 years flying helicopters, almost all of my autos were to the ground, beginning lo those many years ago at Ft Wolters, and continuing up to my present job. I still have difficulty doing power recovery autos, because they are entirely different, and there is no similarity at all on the bottom, beginning at the flare or before.

 

The short answer to your question is that on that day, using the standard parameters all the way didn't work. You have to learn how to recognize when you need to do something different, what to do, and how much, but you will not learn those doing power recovery autos. Just accept that on some days things will work out a little strangely, and hope that someday you get a FI who actually knows how to do autos. There aren't many of them around these days.

[Spike]

What you are asking is difficult to express in writing. It’s like trying to explain to someone in writing how to swim. For me, autos are more like an art form rather than a scientific lesson in aerodynamics. That is, IMHO, the foundation for a successful auto comes from the creative side of the brain. Not the cognitive side. Even so, Mr. iChris will be here soon to provide you with the neccessary academia for your particular situation…..

 

With that, I used to tell my students (during autorotations), if you don’t like where you’re going, why continue to go there? For this particular situation, I’d say; if the condition is not what you intended, you should change something to make it intentional. Change being; IAS, RPM, angle of descent or the machine itself. While ever changing, the end result should be predicable….

 

Like Mr. Gomer Pylot, I’ve done mostly touchdowns throughout my career. Currently, they are a required maneuver for our operation every 6 months during the day, and night. And, I agree. A lost art form……….

Edited February 23, 2013 by Spike

[Airhead]

Thanks for the replies. My school has a no touchdown auto policy. We won't get to do them until the commercial checkride. I don't agree with it but there isn't much I can do about it. I have considered that some day I should just take a couple lessons elsewhere with an operator that will take greater risks. I would also like to work on different simulated tail rotor failures and zero speed autos at some point in my informative years (which probably never end). The school I am at is very safe but also limiting in what we can learn.

 

As for the topic of my post... at the height of the alarm bell in my head as this was happening, somewhere in my brain I believed that pulling a more aggressive flare was going to increase this sinking (like a plane stalling in a steep turn) and when I began to flare past the level point we were still sinking. My hunch was playing out but I don't really believe it to be true. I recovered before I could find out at what point the flare was going to stop the descent rate. We were low and I am sure the stinger was about to get a kiss.

 

I am just trying to understand what was going on that made this one seem so different. The more I think about it I just don't think the flare was being applied fast enough.

 

The next auto we did should have been higher and with a more direct flare, to troubleshoot the issue, but we basically did the exact same thing and got the exact same result.

[pilot#476398]

Entry and descent were normal but once the ship was level at around 40-30 feet AGL, at the normal point the vertical descending motion is gone, we were still heading down towards the runway...

 

...somewhere in my brain I believed that pulling a more aggressive flare was going to increase this sinking (like a plane stalling in a steep turn) and when I began to flare past the level point we were still sinking

 

I'm a little confused here. You do realize that when you start to flare at around 40' you won't stop descending immediately, and unless you flare hard enough, you won't even stop at 8' where you are supposed to level off and either roll on the throttle, or set it down?

 

Most autos I've done (including touchdowns) involved us descending all the way down (the rate just slows when you flare). There has only been one time where my CFI flared the sh*t out of it and we actually stopped, just before rolling on the throttle (I also saw a guy do it at an airshow, its pretty cool to set an R22 straight down)!

[iChris]

At the normal point the vertical descending motion is gone, we were still heading down towards the runway. The words that come to mind are falling through the flare. As the actual flare was pulled we were still sinking a little bit.

 

Every autorotation is different. No two are the same, ever. The wind, DA, and pilot technique constantly change. You have to adjust your technique to make the aircraft do what you want it to do, when you want it. Teaching the use of the same parameters every time, to a power recovery, will not, can not, teach anyone how to make a successful touchdown auto with power failure.

 

What you are asking is difficult to express in writing. It’s like trying to explain to someone in writing how to swim. For me, autos are more like an art form rather than a scientific lesson in aerodynamics.

 

The words that should come to mind are, there isn’t any normal point. They are all right, there’s no incontrovertible procedure for how much to flare, where to flare, or when to end the flare and level. You’ll have to learn that situational judgment from your experience under varied conditions.

 

When it comes to the flare, assuming you’ve maintained you airspeed going into the flare, the most common errors are either too much or too little, too soon or too late.

 

Example: If you’re doing most of your autorotation the same way with the same defined points, into 10 - 15 knots of wind, you’ll have an awakening on a hotter no wind day with more fuel onboard.

 

When you try that same early, slow, and weak flare, you’ll end up near the ground falling through 40 - 35 knots in an unsuccessful attempt to arrest the rate of descend. Those 10 - 15 knots of wind made up for some of your past errors, not so on calm wind days.

 

Don’t get too slow prior to starting the flare. There’s always a tendency for students to rush and start slowing down with aft cyclic prior to the flare, bleeding-off airspeed to soon, because the ground is rushing up. They have to overcome that tendency.

 

The main purpose of the cyclic flare is to arrest the rate of descent to zero; however, that can only be accomplished if the helicopter has sufficient forward speed (kinetic energy) across the ground (Hopefully 60-65 knots).

 

In your case, when the time came to arrest the rate of descent, you either didn’t have enough airspeed (kinetic energy) going into the flare or if the kinetic energy was there, it was not correctly managed and applied, due to a flare too soon, too late, and/or too little.

 

If you start the flare at the correct point in time with optima rotor RPM and airspeed for the present conditions, the flare will be effective in arresting the rate of descent. You only need learn that correct point in time by practice, that’s the only way.

 

At the height of the alarm bell in my head as this was happening, somewhere in my brain I believed that pulling a more aggressive flare was going to increase this sinking.

 

You’re correct at that point it’s already too late. You’ve already given up (bled-off) airspeed thus there is very little kinetic energy left to accomplish any effective decrease in the sink rate. You need to make these key determinations sooner. More practice will build the experience you need.

Edited February 24, 2013 by iChris

[Eric Hunt]

when I began to flare past the level point we were still sinking.

 

It looks like you are a bit set in your actions, flaring at a particular height, stopping the flare at some "level point" and then being surprised when it didn't work.

 

Flaring for a touchdown or termination is an integration process, the same as steering your car. When you see a corner approaching, you don't just crank in a pre-set amount of turn, wait for a pre-set time, and then straighten up.

 

You put in what you think will work, and you assess - nope, need a bit more - wait - need a bit more - wait - back off a bit - wait - now straighten up.

 

Same with applying brakes as you approach a red traffic light. You don't just slam on full brake, and you don't set a specific brake input. You step on them a bit, and assess - is it enough? Too much? Play the pedal a bit to control the approach to the light, and take the pressure off entirely as you arrive at the line, then re-apply to stay still.

 

Same with a flare. Start with what you have been shown, then assess - have I stopped the descent? No! Flare a bit more - oops, did a bit much, just stop it there and wait for the balloon to finish - OK, have I stopped the forward movement yet? No? Ok, keep the flare going, wait for the sink, take the initial pull, wait for the sink, select a suitable landing attitude, then either cushion on or stay in the hover.

 

It is a high judgment exercise, and judgment only works with memory - if you can't remember what worked and what didn't work, you will have trouble deciding what to do in the next situation.

[Airhead]

Thanks again for the informative replies.

 

pilot#476398-Your right to be confused because I made no sense. What I am referring to is that 8 feet area. I'm not sure why I wrote level at 30-40 feet but I think I meant to say I started applying cyclic, around that altitude, to get level <10 feet.

 

That 8 feet was shrinking as we were level, then flaring. Still shrinking, approaching 0 feet, as the flare was building. So when I say "normal point" in the flare I mean the fact that the flare keeps us away from the ground with a certain amount of clearance. This usually happens.

 

One instructor at school said that she thought the wind might have been a factor. Since a storm has recently passed, the winds were inconsistent for a few days. A little gusty and very variable. Maybe we didn't have the headwind or airspeed we thought we had.

 

Like ichris said, more practice will build experience.

 

Gomer pylot- You said that touchdown autos are different even before you get to the flare. Can you explain that to me?

[SBuzzkill]

In other words, "doing that pilot sh*t."

 

We spent almost all of our training doing full down autos every day. After a while you develop a certain muscle memory which allows you to control the deceleration and pitch pull without really thinking about it, you just know what right looks and feels like and you make the adjustments accordingly. Sometimes the decel is more aggressive and other times it's very minimal. Sometimes you pull a lot of pitch at the bottom, other times not so much. You can't really talk about it you just have to go fly it.

 

It sucks because when we made the transition to terminating at a hover it was difficult because it's a completely different maneuver which I think is much more difficult than just taking it all the way to the ground.

[Airhead]

Hey buzz- The helicopter flying handbook says a power recovery is one of the most difficult maneuvers. Just curious, does the Army teach anything from the FAA or do they have separate publications?

 

You went right into full downs? Sounds crazy to me. Before doing some run on landings/takeoffs I was freaked out by the idea of skidding on the ground. Now it's fun but that first one was scary.

[iChris]

 

My instructor was a little baffled, surprised, and concerned.

 

 

 

Ironically, more accidents happen each year from practice autorotations than from actual engine failures. It can happen even with a Factory Instructor onboard.

 

 

HISTORY OF FLIGHT

[Gomer Pylot]

Airhead, keep in mind that anything I say will probably be badly outdated, since I went through Army flight school more than 40 years ago, but back then we started doing full touchdown autos almost from the first day of flying. We did power recoveries only as a way of teaching us to react to unexpected engine loss, and didn't go all the way to a hover. The instructors just wanted to see us enter an auto and head for a clear area, then we rolled the throttle back up and continued with what we were doing. All autos at the stagefields were to the ground, and most of mine were 180's. We never saw any FAA publications that I remember, the Army had training manuals for everything. Back then, the FAA was pretty much ignorant of helicopter operations. After flight school, I was in an ATC unit, and got sent to Oklahoma City, the FAA's version of Ft Rucker, for a seminar on helicopter operations. The ignorance of the FAA personnel there astounded me. They thought they could just tell us to hold position over a navaid on final approach, in the clouds, and we could just hover there in the clouds. They had absolutely no idea about how helicopters work. While there, I got my FAA commercial and instrument certificates, and the FSDO guy insisted that the flight instruments in helicopters were different from those in airplanes. To this day, I don't trust the FAA to know what they're doing if it concerns helicopters, and I've had to talk to lots of inspectors over the years.

Edited February 25, 2013 by Gomer Pylot

[SBuzzkill]

It's pretty much the same Gomer except that in IERW we didn't do 180 autos to the ground, those were saved until FSXXI. In the 58D course we had helicopters with the sights removed that we did full downs in and it was only in the FMC birds that we terminated to a hover. Now out in the big Army we only do autos to a hover.

 

But yeah, if I recall correctly we were doing touchdown autorotations in the first week, and they certainly were the first things we did. What sounds scary to me is trying to auto to a hover when I could barely keep the helicopter in a 10x10ft area.

[Airhead]

That sure sounds like a lot of fun and the best way to learn. A week of experience, in a mulit-million dollar machine, doing full downs. Awesome!

 

We worked up to getting into autos so I could hover decently by that point. At first, the instructor would handle bringing the throttle down and then throttle back in and eventually I had full controls. He was also on the other controls a lot. It was a slow build up. The recovery where it was all me was rather awful because I was still a little slow on the pedals. The R-22 really yaws fast and has a small tail rotor so the pedal input needs to be large. Now I am itching to complete the maneuver to the ground but I better be careful about what I wish for...

 

For now we do a lot of hover autos and run on landings, so we should be able to handle ground contact in an emergency if we had to.

[Mikemv]

To All,

 

As a member of the IHST, JHSIT training work group, I can inform everyone that there is a new "AC" on touchdown autorotations soon to be published. Most of it was formulated by Tim Tucker and Nick Mayhew with input from the work group.

 

It is an excellent guide to considerations and procedures for training autorotations. We have been addressing ways to provide better training for the "Trainers" ---CFIs, as this is an area of numerous accidents in the training environment.

 

Mike