King Air C-90

Some time ago I visited the Dallas Airmotive PT-6 hot-section shop at Love Field The purposes of the visit were to see what all was involved "behind the curtain" with respect to HSI repair/overhaul work, to glean whatever care and feeding information they might have accumulated that wasn't generally available to the public, and to perhaps be able to better differentiate fact from fiction when working on King Air acquisition deals for clients of the consulting business.

A set of new blades for one engine can cost $35-50k (if you're dumb enough to buy them) so owners are conscious of the need to obtain maximum life. Traditional advice regarding power settings has been "don't run the engines too hot or the blade tips will burn up" and shorten hot section life. As a result, many owners became very conservative with regard to temps, and flew at reduced power settings only to discover that sulfidation (a chemical process that causes blistering of protective blade coatings that will also condemn the blades was a significant threat as well. So more-recent word-of-mouth advice has been modified to include "but don't run them too cool or they will sulfidate."

Since many operators use trend-monitoring services to help detect engine health problems, I asked the shop guys if they could detect/correlate any significant operational patterns that might be useful insofar as maximizing engine life. Their tongue-in-cheek answer was "yeah, run them cool enough that they won't burn and hot enough that they won't sulfidate." They then said that most owners run their engines too cool and that sulfidation kills many more blades than heat, and they recommend using the "max continuous" temp settings rather than the "normal" temp settings to obtain best useful life. I haven't talked to Tom about his recommended settings, but sounds like he has come to the same conclusion by recommending the 90-1 settings for the entire -21 fleet.
 
The fuel flow on turbines below the flight levels is what gets to me, and of course each operator must choose his or her balance of speed and economy. When we're in the Commander, we basically file at FL260 or FL270, and do 250 pph each side. We might do a bit lower if strong headwinds, but not by much. The Cheyenne we'll do FL200 at 240 pph each side, and FL250 at 200 pph each side.

Basically, we've figured that, even with the worse winds, the lower fuel burn makes up for it. Seeing 140-150 kts ground speed while burning 500 pph combined in the Cheyenne is painful... to the person paying the bills. But the good part is I'm not paying for it, and I'm building turbine time. ;)
 
Wayne, must have been quite a while ago. The -21 will be a little cheaper than what I run but, one set of blades for a -61, 2 years ago listed for $82K. I actually paid a lot less around $45K but, that is for one set. Each engine has two sets of PT and one set of CT, can you say ouch.
I asked Tom Clements about temps I run which is 50 deg below red line on the hottest engine. He concurred with those parameters.
A turbine is a normally aspirated engine so it is very altitude sensitive. In determing altitude I first define the mission. Does the boss want to get there quick, screw the fuel then I will be at a little lower altitude. The plane should be its fastest (TAS) at the altitude the engines temp out. However, the fuel burn will be tough. The fuel burns are pretty bad on the -61 down at FL180 (they will temp at 17 - 18 thousand) but I can depend on 290 +KTAS. If I have a long enough trip I like to be above FL240 in order to get fuel burns down. On a standard day going from FL180 up to FL280 will lower my fuel burns by about 120-130 pounds total but I only give up about 7-8 knots. Pretty good trade off if winds permit and the trip is long enough to get up there.
I suspect the -21 will temp much lower, perhaps 10-12K on a standard day. This puts more of a limit on you options. Temps make a heck of a difference too. A little over a year ago on a trip to Cody I was at FL260 and had a TAS of 296 knots. I have a picture of the air data computer. The outside temp was minus 40 deg and I was useing around 325 pounds per side at that altitude!! Lot of air that day and VERY cold.
Each trip in a turbine will have to be looked at in regards to time to climb,(per cent of trip used to climb) distance of trip, temp, and winds. This is much more important in a turbine than a recip because of the altitude spread available to you.
Many turbine operators have a program (I use Flight Soft) that will give total fuel used verses time enroute taking into account the temperature, altitude and winds. As you go up or down in altitude it shows fuel needed and time enroute. This makes it a lot easier to pick an altitude for a particular mission. I highy recommend some type of program that will give you this info.
 
If you look at the numbers I posted above, I was at 14,000 and ITT limited torque, but not my much.
Yes Wayne, Tom send me a summary table of C90-1 performance charts and that's what I ran that day. We were faster then book than IAS on the chart he sent.
If you know how I can get a full set of C90-1 performance charts, I'd appreciate having them to compare. What Tom sent was just a one page summary of basic settings without all the other normally provided information.

Looks like 700CP is going in for Phase I and II inspections which the seller and I agreed to use as a pre-buy.

Best,

Dave
 
We had a -1 at the Brush Company for about 18 months, but that was many moons ago. But the good news is that if you trade up to a B-200 I can probably scavage up a heavy-ops performance supplement.


Dave Siciliano said:
If you look at the numbers I posted above, I was at 14,000 and ITT limited torque, but not my much.
Yes Wayne, Tom send me a summary table of C90-1 performance charts and that's what I ran that day. We were faster then book than IAS on the chart he sent.
If you know how I can get a full set of C90-1 performance charts, I'd appreciate having them to compare. What Tom sent was just a one page summary of basic settings without all the other normally provided information.

Looks like 700CP is going in for Phase I and II inspections which the seller and I agreed to use as a pre-buy.

Best,

Dave
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Yee haw! (Is that the proper Texas expression?) Hope you can bring it on the Caribbean trip next May! :)
 
Everskyward said:
:cheerswine: You still need to show it to me.
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Certainly. Crazy week for me that wasn't supposed to be so. All of it good, but there wasn't enough of me to get to everything.

It should settle down this week. Any time your back in, let me know.

Dave
 
gprellwitz said:
Yee haw! (Is that the proper Texas expression?) Hope you can bring it on the Caribbean trip next May! :)
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I'd have to have several folks along for it to make sense in the KA. One nice thing is jet A is easier to find at many out of the way places.

Dave
 
Dave Siciliano said:
I'd have to have several folks along for it to make sense in the KA. One nice thing is jet A is easier to find at many out of the way places.

Dave
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Since when has anything that we do with these damned winged things made sense? :goofy::goofy:
 
That's great Dave. Have fun. Fly safe.
 
Dave Siciliano said:
I'd have to have several folks along for it to make sense in the KA. One nice thing is jet A is easier to find at many out of the way places.

Dave
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Believe it or not, when flying up to Newfoundland a few weeks ago in the Cheyenne, the trip up north was lower in cost than flying the Aztec or 310 for that reason.
 
Great! Missed Sue and you. Bringing the
Leer (g). Actually, haven't heard anything about your plane with the funny tail for a long time!

Dave
 
Having flown this plane for a few months now and having taken a few trips, I have a much better feel for it's capabilities and what I like about it.

I just flew from Dallas to Greenville SC and back (728 miles) twice to bring family out and return them after a week stay in Dallas, and we all really appreciated the difference between it and the 58P. While I still love the 58P and will use it for some trips, with family and on longer trips the KA provides a lot more flexibility and creature comforts. OTOH, fuel burn is quite a bit higher, but not twice as much.

I've attached a pic of the panel on my return flight from SC to Dallas

First, the plane climbs much better and gets up to cruise altitude faster. It's not just the rate of climb, but how we're handled by center in it. They understand it's capabilities and step up us up faster than they do in the 58P. Even when leaving Dallas when it's busy, we get higher altitude assignments faster. Returning from Greenville, Atlanta brought us up to FL180 in one step from 11,000.

The plane is quieter and flies a bit smoother. All my passengers that flew in the 58 and now the KA have mentioned how they can talk in the plane without headsets and how there is less vibration in the plane. When we do hit some bumps, the KA does deal with them a bit better.

The potty is a real help on trips. My four year old GD gave it a real work out and even for me, it's much nicer when I can drink without worrying about having to land to use the facilities. For kids especially, it's great. It's just hard on them to ask them to control kidneys on what may be a four hour or longer trip. And the ladies seem to immediately bring out the facilities are important.

Having a little cooler and coffee pot adds nice touches to convenience. The walk up stairs to the cabin immediately make the impression that it's big plane to those that aren't pilots and the curtains between flight crew and passengers helps show it's size. It also insulates passengers a bit from the flight crew when that's appropriate.

There is plenty of room for luggage in the rear of the cabin next to the potty. It's been very handy and can hold up to 350 pounds in back. I can carry four reasonably sized adults and some baggage with full fuel. I'll have to look at the actual numbers, but the 58P was limited to 650 pound payload with full fuel. This seems to be over 900.

I've found flying in the low flight levels is where the plane does very well. At FL180 to 200 the cabin is below 7,000 feet. I run about 800 pounds of torque and get a nice balance between performance and speed. Usually about 210 TAS to begin and as high at 215 when lighter. I have about a six hour total range, which gives a lot of flexibility in all but the strongest headwinds. Just over 1,000 mile trip is doable with IFR reserves with headwinds under 25 to 30 knots. Going east to Orlando is easy. Coming back will require a stop if the winds are strong.

Fuel burn is about 50% higher than the 58P for the same trip from what I see now. It takes much more to climb, but I get up faster. In cruise at this power setting, about 50 gallons per hour seems right as compared to 33 for the 58P. I'm still comparing a bit and the fuel flow gauges aren't digital, but it's less than 60 gallons per hour in cruise as I'm averaging that for a four hour trip and use about 90 in the climb. I landed in Dallas with just over two hours of remaining fuel on the last trip.

As I think of more, I'll post it, but this really fits my mission when I need an SUV for family trip.

Best,

Dave
 

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Ted DuPuis said:
Dave, combine the WAAS upgrades with an Aspen or a G-600 and then you're really styling. ;)

Looks like a beautiful plane. Definitely a great panel, pretty similar to the Cheyenne that I fly from time to time. Are the engines on MORE?

The "thought they would keep it forever" owners are usually the best to get a plane from. The 310 is certainly in good shape for that reason. The Aztec will be good for its next owner as well, same reasons.
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We did the WAAS upgrade and GPSS steering. Looked at the Garmin 600 but we have a 200 and it gives a lot of what would be duplicative capabilities; so, we'll stay with that for now. Put headset jacks in back for four passengers.

Best,

Dave
 
Dear Dave,

You don't suck.

Love,
PoA

(just thought I'd shake the meme up a bit)
 
Looks like temps are running pretty cool. Do you cruise 2,000 RPM N2?
 
Actually, I was just using a power setting I had used before to compare. I've started running about 800 pounds of torque and find it isn't a lot higher fuel flow and TAS is in the 210 to 215 range with just over six hours of endurance. I'll take some pics of that. I have the numbers from the last flight and will post those. Still want to try a bit higher with higher power and look at fuel flow. Generally, I'm very pleased with the 800 pound performance/fuel flow.

Dave
 
Here are the numbers from a flight on April 9th where I ran 800 pounds of torque per side.
-14C
Fl180
IAS 159
ITT Left 595; right 593
2000 RPM
N1 Left 91.1 Right 91.1
Fuel Flow: left 190 right 210
Oil temp: left 53 Right 50

It's apparent the right FF gauge is high. When I fill the tanks, there's not much difference in the sides and the right consistently shows higher consumption. The left seems to be closer to what we actually use, but the tank gauges don't drop evenly; so, difficult to really be precise in flight. I have run the tanks down to 210 pounds and I'll top the plane for a trip Tuesday to see if that's really accurate.
 
Looking at my performance tables: this was very close to a standard day. -16 would have been. I was running 2,000 rpm and the book numbers are at 1900
The book called for 909 pound of torque; FF per side should have been 216 and TAS for 8500 pounds should have been 218. On my next trip I'll pull the props back to 1900 and check the number by putting in book torque, but I seem to have been doing pretty well compared to book. I was running over 100 pounds less torque; FF was of course lower, and TAS was about 216 according to a calculator I used. Of course, I haven't done the triangular pattern yet for Air speed correction and my left airspeed indicator is 3 to 4 knots higher than the right; so, I still have some tweeks to make. But with what I see now, I'm doing a bit better than book.

Maybe Doc Bruce and I can take it up at Gastons and really figure it out.

Best,

Dave
 
I have a summary chart of the C90-1 power settings from Tom Clements. That chart shows maximum power at 1077 but the chart doesn't show what the fuel flow and TAS should be there; so, until I get more complete performance charts for that plane, I can't really compare it. I have run it with power that high and found fuel flow was much higher for the small increase in TAS.

So, I've kind of determined that 800 pounds of torque is a very nice point for the trade between speed and reasonable fuel usage. If sulfidation is an issue, I'll run it with more power on occasion to address that. But in general, the higher fuel usage for the small increase in TAS isn't worth it to me.

Best,

Dave
 
The Pratt & Whitney hot-section repair guys at Dallas Airmotive (at Love Field if you ever want to stop in and see their operation) say they see more blade damage from sulfidation than from running too hot. Max continuous for the -42 in our B-200 was 770C, they recommended at least 760. Max allowable is 800C.

Dave Siciliano said:
I have a summary chart of the C90-1 power settings from Tom Clements. That chart shows maximum power at 1077 but the chart doesn't show what the fuel flow and TAS should be there; so, until I get more complete performance charts for that plane, I can't really compare it. I have run it with power that high and found fuel flow was much higher for the small increase in TAS.

So, I've kind of determined that 800 pounds of torque is a very nice point for the trade between speed and reasonable fuel usage. If sulfidation is an issue, I'll run it with more power on occasion to address that. But in general, the higher fuel usage for the small increase in TAS isn't worth it to me.

Best,

Dave
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Dave Siciliano said:
If sulfidation is an issue, I'll run it with more power on occasion to address that.

Best,

Dave
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I don't think that will work. Once the sulfidation occurs it is there until you replace the blades.

We learned the hard way on our -41's. Baby them now, pay later.
 
Houston, we have a problem. I don't have C90-1 performance charts and the C90 was derated. This plane seems to have done fine using book numbers so far, but the C90-1 higher power settings are where Tom Clements recommends running them. So, how do I get a copy of those charts?

Best,

Dave
 
Does anyone have a reference for checking the indicated airspeed indicator in the air? As I recall, one ran a triangle of a known distance with the GPS and compared the three legs. Can anyone point me to a good explanation of how to properly perform it?

Thanks,

Dave
 
I'll check the file. I flew a 90-1 for several years, then when I taught at SFI and then operated my own KA-90 school I had all of those charts. Whether it's still in one place at this point is unknown, haven't had need to use it for several years.

QUOTE=Dave Siciliano;881523]Houston, we have a problem. I don't have C90-1 performance charts and the C90 was derated. This plane seems to have done fine using book numbers so far, but the C90-1 higher power settings are where Tom Clements recommends running them. So, how do I get a copy of those charts?

Best,

Dave[/QUOTE]
 
Dave Siciliano said:
I have a summary chart of the C90-1 power settings from Tom Clements. That chart shows maximum power at 1077 but the chart doesn't show what the fuel flow and TAS should be there; so, until I get more complete performance charts for that plane, I can't really compare it. I have run it with power that high and found fuel flow was much higher for the small increase in TAS.

So, I've kind of determined that 800 pounds of torque is a very nice point for the trade between speed and reasonable fuel usage. If sulfidation is an issue, I'll run it with more power on occasion to address that. But in general, the higher fuel usage for the small increase in TAS isn't worth it to me.

Best,

Dave
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King Airs are not immune from exponential fuel for speed growth. The only time great excess HP is of economical use is in climbout.
 
Dave Siciliano said:
Does anyone have a reference for checking the indicated airspeed indicator in the air? As I recall, one ran a triangle of a known distance with the GPS and compared the three legs. Can anyone point me to a good explanation of how to properly perform it?

Thanks,

Dave
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AC 90-89A. Page 43

It's not a triangle but it gives a procedure.

Alternative is fly a triangle with 60 degree angles between legs. Average the three speeds.

For either option, you can do timed legs And whiz wheel. Or use gps ground speed.
 
Thanks Dave, I read through that. I lean toward the triangle with 60 degree turns. The two directions seems to get one in the ball park quickly. May do both over a period of time. I have timed myself on an airway segment and may to that on a trip to Orlando next Tuesday, but it's only one way on different days (flight out and return).

Dave
 
No luck on 90-1 operating/performance stuff, only some limitations. The good news is that if you trade that dog for a B-200, I've got an entire library.:D:wink2:

I found that 1,900 N2 is much more comfortable on the ears, and I think a bit more efficient. Torque increases just a little but SHP remains relatively constant using the torque X N2 X .0199 formula for PT-6A engines.
 
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