On Wednesday, October 9, 2013 11:47:21 AM UTC-7, N_Cook wrote:
Does pilot duty relate to a second, preliminary pump, for clearing air
from the system , priming, before the main pump will cut in?

In this case there is only one pump.

A submersible pump would not require priming unless an air/gaseous block
gets in there

The pump is located at the well head. To my understanding it is a shallow well jet pump as described here.
http://en.wikipedia.org/wiki/Eductor...ump#Well_pumps

Thanks for the reply, ... Peter E.