PT-6 Starts

[Brantford Beech Boy]

got a raging debate at work right now.

you are away from base with no GPU. you start the first engine with the battery.

to start the second engine do you:

a)charge the battery down to below 0.5 (or lower) load and then a second battery start from the charged battery

b)do a generator assisted start

c)both a & b

I've always been told to never do a cross generator start and only use generator assisted starts if necessary (cold day/weak battery etc)

Now I'm being told to do assisted starts every time I don't have GPU in order to "save the battery".


I guess I'm looking for industry standard for the Kingair

cheers
BBB

[KAG]

I've done Gen assisted starts for 5 years in King Airs (100/200) for 3 different companies. No worries doing it. Never fried a battery or a current limitor.

[KingAir_pilot]

Hey KAG

we do the same on the 200 but what was your procedure on the 100??? do you wait after 20% or you put gen. online before that??

always heard that 100 C.L. are to ''fragile''!!!


thanks

KP

[oldtimer]

I have been starting PT-6's (DHC-6, PA31T,Be10,Be20 Be350) since way back when Christ flew for the Jewish Airlines and I have always done a Generator Assisted Start of the second engine and I have never ever burned out a current limiter. For all PT-6 powered airplanes, the procedure is quite simple.If you want to know how, just read the AFM. It will tell you to start one engine, introduce the generator and recharge to below approx. 40-50%. Turn the generator off,commence starting the second engine and reintroduct the generator through 15% ng or whenever the engine lights off. Plain and simple.
Here is the biggest reason.
A DC motor, as in starter, will produce maximum torque and draw the maximum power at stall. Once the motor is rotating, the load drops off. The load drops off even further when you have combustion assisted acceleration. By dropping the generator off line, you are no longer subjecting the electrical charging system to the big big load.
What the PT-6 needs is acceleration. The faster the engine accelerates, the cooler the start, and that is what you are attempting to do. More airflow means cooler starts.
By introducing the generator, you are assisting the starter to accelerate the engine more rapidly.
I have started both PT-6-28's in a King Air 100 without charging the battery with no problem. I have started a PT-6 28 and 42 with the generators on (cross-generator start) without a problem but I would be careful there.
In the Be350, they have a start current limiter in the smart GCU's so a cross-generator start is not only the procedure, it is the manditory procedure.

[Schlem]

I've done Gen assisted starts for 5 years in King Airs (100/200) for 3 different companies. No worries doing it. Never fried a battery or a current limitor.

No problem with the 200 with assisted starts just don't do them on a gravel apron unless the prop is over a pad. On gravel let the battery charge... I usually waited till the load was down to 30% then did the second battery start.

Never had a problem here either.

[KIAS]

Schlem,

I don't understand why the gravel vs non-gravel differentiation.

Just curious, can you tell us more about it...

[Scuba_Steve]

KIAS to perform a generator assisted start the engine has to be run up to high idle (65-70% N1), on gravel this would cause a lot of prop damage, unless as stated you are over a pad.

I've performed gen assisted starts on the Be90 and Be200 (or charged the bty and performed duel battery starts if on gravel) and a Cross generator start on the Be350. I came to the 90 and 200 from the 350 so it was a bit of a change for me to perform gen assisted starts at first so my first few times I performed a cross genrator start in the 200, never had a problem, but then I leared it was wrong. In our 90 checklist it actually has you perform a cross generator start, but since I fly the 200 as well as the 90 I stick to gen assisted as I don't want to accidently start the 200 cross gen and blow a current limited

Cheers

[Schlem]

Schlem,

I don't understand why the gravel vs non-gravel differentiation.

Just curious, can you tell us more about it...

As Scuba Steve stated... you have to run the operating engine in high idle and the prop must be out of feather and in fine pitch so on gravel this would pick up rocks and damage the prop.

[twotter]

Oldtimer, kinda hard to blow the current limiter on the DHC-6.. You may be thinking of welding the RCR.. There is however a procedure to do the generator assist start with them as well. The 100 and 200 are much more critical with the procedure than the 300 but it can still be done.

The whole question depends on what kind of airplane you are operating. Once you get into the newer airplanes, they are quite capable of doing cross generator starts and it quite the norm.. Think anything with a PW engine among others of course.

But as mentioned, with the KA series it should be no problem.

[Doctor Evil]

I understand the idea of not picking up prop damage during starts on gravel but was just wondering if there was an actual limitation in the AFM regarding use of high idle in feather(on pavement)?In the B200 there is a torque limit of 1100lbs below 1600rpm but thats all I could find.

[Schlem]

I understand the idea of not picking up prop damage during starts on gravel but was just wondering if there was an actual limitation in the AFM regarding use of high idle in feather(on pavement)?In the B200 there is a torque limit of 1100lbs below 1600rpm but thats all I could find.

I haven't flown the B200 in a long time and don't have the manuals anymore but I would never have the prop feathered in high idle... too much side loading.

[Spinner]

Also look out for generated heat blowing on the side windows from the exhaust with the prop in feather. Quite possible to damage the windows.

As said the idea is to kick on the other generator after the initial start sequence. There is quite a healthy amp kick to getting that engine turning.

[sky's the limit]

In the Bell 212, the 1st engine is started with both batteries On, the second engine with the Gen On, and both batteries On. You just leave the 1st Gen On during the whole start, no worries. -38, no problem.

Fuel is introducted at 12% and you're off.

STL

[KAG]

I've done Gen assisted starts for 5 years in King Airs (100/200) for 3 different companies. No worries doing it. Never fried a battery or a current limitor.

No problem with the 200 with assisted starts just don't do them on a gravel apron unless the prop is over a pad. On gravel let the battery charge... I usually waited till the load was down to 30% then did the second battery start.

Never had a problem here either.

Seriously, I've done it on gravel and have had very few dings on the prop - I'm anal about prop dings. When I start the 1 engine using the BATT (I start it in FINE), and lift the power lever over the gate and get it into beta at it's most fine blade angle once the engine is running and the prop is on speed. Then I place the engine in high idle, and start the other engine.
The biggest thing is to sweep very well under the prop and in front.

I also shut down in fine, and feather through 30%. Might be because I was origionally taught that way, but I do find it kicks up less crap when there is no power when feathered.

Also, one thing borek didn't do, but I thought they should of is use inertial seperators while opperating into or out of gravel strip. Still can't figure that one out.


Cheers.

[just another pilot]

We used the separators on gravel starts with the 200/350 at G of A.

[Schlem]

Seriously, I've done it on gravel and have had very few dings on the prop

Also, one thing borek didn't do, but I thought they should of is use inertial seperators while opperating into or out of gravel strip. Still can't figure that one out.

I never entertained the thought of even attempting a gen assisted start on gravel... didn't want to take the chance but interesting to hear that you had no problems with it.

We always operated with the ice vanes open in and out of gravel.

[twinpratts]

That's much too complicated.
The right answer is to go back to the hotel...hopefully they're still serving breakfast.

[Lommer]

For us newbs, what's and inertial separator and what's an ice vane?

[Schlem]

For us newbs, what's and inertial separator and what's an ice vane?

Rather then me explain it here's your answer. On the King Air 200 they are called ice vanes and on the PC-12 it's called an inertial separator.

http://www.flightlevel350.com/forum/lof ... t6983.html

[Scuba_Steve]

For us newbs, what's and inertial separator and what's an ice vane?

basically they are one in the same, its a vane/serperator that extends in front of the airflow coming into the engine prior to the compressor turbine inlet, which basically changes the path of the air coming into the engine itself, it requires any/all air that is to enter the compressor turbine to in essence make a 90 degree turn to enter the turbine, the theory is that any particle (rain ice, gravel etc) will have to much intertia and will continue moving forward while the lighter air makes the turn, and will just spit out the back of the nacelle through a outflow opening that opens up when you deploy the vanes. At least thats how it works on the king air. You lose some engine power when you do this, as you ITT rises and you loose some tq. So you only use it when flying into visible moisture below 5 degrees or into gravel strips

hope that helps.


And yes I've flown with a operator who never used them on gravel, and I've flown with a operator that used them when on the ground at ANY airport. In fact when I was taken flight safety training they said to use them at all times durring ground operations to prevent fod. That was on the 350. With my current operator we deploy the vanes prior to landing at any airfield in the winter, and leave them deployed for ground ops until we line up for departure on a cleared runway.

Cheers