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Odd radio hit after 92 flights on gasser... any idea's?

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Old 09-28-2003, 07:49 PM
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JohnVH
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Default Odd radio hit after 92 flights on gasser... any idea's?

PCM in a 33% bird, always worked great until today. On my 3rd flight of the day, coming in on final about 5-10' up it went into failsafe wich is alot of up elevator, so it did a wall just off the end of the runway, luckily was only a fast hit, and I got it down with no problem, but cant find the problem yet. Any idea's as to why it would get a hit now after this many flights???

It does some odd things on the ground now. I always range check every so often over the last 7mo I have been flying the plane.

Like to get some opinions on what it could be... crystal maybe?? RX going bad? Ignition going bad?
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Old 09-28-2003, 11:20 PM
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ghendrix01
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

if the receiver has ever been in a plane that crashed, I would have it checked. I always replace the crystal in a receiver that has been subjected to a crash. I had an Extra 300 that was crashed many years ago. I repaired the plane, checked the receiver for damage and found none. I didn"t replace the crystal. I flew the plane without incident for over a year. One day I flew and landed. Later that day, while preparing to fly again the crystal failed. All of the servos went to one end of their travel and would only respond if I put the tx antenna right on the rx antenna.

George
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Old 09-28-2003, 11:23 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Im going to try that too. Someone also mentioned checking the plug to make sure its clean too?
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Old 09-29-2003, 01:53 AM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

What's your setup John? Radio, Rx, Batts, Matchboxes etc? If it happened once, it probably won't go away, at least in your mind_bob
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Old 09-29-2003, 08:46 AM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

JR10X, 649rx, two 1800 4.8v packs, 3 matchboxes, 10 servo's 5 being digital., zdz80.
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Old 09-29-2003, 10:51 AM
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Rodney
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Very likely a connector that has become loose, coroded or intermittent for some reason. Switch maybe?
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Old 09-29-2003, 11:42 AM
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Default Odd radio hit after 92 flights on gasser... any idea's?

Although I haven't been following it, there is a fairly large thread on some sort of anomloly with matchboxes. May not be your scenario, but thought I'd mention it_bob
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Old 09-29-2003, 12:09 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Just read the thread. IMO people are looking for an out, there must be a problem somewhere else in the system... we will see....
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Old 09-29-2003, 01:10 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

I had a similar experience...after many flights, over many months, I suddenly found myself in the middle of a flight, without any control over my plane. My Extra 300 was in a gentle bank to port, and never recovered from it. The plane proceeded to land nose down in a swamp. Amazingly, every servo worked after pulling the debris out of the oozing mud. After much deliberation, and disassembly, the connectors from battery to switch were found to be so loose, they would very nearly fall apart. I suspect the vibration separated the power connectors slightly in flight, just enough to open the power circuit, and the subsequent crash pushed it back in, and everything worked again. Too bad I had to lose a good plane to discover the fatal problem. It has been mentioned that all connector mating pairs should be pulled apart and reinserted ocasionally, to provide a wiping action and help remove oxidation on the contact surface, which can inhibit conductivity. Connections burried in the plane, such as wing aileron and flap extentions should be soldered for a more permanent and reliable circuit. The simple, and cheap slide switches are an accident waiting to happen. I replace mine with a much more reliable commercial grade switch. Good maintenance will help prevent some mishaps, but there'll always be the ones you just can't explain. Good luck.
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Old 09-29-2003, 01:13 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Thanks for the info Jim, mine had power the whole time as it had the juice to go into lockout..so thats out, but will check the connections again anyway.
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Old 09-29-2003, 03:27 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Hey John,

Is full "up" the only thing you have programmed for failsafe? i.e. are you sure it went into failsafe?

And what odd things are happening on the ground? What type of servos do you have?
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Old 09-29-2003, 03:39 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

I have engine to idle, and pretty much full elevator into it, and that is what happened. 8411's on tail matchbox only on rudder. 4735's on ailerons, one matchbox per aileron.
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Old 09-29-2003, 03:48 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

I had a similar situation with a ZDZ 80 and SuperSonic pitts muffler.The smoke coil broke loose inside the muffler causing interference while the engine was running.Lee
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Old 09-29-2003, 04:13 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Well, I have the bisson pitts, no coil in it..
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Old 09-29-2003, 06:53 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

JohnVh. Is this your Sukhoi you're referring to?
Where is your battery, receiver, servos in relation to your ignition system? Is it possible that Rx noise caused the hit. Then when it went into failsafe and cut the throttle, the noise went away enough for you to regain control? I would try a full throttle range check without the PCM Receiver. If there is ignition interference an FM Receiver will show it better.
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Old 09-29-2003, 06:55 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

well, the batteries are all by the fuel tank, as I need all the weight I can get up there. BUT, I was coming in for landing and was at full idle before the hit..
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Old 09-29-2003, 07:05 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Wouldn't hurt to give the ground check a try with FM. I know that those PCM receivers can "hide" interference. I'm glad you got it back in 1 piece. Please keep us updated.

Other than that what could it be? A bad connection, a switch starting to go? Are you using 1 or 2 Rxs'? If using 2 did they both go into failsafe?
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Old 09-29-2003, 07:07 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

one rx two batt.s and switches. Im not sure, first things to replace I think are the crystal then RX and see what happens... Sucks not knowing what the problem is!
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Old 11-06-2003, 07:33 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

JohnVH. Did you ever figure out what caused the hit?
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Old 11-06-2003, 08:36 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

Never did, I did range checks, and never came to a conclusion, so I just kept flying it, Ive got 100 flights on it now, must have been a freak thing, or someone turned something on really quick then back off? I repositioned my antenna on an angle is the only change I made.

You having problems?
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Old 11-06-2003, 09:16 PM
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Default RE: Odd radio hit after 92 flights on gasser... any idea's?

No, not yet. ( I haven't run the engine yet.) I was just wondering if you found a problem.
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