Twist Grip Throttles

[MightyGem]

To those who use them, which way do you turn them to increase power? The reason I ask is that in the EC 135, you roll the top of the grip away from you, and the first time that I did it on my conversion it seemed (to me) to be the "wrong" way.

[oldpinger]

By the wrong way, yep, they're opposite to motorbikes but all the french beasties are in that direction(I think) Kiowas the same. Don't know about older piston aircaft.

Where can I get a cheap(Free:D) ride in a 135??? saw a EC120 close up once, just got to wait for the big lotery win.......

[rotorcraig]

On the R22 it's the same, ie: twist away from you to increase power. Not being a biker, it didn't make any odds to me.

[John Eacott]

MG,

All (that I can think of) twist grip throttles roll "away" from the pilot, which would normally be an easier action of the wrist, allowing the outside of your hand to move down as the collective comes up, and vice versa. Bell 212, 206, 205, Hughes 500, Hiller 12E, R22 all spring to mind as operating that way.

[212man]

I think that sense of direction is the industry standard, except for Russian (Polish too I assume) machines.

On the EC-155 there are no throttles, either twist grip or Speed Selects, at all. Just 2 switches marked 'OFF', 'IDLE' and 'FLIGHT'. Takes some getting used to but makes life simpler in the end.

[MightyGem]

Thanks for that. It just seemed the "wrong" way. Obviously not.
212, the twistgrips on the 135 are to control the engines when the fadec fails(it also has Idle and Flight switches). How do you do that on the 155?

[212man]

MG,
fail? how do you mean? It's French...

They have not given us a means of controlling the engines should both channels of the FADEC fail; the metering valve will freeze in the last position. You then maintain the status quo until landing when you then shut down the engine with the FADEC problem.

Originally the idea was to have beeper controls for the metering valve motor, but it was found to be too difficult to control and was binned. In the near future a modification will be added that allows the 'good' FADEC to take control of both engines should one freeze.

[flygunz]

MG
All the Ac with twistgrips I've flown operate the same way i.e roll left to increase. I think the industry standard statement is valid and some dude in the 50s probably thought clockwise to increase anti(counter)clockwise to reduce was a safe format. Can you imagine the number of incidents there would be as we got things mixed up in a high workload situations on different Ac!
Isn't it true that most 'Bikers' have limp wrists anyway?

Drop me a line.;)

[Arm out the window]

Yep, away to increase power, you soon get used to it.

Early on in my Iroquois conversion I developed the habit of regularly giving the throttle a tweak away to confirm that it was fully open (obviously not a great idea unless you've got a governor!) - this was probably in response to the evil QFIs who would sneakily wind it off; b@stards!
I reckon it's a good idea to fly with your wrist slightly cocked towards you, if you know what I mean, which provides a natural 'throttle-opening' force to avoid inadvertantly winding it off a bit.

I had one student do that very thing as we were coming out of a pad in the training area, causing the low RPM audio and light to come on, wasting a few of my heartbeats as we were over the trees. Luckily the automatic response of tweaking the throttle on soon fixed the problem.

:)

[idle stop]

Basic anthropometrics. Just try doing a clockwise throttle rotation as you raise the lever and anticlock as you lower it. Pretty uncomfortable!

[Thomas coupling]

W.R.T. the 155: if you had a fadec freeze during a climb, how do you control Nr while trying to descend to land, after the remaining serviceable fadec rolls off as much power as possible before it bottoms?
In the 135 world we have had a couple of Nr ups and downs that have only been controlled by manual intervention...

[t'aint natural]

As a biker, I never got crossed up. Different machine, different arm. Barry Sheene had no bother either.
Flygunz: Neither wrist is limp, big boy.

[Capn Notarious]

So then Barry Sheene flies a helicopter?

[t'aint natural]

Barry Sheene is a hopeless rotorhead. Started off flying an Enstrom 20 years ago. Reckons the highlight of his life, Steph apart, was getting to pole the King of Spain's Puma.

[advancing_blade]

When learning auto's, I used to have to think about which way to twist the thottle. But really it could only work one way, due to the design limitations of your wrist. try pulling an imaginary collective and twist toward yourself:)

[212man]

TC.
Regarding the failure in the climb:

If you assume that the FLI parameter is Torque, then by levelling and accelerating you will simply reach a stabilised cruise with less than MCP, if the collective is not touched. The Torque reduction with speed for a fixed collective position is quite dramatic. When the time comes to shut down the engine, the FLM gives no advice other than to "join single engine flight conditions". With the FLI no longer working correctly, this is perhaps not that simple.

My 'policy' is, that if possible, decelerate the a/c to 80kts (Vy) and if required (further) reduce collective to allow the Nr to rise towards the transient limit (390 rpm vs 342 normally). This will give the minimum power demand possible and, allow considerable Nr decay while the 'good' engine spools up to take the load, without drooping below normal (good acceleration with the Arriel). It should also give the best chance of avoiding the use of the OEI HI (30") rating on the 'good' engine, which if used requires the engine to be changed.

Obviously if circumstances dictate otherwise then use it, but it is a rather expensive consequence of a FADEC failure if not absolutely required.

Of course, you can just switch off the engine and deal with the subsequent Nr decay and OEI power useage later, but I (would) prefer to set things up beforehand. Hopefully the mod will be out shortly and this will be a thing of the past, though I don't think the EC-155 has the same history of problems that the 135 has had (well, I know it hasn't).

Whether a run away up or down is possible, is not easy to determine, but I think the likelyhood is remote given the certification requirements. If a failure mode did allow this to happen, I doubt that the engine switch would have any function and in the event of a run up you would have to rely on the overspeed protection shutting it down or, if time permitted, use the fuel cut off lever.

[John Eacott]

T'aint,

Baz has now bought a 109C, which is due here Saturday. I asked him why he has reg'd it N109BS, unfortunate set of initials :p