Applying the ground power is the cause
The NATO connector that is on the 206 is specially designed with the control pin being shorter than the 2 high current pins. This is to ensure that the power is there before any control circuits are activated.
If you plug the connector into the aircraft THEN apply power from the battery cart/APU, you defeat this protection in so far as everything becomes active in the aircraft at the same time. This scrambles the logic of the TOT light circuit.
So, only connect the APU/cart lead to the aircraft when it is live and you won't have a problem.
Geoff
Last edited by Geoff Williams; 17th Aug 2013 at 23:19.
Reason: typo