RE: THROTTLE RETURN SPRING
I am unsure what failsafe you are looking at bunny but your statement in general is untrue.
The Futaba 3PJS has frequency lock out as well as a battery failsafe while in PCM mode.
I have been running it for years and never had a problem.
To my knowledge there are several failsafe systems out there that not only do the lock but also the battery failsafe.
Dbow