This thread is only intended for those of you who don't know this already (like me).
Also, if you use the Aux channel for emergency shut down, this won't apply either.

In most of my planes I program an "idle up" or "high idle" with gear up.
This allows to cut the power during some maneuvers without fear of the engine going too low on RPM and potential flame out.

This sounds very good.... BUT, I just found out while doing some radio programming, that the engine will then not shut down while the gear is up !!!!!! So, this procedure is definitely a NO, NO. Sounds obvious, but..... I guess learning never ends !!!

I know: As a result of my ignorance, I was not complying with the rules !!!! (just trying to save some posts ).

The best thing to do will be to program the ECU with the throttle trim for start up in the middle position, and use some trim for a higher idle. Unfortunately, there will be one more thing to remember during the landing approach [:@]

Using the shut down switch is also an alternative; but when I learned to fly, the radios didn't have switches... so, I still sweat every time I have to flip one different from Gear or Flaps (the only two I use, btw).

Hope this helps somebody.

Jack

Jack, good post. And good catch.

My question is, are you having trouble with your engine maintaining idle in flight at the typical idle thrust settingh you see after start? Enough to cause a flame out? Either I have been lucky or I just have not had an engine with this issue. So your post has been valuable for me in this regard, I'd like to know a bit more.

I would have thought you could program a flight mode with gear up to also allow a higher mixing authority of your kill switch on the throttle position. But I guess I am wrong.

Jack

Not trying to be a smart a**e, but why would you want to shut down the turbine with the gear up? I use a throttle up on my full vectored thrust Rookie, I consider it almost esential with some of the silly positions I get it into LOL, In a tail slide the air going backwards into the turbine at normal low throttle has I think caused a compressor stall and shut down of the turbine until I put in the idle up, there is a mix for this on the 12FGA.

Mike

Imminent crash ?

If you have enough time in an imminent crash situation to shut the turbine down, you have enough time to flick the gear switch, turbine responds as normal.

Mike

Well in that case you've got enough time to switch off the Tx, put it in it's case, sit down in your chair, crack open a beer, and wait for the fireball and mushroom cloud.

Mike

I've done that with a Junior60 pulling out of a Stuka dive and clapping wings................

When my Hype folded its wings I had back stick applied all the way to the ground.

Mike

A gear malfunction where only 2 gear come down. Many jets are safer landed with the gear up and to help avoid fod while sliding on the grass it would be nice to have the turbine shut down.

Sliding in on grass is more likely to introduce FOD not less, I fly from grass all the time, and have landed without a nose wheel, just the mains down, I am sure most of these replies are from those that have not used an idle up or have ever land without the turbine running, makes the whole disscussion academic, how many times have you actually wanted the turbine shut down with the gear up, In the four years and hundred of flights I have been running turbines I can't think of one, now that is tempting fate perhaps I should not have put that in writting.

Just checked on my 12FG, when you use the "Throttle down" mix as a throttle up (you can with the latest firmware update) the trim will still close the turbine down, so I don't have this problem anyway.

Mike

Eddie, a few years ago (before I began using the idle up), and most likely due to earlier versions of ECU software, most of my flame out happened when I went to idle and immediately added power again. (I do it in some maneuvers).
My theory is that when you suddenly cut the power, the UAT begins to expand (the negative pressure created by the pump suction ceases). When you apply power again while the UAT is still expanding, the pump: either starves, or the learned voltage is not enough to maintain the flow during that sudden condition. Again, this is just my theory. But it happened a few times in different installations and with different turbine brands.
In some opportunities I have also had turbine stagnation (doesn't want to accelerate).
All these disappeared after using idle up.

It may also have to do with the fact I fly at density altitudes of over 2000 ft., I don't know.

But anyway, I am not suggesting the use of idle up, but a heads up to those who use it.

Jack

Mike, my point is that "I did not know that I wasn't able to kill my engine during an emergency shut down"

Is not that I want to do it !! (I swear I don't ever want to... LOL)

I agree with you that there may be ways to program the radio in such a way that it does it. I will investigate.

But again, had I had an emergency with imminent crash, I would have set my throttle lever to idle and my throttle trim to minimum as I have been trained to do.... Just to discover that the engine didn't shut down, and a big ball of fire. And then run to the internet to blame the ECU or the radio... and people thinking that I didn't do the procedure.

I don't think that a procedure that requires lowering the gear first, is practical.. specially under a situation where you are scared to death...

I hope this clarifies my point: "If you are using idle up, you may not be aware that the shut down procedure won't work. Unless you knew it, and did a program for this purpose"

Thank you guys for allowing me to clarify what I consider very important.

Jack

Mike, could you tell me how the "throttle down " works?
I may emulate the program in my radio.
I use two different throttle curves, switched by the gear.

Jack

1) I think there's no point in making the shut down harder than it has to be, because there simply may NOT be that much time.

2) There is the occasional hung or unlocked main gear, then the flying site is grass the preferred landing is gear up with the engine shut down on short final.

Jack

The "Throttle Down" on the Futaba radio is able to move the throttle curve up or down the set trim position on the latest firmware so it can be used as an idle up, but what it does allow is the trim to bring the throttle position down to its low point irrespective of the idle up being activated, I don't know about JR equipment, but again on the Futaba 12FG we have a "Throttle Cut" facility as well, I have not tried as I don't need it, but I think it can be set to over ride the trims in the low throttle position.

When buddying a pal of mine on my Elan, he moved the trim to the low position as he had been trained to do whilst I was taking off, on handing over control to him, he flew around a bit then did a loop and lowered throttle stick like he normally would, this caused an instant shut down of the turbine, that was my first dead stick landing with a jet, luck would be that it was at the top of a loop and I had plenty of height and hrs on the Elan so an easy matter to land back on our very small grass patch.

Mike

EDIT: sorry to miss lead, the "Throttle Down" only moves the bottom of the throttle curve not the whole curve.

Be careful if you do this, if the throttle curve is taken above the learnt parameters of the ECU the turbine will shut down, that was my second dead stick landing with the Elan, than one was not so cleaver.

One other useful programme in the Futaba Tx's is the trim travel function being reduced in time, instead of 10 clicks on either side of neutral you can set it to 4 clicks, but still with the same amount of travel, this makes trim travel from one end to the other very fast.

Mike

Agreed, trying to find the Aux 2 switch that you have only used on the ground before is going to make it very hard to shut it down on short final's.

I'm not so sure about shutting the turbine down with hung up gear, when I landed the Elan without a nose wheel, I kept the turbine running so I could bring it in at a very high AOA and let it lower itself onto the nose, the only problem is the flaps and tail booms take a beating unless your quick enough to put the flaps away just before touch down.

Mike

You forgot to mention getting out the video camera to film the impending crash.

My biggest fear is accidently deploying the drag shoot while in flight. I have it hooked up so that it can only be activated when the gear is down. But that still worries me each time I drop the gear for landing. Most of the time I just disconnect the drag shoot just to be safe.

Mike, what I understand from your explanation is that the "throttle down" feature brings the "low throttle trim" channel output to the same value, regardless of the throttle curve in use. Am I correct?

If yes, it is clever.

Jack

Ummm think so, "Throttle Down" is a separate programme within the 12FG Tx that can also be used as a "Throttle Up" I have mine on the gear switch so when gear up is selected the throttle advances to increase the tick over point on the curve, irrespective of this the trim will still shut the turbine down if low throttle and low trim is selected, one thing I have not checked is whether the Futaba 8/14 channel set has this facility?

Mike

LMAO