[NSRCA-discussion] Ideas on radio beserkness-cause of crash??

[Richard Strickland]

Sounds like a low battery--enough voltage to keep the rec. operating--but not enough to run the servos.  Not a complete de-coupling of the radio link--so fail-safe wouldn't kick in.  Just an opinion.
Was having prioblems that ended up being a bad cell in a 4 cell nicad pack--and with some glitches on a couple flights and trying different things. The third flight one eve,, I started losing elevator trim and the airplane was sluggish--was able to land and the rec. pack was very low.  No 'hold'--the sevos just started going away.
 
RS



To: NSRCA-discussion at lists.nsrca.orgFrom: gfowler at raytheon.comDate: Tue, 2 Sep 2008 08:30:17 -0500Subject: [NSRCA-discussion] Ideas on radio beserkness-cause of crash??Guys Yesterday on my 4th flight of the day my PCM Stylus went nuts. PCM program was set for idle throttle and about 5-6 clicks(trim wise) of up elevator-all other surfaces neutral, and this was tested as such by turning off the transmitter.  As I passed by center I noticed that I could not gain altitude and the the throttle started going from idle to high...then ailerons started oscillating small left-right deflections. I cut the throttle to the kill position but the engine persisted up-down bursts. I was able to do a 180 degree turn with aileron coming back to center...never losing altitude, but unable to change the altitude,elevator seemed unresponsive. As I passed by center again I was losing more and more control. The plane flew over the wooded area south of the field at about 200 feet high, I could not turn and the ailerons rolled the plane upside down and it went straight down into the trees. This whole episode last about 45 seconds. Cannot find the plane, and remnants of Gustav are headed my way. Plane was new had about 10 flights on it. New battery..NiMH 5 cell pack -no regulator (ran 5 cell packs for years, no regulator) Reciever-1999 Stylus PCM-never crashed, wrapped in foam New switch Transmitter-1999 Stylus, never been serviced, never had problems What would cause a PCM receiver to do such a thing? If I had and intermittent signal, once the receiver did get a signal the only two throttle signals should have been idle (PCM hold) and off (transmitter).  I am going to send the transmitter in just to get checked. Thanks guys....Gray FowlerSenior Principal Chemical EngineerRadomes and Specialty AperturesTechnical Staff Composites EngineeringRaytheon
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