Hi there Copterfan. A Hot Start is an exceedence in temperature when starting. Simple really.
Basically the TOT, or Turbine Outlet Temperature, becomes too hot and can cause damage to the engine. The hotter, the larger the repair bill!
They normally happen due to a low battery. They will NOT happen if the pilot is paying attention!
A basic start involves spinning the turbine up via the start button, then introducing fuel with the throttle. If you do not have enough engine speed, ie cold air coming through, then the fuel will ignite and it will very quickly become too hot in the engine. You also need plenty of power in the battery for it to reach a "self sustaining" speed where it no longer needs the starter motor spinning, to keep things happening. This is a VERY basic discription of the procedure
Cure? simply close the throttle and keep your finger on the starter until the Temp drops below 150.
Joined: Mar 18, 2006 Posts: 16 Location: San Diego, CA
Posted: Fri Mar 24, 2006 8:34 pm Post subject:
If you have access to one, an external power supply will get the starter up to speed a lot sooner than a battery. The N1 will be at and above 15% before you know it, and the turbine temperature will be much, much lower after lightoff. (Ensure you get the twist grip open as soon after 15% as you can.) The external power will also get the N1 turbines up to 58% quite a bit quicker than with a battery start. This will also allow (and require) the starter and ignitor to be engaged for a much shorter period.
Joined: Feb 26, 2006 Posts: 236 Location: Cheshire.
Posted: Fri Mar 24, 2006 9:58 pm Post subject:
Thanks guys, amazing responses, as usual.
thanks for the reference, and didn't WW come up with the goods? I too followed the Ec120 thread, and came to the same conclusion about the money, especially with all the other niggly things that required expensive maintenance.
Hello back, and thanks for the great answer. It's good to know that it's the nut behind the cyclic that's at fault and not the helicopter.
thanks for this great tip, I will certainly remember it and consider it as part of the costs.
Wow, what another amazing answer with diagrams and photo's too. You excel yourself as usual, thank you.
OK; the reason I'm asking this question is that I am re-considering my training options (thanks for the great help you've already given me on this point WW ). I went to Heli2000 t'other day and had a good look at the R-44 II. I joined in with a chap who was type-converting from R-22 to R-44 (on the A-check). R-44 is lovely and flies very neatly, but I was amazed how much the tail boom shook when the rotors were winding down.
After considering costs, and my turbine ambitions, and my plans for next year too; I came to the conclusion that it would be better, or should I say, more cost effective long-term, to do it on the B206. I know WW that this was your initial advice and conclusion, feel free to regale me with howls of derisive laughter...
So, having been round the Mulberry bush at least twice, I feel I have a workable plan.
WW; could I send you a .pdf of an aircraft I have found for sale? I think that I have a basic idea of hours, years, cost, equipment etc. But I wondered if you could just look and see if the aircraft is, at all ballpark ?
BTW; I didn't pm you initially because I didn't just want to bombard just you with questions.
With regards to the term "Hot Start" WW is refering to a start that is warmer than normal. A Hot Start generally refers to an exceedence.
You will find that the engine is almost self-sustaining at about 46% N1 onwards. Have a look next time you do a start and watch the TOT drop away at about this point(but don't take your finger off the starter!!)
If you think you Ex-power is a bit low then keep the battery switch on as well to help.
The best start is one that is quick, with the temp around 800. Don't get fixated on reaching 15%. If you hear it starting to "hang" another words that is as much as you will get out of it, then light it off. Remember you still need some power to get it self-sustaining. You can light it off at 12% depending on the outside temp, just make sure that if you do a start not long after a shut down, make sure it is below 150 before lighting it off.
The more you do, the more you start to get a feel for it.
BUT, don't ever think it will always be normal.
I have been caught out by a stuck throttle cable, where after a compressor rinse, and pushing the ignitor CB in, it immediately lit off (throttle still closed!) and I watched as it raced up to 890, hung then slowly dropped below 810.
What ever happens, KEEP YOUR FINGER ON THAT STARTER BUTTON
R-44 is lovely and flies very neatly, but I was amazed how much the tail boom shook when the rotors were winding down.
Don't be put off by that - firstly they'll not all be the same. Secondly, if you (sensibly*) play with the pedals a bit, you'll eliminate some of that wobbling. Largely caused by the tail rotor still moving air around.
The main rotor too will cause wobbling, again just gently adjusting the cyclic can alleviate it.
(Sensibly in the case is don't put it to the extremes at relatively high rotor speeds...! _________________ J.
WW, warmer than normal is what I thought you meant as you said you had 6 Hot Starts in 1 day. I can understand 1 off a weak battery, then another off a low GPU, but then 4 more? from the same GPU? or from 4 different one's?
Which model 206 dosn't let you start with the battery on?
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