PT6
Joined: Nov 2007
Posts: 2
Likes: 0
From: Australia
Just to clarify the generator thing. I mean turning on the generator on the first engine after 12% has been reached on the second (start in progress) engine which it sounds like you are doing anyway. Like you said this reduces stress on the generator.
If you did turn on the generator on the second engine during start it should have no effect. The starter takes priority over the generator, ie the generator would drop off line not the starter. I do seem to remember this may vary if you have older generator control units, so don't quote me on that one.
Cheers
Ian
If you did turn on the generator on the second engine during start it should have no effect. The starter takes priority over the generator, ie the generator would drop off line not the starter. I do seem to remember this may vary if you have older generator control units, so don't quote me on that one.
Cheers
Ian
Joined: Mar 1999
Posts: 220
Likes: 0
From: KDEN
Condition Lever to high idle has nothing to do with the generator shaft, (which never break, by the way.) The objective is to turn the generato faster, so you can get more amps out of it. PT6A-67D required 65% N1 for generator loads below 50% (150 Amps.) To use 100% (300 Amps) required a minimum N1 of 72%.
Some models of the KA200 do not have cross-start current limiters. Their absence allows massive amperage to be pulled on the operating generator and dumped into the cranking starter. To avoid this one can bring the running engine's generator on after the starting engine is rotating well and the starter's draw has decreased significantly.
Some models of the KA200 do not have cross-start current limiters. Their absence allows massive amperage to be pulled on the operating generator and dumped into the cranking starter. To avoid this one can bring the running engine's generator on after the starting engine is rotating well and the starter's draw has decreased significantly.
Thread Starter
Joined: Feb 2000
Posts: 731
Likes: 0
From: Pacific
My mechanic says the E90 (and a couple others) has the capability of starting with the generator on line. Also that it has a lead-acid battery which allows for a faster recovery. So far it has worked great for me. Apart from the climb rate (and I only use 1200 Tqe so that might be a factor) it flies well, and is very quiet. I checked the pressurization system by opening the bleeds and the dump valve (had a problem with a camera door) and the crew were much perturbed by the depressurization rate. Wooses all of them. Which brings to mind another non-PT6 question: Is it necessary to set the cabin alt control down before descent? If the alt flown has been around 15,000 the cabin is already close to sea level so a descent will simply hold that and the Diff will come back to zero even if the cabin alt selector is left at the cruise level? Can the cabin alt be flown through (negative pressure)? What would be a practical minimum Torque for descent? (I have been holding around 400 or when the gear horn sounds). Any particular emergency procedure that is popular with the sim training schools?
