Spektrum DX-7 switched off with engine running

[ticedoff8]

Yesterday, I did something so dumb, I can't believe it.

I had my GMP King Cobra (OS Max .61 FSR-H) fired up and in position to take off. I had started the engine and walked it out to my landing pad. The engine was idling nicely at a low enough speed that the rotor wasn't turning - just like normal.

While I was walking back to my "flight line" (like I've done 1,000,000 times before), I clipped my neck strap to the ring on the transmitter - and turned off the transmitter!!

I had engaged the clip of the neck strap to the ring of the TX body at just the right angle, so when I pulled on the strap to secure the clip, it pushed down on the slide switch - turning the TX off.

What made this such a heart-stopper was that the GV-1 governor I use wasn't set properly for fail-safe. I thought I had set it - but something had changed. So, while the collective went to 0-degrees and all flight controls went to neutral (direct control of the AR7000) - throttle went to 50% (direct control of the GV-1).

Holy Crap!!! :eek:

As soon as I clipped in the neck strap, I knew I had done a bad thing. In a heartbeat (it seemed), the receiver had gone into fail-safe - and the rotor was spinning up.
I fumbled for a second - thinking "Okay, should I run like hell (safe distance), tackle the heli (limit the damage - to the heli), or is this thing going to take off (spectator)?".
It didn't take off (luckily for me).

After a L O N G time (it seemed) of thinking about what I should do, I switched the TX back on and held my breath.
And the freaking TX starts "beep, beep, beep, beep" - I had the Throttle Hold switch on! As always, my 1st reaction to ANY helicopter trouble is to hit T-Hold.
BTW - Did you know that the DX-7 wont start transmitting until the switches are set in a "safe" position? Yeah, I did too - but I am panicked.
So I turn OFF the TX (not sure I needed to do that), reset the switches (F-Mode & T-Hold), and turn the TX back on.

Do you know how long it takes for a DX-7 to reboot? Or, an AR7000 to come out of hold?
F O R E V E R ! ! ! !
I know the book says 3 seconds - but it L I E S!!
It is really F O R E V E R
- as long as your helicopter is sitting on the pad with the throttle at 50% and you are waiting for the chicken dance to start.

But, it does finally come back online. And, once everything settles down, and the motor goes back to idle, I notice the helicopter hasn't moved an inch. It is still sitting exactly where I set it down. It hasn't torqued the tail around and it hasn't leaned over - it is just sitting there.
I shut everything down, and waited a few minutes to restart (deep breath, drink of water, etc) and fly 2 or 3 more times.

Now, I've been flying fixed wing (gliders and glow), cars (electric & glow), sailboats and helicopters for 30+ years. I've ALWAYS used a neck strap - and I've NEVER turned off a radio (that I remember - I am old) while I've attached the neck strap.
I use the same procedure every time - I leave the neck strap unhooked until I am ready to launch, then I hook up.
Obviously, I'll make some changes in this procedure. I was MUCH more careful about hooking up after this happened.
And, of course, I'll set my GV-1's fail safe throttle to idle-cutoff.

Notice to RC Heli Forum manager: I propose a new section "I Leaned about Flying from that" (like AOPA has in their Pilot Magazine).
I don't consider this story to be a "safety" issue - there is nothing wrong with the neck strap or the neck-strap ring on the DX-7. But I think there are a lot of these stories out there - and I bet people would be interested in reading them.

[blax1]

Well all's well that ends well.... :)

Has your AR7000 had the firmware upgraded for quick connect by Horizon?

Interesting post, glad it turned out Ok in the end, which obviously took some time to end. :eek:

[schwa]

i did something similiar. a friend who was thinking of getting into helis was standing with me. i finished and landed the heli. started to walk over like i always do and for some reason i still dont understand, turned off the radio. it took me a few secs to releize i just did something incrdeibly stupid. warned him to step back while to reset its self. luckily nothing happened, but it did get the blood flowing.

glad to hear it didnt start to take off

[cbflys]

Has your AR7000 had the firmware upgraded for quick connect by Horizon?
Just so you guys are clear on this, QuickConnect would not have helped out in this instance. It provides rapid re-connection after a voltage drop at the RX end, not when the TX signal is lost.

In this case the TX power cycle caused the TX to re-scan the band for open frequencies, a process that takes seconds.

[heli-cuzz]

Glad to hear it wasn't a disaster.
I never unhook the strap from my TX.

[schluterdude]

man, i'd need to sit down and have a smoke after that one... it woulda sucked if she tipped over. finding parts for that gmp would been a challenge! but,live and learn! glad to hear she, you, and everyone else there went home in one piece.

[gouki74]

we're glad nothing bad happened to you and your gmp cobra :)

[Jeff Bulmer]

glad to hear it didn't lft off on you, or tip...

I wonder if your reaction to turning on the throttle hold prevented anything from happening??

[ticedoff8]

glad to hear it didn't lft off on you, or tip...

I wonder if your reaction to turning on the throttle hold prevented anything from happening??
I don't think the t-hold did anything positive for me in this case. But its saved me (from more damage, at least) so often in the past, I'm not going to change that reaction.

I played around (on the bench) with this scenario.
I've confirmed that if you have either one of the t-hold or f-mode switches set when you turn on the DX7, it will not transmit, it will just "beep, beep, beep, beep" warnings with the LCD display saying you did a bad thing.
If you set the switches back to a "safe position" (t-hold "off" and f-mode to "norm") the DX7 will start to transmit - turning the TX off then back on is not required.

I also played around with the fail-safe settings. As documented in the manual, and I confirmed on the bench, there is only ONE channel that has an actual "fail-safe" setting on the DX7 - it is the throttle. This fail-safe position is established by your the throttle stick (collective) position when you bind the TX to the RX.

When you have a loss of signal on the AR7000 RX, it will "freeze" all channels in their last position and move the throttle to the fail-safe (as established during the binding) position.
My "problem" was that I had the collective stick at mid-point (50% throttle) when I did the binding.

So, when I was on the landing pad at the field and I switched off the DX7, all my sticks were at a "low point" - collective stick full down (-4-degree pitch), pitch, roll and rudder at mid-point - AND... the GV-1 arming switch was off. When the AR7000 lost the signal, it went into "hold" for everything and to 50% throttle (per the throttle setting when I did the binding) and the GV-1 never took over the throttle from the AR7000. That's probably why it didn't take off or roll over and do the chicken dance.

So now, I've re-binded the DX7 to the AR7000 with the collective full down and the throttle trim set to "idle". I figure having the engine at idle is better than "idle cutoff" if I have a real signal loss - assuming it regains signal before it crashes, I stand a slim chance of flying out of it if the engine is still running.