#76 DON'T GET BIT by | LTE | Loss Of Tail Rotor Effectiveness | CWK

Don't get bit by LTE Day 67 Coffee with Kenny and we're dedicating this cup today to dan Taz Christman, 2018 Flight Instructor of the Year. Since he loves Schweitzer so much, he now loves the instrument as well. So for you Taz, thanks for all you've done for us. And remember, Taz is co author with.

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Okay so from one of our members.

He said, hey Kenny, I have a topic for Coffee with Kenny video that I think might be helpful to other viewers besides myself. I understand what will cause selling with power, dynamic rollover and retreating blade stall.

And how to avoid them.

But truthfully, loss of tail rotor effectiveness.

Worries me a bit. I know certain wind conditions can cause it, but how do you know what the wind is doing all the time?

Can you do a video dedicated Loss of Tail Rotor Effectiveness Thanks. So thanks for that question. Let's first cover the technical textbook answer to what LTE is and what the winds are that can affect lte. Yeah, the nuts and bolts. We're going to roll that video and I'll be back. Just to kind of sum it up in more of a just everyday, simple.

Kind of term, Loss of Tower Effectiveness lte. What is it the Helicopter Flying Handbook tells us? Loss of Tow Rotor Effectiveness lte, or an unanticipated yaw, is defined as an uncommanded rapid yaw towards the advancing blade which does not subside of its own accord. It can result in the loss of the aircraft if left unchecked. It is very important for pilots to understand that LTE is caused by an aerodynamic interaction between the main rotor and tail rotor and not caused from a mechanical failure. Some helicopter types are more likely to encounter LTE due to the normal certification thrust produced by by having a tail rotor that, although meeting certification standards, is not always able to produce the additional thrust demanded by the pilot. So first let's cover the three winds that you have to be familiar with so that you don't get yourself in an LTE situation. First, we'll talk about main rotor disc interference. If you have a wind off the quartering left front degrees 285 to 315 degrees and winds at velocities of 10 to 30 knots from the left front cause the main rotor vortex to be blown into the tail rotor by the relative wind. This Main rotor disc vortex causes the tail rotor operate in an extremely turbulent environment. So try to visualize a great big huge donut of air around the outside of that rotor system. Turbulent air being recirculated and that wind coming on that angle is pushing all that dirty turbulent air into that tail rotor. The second is weathercock stability. Winds from 120 degrees to 240 in this region, the helicopter attempts to weather vane or weathercock its nose into the relative wind. Unless a resisting pedal input is made, the helicopter starts a slow uncommanded turn either to the right or left, depending upon the wind direction. If the pilot allows a right yaw to develop and the tail of the helicopter moves into this region, the yaw rate can accelerate rapidly. In order to avoid the onset of LTE in this downwind condition, it is imperative to maintain positive control of the yaw rate and devote full attention to flying the helicopter. The third one you need to be aware of is tail rotor vortex ring state. These are winds from 210 to 330 degrees. Winds within this region cause the tail rotor vortex ring state to develop. The result is a non uniform unsteady flow into the tail rotor. The vortex ring state causes tail rotor thrust variations which will result in yaw deviations. Rapid and continuous pedal movements are necessary to compensate for the rapid changes in tail rotor thrust when hovering in a left crosswind. Maintaining a precise heading in this region.

Is difficult, but this characteristic presents no.

Significant problem unless corrective action is delayed. However, high pedal workload, lack of concentration and over controlling can lead to LTE. So again, those three are main rotor disc interference 285 to 315, weathercock stability 120 to 240 degrees and tail rotor vortex ring state 210 to 330. So there are a number of contributing factors to this LTE that you need to be aware of. Number one low and slow flight outside of ground effect. Number two, winds from plus or minus 15 degrees of the 10 o' clock position and possibly around the 5 o' clock position. Number three, tailwinds that may alter the onset of translational lift and translational thrust that induce high power demands and demand more anti torque left pedal than the tail rotor can produce. Number four, low speed downwind turns. Number five, large changes of power at low airspeeds. Number six, low speed flight in the proximity of physical obstructions that may alter a smooth airflow to both the main rotor and tail rotor. You need to be aware of LTE at altitude and we know anytime we have high Gross weight, high SC altitude. That always is a contributing factor to anything bad that goes on in the helicopter. So of course, at higher density altitudes, higher altitudes, you're going to be more susceptible to lte. So there are some steps for reducing the onset of LTE. And these steps are. 1. Maintain maximum power on rotor RPM. Even if the main rotor RPM is allowed to decrease, the anatoric thrust available is decreased proportionally. Number two, avoid tailwinds below airspeeds of 30 knots. If loss of transition lift occurs, it results in an increased power demand and additional anti torque pressures. Avoid OGE operations and high power demand situations below airspeeds of 30 knots at low altitudes. Number four, be especially aware of wind direction and velocity when hovering in winds of about 8 to 12 knots. A loss of translational lift results in unexpected high power demand and an increased anti torque requirement. 5. Be alert to changing wind conditions which may be experienced when flying along ridge lines and around buildings. Be aware that if a considerable amount of left pedal is being maintained, a sufficient amount of left pedal may not be available to counteract an unanticipated right yaw. And number seven, execute slow turns to the right which would limit the effects of rotating inertia and the loading on the tail rotor to control yawing would be decreased. So the best thing to do is avoid these situations and not even get yourself into it. But let's say you did. For whatever reason you got yourself into a LTE situation, then you need to know the recovery technique. If a sudden unanticipated right yaw occurs, you need to apply forward cyclic control to increase speed. If altitude permits, reduce power as recovery is affected. Adjust controls for normal forward flight. A recovery path must always be planned, especially when terminating to an OGE hover and execute immediately if an uncommitted right yaw is evident. Collective pitch reduction aids in resting the yaw rate, but may cause an excessive rate of descent. Any large rapid increase in collective to prevent ground or obstacle contact may further increase the yaw rate and decrease rotor rp. The decision to reduce collective must be based on the pilot's assessment of the altitude available for recovery. If the rotation cannot be stopped and ground contact is imminent, an auto rotation may be the best course of action. Maintain full left pedal until the rotation stops. Then adjust to maintain heading.

Okay, so there's your textbook description of LTE and the winds. So our member asks, well, how do you know where the wind is at? You should always be keeping track of.

Where the wind is.

You're always looking using flags on the ground, smoke coming out of smokestacks, wind socks, waves across the lake or a pond, anything you can be looking out for. You really as a helicopter pilot need to do your best to always, always, always know where the wind is at. Down to earth basics what I think in lte it's about using good pilot technique, staying on top of the pedals at all times, avoiding the scenarios that we just talked about in the video. It's something you need to be thinking about. You know we harp on all the others. Sometimes I think maybe LTE we don't talk about it enough. So being knowledgeable, understanding what it is and knowing how to avoid it. And the one key term is 30. If you're above 30 knots, you're not going to get into it. So really be careful with slow flight, really be careful hovering in those scenarios in the winds that we talked about in the video, be very cautious and stay on top of the pedals. I think it's one of the really biggest thing is just using good pilot technique all the time. So I'm Kenny Keller, creator of Helicopter online ground school top 10 checkride tips. Get it below and remember we have a 24 hour test flight along with a 30 day money back, no hassle guarantee for helicopter online ground school. Birds on us to provide you the value. So we got lots of resources for all of you that are wanting to go through and smoke your checkride. Just like all these people on the Helicopter Online Ground School hall of fame. We're so proud of this. We're getting close to filling the wall up and moving to another wall. Started as an idea about a year ago, right Heather? About a year ago probably. So members keep sending them. We love getting your hearing about your checkride success. We love getting your pictures and you know it's been a while since somebody sent us a video. So pass your checkride, grab your smartphone and go out and do a quick 30 seconds. Just you don't even have to plug ground school. Just share your experience and your excitement the day of. Once you pass that checkride, grab your phone, go out there with your certificate, make us a short video and send it in and we can share it with everybody and we can just clip a picture out of your video for and we'll send you a T shirt. Absolutely. We'll tend 10, 10, 10. We will send you a T shirt for a video. Send us a video.

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