Dennis-
I don't know the source of your wisdom regarding the T62- the engine Eagle is using with the large turbine nozzle is rated at 60KW for all conditions below 8000 feet and 125 degree ambient and as such has PLENTY of margin.
If you refer to the 30KW version with the small turbine nozzle, this one will run hot and will have less life and little margin dependent on ambient.
For the 60 KW engine number of starts is going to be more of a limitation than time at temperature/power.
avk
I won't get drug into a debate again on using an APU as a primary power source for a helicopter, so I will leave a bit of hard learned wisdom and just let you guys chew on it. The problem with trying to discuss these engines is mostly based on dreams, hopes and faith. You can't argue or reason with people when you are up against those things.
Over many years now, people have archived flying helicopters with these little single-stage APU's. Actually, that is very easy to accomplish, but, the person does achieve hero status afterwords, because everyone loves the sound and smell.... You do read about all the successes of their first hours of flight, and left with the impression that it is a successful endeavor. The fact is with all the hundreds of installations that have been made, you don't see them around after awhile. But yet, you don't here about the end of the project, so you are only left with the memory of the initial successful beginnings of the project. There is a reason for that...
When a person succeeds in the installation and flights of an APU, they do achieve the status of greatness and successfulness, and are proud of their accomplishment, as well they should be. But later, after they start burning up the engine a few times, it is a little hard to announce that your project didn't work after all. That is understandable, and that is why you hear of so many of these first successes, and then silence later.
I'm not going to get into why these units will burn up, because it will start a never ending debate of which I am not willing to invest the time, because I can never win an argument against people that want these engines to be a reality.
I will say that every engine made is designed to have an operational duty cycle parameter. That means what percentage of the use of the engine is operated within it's working parameters. Some engines like APU's are designed to operate at 25% of their 100% power 98% of the operation, and doing this will last thousands of hours, let's just say 10,000 as a number. By operating at 50% does not mean the engine will be expected to last 5000 hours. It may only last 100 hours. Some of these APU's are being ran at 75, and even 95% power to fly these helicopters.
Start cycles are a major factor in the life of these engines, and most of the time after being started, are left to run for hundreds of hours.
Shielding is also a major concern, because there is none. Real turbines are designed to contain a catastrophic failure, but not APU's, they rely on the aircrafts or groundpower units containment housing to do that.
I know, what I say is meaningless, I've been here before so I know the outcome of the debate and as I said, you can't argue against faith, hope and wishful thinking, and you will also argue that it is not just faith, hope and wishful thinking, I know, I know. The only way for me to win the debate is to let time take it's course, and even then I find that people have short memories.
Good luck, try to be safe going down this old traveled road, at least it's keeping out of the pool-halls.