LTE (Loss of T/R effect or similar)

[Cadfael]

Has anyone ever experienced a similar feeling/actual LTE in any other helicopter other than a 206?

If so, what type of helicopter and during what circumstances?

[Randy_g]

I was in a 500, on my first job. We were lifting some camp gear on a short lanyard. The alt. was about 4,800 and the temp was around 25. The wind was variable and approx 5 kts. I went to lift the load, as I reached the power limits, the wind changed direction and around I went. Luckily it was a nice big meadow we were operating from, so I had lots of room to maneuver. I set the load down, and as I lowered the power, the aircraft stopped spinning. Oh and my heart rate started to slow as well. :)

I'm sure glad I had made a pitstop before I went flying, otherwise I might have had some laundry to do. :) (If you know what I mean. :) ) I got caught out trying to lift something that was too heavy for the conditions, and was lucky the only thing damaged was my pride. I now would prefer to use a longer line as well, but I didn't have one at the time.

Cheers and the season's best to all !!! :)

Randy_G



[This message has been edited by Randy_g (edited 21 December 2000).]

[SPS]

I can't speak from a great deal of experience (only did about 20 hrs in one a while back) but I pretty sure if you can get to speak to someone who flies one of the 1970's Enstrom 280 shark models he would be able to bore you witless about loss of TR
Authority/effectiveness. With me loss of TRE/A didn't arise as I found I had to keep the thing into wind all the time to maintain hover height. Teaching Bloggs to fly backward in it was hilarious - Climb to 12ft hover, then forget backwards and descend again as RPM decay whilst at power limit at + 10 degrees with 2 people in 3 seater with 1 hour fuel ( !) More power in an ERIC! (But it has got a better rotor head, just can't turn it as efficiently!)

So there we are, another small heli to berate for a while, give the ERIC a rest for Xmas!

Also the early H269 A model was prone, I did a few hours in one but nothing to report
(I'm a stickler for staying into wind!)

BFN SPS

[fishboy]

The early Hughes 269. Definitely. the TR blades are a lot smaller (diameter) than the newer 300, and also have less surface area. If you don't keep the RRPM as high as possible you will run out of authority real quick.
I have experienced LTE in a 300. Around 400 feet taking photo's in a very slow downwind condition. Around it went. Fortunately the FAA were making a big deal about it at the time; I had recently been instructing lots of students in recognition and recovery. No problem. Push forward get airspeed, and continue flying. Probably not so nice with an external load!
Everyone who flies helicopters has experienced LTE of some sort, If you read about the subject you'll know whatI mean.

[whatsarunway]

robinson r44 . happens when the vertical fin comes between the wind and the tail rotor i think same on the as350 , only in strong winds though.

have fenestron now .


mmmmmmmmmmmmmm............ french helicopters

[SPS]

I have experienced it in an R22 (a long while back!)and I was totally to blame.

Right pedal turning when in a hover is not a good idea with 25kt of wind. TR begins to develop Vortex, losing thrust but the weathercocking of the vertical stabiliser does you a favour by turning you back into wind. That's just fine as long as the goon on the pedals remembers to remove the right pedal input...

If not, the TR regains its lost thrust, turning the tail crosswind again. A nasty oscillation is set up.

And guess what? You may be within limits with
wind on the nose, only to exceed xwind limits (R22 17kt)when making a pedal turn.

The R22 is not susceptible to LTE/A as long as the limits are observed.

[whatsarunway]

I think if you look at the r22 hand book the DEMONSTRATED crosswind / sidewards flight is 17 knots , its not in the limitations section and therefore isnt one .
I could be wrong though.

[212man]

Sounds about right; FAR 29 requires demonstration of a 17 kt crosswind hover, so I imagine FAR 27 is the same (don't have it on this computer). Interestingly, the 212 FM states that hovering in up to 20 kts has been demonstrated, but again it is not a limitation.

In general, if you suspect you may encounter TR problems in a spot turn, it is better to turn left (non French a/c), that way if you reach max power you can off load with right pedal and rethink your actions. If you start to lose it turning right and reach max power, you may exceed a limit trying to return to the left.

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Another day in paradise

[SPS]

212 -

ABSOL-UTELY! That advice is the mainstay of my teaching of spots. I made a big thing about it in the book. Far safer than right for so many reasons, notably that you are trying (in a 360) to stop the turn in conditions of increasing rate of turn and minimum TR effectiveness in the last 90 degress. (Im am sure you both know this but it is good for observers to read.)

Whatsa - No, I think you are right, well spotted. I haven't got a copy at home. I am sure it is demonstrated. Mind you, I am also sure I have been making it a sdt. limit.

As the exams (written) are not type specific it hurts no-one but I'll be more careful to say 'Demo" over 'limit'.

Have a goodie.....!

[sarboy]

Felt the tail go squishy in a Sea King once. High hover - winching - strong cross-wind. I suppose so long as you've got two rotors and they point in different directions, such things may occur. The US Coast Guard flies Dolphins (Dauphins) with such puny engines that they can barely hover a lot of the time anyway (let alone cross-wind). Nonetheless, there is talk of them investigating a 'new' fenestron with stators in addition to the ducted fan to improve authority (although Aerospecial tells them that there is no fenestron stall anyway). Anyone flown a ducted fan + stator set-up?

[The Nr Fairy]

My understanding is that the certification requirements for the R22 need a minimum 17kt crosswind from both directions at both lateral CG limits. This was proven in testing, if I remember rightly from my safety course by sideways flight at up to 17kt with external weights to bring CG to lateral limits.

Once the certification requirements have been met, there's no economic incentive to prove further.

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I got bored with "WhoNeedsRunways"