Andrew Tridgell <> (Sun. 14:19) (attachment)
Subject: bushmaster crash at CMAC today
Date: Sun, 25 May 2014 14:19:38 +1000

Hi Steve,

I have attached the incident form from the crash today as we
discussed. I've also CCd a few people who may be interested (including
Ray as it was a heavy model).

The plane was flying under manual control at the time of the crash, and
had been for the last 46 seconds of the flight. It did have gyro
stabilisation enabled, but was under pilot control by Jack.

The on-board logs show that the servo rail voltage dropped over the
flight, and was at just 2.3 volts when the plane hit the ground. Jack
had no control.

I've attached a graph of the servo rail voltage over the flight. The
logs show the voltage (in millivolts) dropping over the flight. Takeoff
was at 11:08, and the voltage was already down at that point, although
it wasn't low enough at that point to show up as a warning on our ground
station display (I will be changing the warning thresholds). The servo
rail voltage dropped rapidly at 11:09:36, although the logs show that
Jack still did have good control at that point. The voltage dropped
again 11 seconds before the crash, at which point Jack had no
control. The logs show he activated choke to cut the engine and that he
put the throllte to zero, plus was trying to control it right to the
end. Inspecting the engine after the crash showed that the choke servo
had not activated.

I have confirmed from the logs that RC control was not lost. There were
3 other crashes today and some people thought there may have been a
general problem with 2.4GHz RC control today. It does not look like that
was a factor in our crash.

Nobody was injured, but it certainly was a serious incident. Let me know
if you need any more information.

We don't yet know what caused the servo rail voltage to drop, although
Jack is looking at it. A short is suspected, but we don't yet know in
what component. The batteries were charged this morning, and servo rail
voltage was checked as part of our pre-flight checks (plus you can see
it was good in pre-flight checks from the attached graph). We have flown
this aircraft for nearly 3 hours in total over the last few weeks with
the same setup.

Regards, Tridge

PS: Kent, I'm not sure who it was that was standing near you at the time
of the crash?