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R22 Hard Landings


brushfire21
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Not sure if this is the place to post this or in a new thread, but here goes:

 

How does the R22 handle hard landings, in particular hover auto's? Reason I am asking is that a week ago a few R-22's were practicing hover auto's on the side of the taxiway and it was funny watching them bounce because a little to much collective had been pulled (like I have NEVER done that before LOL!). What is the weak point or end result of one to many hard landings?

 

My usual A/C is the 300c and am somewhat familiar with the suspension and weakness that pertain to it, but trying to see what I might be getting into on a R22. Thanks everyone.

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Not sure if this is the place to post this or in a new thread, but here goes:

 

How does the R22 handle hard landings, in particular hover auto's? Reason I am asking is that a week ago a few R-22's were practicing hover auto's on the side of the taxiway and it was funny watching them bounce because a little to much collective had been pulled (like I have NEVER done that before LOL!). What is the weak point or end result of one to many hard landings?

 

My usual A/C is the 300c and am somewhat familiar with the suspension and weakness that pertain to it, but trying to see what I might be getting into on a R22. Thanks everyone.

 

 

Roger- being the smallest guy to ever fly a R22, I am qualified to speak of hover autos. The skids on the R22 are designed to bow outwards...even flatten out if needed to help absorb energy in a crash. A hard hover auto, or multiple ones, can bend the rear support of the gear, causing it to "smile" a bit too much. ( located just under the fan looking from the back) Of course, that is the obvious damage, the hard jarring of metal over and over can't be good for its health. Also, if you pull collective so that the blades are coning as you descend that last foot or so you will be ok....however, if you dont, the main rotor could take that shock, a rotor blade dips and off goes the tail...thats kinda a bad thing....but what the hell, at least you are on the ground!

 

Actually, due to my size and having a safety pilot on board to practice, hover autos are probably the toughest thing for me. You get no reaction time, no time to delay like maybe a B47 or a 206 or even a R44 would give you. Sorry, I didnt practice any hover autos in the 300...so I can't compare the two, but I guarantee it all happens faster in the 22..

 

Oh yeah...you can measure the height above ground of certain components to determine if the aircraft is sagging too much from too many hard landings.

 

See ya. Goldy

Edited by Goldy
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Signs of a hard landing

 

Look at the cross beam (as mentioned). If there is excessive smile, get a mechanic.

Look at th vertical support at the aft. The one that goes directly up from the rear strut and crossbeam join to above the engine fan cover. Seen from the back, a kink in this is an obvious sign of a hard landing.

Look at top of tail boom, to ensure no MR blade contact.

Look at the Tailboom support points. Deformation of these may also be evidence. Should NOT be able to slide fingers between the tailboom and the scroll fan cover.

Look at gap between main rotor mast cowl and fuselage. Could be signs of impact with longitudinal velocity.

 

 

Coming from 300CB, the stiffness of the R22 landing gear system can seem a little un-nerving. You'll get used to it though. Don't worry about Hovering Engine Failures any more or less than the 300CB. You'll know if you've hit too hard, just like in the 300CB.

 

Having said that, it is good measure to do thorough post flight check, any time you do ground work like that.

 

It doesn't feel so bad on grass, but this is not reccomended.

 

Joker

 

Edited: There everyone! I have edited all my errors!

 

MVC-331F.JPG

Edited by joker
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I saw some crosstubes a the Robinson factory that were a real good example of the smiley face phenom... almost a half circle.. that was right nextto the set of skids that were worm half threw.. great preflight guys..

 

Anyone have a picture of a smiley cross tube?

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Goldy,

Thanks for the info and experiences on this, and I would have never guessed that you would have had hover auto problems with your petite figure! Honestly, I never even thought about the rotor blade flex and the possibility of it shortening up the tail boom.

 

Joker,

The pic you attached was perfect! Still boggles my mind that there is enough flex without dampeners to absorb the impact and still be fine.

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First off......STOP calling them "Hover Autos". The FAA got away from that 10 years ago because there isn't any "autorotation" in the aerodynamics or demonstration. Do you lower the collective, add aft cyclic, and let the upward flow drive the rotor systems? NO! You hold the pitch and cushion the set down with the remaining rotor RPM. They are "HOVER POWER LOSSES", "Loss of power at a hover", or whatever you want to call them that doesn't involve the word "auto".

 

Now that I have that out of my system.............

 

Actually, you're not suppose to do hover power losses on grass. Grass, sand, or any other soft surface will grab the skids and prevent them from flexing outward. Therefore, the tailboom, tailboom attachment points, etc take more of the impact.

 

Do hover power losses and full down autos to a smooth hard surface.

 

This is not only for the vertical vector of the impact, but the rotational/torque as well. I've seen several R22s with kinks in the fowardmost bay of the tailboom because they hit the ground even with the slightest spin. If that torque is great enough to kink the TB, it would have spun you on the pavement (and prevented the kink). Not the case on the grass.

 

And as far as crash standards go, the R22 did fabulous on that end of the certification. You have to static drop a fully loaded bird from 18 inches without damage, Robinson did it from 30 inches. And from higher than that, many people have walked away from very hard landings as long as they didn't have anything hard under their seats.

 

Refer to the RHC MM (inspection section) about hard landings. On a flat surface the bottom of the stinger should be a certain height above ground (I think it's 42 inches on the Alphas, Betas, and Beta IIs.) It's pretty obvious with that back cross tube has been "smiled".

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First off......STOP calling them "Hover Autos". The FAA got away from that 10 years ago because there isn't any "autorotation" in the aerodynamics or demonstration. Do you lower the collective, add aft cyclic, and let the upward flow drive the rotor systems? NO! You hold the pitch and cushion the set down with the remaining rotor RPM. They are "HOVER POWER LOSSES", "Loss of power at a hover", or whatever you want to call them that doesn't involve the word "auto".

 

Now that I have that out of my system.............

 

Actually, you're not suppose to do hover power losses on grass. Grass, sand, or any other soft surface will grab the skids and prevent them from flexing outward. Therefore, the tailboom, tailboom attachment points, etc take more of the impact.

 

Do hover power losses and full down autos to a smooth hard surface.

 

This is not only for the vertical vector of the impact, but the rotational/torque as well. I've seen several R22s with kinks in the fowardmost bay of the tailboom because they hit the ground even with the slightest spin. If that torque is great enough to kink the TB, it would have spun you on the pavement (and prevented the kink). Not the case on the grass.

 

And as far as crash standards go, the R22 did fabulous on that end of the certification. You have to static drop a fully loaded bird from 18 inches without damage, Robinson did it from 30 inches. And from higher than that, many people have walked away from very hard landings as long as they didn't have anything hard under their seats.

 

Refer to the RHC MM (inspection section) about hard landings. On a flat surface the bottom of the stinger should be a certain height above ground (I think it's 42 inches on the Alphas, Betas, and Beta IIs.) It's pretty obvious with that back cross tube has been "smiled".

 

Dude, stop whining about semantics....Call it whatever you like, as long as you know what it means. Hell, I don't care if a student calls it a zero airspeed quickstop with a zero torque touchdown as long as he does the maneuver properly.

 

What is up with all the whining helicopter pilots?????

 

The Army doesn't refer to the maneuver as a "Simulated Engine failure" or a "Power Loss" because they found that with a new student "Simulated Engine Failure" meant down collective, aft cyclic, right pedal, blah blah blah and caused them to react improperly. To get away from this they called it something different. Makes sense to me. Get off the helicopter high horse a little, will ya?

Edited by nsdqjr
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So what do you associate the word "auto" with? Collective down now! That's other reason why the Feds stopped calling it a "hover auto"...... because students and checkride applicants were crashing helicopters when the instructor or examiner yelled "Hover auto!". They'd slam the collective down at a 5ft hover and you can imagine what happened from there.

 

You can bash semantics all you want, but they're pretty damn important in this industry. I bet we can't comprehend how many people have been killed in this industry because they misunderstood or were mislead by improper semantics. How about the 747 in Malaysia on the NDB approach told "descend TWO-FOUR-ZERO-ZERO"? Controller meant "descend 2400" ft, but the pilot heard "decend TO 400" ft and crashed into the side of a mountain killing everyone on board.

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Maybe the problem isn't confusion between "auto" and "hover auto." More likely that they crashed because the examiner or CFI yelled hover auto and scared them. I never announce hover autos, I simply roll off throttle. If I am with a newish student, I am on the controls. If I am with a more experienced student I am hovering millimeters from the controls, with my hand under the collective to prevent them from lowering it by accident. I almost never let a student perform a hover auto without my hands/feet near the controls, and if I do it's because they have consistently demonstrated the maneuver properly.

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delorean, I totally agree with you. The name of the manuver plays a huge role in how a student thinks about it. I'm sure in some school's, probably part 141 schools it isn't as confusing because of the way ground school is taught. But in the part 61 schools where you can do all home study (like I did) quite a bit of the learning is behind the controls. One day in the begining of me learning, what I had always called them till tonight, Hover Auto's I kept making a mistake of treating them like Autorotations. Thank goodness I had an absolutley awesome instructor (Paul Petrone). Because I kept lowering the collective when we would start. I did this like three times in a row and we then stopped and talked about what I was doing. I totally got the steps with the autorotions mixed up, and it was totally because of the name. If we would not have been calling them Hover Autos I don't think I would have done what I did at all. Maybe I would have but I don't think so. I know that for sure, from now I won't be calling them Hover Auto's and I will not teach my future students that term.

 

I for one thank you delorean for your view...

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DeLorean- you are absolutely correct in emphasizing practice to a hard surface. We lost an R22 in November due to just that reason.

 

And from now on they are no longer "hover autos" . I will now refer to them as "hover crashes", if you are asking why I call them that...come practice one with me !

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Well, didn't I get my hand slapped?!

 

Delorean, all points graciously taken.

 

It's certainly true that there is no autorotation in that maneuver. As a stickler for semantics, I should know better. I never had any misunderstanding of what action I need to take, but I see the point.

 

And good point about the grass issue. I never really thought of it in that way. I would like to see further evidence of this being a documented problem though. Do RHC say anything? I'm talking about the stress on the aircraft. I don't mean simply a poorly executed HEF (Hovering Engine Failure!) in which a skid was caught. I'd be interested to hear more from Goldy on his experiences / knowledgee.

 

Cheers

 

Joker

Edited by joker
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After doing a bit of JAA instruction, I also changed the verbiage of hover auto to engine failure in a hover, and also make a distinction between autorotation as a performance maneuver and the emergency of engine failures in flight. :o Just a few things to add to Jokers statement, which is that the aft, left fuselage vertical frame where it bolts to the fairing at the fuel tank is a known weak area and is generally the first sign of a hard landing as it will take the shape Joker describes. It can be difficult to notice, if you don't know what you're looking for, as it often doesn't crease the paint and look to be possibly done on purpose. The bends can be very symmetrical. The other bit, is just a slight correction, that you should not be able to get your hand through the underside of the tail cone and the fan scroll. This being a very subjective measurement, but it would be an indication of the engine mounts being bent. Which brings up a question, what system would be most affected if the engine shifted? :huh: All replies are appreciated. As a hint, this question is built off of a question Joker posed some months back.

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And good point about the grass issue. I never really thought of it in that way. I would like to see further evidence of this being a documented problem though.

 

There was a great article about this in Vertical Magazine back in oct/nov of '06 (The one with the gorgeous orange/black "Native Air" A-star on the cover), it's called "Pass on the Grass" by Shawn Coyle and features both pictures and drawings to go along with the text.

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Which brings up a question, what system would be most affected if the engine shifted?

 

My "guess" would be the drive belts and or the sprag bearing

 

 

First off......STOP calling them "Hover Autos". The FAA got away from that 10 years ago because there isn't any "autorotation" in the aerodynamics or demonstration. Do you lower the collective, add aft cyclic, and let the upward flow drive the rotor systems? NO! You hold the pitch and cushion the set down with the remaining rotor RPM. They are "HOVER POWER LOSSES", "Loss of power at a hover", or whatever you want to call them that doesn't involve the word "auto".

 

Yep............. One thing I've learned from Delorean is to ALWAYS cross your I's and Dot your T's :ph34r: :lol: :lol:

 

Fly Safe

Clark B)

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My "guess" would be the drive belts and or the sprag bearing

 

Fly Safe

Clark B)

 

 

How does the belt tension system work, and would this be affected by the difference in distance, or are you thinking alignment?

 

Joker,

 

 

May the what? My schedule is pretty set, so we have a 50/50 chance. Lemme know, and hopefully I'll see you with a beer in hand. :D

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I always call it an engine failure in the hover. I just want the student to be clear on what is happening.

 

As for not doing them on grass - good point and not one that I had ever really thought of. I used to do them over dirt, which I suppose is a bit more forgiving. Never had a problem. Came pretty close a couple of times to rolling one over though.

 

As far as the engine moving I would imagine that a small vertical or small horizontal movement is not going to be a huge issue. However a fore or aft movement so that the alignment is off is going to do some damage, maybe not immediate, to the drive belts.

 

I'm not going to volunteer to find out!

 

Closest I have come to seriously damaging an aircraft was doing engine failures in the hover with a guy in an L4. He had bought and learned to fly in his own R22. He sold that and bought an L4. I asked him if he had ever done them, and he replied yes. So I rolled the throttle off and.......................he raised the collective straight away, R22 style. Now an empty L4 with very little weight on board will climb fairly well until all the rotor inertia is gone. It gets to maybe 15 feet or so and then falls out of the sky. As he pulled the collective up I realised what was going on, tried to push it down with limited success and then started to roll on what throttle I could without causing an over torque. We came down and landed level, which saved the aircraft.

 

Luckily no damage done

 

Not only is terminology/symantics important, but also proper description of what you're about to do!

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Well, didn't I get my hand slapped?!

 

Delorean, all points graciously taken.

 

It's certainly true that there is no autorotation in that maneuver. As a stickler for semantics, I should know better. I never had any misunderstanding of what action I need to take, but I see the point.

 

And good point about the grass issue. I never really thought of it in that way. I would like to see further evidence of this being a documented problem though. Do RHC say anything? I'm talking about the stress on the aircraft. I don't mean simply a poorly executed HEF (Hovering Engine Failure!) in which a skid was caught. I'd be interested to hear more from Goldy on his experiences / knowledgee.

 

Cheers

 

Joker

 

 

joker- RHC absolutely endorses hard surface emergency landings. I think DeLorean pointed out in an earlier post that if you land with some sideways force on a hard surface you just slide a bit..no stress to the airframe. Same landing on dirt or grass....and the force applied twists the airframe...or rolls it over. The airframe is built to take the forces as would normally be incurred on a hard pavement. I know it does not sound accurate, but in case of a real auto or practice..head for the nearest chunk of pavement, just make sure the ship is level prior to skids touching.

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Goldy,

 

Thanks.

 

I absolutely understand the explanation w.r.t. airframe stresses. I agree with the physics. I also know how to do autos, thanks.

 

I was hoping for RHC documentation on this, for my reference. Have they tested for this, or is this simply a 'training recommendation' that comes up in a Factory Course as good practice? Do they even mention it?

 

Someone has mentioned an article by Shawn Coyle which I will try to find. Still, this is not RHC's statement.

 

Earlier you mentioned that you lost an aircraft that way. I'd be interested to know whether it was simply a poor technique resulting in a roll, or whether the airframe experienced stresses which led to catastrophic failure.

 

An instructor may feel safer doing them on grass, as it is more forgiving to poor technique. That's not what we are talking about.

 

I suppose my question is this: If a landing was correctly performed, with no rotation, lateral or backwards drift, actually how much more is the airframe stress?

 

My point is that if it was a major issue to RHC I'm sure they would have some documentation on it. I haven't seen any.

 

Joker

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Semantics is everything!!!! On a CFI checkride the applicant was doing a 180 auto. As they got close to the ground, the DPE shouted "Power Power" to get some rpms back and check the high sink rate.. At his previous school, the applicant knew that "Power" meant pull collective - so that's what he did. Needless to say, they hit hard and chopped the tail off (MD500). Always brief the maneuver thoroughly.

 

Another one: DC 8 (big 4-engine jet transport for you newbies) is starting to go around after an approach. Captain says "Takeoff power" to the flight engineer who set the throttles at this particular airline. So the engineer did just that - he "took off" the power, and they crashed. So now the terminology is "Go around power" or "Max power" or similar. No chance for confusion here.

 

Propwasher (former English teacher)

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Semantics is everything!!!! On a CFI checkride the applicant was doing a 180 auto. As they got close to the ground, the DPE shouted "Power Power" to get some rpms back and check the high sink rate.. At his previous school, the applicant knew that "Power" meant pull collective - so that's what he did. Needless to say, they hit hard and chopped the tail off (MD500). Always brief the maneuver thoroughly.

 

Another one: DC 8 (big 4-engine jet transport for you newbies) is starting to go around after an approach. Captain says "Takeoff power" to the flight engineer who set the throttles at this particular airline. So the engineer did just that - he "took off" the power, and they crashed. So now the terminology is "Go around power" or "Max power" or similar. No chance for confusion here.

 

Propwasher (former English teacher)

 

Ok, lets clear this stupid semantics thing up once and for all.

 

My post about semantics was in regards to a particular post, not aviation in general. The reason I posted it is because you see on this forum time and time again, someone asks a valid question only to be bombarded with arguements about the way something was spelled, or named, or explained. I have a great idea: If someone asks a question just answer the damn thing. If they spell something wrong, or their grammar is wrong, ignore it and keep in mind what the poster is really asking. When someone gets on here and corrects someone else about these things it makes the helicopter community look like a bunch of hypersensitive, know it all egomaniacs, with sticks showed WAY up their own backside. Someone calls it a map, so what, we know it's a chart, just answer the question. Someone calls it a hover auto, so what, just answer the question.

 

The CFI applicant in your example didn't hit the ground because of semantics, he hit the ground because 1: The applicant executed the manuever poorly and 2: The DPE failed in his own duty as the senior and more experienced aviator in the aircraft. I agree, semantics is extremely important for safe flight operations; however, in a forum it's just semantics. I'm interested in thoughtful and insigthful answers to questions that are posted here, not filler about how cool someone is because they know a more proper verbage.

Edited by nsdqjr
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Back to the grass vs hard surfaces...

 

Another point on grass/dirt vs hard surfaces is the difference in friction that can occur. On hard surfaces friction will be fairly uniform, unless you touch down with one skid on the runway markings or a big crack or something like that. On grass/dirt, you just never know. There might be a puddle, a bump or some soft-spots, anything really, that creates a difference in friction between the two skids and could make it a bad day very quickly.

 

Also the grass/dirt will in any case produce more friction then the hard surface, this slows down the helicopter faster and it tends to "tip forward" on the tip of the skids. The instinctive thing to do when you feel this, is to pull the cyclic back.....now you have a rising tailboon, and unloaded blades that go down over the tail. Lots of helicopters have had their tailboomes chopped this way......

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