LTE, Wind Direction Preference

[Auto Relight]

Just looking for a few opinions.

In the B206, what direction would you take a cross-wind landing if given the choice, right, or left?

Of course there are many places where you don't have that luxury, but given the choice do you prefer riding the right or left pedal on the way in, and why. Also, thoughts on Critical Wind Azmuth's/LTE directions and how they affect this choice would be appreciated - especially at altitude.

Thanks in advance,

AR

[Shawn Coyle]

Neat question.
Depends on whether you are concerned about running out of tail rotor control, or handling (i.e having a lot of yaw oscillations).
If you think you're close to the limit on tail rotor, then a wind from the left is not a good thing.
On the other hand, if you are concerned that you will be yawing a lot, and that you have to hold heading precisely, then a wind from the aft right is not a good choice.
No easy answer.

[Mars]

Unless you're French.

[PPRUNE FAN#1]

Left. No doubt about it.

I learnt to fly in Franklin-engine Bell 47's and Enstrom F-28A's with the tail rotor on the "wrong" side. Neither aircraft was blessed with an overabundance of power and the wise pilot became very careful about not getting into a right crosswind in a hover lest the ship begin a right yaw that full pedal could not stop.

Now, eons later, I've flown with inexperienced pilots who get all antsy about left crosswinds. They'll recall the critical wind azimuth chart and tremble with fear that a left crosswind will put them into LTE. They forget about things like weathervaning tendency. Good thing it's not a factor anymore.

A right crosswind will require more left pedal in the hover than a left crosswind. So as Shawn says, if you're confident about your tail rotor power, go for it. Keep in mind that the 206 does not exactly have the World's Most Powerful Tailrotor.

However, a right crosswind will always require more engine power to hover. The difference between a left and right crosswind can make a big difference in hover power. I'll take all the available engine power I can, thank you. I fly primarily at low altitudes but it always seems that I am at MAUW.

Left crosswinds do produce some "yaw instability" as the vortex from the main rotor randomly interferes with the tail rotor. Big deal. So the pilot must actually stay awake and on his toes to keep the nose straight. In all my years of flying 206's, I've never found the workload overly objectionable, burdensome or excessively demanding of my meager skills.

There is one final consideration, the size and importance of which will be yours to decide: Let us assume that we are making a "normal" approach with a fair amount of power pulled and a relatively low airspeed (i.e. not autorotative). If the engine decides to quit during this time, which way will the nose snap? Righty-o, to the left. That being the case, I'd rather that the nose yaw into the wind instead of away from it.

Now, I know that we all think that we are Yeager-reincarnate and will instantly and correctly react to every emergency. We all probably assume that if the engine were ever to quit in real life, we'd automatically boot in enough right pedal that the nose wouldn't even yaw enough to wag the turn needle for a split second. The truth is, even I don't think I'm that good. Your mileage may vary.

Again, planning for a power failure may not be very important anymore, and so it may not matter to you which way the nose will yaw when this unlikely event does not happen. But it's something that I think about as I fly.

Shawn is right; assuming that into-the-wind is not an option, the question of left or right crosswind is interesting. Sometimes it will not matter much. And there may be times when right is preferable over left. But for me, those times would be few.

[Auto Relight]

Thanks for the responses.

I personally have taken the left X-wind option when available for many of the reasons outlined by PPrune Fan. The loss of power, while not near as common as it used to be, is still something to be taken into consideration - both for your clinet's and company's sake.

I have found that at high wieghts riding the right pedal allows for quite an increase in available torque in the hover, and so far I can't find a reason to do it the other way. As far as main rotor vortex interferance, I agree that if you are aware of it and anticipating the a/c's reaction, you shouldn't have too much trouble.

Another reason I have been given for the left wind direction is that the tail rotor is operating in relatively undisturbed air, anyone care to comment on this?

Thanks

AR

[MD900 Explorer]

All great answers, but i would like to stick my neck out here just a liiiiitle.

Would it not depend on the type of 206 you were driving?, i mean if you were concerned about losing tail rotor authority, would this not be a factor in chosing the type of 206 to drive. I mean in relation to earlier types or later types. Now correct me if i am wrong, but is there not a difference in tail rotor size from the earlier to the later (68" to 72") tail rotor diameter, thus aiding with tail rotor authority?

The second point i was going to touch on, was that it seemed that it was noted that maybe tail rotor vortex ring state, was a question, but my statment to that is that if you are flying in such conditions to warrent that, wouldn't you be better off home with the wife and kids ALIVE?

Just some sultry points, which i am sure will be covered swiftly by the big boys here :\

MD :ok:

P.S Left is the wind i would have chosen too, as in agreement with pprune Fan#1

[Rich Lee]

Wind from the right, wind from the left - in the old days we just used to point the nose into the wind.

[Devil 49]

Tail left, slow, low power and descending, are the danger points. Like the stereotype vortex ring, you can reduce your risk by minimising degree of exposure in any of those states. Having real exit options and an abort plan *could* allow you to take it to the edge of control authority, safely.

Some suggestions, based on experience with the "big" tail rotor variety 206, only-
Point the nose into the wind and shoot the approach sideways. (See danger points, above.) Remember, it's a helicopter. At the hover, when you have to put the skids down, turn the aircraft whichever way you wish. This should be done cautiously, especially yawing nose right more than 45 degrees, see initial danger conditions.
You'll run out of TR thrust yawing left in a stiff breeze, although playing with the collective can help a little. S-L-O-W rates of yaw, either direction, are critical in my experience.
If the yaw rate varies unexpectedly, deal with it immediately, and have options- don't play with limited control authority in a hover hole.
The 206 will hold more crosswind than you can turn the tail into at the hover. You have to be meticulous in heading at all times.
Finally, if your approach path has sufficient clearance, you can shoot the approach pointed into the wind as above, and yaw right to the desired heading while power reduced short final, just before losing ETL. You have to be able to abort by reducing power and accelerating simultaneously to use this technique!

[PPRUNE FAN#1]

Airplane pilots are lucky. Their approach options are relatively few compared to ours. I suppose a book could and probably should be written on all of the different types and kinds of approaches that helicopters make. But such a book would be necessarily incomplete because there are uncountable variations.

The beauty of...and the trouble with...helicopters is that we take them to strange places that airplanes cannot go. Land into the wind? Yes, whenever possible, although it is not always. Simply abandon a landing because it might involve operating in a small corner of the flight envelope? Hey, all of life involves some risk. Good helicopter pilots are very flexible in their thinking.

Not to brag, but I have made over 50,000 landings in helicopters...maybe 60,000 depending on whether I use five or six landings per hour. Let's say five. Whatever. It's a lot of landings. And virtually every one of those helicopter landings was improvised; I made them up as I went along.

Unlike airplanes, every helicopter approach is an improvisation. We tailor the speed, angle and azimuth to the specific situation. Our "finals" may or may not be straight and there is no "standard" approach angle to use when landing off-airport. This need to improvise seems lost on a lot of pilots who cannot break free of regimented thinking and flying.

Recently, I flew with a new turbine owner, who's only other practical flight time was in Robbies. Aside from flying his approaches at Robbie speeds (i.e. too fast), he was a pretty good stick and I felt comfortable with him flying the turbine. ...Except for one thing.

The LZ at his property was tight but not unsafely so. He'd been in there before, so I let him show me his procedure. Instead of landing right at his house, we made a very nice approach to a huge nearby field. I was impressed but puzzled. To transition to his "front yard" parking spot, we would have had to hover over a large stand of 75 foot trees that blocked our path. When it was apparent that he intended to do just that, I called foul. I asked, "Do you mean to tell me that you're going to hover over those trees?" He did indeed. "Not with me in the ship," I said.

We took off and circled around and I taught him a real-life steep approach, not the theoretical ones we make at the airport during training. High-recon, low-recon, then set it up into the wind, aiming for that spot there and fly down to it. It was kind of a one-way-in sort of place, and the wind gods were smiling on us that day. There were good areas all around us to plop into if the engine quit, and it worked out perfectly with very little pitch-pull at the bottom. At least, worked for me.

No, we did not maintain 60 knots all the way down. Yes, we were probably in the shaded area of the H-V chart for a portion of the approach. Oh well. Better than a 100' OGE hover over friggin' trees with a nearly-vertical descent on the other side.

Clearly, this guy was more comfortable hovering at 100' over trees than making a steep approach. My approach worked on that day because the wind was favorable for the best path in. Tomorrow it may not be. Or now that I'm gone, he may simply go back to doing it his way, or whichever way he's most comfortable with. Which is fine I guess. He's a fully rated Commercial pilot and has to live (or die) with the consequences of his actions.

The more conservative among us would question his need to keep his helicopter at home. They would suggest that he simply park it at the nearest airport. But you know what? People like having their helicopters where they live, when they can. Is it unreasonably dangerous for this guy to operate out of his house, which is way out in the country with no close neighbors? I don't think so.

If we wanted to fly from airports all the time, we'd fly airplanes. We like and fly helicopters because of their versatility. But along with that characteristic, it is imperative that we learn to properly take advantage of it...and do it safely. To do that, we must know how to tailor each approach to the existing conditions. It's not something that you can learn from an internet website. Some things only come through experience.

[Shawn Coyle]

Just to clarify a point. There is no requirement in a Part 27 helicopter to stay out of the HV curve. Part 29, 10 passengers or more, there is a limitation on it.
There is also no HV curve information for a descent situation - the HV curve is published for takeoff power at a heavy weight, high density altitude from the hover to the 'knee' of the curve.
So, there is no requirement to stay out of the avoid curve in a descent to landing. There is a requirement that the takeoff distance (measured and if published) as well as the recommended takeoff flight path stay clear of the HV, but nothing else.

[PPRUNE FAN#1]

Shawn Coyle:Just to clarify a point. There is no requirement in a Part 27 helicopter to stay out of the HV curve. Part 29, 10 passengers or more, there is a limitation on it.
There is also no HV curve information for a descent situation - the HV curve is published for takeoff power at a heavy weight, high density altitude from the hover to the 'knee' of the curve.Oh? 'Scuze me Shawn, but where exactly is this explained or established in the RFM? The ones I've used and perused make no mention of where or when the H-V curve applies or does not. This business of, "the H-V chart only applies for MGW take-offs" is interesting and I've heard it a lot from quasi-authoritative sources, but might as well be an urban legend for all I know. Is that one of those nudge-nudge, wink-wink things? Maybe Bell, Eurocopter, et.al, plaster each chart with "FOR INFORMATIONAL PURPOSES ONLY!"

See, to us dumb pilots (you know, those of us who are not test pilots), a chart is a chart is a chart. Without those little eyesight-straining explanations at the bottom, we might logically be expected to assume that the chart was applicable to all flight regimes.

Furthermore, I think asking pilots to disregard performance charts- even those "non-mandatory" ones like the H-V, is dangerous and irresponsible. Not to be insufferably pedantic (pretentious, moi?), but if the manufacturers or the FAA want us to believe and act as though the H-V curve only applies in certain flight conditions, they can come out and say so.

[Mars]

I'm with you Fan, the HV diagram appears to apply to the landing phase; one of the elements that is covered in AC 29-2C is 'high hover' test which is conducted with 'power required to hover' - this is probably more related to landing than take-off.

In the absence of better guidance, it would be somewhat foolish to place the aircraft within the HV diagram - even on landing.

[Head Turner]

The HV Curve relates to take-off. See MD 600 RFM 5-8.
'Airspeed/altitude combinations to be avoided in the event of an engine failure during take off are shown in the height-velocity diagram' Quote

Agusta don't say whether it is for take off or landing. So one must assume it covers both profiles.

I don't have the B206/Enstrom/Robinson or Schweizer manual to hand. So I cant quote from them.

I've always taken it to be for both t/o and landing.

[[email protected]]

PF#1 - as usual you were doing really well and passing the benefits of your experience to others with less knowledge - right up to the point when Shawn pointed out some facts with which you do not agree. You are only a 'dumb pilot' when you won't listen to those who do know better - we have been round the origins of the HV curve argument before on this forum - it is created by test pilots so why not listen to a test pilot when he tells you its application.
From various test points of height and speed the throttle is chopped, an appropriate delay is applied and then the TP puts the aircraft into auto and attempts to achieve a configuration from where a survivable engine off landing can be made. Where it can be done you are outside of the HV curve, from the point the TPs assess it can no longer be achieved you are inside the HV curve.
There would simply be too many graphs and information if all configurations of climb/cruise/descent were included, therefore they do the tests in level flight/hover only and accept that in a climb with higher power you will be worse off and in a descent with lower power you will be better off.

PS why didn't the guy with the private site just chop the trees down instead?

[Shawn Coyle]

pprune fan#1
You have pointed out an area that only adds to the relative lack of information on the HV curve. And that lack of knowledge breeds misinformation in many areas.
If you get a copy of the Advisory Circular 27-1, it explains quite nicely how the HV curve is determined for certification purposes. Unfortunately, that information is not presented anywhere in the flight manuals, and until my books were published (unabashed advert for same), it wasn't explained anywhere.
Above the 'knee', the test is done from power for level flight, with a one-second intervention between throttle chop and collective intervention. Below the 'knee', the power is takeoff power and no intervention is used between failure and pilot action (the logic is that you had better have your hand on the collective on takeoff...)
So, it is not reasonable to expect the HV curve to apply to a landing profile where you are decelerating and at a lower power setting than level flight.
As far as I know, there is also no operating rule (at least in the FAA world) that requires you (in the Part 27 or Part 29 <9 pax world) to stay outside the HV curve at any time - can't remember the CAA rules, but you might check for them.
Terrain underneath will make a mockery of the HV curve even if you're outside of it in mosts cases anyway.
But your message about 'where is this written down?' is a valid one.
wish it were otherwise.

[PPRUNE FAN#1]

Crab crabbed:PF#1 - as usual you were doing really well and passing the benefits of your experience to others with less knowledge - right up to the point when Shawn pointed out some facts with which you do not agree. You are only a 'dumb pilot' when you won't listen to those who do know better - we have been round the origins of the HV curve argument before on this forum - it is created by test pilots so why not listen to a test pilot when he tells you its application.Crab, you can kiss my ass. Frankly, I don't give a...wait...deep breath now...I don't care what Shawn, Nick or God hisself *says.* What I care about is what my RFM says...or in this case doesn't say. I'm not quite sure why you don't understand that a "fact" isn't a fact if it does not appear in the RFM, especially when it concerns a performance chart published by the manufacturer. Then again, you may not be a pilot. It wouldn't be the first time someone with limited knowledge of aviation posted on this board.

Having said that, I'm fully aware that in most helicopters, adherence to the H-V chart is not mandatory and that the shaded area most certainly would be "smaller" for a descent than for a full-power take-off at MAUW. But as I've often said, I fly in the real world - the one full of lawyers and FAA types who maybe interpret rules differently from one region to another.

As Shawn says about my original point:But your message about 'where is this written down?' is a valid one.
wish it were otherwise.So do I, Shawn, so do I. Think we can convince Bell to amend the H-V chart in their 206 manual with a statement that the it only applies on max-gross take-offs?

One other issue that I've always wondered about concerns helicopters equipped with the RR/Allison C-20 series engine. These engines have a "scheduled decelleration" which defines the minimum time that it must take the engine to go from full throttle to 62% N1. Thus, the power comes off "softly" no matter how quickly you snap the throttle shut. I've never had a real engine failure in a ship equipped with a C-20, but those who have had one tell me that the power goes away in a drastically different manner from those oh-so-easy autos we practice in Training. So I question the validity of the FAA's "wait one second" methodology in determining the limits of the H-V chart and the accuracy of the results produced, especially at MAUW.

Your thoughts, Shawn?

[Shawn Coyle]

It's also necessary to understand that the FM is not intended as a 'how to fly' book, nor will it contain everything you need to know to fly the machine. Lots of stuff that would be useful is not in the 'approved' section, as it doesn't need to be to be certified. Range and Endurance information, if it appears, is in the 'manufacturer's data' section and is not subject to any scrutiny by the FAA or any other certification authority.
Getting more info in the HV section is, sadly, wishful thinking. The FAA isn't going to demand it of a helicopter that was certified more than 40 years ago, and Bell isn't going to provide it for (pick any one of the following)
liability reasons,;
cost of obtaining the data reasons;
usefulness to operators reasons;
and so on.
As for the 'real' engine failure being different than the deceleration of the engine with a throttle chop - during the certification program, the airframe manufacturer would have to show the FAA that the engine deceleration was similar enough to a real engine failure as to be representative- if not, they would have to demonstrate at least one HV point with a 'real' engine failure to show similarity. (Pretty gutsy point to do). But it would be done.
We had to use the training mode switch on the 427 to simulate engine failures, having proved that it was identical to the real engine failure, and that throttle chops were nowhere near the same as the real thing.
So it does happen.

[Rich Lee]

These discussions tend to always focus on the theoritical rather than the practical.

The HV curve is valid for both the take-off and landing/descent profiles. It is very, very conservative during descent and landing, but the curve remains valid nonetheless. The "recommended take-off profile" corridor works forwards or backwards, climbing or descending. take-off or landing.

The bottom line, real world result of an engine failure within the low speed avoid area of the HV curve during an approach to landing where the collective pitch angle is considerably less than that on a maximum power take-off is that the pilot will have a greater chance of landing without damage or injury.

Does any helicopter pilot really need a manufacturer to tell them that?

[[email protected]]

Rich - it would appear that PF#1 does need everything to be written down and stated unequivocally - he was the one who called himself a 'dumb pilot' after all.
PF#1 -if the only acceptable 'facts' are those quoted in your RFM then it must be one hell of a big book - I presume you have been quoting from your RFM in your many long winded posts on this forum where you have stated many 'facts' - which in fact turned out to be simply your opinion.

[Flingwing207]

250' AGL, 40kt and 80% power in a climb is way different than 250' AGL, 40kt and 40% power in a descent. In the first case, the RRPM will drop much more, and it will take longer for the autorotative airflow to develop. Given the choice, I'd much rather be inside the curve in a low-power descent than a little outside the curve in a high-power climb.

In fact, it would be very difficult to make normal approaches and stay out of the H/V curve. IMHO, the only time you truely enter the curve in approach is on a steep approach, where you are operating at a relatively high power setting while still pretty far from the ground.

[Devil 49]

From the peanut gallery-

My experience is that the dead man’s curve, a/k/a “H/V chart”, is most useful as advisory. Think “VFR flight not recommended” in your WX briefs for a comparison. Adherence is not required, but if you’re officially interviewed, you’d better have bullet-proof reasons for failing to heed.
There are plenty of sound reasons why a pilot might operate in the shaded area: Confined areas, or almost any unimproved landing surface; Elevated pads; Tail rotor strike hazards proximal to the point of intended landing; External loads; Etc. These situations would be much more dangerous if not impossible were the H/V chart regulatory. It's information to guide your decision.
At least it's a known point to refer to- it's a new aircraft with a highly skilled pilot extrapolating. I know I'm, sub-par some days, I'm not operating over a smooth hard surface, and that pile of parts on the pad isn't perfect...

P.S. Real world power failures can be gradual losses, or sudden and complete. The aircraft comes down like a brick without engne idle thrust, especially as you cushion and land. Be somewhere with options.

[the coyote]

If the H/V curve was an operational limitation, then surely it would be in the "Limitations" Section of the Flight Manual?

I simply use it as a guide for any height/airspeed combo to be able to say to myself "At this combo I should be able to land OK if the power fails, but at this combo I might hit hard" and of course stay out of it if possible.

Back to the original thread, I can dig the left crosswind thing for giving you a bit more power at the bottom, albeit with a bit more yaw instability.

But if your shooting an approach with a left crosswind, presumably its to clear obstacles, and I'm not sure if I agree with the benefit of having the nose yaw further left into wind should the power fail in that situation. Wouldn't you then be totally crossed up to your original approach path with nowhere to go, if it happened on short final? I can't really see the benefit of that, personally I'd rather still be vaguely pointing at the orginal landing area I'm committed to, rather than sideways, if I'm going down. Just a thought.

[Auto Relight]

Thanks for all the responses. Good pespectives.

The original question was in reference to pads, ridges, or toe-ins on steep terrain and usually at altitude. Of course into wind is the best option, but often an up-valley wind in the afternoon will set up a situation where you have to accept a stiff x-wind on the last phase of the approch. Again, you want to minimize that time as you are then fairly commited, but avoiding it altogether is not often possible.

The H/V debate was an interesting one as well. I think if you spend most of your time hovering on the (100ft.) line, it's an arguement that really doesn't matter much, does it?

AR

[1aviator1]

hello guys
lets talk about anti-clockwise rotorcrafts,,,,
if we are in a hover flight and an adverse wind condition, and the wind is from the left side of the helicopter which could cause tail rotor vortex ring state, and if the wind is from the right side of the heli, will reduce power of the aircraft, and may lead to a full left pedal.
so what do you think is better, if we don't have the choise to be head wind, to put the wind left or right????

[Jet Ranger]

If we talk about "left-turn" rotors (for example Bell etc...), always choose left wind. Bell flight manual tell you to avoid operations from some right-rear angle ...

But, when you are in "hot & High" conditions, low speed, and high TOW, be carefull when you have wind from 11 o´clock, possibility of LTE (loss of tail rotor efficiency)...you can recognize that situation during the flight, for example in Bell 206, when you start with speed reducing, you can feel, lack of left pedal is coming ...

[Rotorwashed]

In the R22 I would rather have a right crosswind, being that the vertical stabilizer is so small, and tail rotor authority is high.

The JetRanger however, has a a giant vertical stabilizer which eats up a ton of torque in a right crosswind situation, in addition to low tail rotor authority to begin with, so I would rather have a left crosswind.

just my 2 cents

[hillberg]

I have seen lots of talk on left or right turning rotors on helicopters-Forget all that,Fly heading and don't get lazy on the foot peddles, Know the querks of each machine. Even the same manufacture and type can feel different. Be more than a stick wiggler. Be safe.

[1aviator1]

thx guys
your comments are so meaningful :)
but in most aerodynamics books like "principles of helicopter flight", the most dangerous areas are from 330 deg to 210 deg from the nose and can lead to tail rotor vortex ring state which is similar to the main rotor vortex ring state, and in other way a full loss of tail rotor effectiveness. And this discussion regardless of the vertical fin.
In several mountains flights, we can't terminate our approach head wind, we have to put the wind a little bit to the right or left.

[1aviator1]

Loss of Tail Rotor Effectiveness (http://www.dynamicflight.com/aerodynamics/loss_tail_eff/)
this link may give a sufficient explenation about tail rotor vortex ring state

[1aviator1]

http://www.pprune.org/newreply.php?do=newreply&noquote=1&p=6815974

this link may help in "tail rotor vortex ring state" explanation

[hillberg]

Forgot the title on youtube, It shows main rotor vortex interaction with tail rotor on the oh 58 , Neat stuff just can't find it.

[Evil Twin]

Here ya go Main Rotor tip vortices - YouTube

[[email protected]]

Don't call it tail rotor VRS because it most certainly isn't - we used to show this on the Wessex to highlight a wind from the 10 o'clock would cause yaw deviations and could lead to overtorque, especially at high AUM. On Bells like the 206 it just leads to LTE.

To get VRS on a rotor it has to be moving into its own downwash at a minimum of half the speed of that downwash - normal yaw manoeuvres and crosswinds don't even come close to that speed.

[1aviator1]

Evil Twin - thx for sharing us this interresting video :)

crab - the tial rotor vortex ring state, is similar to the main rotor vortex ring state; if we have a left cross wind (anti-clockwise), the induced flow of the tail rotor is encountered by the left cross wind which reduces the induced flow and increases the angle of attack to reach the critical angle and the blade looses its efficiency; it's similar to the main rotor vortex ring state(settling with power). But this is not our objective of discussion, this is a fact, but between the two evils: the left cross wind(resulting T/R VRS) and the right cross wind(resulting reduction of power) which evil do you choose?

Your thoughts guys ? :D

[Jet Ranger]

Avoid right wind (if you, for ex. fly 206), fly into the wind and dont think to much. Just fly.

Don˙t be so impressed with LTE and left wind. But it is good to know about that, and be aware of that when you are on MTOW and "hot&high" (off course, in Jet Ranger)

[GeorgeMandes]

All things considered, in a Bell, I would take the left crosswind because the ships hangs left skid low, and it will be easier to land with the left crosswind, Also, as I approach and crab left into the wind, I have better visibility of my LZ sitting in the right seat.

Having done Private, Commercial and ATP ratings and check rides at the Bell School, and many recurrent courses, Bell ground school and flight instructors state that the HV curve does not apply to descent/landing.

[[email protected]]

1aviator1 - thankyou, I am well aware what VRS is and how it is caused - I was trying to explain that a crosswind or a yaw manoeuvre is very unlikely to produce sufficient airflow to cause VRS in a TR.

The thread is concerned with which crosswind to accept and that is straightforward, you take a crosswind from the retreating side of the disc (from the left on an anti-clockwise rotor) if you are short on power because you use right (non-power) pedal to stop the aircraft weather-vaning into wind.

If you have control authority problems - running out of pedal or lateral cyclic (poor design or a large tail fin) then don't try to hover crosswind.

Winds from the 10 o'clock or 2 o'clock (depending on the direction of rotation of your rotor) can cause the MR tip vortices to disrupt the flow into the TR/fenestron giving yaw and Tq fluctuations.

Winds from the aft quadrants on either side will try to weathercock (weather vane) you into wind - (the helicopter fuselage is designed to fly forwards) - and so will always cause problems with heading control.

[1aviator1]

GeorgeMandes- thx for sharing us ur thoughts it's verry interesting :)

Jet Ranger-fly into the wind and dont think to much. Just fly in some cases especially in mountains flights, we can't terminate our approaches into the wind
during flight, we don't have to think to much-it's true- cz we don't have enough time to think, but if we want to return to our bases or helipads or whatever..safe, we have to think before every flight, and think a lot ;)

crab- I appreciate that you are a good pilot :) maybe I didn't understand ur thought well :) now it's pretty clear
the only benefit of right cross wind is to provide more power when we operate in high gross weight, but the danger of left cross wind always exists especially in high density alt and high temp.
If we all agree with this consept, if we are operating in high alt/temp it's better to avoid T/R VRS and keep the wind to the right, and if we have high TOGW we have to take the risk of T/R VRS but to enforce the power with left cross wind? can we consider it true?

[Jet Ranger]

If we all agree with this consept, if we are operating in high alt/temp it's better to avoid T/R VRS and keep the wind to the right, and if we have high TOGW we have to take the risk of T/R VRS but to enforce the power with left cross wind? can we consider it true?




No.

I can´t agree with that statement. If you fly for example Bell 206, if you choose wrong wind :ugh:(right wind, from 60-220 degrees relative), in that high alt conditions, you can stay without power (TQ) and may crash! (not enough left pedal). Flight Manual, Performance section, tells you - avoid hover operations from that relative wind operations :=! That is no.1!

Left wind is very OK. Gives you low-left pedal and good TQ. LTE is something new, 20 years ago nowbody knew nothing about that-and fly. It is good to know about that ! But, thats no.2 problem.

Only my opinion. JR

[FH1100 Pilot]

A left crosswind in a 206 will be something of a compromise between LTE and weathervaning tendency. If the wind is strong enough to push the MR vortices into the tail rotor (as in in the video of the OH-58 model) then there will be enough weathervaning tendency that LTE won't be a worry. Weathervaning tendency in a 206 is strong.

But remember that wind is hardly ever constant like in a wind tunnel. In real life, the flow through the rotor systems (main and tail) is fairly chaotic. The instances of LTE will only be transitory. The tail rotor will not summarily "stall" and stop working altogether, allowing the fuselage to spin like a top. Yes, your feet will be "busier" with a wind from the left-front but you'll have more pedal available (than with a right crosswind) should a yaw rate start to develop. I will always take a left crosswind in a 206. Landing with the wind from the right is just asking for trouble, especially at higher MGW's.

[Jet Ranger]

The instances of LTE will only be transitory

@FH
You explained that on excellant way:D.

[1aviator1]

Jet Ranger - thanks for the clarification of this concept, maybe i missed some points about this object. but now it's clear.

FH1100 Pilot - your explanation is very good and your informations are so interresting. thanks for sharing us your thoughts :D

guys now i have a clear opinion about this object, and if i get new informations about this object I ll post it to discuss it.

cheers!!

[deeper]

for the thirty years i have been flying helicopters i don't think i ever cared about or spoke about lte, (loss of technical expertise), vortex ring state, engine failures, had two, from the open grass plains of the australian out back to the jungles of png the americas.

you fly the machine within its parameters, sometimes out, and it shouldn't bite you. it is 99% pilot error if you come to grief.

some people are just anal about written stuff and fly a lot but don't learn from the experience. you read posts from lee, lappos, coyle, sasless and crab who for the very most part over the years have given great advice on these threads. and you argue the facts. they are pure and simple and haven't changed from the beginning. (some one will argue that statement).

it is very amusing and much more disappointing to see so much fear and ignorance generated by some posters.

this bad vibe on helicopter operations transfers to the up and coming pilots and because they think it is written by someone who knows it goes on to be fact whether it is or not.

i think that if you are out there and doing it as a pilot for any length of time and you don't know how to safely take of, cruise, work, return and land in diverse situations you should think about what you know about the machine you are in or even if you should be in this line of work.

some of these threads show a lack of knowledge and confidence in the machinery and the environment we are in.

i am aquainted with many pilots from all parts of the helicopter world and have flown with some of the posters on these threads, to a man they understand the conditions they are flying in and the machines capabilities and fly each one accordingly. they don't call up and ask if it's ok for a left or right wind, what's the world coming to.

i bet some of you think you have to back into the height velocity curve to land.:E

one new pilot i worked with in the bush a few years back asked the question, "are you getting any lte over there, i'm getting a bit over here".

that's what the helicopter world is coming to.

[nellycopter]

I suppose like the unfortunate chap that crashed the 350' today,
Lte is also experienced when the tail falls off completely
What a lucky bloke...... To walk away, even luckier the bloke under him......
Nelly

[AnFI]

deeper:D:

you say LTE = "loss of technical expertise" - ie How to fly in general...(?)

but in this case we are talking about..

LTE = Lack of Tailrotor Education - ie How to fly as far as the Tailrotor goes.

very easy to confuse the two LTE's - although they are related



not exactly the same as:

LTE - Lack of Tailrotor Effect - underpowered Tailrotors which were apparently produced in the stone age.... don't try and use more tailrotor thrust than you have....(?) (More prevalent in twins ?? )

nor

LTE - Loss of Tailrotor Effectivness - Pilot didn't know which way he was flying through the air and took a while to figure it out - and do something appropriate(?) Often happens to pilots when learning.


who cares if you can actually fly a helicopter when you obviously haven't studied the terminology properly.... ?

[Shawn Coyle]

Anyone have any experience with the new STC'd replacement tail rotor blades?
Especially vis-a-vis LTE???

[Gomer Pylot]

Never had LTE, but the new Van Horn tail rotor blades do give more authority. Some pilots don't like them at first because they make the machine feel more 'twitchy', because it takes less pedal input to get an effect, so you have to relearn your footwork if the 206 is all you've flown. They're more than worth the money, though, IMO, because they give you a longer TBO, and they work much better.

Saying the 206 weathervanes strongly is an understatement. Once on an offshore platform I had to do a 30-minute penalty run after a chip light, 'with some collective'. There was a 15-20 knot wind, and bored, I started experimenting with more collective. Eventually, I found that I could go from flat pitch to an OGE hover and back, repeatedly, with my feet flat on the floor. Put the nose into the wind, and it will try to stay there. With a crosswind, it tries mightily to turn into it. I agree that flying an approach sideways, with the nose into the wind, is a good way to get the job done. It takes much less power, and there is no chance of LTE. I know of no requirement to have the nose pointed directly at the point of intended landing.