Hughes Tailspin
 

I want to gather as much info as possible on this subject, especially from anyone who has experienced it.......I have and I'm sure I'm not alone. A/c was a 369, on 28 June 02. :cool:

merry christmas and a happy new year
regards steve

Sorry to hear that it happened to you. What were you doing at the time - weight, Density Altitude, wind conditions, power, phase of flight etc.
Doesn't just happen to Hughes 369s.

Can you elaborate?
If your'e talking about LTE then you should consider flying fixwing.
There is no excuse for LTE unless of course your military

especially in a 500

seasons greetings

humbly yours

That's Bull$hit Capt. Lai Hai,
One of your lads in Macau got a B206 to do a couple of orbits during a photo job in 1999. He was a good driver and it can happen to anyone who isn't paying attention.

Perfect example of Passive Agresiveness
 

Captain Lai Hai,

It really upsets me when someone instead of helping makes such a naive statement to someone who is asking about a legitimate question

From CLH:
"If your'e talking about LTE then you should consider flying fixwing.
There is no excuse for LTE unless of course your military"

I flew 500's in Africa and I have no idea what this "tail spin" thing is, but if I can't help, at least I won't make dumb comments, I really don't know what kind of flying you do, but in the kind of work I have always done, even while trying to anticipate everything (incuding LTE) I have ran into it several times especially in 206's, we are all humans and we can make mistakes in judgement once in a while.

I have never gotten off a helicopter feeling there was nothing else I could have done to make things better or safer, there is always room for improvement.

And I would never "send" a fellow helicopter pilot to go fly stiff wing for only asking a question. I have been flying for a decent amount of time now and just until recently I truly understood Vortex Ring State thanks to the patience and careful explaining of one of my fellow helicopter pilots. (thanks by the way)

If you can't be positive then just . . . . . .

AND NOW CAN SOMEBODY PLEASE EXPLAIN THIS TAIL SPIN THING?

It's a real shame to read Captain Lai Hai's curt remarks when I'm only looking for constructive input, and I thank you BlenderPilot and Steve76 for yours. Visit Google and enter 'Hughes Tailspin' and you will find at least two specific references to the issue, one entitled 'A History Lesson' and the other 'A Tribute to a Great Aviator'. Oh and a message to CLH.......I have been (and still am) a fixed wing pilot for many years......however, five years ago I moved on (and some might even say up) to rotary and it's wonderful. :cool:

BMK,

It sounds like you encountered Loss of Tail Rotor Effectiveness (LTE). I know of a fellow that this happened to in a H-500. I don’t have all the details but what I do know is that he was out on a mission on a hot summer day, hovering OGE, and all of the sudden the helicopter starts turning to the right. He thought he had a tail rotor failure, he entered an autorotation and landed with some minimal damage. The main thing about this incident is how surprisingly quickly it happened, one second he was fine and the next he was yawing to the right.

I know of two instances of this situation. That you have given so little data for us to unravel the problem, I can only tell of these two 'tail rotor spins'.

Both occurred on the same airframe and it would appear that the reason was as follows.
Approaching to the hover, little wind. too greater rate of descent building up as the craft closed with the hover point, large input of collective with no immediate pedal to compensate, heli yaws, pedal applied but too late, pilot thinks he has applied the wrong pedal, applies the opposite pedal, heli spins faster, pilot applies original pedal but too late and doesn't push hard enough or for long enough, first occurrance pilot recovered, second time heli splattered over ground, nobody hurt.
I believe it was too much collective too late without sufficient and coordinated pedal input.
It's odd that now that the Gazelle is in civilian hands this problem is happening and for no other reason than explained in the paragraph above.
If anything lead with the pedals!

We tend to think of the tail rotor having unlimited power-- if we think about it at all. We blindly assume that we can just push and push on the anti-torque pedal and it will always have enough "oomph" to counter the effects of engine torque, weathervaning tendencies...whatever.

Some helicopters have notoriously weak tail rotors. And it is a sickening experience to feel the clunk of the left pedal (CCW rotors) hitting the stop. Worse still is when the tail rotor gives up the ghost prior to getting to the pitch limit.

Smart helicopter pilots will always be aware of the amount of reserve thrust in their tail rotor. When we find ourselves in conditions of low airspeed, high power and a right-hand turn to the downwind (again, CCW rotor of course), it gives us goosebumps. Or it should. Because we must be ready for the yaw. Not only that, we must have a plan of action for when we do get it. Like, how to get out of it.

Flying helicopters is a "pro-active" and not a "reactive" activity. You cannot wait for the aircraft to do something before reacting to and correcting for it. Not to be harsh, but one cannot say, "I got into the dreaded Hughes tailspin!" without acknowledging that there were predictable circumstances that lead up to it......circumstances that the pilot should have noticed and been prepared for. That's like saying, "I got into dang ol' settling with power...it's the aircraft's fault!"

This is, I believe, what Captain Mai Tai was alluding to.

This is from Transport Canada's Safety Web Site.
Vortex is Canada's helicopter safety news letter.

Aviation Safety Vortex 1/2002






LTE Accidents

Many of you have seen the literature on LTE before. Bell Helicopter and the United States Army have been aggressive in getting the message out for many years. Still, these accidents continue to occur, and many models are susceptible to this phenomenon (I’ve personally had it happen to me in a Hughes 500D, luckily without incident). Here’s a brief sample from the archives.—Ed.

May 1994
Hughes 300C


The helicopter was being used to search for a missing person. The pilot turned the helicopter abruptly downwind to search down a river bank and lost tail rotor effectiveness. The helicopter rotated through 3600 and descended rapidly toward a swamp. Despite the application of full power, the 300C landed heavily in swampy ground, breaking the skids.

July 1996 Bell 206B


As the 206 approached the pad at 7600 ft., it lost tail rotor effectiveness and spun through 3600, striking the pad heavily and damaging the skids, tail rotor and lower fin.

Oct. 1985 Hughes 269A


Tail rotor authority was lost and aircraft rotated into trees.

August 1988 Bell 206B


While looking for a remote site in mountainous terrain, a loss of tail rotor authority occurred. The helicopter struck the trees and came to rest about 6300 ft. ASL.

Sept. 1994 Bell 206B


The pilot had just released a sling load and was preparing to land when he lost tail rotor authority and the helicopter began to rotate. The helicopter struck the ground and rolled over on its side, suffering substantial damage.

July 1993 Enstrom 280


Just after liftoff the pilot lost tail rotor authority, and the helicopter began spinning. After numerous 3600 turns, the pilot rolled off the throttle and attempted a landing. On touchdown, the tail struck the ground and the tail rotor guard bent over, damaging the tail rotor and drive shaft.






Last updated: 2002-08-16 Important Notices

For more info on LTE check -out.

http://tcinfo/civilaviation/systemsa.../1-02/V007.htm

BTW

Sincere apologies.

However I don't believe an experienced pilot should ever unintentionally get into LTE.

May I suggest to you that if for example you're on a photo job with the photograher and all his friends and their relatives as always happens hovering OGE say at a 1000' you have to expect you will be approaching the A/C's limitations and you will feel it without having to refer to the panel.

The collective position the amount of tail rotor you're using etc etc
Try using your collective as well as TR to control yaw.
You will be surprised how much more control over heading you can retain hovering in that spot with the wrong winds without losing any noticeble altitude.

Of course if your close to the ground you might want to consider keeping a bit of airspeed up and if you need to turn down wind climb a first to give you some margin to covert height into airspeed if required.

Steve 76 wrong assumption again

Seasons greetings to all and fly safe

Blame it on the tail rotor.
 

On December 5, 2002, at 0900 central daylight time (cst), a Hughes OH-6, N353RK, operated by Freelance Air, Inc., lost tail rotor effectiveness during cruise flight and executed a sliding landing at the Omar N Bradley Airport (MBY), Moberly, Missouri. The helicopter was not damaged and the pilot was not injured. The 14 CFR Part 91 repositioning flight departed the Spirit of St. Louis Airport (SUS), St. Louis, Missouri, at 0810 cst, en route to Omaha, Nebraska. Visual meteorological conditions prevailed. No flight plan was filed.

:D

lte
 

Lu, in the case of the OH-6,this must have been a " loss of tail-rotor control", in that either the t/r fell off, the drive to the t/r failed ,or the t/r controls failed, or even a combination.
I can`t see how you can have LTE in the cruise,as it usually manifests itself at low speed,high power,a lot of yaw pedal input,,and combinations of high alt,or downwind approaches, or similar situations as you lift to the hover.
Nevertheless, it was obviously well handled and ended safely- the main criterion!!:)

Sycamore trees have "monkey balls"
 

To: Sycamore

Those are not my words above. It is a direct lift from the NTSB accident site.

:cool:

Interesting thread this ...a good one for new chums to think over... The OH6 mentioned I hope had the metal T/R blades fitted....cos I can rember many many moons ago flying Hu 500As and Cs with the older Fibreglass T/R blades and they DEFINATELY would allow for the pedals to hit the stops and occassionally if one was not careful would STALL and cause LTE ...IT CAN happen to anybody. Anybody familier with the Bk117 flight manual ...the B1 & B2 versions have a torque limit imposed below 40kts IAS cos you "might" run out of T/R authority during slow speed ops! :eek: :eek:

hughes tailspin
 

Lots of input from knowledgeable people reporting other incidents of LTA.
But none explaining (or pointing to a source of explanation) the aerodynamics of this phenomena.
Vortex ring and settling with power get lots of coverage in training manuals and I have had them demonstrated by instructors. But never have I had a briefing on what nearly killed me in my H500 last summer (I was P2)
To find that the US army(go to www.google.com and put in 'hughes tailspin') knew of it with sufficent familiarity to name it "the Hughes Tailspin" means that it's covered somewhere, and others have died because of it.

Can someone tell me where, so that I can better understand it and avoid becoming another statistic?

@spinningwings

BK 117 B1 / B2 have a torque limit from 2 x 83 if the IAS is below Vy=65kt. That's 12% more than on higher speeds!!!
LTE on a BK 117 with the large fins and forward speed within the approved weights and altitudes, should be impossible. The torque could also be limited in line with construction and airframe problems. Think about the loss of the tail rotor on a BK 117 in the US and some equal crashes on other types.

Please don't mix several problems. The effectiveness of the tail rotor on all helicopters is limited.
It's public that some helos have more problems than others. It's a very complex problem with great parts from aerodynamics, kind of construction, design and used material. And some kinds of construction and design are still a compromise with other helicopter problems.
Tail rotor effectiveness depends from height of the tail rotor to the main rotor, turning direction, left or right hand on the helo, rounds per minute- blade profil - blade lenght - blade tip speed, bending of the blades, construction type (rigid, semi-rigid, fully...) and... and...

Sycamore is right "you can't have LTE in the cruise,as it usually manifests itself at low speed,high power,a lot of yaw pedal input,,and combinations of high alt,or downwind approaches, or similar situations as you lift to the hover"
Pilots must be carefully on such conditions.

Alien, it's not that hard to understand. First you must realize that "loss of tail rotor effectiveness" (LTE) does not happen in cruise flight. It does not happen on a normal approach, or even a steep approach at the altitudes that most of us fly (excepting, of course, a chap who owns his own ship in Nepal perhaps). It will generally not happen if you keep the wind on your nose instead of your tail.

It will always happen at very low airspeeds, close to ETL or below, when the streamlining tendency of the ship is also low, especially when operating with a quartering tailwind, (or at a high d.a.) and usually when you've got a lot of power pulled in (but not always on that last part).

There are three possibilities:

1. The tail rotor gets into a vortex ring state of its own, possibly due to interference from the wake or downwash of the main rotor. The tail of the ship "settles with power" sideways. This manifests itself as an uncommanded yaw rate.

2. Or maybe the wimpy tail rotor does not have enough thrust at maximum pitch (full pedal) to stop the aircraft from yawing at that particular airspeed, power and wind condition.

3. The vertical fin blanks off enough of the tail rotor that it momentarily can't get enough "bite" and you find yourself in #2.

The solution for all of the above examples is to avoid these conditions in every helicopter in the first place. Be aware of how much anti-torque pedal you have applied, and use caution when you're approaching an extreme.

That way, if it snaps around on you, you'll be ready for it. Then, keep FULL pedal applied, as the tail rotor is not "stalled"...at least, not the conventional way we think of an airplane's wing stalling from flying too slowly...at least, as long as you're not in a recip and you've allowed your MR rpms to get low.

However! There may be other things going on. You may be heavy, requiring a *lot* of power for the airspeed (or lack of it) you've got. The quartering tailwind may be strong enough to get you into LTE, but not strong enough to allow the ship to weathervane once it gets around and pointed into the wind, so momentum keeps it spinning. In these cases, you'll probably have to reduce the power/torque (i.e. lower the anti-torque demand) and maybe lower the nose to increase the airspeed to get some weathervaning tendency back.

Pilots in Viet Nam were surprised to find that the original OH-6A had a small, weak tail rotor compared to the aircraft it replaced, the Bell OH-13. The Army quickly recognized this not-so-improved feature of the new ship, and adapted to the limitation. But just about every small helicopter is susceptible to LTE. And if the LOH competition had been won by the Bell's entry, the OH-4A - at least, with its current fin as opposed to the little half-a-fin that the original design had - it would be known as the "dreaded Bell tailspin."

Oh wait...the Bell design *did* become famous for that! ...Or "infamous" perhaps.