Actually, get ready for a succession of maintenance nightmares in which you
seek help from your TC holder (not Bell), try to operate with surplus parts
that have questionable or no histories, and operate an aircraft with
marginal performance anywhere close to max gross. I flew this model for
years, and it's OK with one observer and no baggage, except on hot/high
"LTE", on the other hand, is a misnomer. It should be called "LPE", for
"Loss of Pilot Effectiveness". It afflicts all single main rotor
helicopters, and results from a failure on the part of the pilot to maintain
smooth, coordinated flight with due regard for the limitations of the
aircraft. LTE is very difficult to demonstrate, because it is caused by
flying in ways that no conscious, thinking pilot would ever fly.
I have to disagree -- at least as far as a Bell 206 is concerned (esp. with
the small tail rotor)
All you have to do is have a brisk tailwind, hover slow, and turn right --
As the tail 'whups ' around when the tailwind catches it you will be in LTE
without loss of
Best be thinking at that point -- I know I was -- some of it unprintable.
I takeoff everyday at max gross weight in a Bell 206 and I have to tell you
it is the best little aircraft I have ever flown with a crosswind or
tailwind component while at a hover. I too believe the biggest problem with
LTE is poor control touch. Someone correct me if I am wrong but if I
remember correctly Bell does not even mention LTE in its operators manual.
It seems to be more of an Army issue.
> Someone correct me if I am wrong but if I
> remember correctly Bell does not even mention LTE in its operators > > manual.
> It seems to be more of an Army issue.
I don't think you are wrong, but Bell Hurst has/had a video
on LTE that all students could view during their breaks in
training. It was put out by the Army, I think.
I can't grab my manual right away, but LTE was discussed
during my initial and re-current training.
Bell does mention LTE in the manual and it is an important compoente when
checking out in a 206, at least where i learned.
But did they ever place it in an operators manual? I know our Bell manuals
do not mention it but the Army's rewritten version does.
34 knots gusting 43? Been there, done that.
If you're buyin', I'm flyin... Wait- That doesn't sound right.
Have to use your bird, I'm not crazy enough to own a helo.
But... The Bell 206 is especially vulnerable in one regard. LTE can also occur
in the following scenario: high power demand with the wind from the right rear.
The vertical fin on the 206 blanks off a LOT of tail rotor area both above and
below the tailboom, and acts as a pretty decent weathervane to catch the wind.
I got into LTE at a high (2,000 feet) hover one day in a 206L (I forget whether
it was a "straight"-L or an L-1). When the thing snapped to the right I
thought I'd lost the tail rotor. I kept the left pedal in, but don't recall
going to FULL travel on it, which is recommended. I sat there, frozen, for
maybe half a turn. Then I woke up, followed it around with cyclic, lowered the
pitch and flew out of it with maybe a hundred foot loss or so. Very scary.
Potentially ugly if I'd have been at only 100 feet over the trees. After that
I was MUCH more aware of hover work (high power) with the wind off the right
Live and learn. Learn and live.
"The dignity of the craft is that it creates a fellowship."
Antoine de St. Exupery
The size and thrust of the tail rotor are the key determinate of
the aircraft's propensity for LTE. LTE is not a pervasive single
rotor helicopter problem, in fact, virtually all LTE occurrences
involve only two types of helicopter, both Bell.
The term LTE describes the right yaw, but it is not a condition
where the tail rotor gives up the ghost. Most occurrences
involve pulling some power at the bottom of an approach, where
the extra power absorbs the small amount of anti-torque
available, and the main rotor torque takes the aircraft for a
Cross winds can cause main rotor wash to enter the tail rotor and
cause a loss of thrust of maybe 5% or so, enough that a marginal
aircraft is kicked out of control. The key is to have enough
extra tail rotor thrust to absorb this small loss, and also
enough to allow some vertical maneuvering.
In smooth hands, LTE can be avoided, as long as the flight does
not involve OGE maneuvering where the torque is high and the tail
rotor is really pushed to its limits.
There was an FAA push to include LTE words in all single rotor
helicopter flight manuals, but it was beaten down by all of those
manufacturers who make helicopters with good tail rotor thrust
margins. I assume the one manufacturer who experiences virtually
all the LTE occurrences chose not to go it alone and create a
I know of no H-60 or S-76 LTE events, not surprising when you
consider their ability to sustain flight in 35 to 50 knot cross
winds. This is also true of Apache and OH-58D. OH-58A/C, Bell
206 and Cobras are notorious for LTE, and the original OH-58D was
rejected by the Army until the tail rotor was redesigned to
eliminate LTE that occurred during bob-down maneuvers.
* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
The fastest and easiest way to search and participate in Usenet - Free!
You are looking at the Army manual. The civil B-206 manual keeps oddly quiet
about all this.
Not sure about the size of the tailrotor, but he said it would be new. What
should it be.
The comment on size and thrust of the tail rotor is more for the designer and
the budding aerospace engineers among us. As far as I know, there is no
optional bigger tail rotor on the members of the 206 family.
All this about LTE being said, lots of 206 pilots fly lots of missions without
tripping over LTE. While other helos have better histories in this matter, if
flown prudently, any certified helicopter should serve you well. (Bell is
mailing me an attaboy right now, I'm sure!)
During flight testing last summer, with winds of 2-3 knots, we absolutely
could not get 17 knot rearward flight. Not after numerous tries, with a
d*&^ good test pilot, using a pace vehicle.
We checked the rigging on the swashplate and it was rigged IAW the Bell
manual. It was biased 2 degrees forward when the rigging pin was installed
to locate the center of travel of the cylic.
The data from some of the original FAA testing said the swashplate was to be
0 degrees at center cyclic. We checked with Bell and they can't say for
sure whether or not it is supposed to have 2 degree forward tilt, only "rig
according to the manual". We checked a few other 206s and they all had the
I cannot understand why we couldn't get to 17 knot rearward flight which is
the minimum according to the FAA.
Does anyone have any data to confirm our results? If your're curious, stick
a 5/16 bolt in the centering hole for the cyclic and put a protractor
(digital preferred) on the swashplate and measure the tilt relative to the
Maybe someone like Bob Barbanes can try running down the runway backward on
a no wind day and let me know how it goes. Be sure you have enough
elevation to fly out when it whips around.
I agree with Nick. LTE is more correctly called "wimpy tail rotor" The
ratio of tail rotor horsepower to main rotor horsepower has changed as
designers became aware of the need for more tail rotor authority. The 206
was designed in the 60s. BTW, the 427 seems to have plenty of tail rotor
power. Good rearward flight speed while the tail rotor is loudly growling.
Nick: I appreciate the care you have taken with your words about LTE. I
disagree with your statement that the size and thrust of the tail rotor are
the key determinant. Your own description of the circumstances most likely
to generate "LTE" shows that the skill and attentiveness of the pilot is the
The key factors in creating the circumstances that lead to "Loss of Pilot
Effectiveness" in the form of LTE are mission-related. Adjust the numbers
actuarily for the predominant presence of certain Bell models in the
high-risk missions, and for the experience level of the pilots, and most of
the disparity goes away. I have seen video footage of "LTE" in a Dauphin,
for instance, which is not generally associated with this phenomenon.
I don't know exactly when Bell changed the tailrotor on the 206 but the
earlier models have a smaller rotor. Mine is S/N 327 and has the smaller
IF you are careful about flight regimen then the smaller rotor is nice
because it uses less power.
Also the 206A model frame is lighter than the subsequent B model by 200 Lbs.
Therefore the helo's like mine which are a A/B or else simply a B conversion
have more lifting capability.
The early models also have hydraulic boosted foot pedals which I like but I
have heard some criticise. The boosted pedals are not a A or B model feature
but for some reason were eliminated somewhere in the series at S/N 600's or
I THINK the heavier frame was military related to allow more 'attachments'
(weapons, etc) but I am not sure.
Anyway, I like my light frame , small tail rotor 206 just fine.
I can promise you need to respect LTE in the West Texas winds (been there --
I have found it to be predictable and recoverable as long as one is not
daydreaming and you remember (always ) which direction the wind is coming
from so you can use the breeze to bring the tail under control (pull cyclic
into the wind).
Can also state R22's will behave very close to the same but are a little
less likely to LTE and quicker to recover. (Quicker to do almost anything!).
I can't remember which magazine I read it in but Bell equipped Harrison
Ford's Longranger (that he rolled in the riverbed) with a beefier tailrotor
because he planned to use it on a ranch at a fairly high altitude.
Don't know if the blades were longer, bigger or what.
There may have been other mods for altitude performance.
Don't count on being able to pick up four cheeseheads with a full bag. Even
if you can pick up, controllability at HIGE will be dodgy, and HOGE will
probably be impossible, even on a cool day. Price? I'm not an expert, but
$50,000 would be the upper limit, unless you're a collector of rare and
valuable sports cars, baseball cards, etc.
However at S/N 4005 and sub on the 206BIII Bell has added a larger diameter
T/R driveshaft which accomodates the long blades and allows them to be
rigged to a higher left pedal angle. This should give better left pedal
control. I will have to look at HIGE and HOGE charts to see if this is
reflected in the charts.
Seay wrote in message ...
What you say about the pilot's ability to screw up is correct, but only as far
as how marginal the helicopter he is flying is. My point is that if the tail
rotor is too weak, LTE is more probable. This is a fact, and if we simply
blame the pilot for LTE, we ignore the fact that LTE only occurs in a few
In short, everybody else who makes helicopters must be doing something right.
If we let them just blame the pilot, we don't improve the situation. LTE is
caused by marginal helicopters. This poor margin of safety burdens the pilot
with being extra careful, and the small percentage of times that someone is
not perfectly careful, he gets burned (literally).
The mission is to blame, too. NOE tactics brought out LTE for the poor helos
because of the OGE maneuvering needs of the new mission. The Army increased
the tail rotor requirements (mostly by demanding more sideward flight
capability) for newer helos (UH-60, AH-64, OH-58D, Comanche) and as a
result, they can't get LTE.
The mission makes the poor helo drop out of the game. It starts with a poor
I do not believe you can get into an LTE situation in the 520N or the 902N
NOTARs. Both these helicopters can be lifted off and fly a pattern with the
pedals fixed in neutral position. as collective is increased so is the fan
The NOTAR can have the air flow around the boom separate in a right turn with a
LARGE slip. When the air flow separates ease off the right pedal and the air
flow reattaches. You will only get this flow separation at slow speeds and a
very LARGE slip.
Thanks for the info! Your observation proves my point about the "weakness" of
the tail rotor. Let me explain.
If the OGE and IGE performance charts change when you change the tail rotor,
it illustrates that the tail rotor was the reason for the altitude limit.
For virtually all helicopters, the max gross weight to hover is set by the
engine power or the transmission torque limit. The tail rotor is not the weak
link. We test the sideward flight capability at altitude to confirm that the
tail rotor is still adequate at the higher power (higher power is higher
torque which requires more anti-torque).
For the 206 family, (and also for the "cat B 9 passengers or less"
certification that the 212 412 and 430 have), the tail rotor cannot provide
enough anti torque to allow the higher weights at altitude, so the IGE and OGE
weight allowable curves reflect the place where the tail rotor gives up the
ghost. More weight at altitude can only be carried if the tail rotor is
Bell has an option for the 206L4 that does just that: increases max
available tail rotor blade pitch angle as the density altitiude increases.
Global Helicopter Technology has a similar product for the UH-1H called the
Density Altitude Compensator. E-mail gh...@airmail.net for more info.
I am sorry, did I say the fan speed increases? The fan blasdes are variable
Any idea why (engineering or otherwise) the military required longer blades are
a lower RPM for the OH-58 as compared to the 206BIII?
So, I think the correct question is "why does the OH-58A have longer blades
than the H-4/206".
Bill "so I'm a nitpicker" Walker
The fans ARE variable pitch Scott, but I'm not sure if they're fixed
speed or not.
Sorry, wrong on both counts, the collective pitch on a 520N or 600N (not
familiar with Explorer - Rare species) for that matter is not connected to
the anti-torque controls. The fan speed also does not vary in relation to
the Nr. As for flow separation in a large RH slipping turn I would like to
see the facts and or how it was proven, there are other factors involved and
this sounds like a believable explanation. i.e. BS.
The anti torque thrust is proportional to the flow generated by the main
rotor which is induced by the coanda effect generated from the tailboom
slots which are fed by the fan. Hence the "pedals on the floor" trick.
One undesirable trait which should be demonstrated to all Notar pilots is
the onset of "anti torque" as pitch is pulled prior to touchdown in auto
rotation. Something that you don't really need. Ponder the possible
IMHO the hook was already taken with the "Fenestron" and this was all that
was left to establish any individual indentity for these aircraft. The
supposed merits hardly justify the time and effort spent.
P.S. What is really "wrong" with a tail rotor?