smilam

A few days ago I was flying my 4 star 40 and crashed due to loss of signal. I haven’t been able to find out what caused the loss of signal so looking for some ideas. I had been flying for about 10 minutes and had done three snap rolls then decided to do a horizontal figure eight. Three quarters of the way thru the maneuver the motor loss power for a split second like an air bubble in the fuel feed. I climbed up to gain altitude to make sure if thee motor die I could make it back to the field. As I banked it about 45 degrees and started my turn I lost all control. The airplane started three nice big circles for probably 15 to 20 seconds while it was loosing altitude and about 30’ off the ground it snapped and went in. During that time I didn’t have any control at all. The next day I removed all of the radio equipment from the wreckage and checked the battery. It was just shy of 6 volts. I plugged everything in and my voltage fluctuated slightly while handling the battery and switch. Everything worked fine and I tapped and jiggled everything and it all worked like it is supposed to. After a few minutes the light on the receiver started flashing like it was ready to be bound but all of the servos were still operating like they are supposed to. I turned it on and off with the switch multiple times and even unplugged the battery and if still flashed every time I plugged it back in and all of the servos kept working even though it looked like it was needing to be bound. The next day I turned the switch back on to run the batteries down a little farther and the light on the receiver came on steady and worked as it should.I never rebound it and I have cycled it multiple times on multiple days and have had it on for over six hours without charging the batteries in the receiver or transmitter. Everything is working as it should with jiggling, shacking, and tapping on everything with no change. The transmitter is a Spektrum 6I and the receiver is an AR400. At this time I don’t know if I can trust the transmitter, receiver, or switch. I haven’t been able to recreate the loss of signal unless the battery came unplugged in flight but that doesn’t explain why the receiver was indicating it was ready to bind although all of the servos were working like it was bound and the next day the receiver indicated that it was bound and I hadn’t rebound it. Any suggestions on what to check now?

A. J. Clark

Do a range check.

smilam

Did that before flight and the next day while checking everything out.

A. J. Clark

Sounds like a bad connection and loss of power. Had the plane been setting for a period or do you fly it on a regular basis.

funflyer99

Sounds like the same issue I had experienced and it turned out to be the switch. I lost one plane and almost another because of it. Plane would lose control momentarily like it got an interference hit then recover. Discovered the bad switch while doing an engine run-up on the new plane before it's maiden flight.

smilam

I originally thought that maybe the battery moved and became unplugged because of the snap rolls and it separated from the fuselage in the crash. Since everything worked when I connected everything on the workbench it led me to believe that the battery or switch was the issue. When the receiver light started blinking like it needed to be bound I thought that was likely the problem except everything worked while it was blinking and nothing should have worked if the receiver wasn’t bound. The next day the receiver light stayed on and it hadn’t been rebound.
That airplane is probably flown every other week and recharged when I get home. Then the day before I take it out it gets cycled on the Ace Digipace to see what the batteries MAH looks like. When I get to the field I do a range check with the transmitter antenna pointed directly at the airplane since the signal radiation is the weakest off of the tip.
The switch is still suspect because I know from experience that they are a weak link in the system and the receiver has me questioning it since it shouldn’t send a signal to the servos if it’s not bound.

tedsander

The big clue: "I plugged everything in and my voltage fluctuated slightly while handling the battery and switch." In a fuel plane, the vibration levels are significant, hence everything should be soft mounted (wrapped in foam, rubber vibration mounts, etc.) But most of us have no way to do that with the switch. So it gets severely shook with every flight. Plus oil, debris, etc.
It is one of the top failure prone components. While you should still exercise care and not trust anything until you have fully tested it all, just throw the switch and replace with new. Cheapest and easiest part to eliminate as an issue.

jaka54

what type of battreries??

mgnostic

I'm not totally familiar with the AR400 but the flashing light on the receiver can indicate a signal loss. Until you switch off the power it will flash once for each loss of signal during the flight.

A. J. Clark

If you lost signal and had failsafe set for low throttle the plane wouldn't be able to do 3 loops. More likely complete power was lost.