[NSRCA-discussion] Un-commanded rudder sweep during flying session pre-flight checkout

[Michael Cohen]

OK NSRCA list, got a weird one to run by the Pattern hive mind to see if anyone has any ideas.  My plane has two FlexReg PLR5 Tech-Aero Voltage Regulators and batteries for redundancy.  My typical flying session pre-flight checkout involves turning one on at a time and sweeping all surfaces.   Today, the rudder swept back and forth after I stopped a similar command from the transmitter on the first regulator I turned on.  Maybe my leads were not fully seated???  I unplugged and re-plug both regulator leads at the receiver and the problem went away.  Today, when I got home, I decided to replace the regulator causing the issue with one from a backup plane and did my sweep checks.  The following was always performed with only one regulator plugging in at a time and without the wings on.....

  1.  With the replacement regulator (R1) plugged into channel 8, the rudder kept sweeping back and forth un-commanded (after I stopped).  The elevator was fine.
  2.  Moving from channel 8 to 7 (R1), the rudder kept sweeping back and forth un-commanded.  The elevator was fine.
  3.  Plugging the same battery (B1) into the other regulator (R0) that has always been in the plane into channel 8, both rudder and elevator we fine.
  4.  Moving from channel 8 to 7 (R0), both rudder and elevator we fine.
  5.  I repeated steps 1 & 2, the rudder kept sweeping back and forth.  The elevator was fine.
  6.  Grabbing the OTHER regulator (R2) from the backup plane and repeating steps 1-4 above yielded the same results.
  7.  I removed the regulator (R2), leaving the original (R0) and the original backup (R1) in the plane
  8.  Hooking up a second battery (B2) and cycling back and forth between the two regulators, once switch at a time, there we no issues.
  9.  There were also no issues with both packs on at the same time

Based on the above, the problem did not follow anything in particular.

B1 + R1 + 7 = X (rudder sweep)
B1 + R1 + 8 = X
B1 + R0 + 7 = Y (rudder fine)
B1 + R0 + 8 = Y
B1 + R2 + 7 = X
B1 + R2 + 8 = X

B1 + R1 + 7 OR B2 + R0 + 8 = Y
B1 + R1 + 8 OR B2 + R0 + 7 = Y
B1 + R1 + 8 AND B2 + R0 + 7 = Y

Thoughts???

Since this is a Futaba R7008SB receiver, I could ditch the regulators and just go straight into the receiver (did not try that yet).....

Regards,
Mike C
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