Back in the early 80's when I was flying behind a PT-6, once the intertial separator was opened, it couldn't be closed again until on the ground (lest you FOD the motor with ice built on the inertial separator door). Is that still the case?

Myron

In any visible moisture turn it on. In the clouds it goes on. Then usable power is a function of ITT. At altitude it is a huge hit to performance as I can only get to about 85-90% torque instead of up to 121% (although I don't go over 115%). Speed is degraded from 310-315 to about 275-280. Today flying from Gaithersburg, Maryland to New Haven, Ct. I had it on about 50% of time as we kept climbing through layers. Then from KHVN to KBMG we probably had it on for 1/3 of the trip. Had it on briefly departing KBMG for home as we through flew through some snow.

It does slow you down. But, all in all, the performance is still pretty good. We flew well over 1800 NM today (SIX reroutes from KGAI to KHVN plus step climbs and step climbs and reroutes on the second leg and still total flying time was just shy of six hours.

Wow, that is significant. 304 to 262 knots is a thrust reduction of 36%.

Oddly enough, for a TPE331, visible moisture allows us to INCREASE power slightly. The water ingestion lowers temperature so we can run higher power for the same temperature. The extra heat goes into vaporizing the water, turning it into steam, rather than just heating the air.

Indeed, there is something called alcohol water injection (AWI) which is an emergency mode where water and alcohol are injected into the intake to allow the engine to make extra power, say, in case of engine out. The alcohol is primarily an antifreeze. MU2s do not have AWI, I think that is mostly on Merlins since they are so heavy and marginal on one engine.

When I enter rain, my temps go down. When I exit, they go back up. So one must be careful if you try to use the extra temp margin for more power, it will go away and you could mildly over temp your engine.

Turning on inlet deice does lower power, though, more than moisture would give back.

Mike C.

Not all PT6's are affected by the intertial separator (IS), the Meridian M500, runs a very optimized (IS) all the time, so VMC, IMC, ice, always get the same performance. We had a pro-pilot for a while that flew a few TBM's as well as our Meridian. He said the Meridian was as good or better climbing and cruising in IMC and ice due to the IS as the TBM. I fly so much IMC living in the Pac NW, really enjoy not having to think about the IS. On those clear days though, if the Meridian had the ability to close the IS, would get some more performance. From a well respected P46 guru, he says that the IS in the Meridian is also better at preventing FOD. Says that he sees it less in the Meridian than the Jetprop with a switchable IS.

Garrett's don't have IS. The anti-ice does rob of little power, but very little. I've not noticed much speed reduction, but then again, have only used it twice.

Garretts have stout compressor blades (the compressor visible in the engine "smile" and aren't required to have IS. The anti-ice consists of bleed-air heat applied to the smile area. There is a little power loss due to robbing some bleed air to heat the inlet.

Dang that's significant. The nice thing about the 850 is that it still makes 700 performance with the IS on!

Don,

That's the piece we left out. Our 850's when in 700 mode have an automatic TQ limiter. When you are in 850 mode, PIC is the Tq limiter. IF you make the mistake of having it in 850 mode and throwing the inertial separator switch to engage.

That there is going to hurt the wallet!!!!

The TBM is only working with 700 SHP available when the IS is engaged due to the above. So at altitude you are already down some part of 17.65% when not in 850 mode.

Had 105KT head wind at 280 today on the nose heading 340 out of FL. My oh my did that take a long time. Later descended when the lower altitudes winds decreased in north GA.

Rough ride today too. Everyone around ATL was complaining. No good altitudes. But better than yesterday.

Chuck flew home from Ft Myers today. OMG.....headwind sucked !?! At one point I had 125 on the nose! First time I have ever stopped for fuel on this trip. I had to stop in Chattanooga for fuel.

I had headwinds coming down on Saturday and headwinds coming home.

A little thread drift. But I hear people talking about phenoms, CJ's, mustangs.......what about Lear 30 or 40 series? I have NO experience. I know they are not single pilot but I usually fly with my wife (also a pilot). Are they maintenance hogs? Jeez they have great speed and range and climb like a homesick angel. What about the falcons 10's or 100's?

IS on the PC12 costs you about 7 knots.

After looking at part costs and avionics, if the Part 23 does not right the ship, that Evolution is one incredibly sweet bird!!!!

Mike,

The Lear 40XR is the absolute most bang for the buck right now. The operating cost are higher than a Citation, but it is much faster and the cabin is MUCH bigger. The biggest objection is the two pilot requirement, but IMHO it's always good to have two pilots at the helm of a high performance jet.

The aircraft was never very popular when new because it was so close in size and performance (and price) to it's longer cousin the Lear 45XR. The logic was to just get the 45 instead, the result was many of the 40XR's became Flexjet airplanes, those airplanes have been hitting the market well below $2M and that has changed the dynamic considerably! There's tremendous value in a 2006 - 2009 airplane with that performance that doesn't break the bank from an operating cost standpoint.

Regarding the IS, as your performance decreases so does your burn rate just about proportionately, so it may not materially affect range. In the 700 you have to engage or disengage at IAS < 180 (book says 200).

Chip,
If the 40XR still has the Primus 1000 isn't that a cause for concern?$$$$$$$. Is it even repairable? Anything Honeywell is costly. (Sorry Honey Ee's) What are the ballpark hourly costs?

Chuck,

The Primus 1000 is really a pretty good system. Honeywell still supports it, but we do have an excellent alternative authorized repair facility that is more economical.

The operating cost of the 40XR is about $1650 per hour including MSP. Nice big cabin, 1700nm range and 425 kts... not bad!!!