Hello guys

I want to share my experience with you hoping that nobody will get the same problem as I had any more.
I lost worth 7000 $ in my A-4 crash this morning due to a Spektrum glitch.
I've come to this conclusion after working all the afternoon on the wreckage , re-connecting all the servos and power supply outside of the airframe and benchmarking it over and over.

UPDATE: the failure of the receiver is due to the soft switch short-cutting. Please read this http://www.rcuniverse.com/forum/m_7221837/tm.htm and the 5th page of this post

It was very strange: the radio locked ( I don't use the word failsafe on purpose ) in a full thrust turn, leading to an uncontrollable engaged turn to the ground.
At no moment the failsafe engaged; the engine remained at full thrust and didn't cut as programmed and verified before the flight ( this happened during a meeting ).
I recovered the control about 1 meter before the impact that was just enought to get the wings leveled and the engine shut down by the switch ( no fire ).

Just before the flight:



and just after:



It looks like at this stage that some of the jets components have a major influence on the working of the chip of Spektrum receivers.
It seems that some radiating HF component ( probably the ECU ) locks the receiver chip by jamming it.
I've done extensive tests and this appears when the ECU and/or fuel pump are close enough to the receiver ( less than 20 cm/ 8 inches).
The RF link remains rock solid with no frames dropped and no hold showing on the flight log but the receiver locks and the servos do not move. This for a unpredictable duration ( till this chip unlocks ).

We've and 6 major glitches of this kind for the past two weeks on 5 different aircrafts and AR9000 as well as the brand new AR9100 on my A-4.
After a lot of discussions we found out that the common point on all these systems was the direct proximity of the ECU and/or fuel pump with the receiver.

On the other hand I have conducted some extensive flight tests with my Phoenix, putting more than 100 flights with the same Spektrum system and 2 different generation AR900 RX with rock solid RF performance.
Until now my trust in Spektrum was total.

Now I believe that the Spektrum RF link is extremely good but the chip design prone to a major bug...

So please, if you fly Spektrum systems make sure that you have more than 20 cm/8 inches between the RX and any radiating device like ECUs, electrical motors, switching regulators, datalink systems.

Here was my setup:

AR9100 receiver
4 remote antennas, one in each wing tip, one up in the fin, one in the nose.
2 A123 batteries directly plugged on the receiver. Total capacity 4600 mAh. Voltage at the moment of the crash 6,5V recorded by 2 Voltspy units pluged on the balance tab of each battery.
8 Jr 4321 servos
2 Jettronic valves
1 complete Modellbau Multilight system with a separate battery

Needless to say that I did all my torture tests before the flight as usual:

Power supply test wit 200grs of lest on each aileron and 300 grs on each elevator, servo test ON.
I measured an average consumption of 1,5 A and a very good response from the batteries.
I also did an endurace test by runing this setup for 2 hours continuously.

I did a range test on the first flight and one before the crash for the purpose of the meeting safety. The RF link with the AR9100 is amazing. The range is up to 2 times better than with the AR9000.
I could go away from the model by 100 paces without a single frame dropped ( pushing the bind button at the same time ), moving the plane in every possible orientation and with the engine ON.
So I was originally very impressed by this RX and was about to post a very positive first test feedback...

I run the AR9000 in a Bobcat, the RX is 4 inches from the ECU, 6 inches from the fuel pump, 1 remote RX is in the rear of the hatch, 10" away and the other is in one wing 20" away without any issue, including logging every flight with the flight log.
to the casual observer of this crash (me, and im very sorry for the loss!) could the lighting system be at fault? were range checks done with the lights on? do they take power from the RX? are they common grounded if not? static build from carbon lamp mounts holding metal lamp holders? light wires next to servo and RX leads?

Kirk

That's terrible man. Sorry to hear about your loss. i have been running the Dx 7 on my Boomer and Flash now for some time, and never a glitch. I recently switched to the 10x module and still rock solid. I guess anything is possible but I still feel very strong about 2.4 in my planes. How many flights did you have on it before this happened? (Sean if you're reading this, that's how many times did you start the motor, go fly it, and land it). Do you have the frame loss counter on board? What did it read?

Billy

Yes the lighting could be at fault in locking the Rx.
The light controller was very close to the Rx.
No common grounding and a different battery.
Range checks were done with the lighting system ON.
The lamps were Luxeon Led, to my knowledge they do not induce static electricity.
Most of the light wires were next to servo wires ( it was a small plane )

Engine bay:



Main tray:



The light controller was just behind the fuel pump.

View from the engine hatch:



The small red/black wires were the lights wires.

I'm very sorry to read this.

I am using the AR9000 in my models with two remotes, in one installation it is just 2 inches from the Wren Fadec.

Your pump sure is close to the receiver

Your antenna is almost touching pump

did i misread the other thread, was this the first flight, 3 min into the flight or the 3rd flight???

also what did the data logger record?

the best question on this thread so far is "what did the flight log say after the crash?"

was there a hold?

i agree, and thats the 'business' end of the pump. the small slots are where you look in and see the brushes arc while running.

allthough with 2.4 it should not matter... especially with the ability to go to another RX when that one gives trouble. somthing (assuming it was a hold) got to the main recievers processor, where all the remotes feed to, or caused the same trouble with 4 recievers at once (!)

Mine is 19.5lbs with 65 sucessful flights on spektrum 10x module system and P-60 power. The jet can bite you VERY quickly if you are not paying attention.Sorry to hear this, your jet is awesome.

BTW: i probably would have not have located my rx there with the antenna wire almost touching the pump. My ecu is forward in the nose and i located my pump between the saddle tanks along side the UAT. My AR9000 is mounted on the fuse side very close to where yours is with the two satelites under the canopy one forward and one directly behind the canopy opening.

V..

What a shame....this is the most beautiful A-4 I have see.
Sorry for the loss.

was this the first flight? If it is an interference problem, shouldn't the rx go into fail safe?

Dubd,
Thinking the same thing, what did the data checker say after the crash ?? also after looking at the install pics again i would also not run the fuel lines right over (or under) that same antenna that is pointing towards the fuel pump. Fuel moving thru the lines can build up a static charge??
V..

It is sad to see such a superb model end up this way. The point has been made that the Rx aerial is almost touching the pump. Forget lighting systems, the pump motor is an electrical noise generator!
I don't want to rub salt in the wounds but I cannot honestly think of a worse installation situation. The pump and everything connected to it should be physically separated as much as possible from the Rx and everything connected to it. The only connection between the two systems should be the connection from the ECU to the servo, and this should always have a ferrite ring on it at the Rx end.
This is a challenge in small models but the only way to go IMO.
John

I believe he said this was the 3rd flight so to get 2 good flights in without incident is kind of odd.

Pump interference is a 72 Mhz issue, not a 2.4 Gigahertz issue.

How many of you guys are subscribed to the "Ask Danny" forum here on RCU? How many of you read the post he made today on power issues??

If you guys are going to use the latest Electrical Control items, please take the time to make sure you have them setup correctly and understand what the issues can be, and what they can't be. Otherwise it is all speculation and opinion.

The reason he is not posting data logger, is either because he did not have it on board, did not think it was important, or did not have electrical on the ground in order to plug it in. Therefore, asking him of it, probably won't get anyone anywhere.

Sorry to see what happened to your nice jet. I had three very similar lock-outs. Send all your receivers to Horizon and get them to update with the Quick connect feature. If they loose connection the receiver stays on the last good signal and you don't get a lock-out condition.

Sorry to see this loss. However I have been extensively testing the Spektrum system in a BobCat and a VERY demanding application a Savex L39 where everything is in close proximity due to small size. One remote was installed in the wing, another in the nose not far from the pump. Results have been perfect with low fades and still not a single frame lost on any flight.

A further test was to fly my BobCat with frequent lightning about 3-4 miles from the field. Again the data logger showed perfect reception with very low aerial fades, below 20 on all three receivers on one flight.

Like the 777 accident at LHR, one-offs happen but don't let this A4 loss condem the Spektrum system, my confidence in it is total.

Regards, David Gladwin.

Sure looks like a data logger between the fuel pump and the receiver unless I'm seeing something else.

jet lag +1 sean -1

Geez, just because he had one on board does not mean he got the info. If this guy was serious about Spektrum, it would have been the first thing he would have checked had the airplane been in a condition in which it could be checked.

I was standing next to John Redman last weekend when an F-4 came down behind the crowd line into the parking lot. The very first thing he did was run through the data logger menus to verify that it had nothing to do with Spektrum.

Since when are we keeping score? I am over sensitive to hearing such broad statements as there is a "glitch" in spektrum with no data other than a damaged aircraft to support it.

When the range check was done, how many fades were noticed, any holds? If there was, how was the antenna system changed?

Where's the real data?

We aren't keeping score.I agree with you 100% on how to ck for a radio failure and if he didn't have it plugged in or just forgot to ck it is his fault and he can guess forever what brought his plane down.Looking at his installation says a whole lot. I guess its a lot easier to blame a radio system without anything to base it on.