Quadra 42 and Futaba FP S148 servo twitches
 

Today, I flew the maiden flight for me of a previously owned giant scale plane with Quadra 42. It had several Futaba FP S148 servo twitches of the ailerons when flying it and that forced it off the runway when landing (no damage). It has a 42-percent products Z kill switch that is located in the fuselage more than 24 inches from these aileron servos. I have a 6 volt battery that read 6.5 volts under load test when checked after landing.

What may cause the Quadra to interfere with Futaba FP S148 servos to cause twitching of ailerons?

RE: Quadra 42 and Futaba FP S148 servo twitches
 

Being anxious for an answer, I also called Futaba today and was told that FP S148 servos 8 years old are compatible with 6 volts, as well as 4.8 volts.

I replaced the metal control flex rod for the throttle cable with Sullivan Golden Rod type and moved the kill switch away from the power switch, as suggested by Futaba FAQ for gas powered planes.

I am using a Spektrum 2.4 GHz AR7000, so Rx is not likely a cause of this problem.

Given Futaba's comments that I received under their support forum here at RCU and age of servos, it looks like their replacement, along with associated wiring, is my best approach here.