Originally Posted by
sgs233a
It's worth noting as well that the Air Tractors (at least the 502/504 that I'm familiar with), are VERY simple airplanes, with quite basic systems...and this seems to be baked into the design philosophy. Might be as simple as separate starter and igniter switches were seen as the simplest way to implement the start.
The igniter switch is a 3 position switch - start/on - off - on igniter continuous. In start/on, the igniters only come on with starter switch held on. In on igniter continuous, they're on continuous - there is no controller or other logic in the system as in many other airplanes.
I can understand the logic of having a separate ignitor switch for use in water washes, etc. In a helicopter we have to pull the CB for these or other reasons when we don't want ignitor activation with the starter. What I don't get is the need to turn that switch on at 12%, why not select it to Start/on, hit the starter and go from there just as we do with a RW installation.