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In-Flight Power Failure

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Old 10-18-2010, 08:57 PM
  #1
flycatch
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Default In-Flight Power Failure

Second flight on my ESM FW190 warbird and it returned to the earth with no one in control. I was flying straight and level about twohundred feet up and the plane went into a gentle left decending turn. I had control of nothing and the impact totaled the airframe and engine. I gathered up all the broken pieces and left our flying field. This flight took place on Sunday afternoon and I was the only there.
I removed all the electronics from the shattered wing panels and fuselage. I benched check all the servos, extension leads, switch harness, receiver and battery pack. Everthing worked in a static condition. I let the system sit powered up for fifthteen minutes and than checked the battery under load. It read 5.7 volts. This is using a load of 500ma. I than took it outside and performed a range check and naturally it passed. I'm still flying on 72mhz. Transmitter 9303 on CH#50 and a JRR2000 scan selectable receiver.
This has got me baffled and I don't trust putting these items back into another aircraft. Since this crash I have thrown out the switch harness and receiver.
Does anyone have further reccomendations on what to keep and want to throw out.
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Old 10-18-2010, 10:08 PM
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Crash Campbell
 
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Default RE: In-Flight Power Failure

Hi flycatch,

FWIW in my experience the switch is often the part that fails causing loss of control. After the crash the RX is a worry until checked by a techo.

Cheers,

Colin
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Old 10-18-2010, 10:23 PM
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Default RE: In-Flight Power Failure

Thanks, Collin, for the reply. I had the same thought and threw the switch harness in the trash along with the receiver. I'ts hard to justify a component that cost less than $20.00 USD could destroy my investment of $1000.00 USD. I purchased the receiver NIB for $75.00 USD. We that are still flying on 72mhz can purchase high end receivers such as the R2000 for a very reasonable price. This and the absence of other pilots flying on 72mhz is keeping me on this outdated frequency band.

I find it amusing that no one in the USA will provide feedback on this topic. There has to be others who have experienced this same problem.
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Old 10-19-2010, 06:04 AM
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Default RE: In-Flight Power Failure

You should not have thrown the receiver away, even though it passed your range check, you should have sent it back to Horizon to have it checked out. I had a friend whose airplane went out of control and crashed.
We did a quick range check and it passed, but he sent it to Horizon, they said it was no good,
Also, what you may want to do in the future is use a dual battery-dual switch setup in your airplanes.
A load check on your battery of 5.7V is pretty low (I am assuming you are using a 6.0V Nicd or Nimh, do a charge discharge cycle of the battery to see the condition of it.
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Old 10-19-2010, 09:40 AM
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Default RE: In-Flight Power Failure

Tne receiver in my opinion was a throw away item. I'll take your advice and cycle the 6V NIMH battery pack. In the past I had purchased a brand new 6v pack and had a bad cell out of the package. I still believe I had a faulty switch. At the crash site the system was dead. Upon cycling the switch several times the power came on.
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Old 10-19-2010, 02:49 PM
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Default RE: In-Flight Power Failure

Hi flycatch,

Over the years I have had three switches fail, two JR and one TYI, fortunately two were on the ground prior to takeoff. Now I use an Emcotec electronic switch that doesn't have any moving parts and allows the connection of dual batteries and ensures equal draw from both on my more precious models. On the others that anr't so important to me I use two individual switches and batteries, the only exception is an electric glider which doesn't have a switch and is simply on when the Deans connectors are joined prior to flight.
Like you I haven't made the switch to 2.4 Ghz as my existing gear works fine, I don't have anyone else at my club on my frequency and I have seen two models lost to brown out with 2.4 owing to less than perfect installations, dicky batteries/connections, black wire and possibly stalling high power digital servos?
Sorry for your loss, I too learned the hard way. I guess it is cheap insurance to go for redundancy in this area as vibration seems to kill switches over time.

Cheers,

Colin
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Old 10-19-2010, 04:30 PM
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Default RE: In-Flight Power Failure


Quote:
ORIGINAL: flycatch

Tne receiver in my opinion was a throw away item. I'll take your advice and cycle the 6V NIMH battery pack. In the past I had purchased a brand new 6v pack and had a bad cell out of the package. I still believe I had a faulty switch. At the crash site the system was dead. Upon cycling the switch several times the power came on.

My point on sending the receiver back to the distributor was not to get it repaired, but to get a verification on weather it was bad or not in order to determine the cause of the crash.
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Old 10-19-2010, 08:29 PM
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Default RE: In-Flight Power Failure

Your absoultely correct. I was not in a rational state of mind, one step from calling it quits.
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Old 10-20-2010, 11:35 AM
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Default RE: In-Flight Power Failure

You might want to check out sun spot activity:

http://www.solarcycle24.com/

Sun spots can create interference with communications.
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Old 10-20-2010, 02:51 PM
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Default RE: In-Flight Power Failure

When the plane locks out and stays at the last command on 72mhz, it's almost never outside interference unless you're using PCM and you have things set to "hold". Did you have a failsave configured? I don't know if that RX has that feature, but many do, even some PPM receivers like the Hitec 9channel.

When you did the range check, did you have something providing vibration? Many guys don't realize that most 72mhz receivers have 2 or 3 additional crystals mounted to the RX board, even some synth RXs have these. And these crystals can crack. The result is a RX that works static on the bench but has terrible range, or acts funky in the air. I've had this happen myself.

I agree with the above that the most common cause of crashes like you describe is switch or battery related. a 50ma load isn't much, depending on the plane, I like to test batteries on a cycler (most new chargers have this feature) at a discharge rate closer to what I get in the plane.

One useful thing I've started to do is to use a watt-meter normally used to measure e-power systems, and hook it between the battery and recevier. You can see the current your servos are drawing while centered, and then again at the ends of the travel, and easily find any binding or flaky servos. It's too late for this on your plane, but you might still check out the servos to make sure one of them doesn't have an internal bind at full travel from something like a loose/stripped gear tooth.
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