In Response to aerobat77
On the PT6 the FTG contains Py putting pressure on the pneumatic bellows allowing fuel through the FCU, on initial startup, you are on the Min Flow valve/FCU bypass. As Py builds the bellows allow some flow through the FCU, through approx 40-45% the secondaries open, and "at least on the -67" at about 60% N1 allow full operation of the FCU. At least that is my experience.
Last edited by rigpiggy; 1st Dec 2012 at 10:30.
Reason: addition