Gday E1453,
Well good posts sofar all the B200 Gurus(OzExpat and Stallie). Im not one,maybe a A90 Guru and a Twotter hacker. But mate generally engine wear with Turbines is done during start up and shut down. You have to take note of the Limits in ITT, and stick to them, but not use them as a power setting (as some people). For example on a A90 the Max continous ITT in the cruise is 705. Now thats a limit , never set it in the cruise.
Also monitor and record you start temps. The limitation we know for all PT6s is 1090 for 2secs. And not to add fuel unless you have a sustained N1 RPM of 12 %. Well ill tell you it will start at 12%! But man your gonna get a really exciting start temp from that. The trick is to recognise this before adding fuel, could be bad GPU, Battery or Startergenerator. Youll here it spin up alot weaker and you may notice the Bat volts get loaded down t0o much. If it is abort the start and get a tech to check it out , dont add fuel, or you get a start , but you may shave many hours off a good engine. Every engine temp spike contributes to blade and Hot section damage over the long term.
Funny thing, people talk about reduced power take offs in Turbo Props. A definition of this, maybe needed. Basically we all do reduced power takeoffs, especially in the Tropics because we get to Our ITT limit much more easily, due to the increased ambeint Temp. When I I flew Twotter -200S WITH -20 engines we had 90% power takeoff cards that we used to set the TO Torque with OAT and TOW, if I am recalling basically it was the same input as on the Torque computer which Dehaviland supply with all their Twotters.
We would have reduced torque settings. If there would be a setting for 2 engines and one for 1INOP which was alittle higher.
Ofcourse when I moved to -300Twotter the temps limits were still there but the engines were alot more accomadating.
Yes bleed air effects power output. But only slightly. With nothing touched after turning on bleed air you notice a slight reduction in torque and slight increase in FFlow.
Fuel efficeincy you will get better with altitude ,just like your 737, no difference really. And the most optimum will be very close to your Max ITT Cruise limit incidently.
When I level off at around FL200 in my A90, I set up the props to 1900 RPM as specified. But if I forget to bring back the RPM to 1900 from 2000 then Ill notice small diffference in Torque and Fuel flows. AT 2000 RPM for a given torque setting I get a a higher fflow than for say 1900RPM. Why you ask? Well its designed for it the Reduction Gear Box and the mutlitude of test flight hours done by the Beech People got the optimum setting. All the Crusie Power Tables in A90 Manual anyway use 1900PRM.
Anyway enough of my blithering
Hope it helps
Sheep
Yep Ex A90s and C90s are
, but hey thats what all the other ones got their genes from.