Supervan900

I would go head to head with the Blackhawk -42A conversion any day they want to do it especially if we could video the results, but I doubt we would ever see that.

TOTTER. You are making more sense, but you are devoted to a Pratt. I am devoted to the engine that makes the most sense for an operator. If Pratt had an engine that would make the power and could be operated at as low an operating cost, I would have put it on in a heart beat, because it is an easier sell. My point is that the TPE331-12 engine cannot be beat in any category on the Caravan versus an equivalent Pratt including reliability. That is why I had to go with the Garrett for the long haul. The Pratt would be an easy sell, but would really not be cost effective over time. I am looking out for the end user not Pratt or Honeywell.

That is again relative to a twin engine application and those don't necessarily cause a melt down just handling problems as you transition toward reverse. That has nothing to do with a single and there is a lot of flexibility in the rigging whether it be flight idle blade angle or flight idle fuel flow. I haven't seen either one cause a meltdown just differing control or handling issues.

Any idea what the average turn time was. PST is ~400msl is it not? OK, this is my last report on this plane because we are not getting it next year apparently. I asked the DZO (not the pilot or the owner) for the numbers for a 30C day and got this... Hmm. At 30 C, the data are pretty limited; we had very few warm days this year. I'd guess that warm, we'd be looking at 20 minute turnaround with 18 or 19 jumpers. Typically 17 gallons (US) per load. Sorry to hear you guys aren't getting it next year. The actual climb time on a 30C day from 700 MSL to 14,000 MSL is 12 min 43 sec at 9000 lbs (or 19 jumpers) or conservatively 14 minutes. and the fuel burn is around 14 gals to altitude. I use a conservative 17 minute turn time with about a gallon a jumper at gross wieght. The fuel burn should be less and that is figuring the average pilot. There should be some more airplanes out there this next summer so maybe you'll get another one up there.

Since we are on a first name basis, who am I talking to??? (just curious) I agree that time will tell about reliability, so people don't need to instantly assume it will have the failure as another dash number engine. The fact is that both engines come apart in spectacular fashion (i.e. uncontained) when the t-wheels come apart, which has been happening quite a bit with the CT's on the -114A engines (See Pratt SIL No. PT6A-160). As a matter of fact, a DZ right next door had an uncontained -114A failure. Our customers alone have run almost 50 engines for hundreds of thousands of hours on the Otters and Caravans and we have not had one turbine failure in the 9 years we have been selling them. This debate can go on forever, but there is no factual evidence to support your argument about uncontained failures on 331's vs. PT6. Let keep to the facts instead of opinion. As for rigging, not true. You have quite a bit of flexibility on a single engine airplane with a 331, just not so much with a twin because of the fast engine response (i.e. Beta toward reverse). Just for clarity how many 331's have you truly rigged???? Not trying to be mean, just checking.

"Blame the pilot", the mantra of the aviation industry. The only engine I've seen "grenade" was on a Skyvan, and I've probably made 100x more jumps from Otters than from Skyvans. When talking about engine failures, it is always funny how people can remember that a Garrett blew up on a Skyvan and put a few holes in the airplane, but forget about the PT6 on the Twin Otter in Missouri that blew up and people were killed. Check out the NTSB website: http://www.ntsb.gov/publictn/2008/AAR0803.pdf And another recent skydiving PT6 engine failure: http://aviation-safety.net/database/record.php?id=20080601-0 The fact is all engines can fail and their reliability is heavily dependent on the operator and the maintenance. Here is another great educational report for those that have time to read it (36 pages), but it explains things that damage turbine engines: http://www.atsb.gov.au/publications/investigation_reports/2005/AAIR/pdf/aair200507077_002.pdf

You ever consider what's gonna happen when the engines quit on either one? When you are simply increasing your gross with added horse power, the your big shinny bird is going to come down much faster. I think time will tell, and I don't think the "SuperVan" is going to be the dream that skydiving is searching for. The Supervan 900 conversion uses the same gross weight increase as the stock airplane to 9062lbs. We did numerous in-flight shut-downs for certification and it glides nice, just like the original. I am not really sure how more horsepower makes it come down quicker. I don't expect it to be a dream, just a cost effective aircraft for the DZ so they can make money and save you money.

We tried to get a fly off done before the season ended in Alaska, but we couldn't get it done. It would have been fun to see, because the Otter does have the slower flying wing, but the 900 shp accelerates quicker. Maybe next year.

The problem is that it is still there for everyone to read and has a lot of mis-information. Just having fun responding, but would rather be skydiving.

TOTTER Check out the video on Youtube. I would actually put this Supervan 900 amphib up against the PT6 powered Otter. The Otter has a higher lift wing, but the Supervan has the raw horsepower. He had around of 2000 lbs of fuel on board. http://www.youtube.com/watch?v=k8C85frEgLQ I agree that the stock amphib Caravan has a long water run.

Under a standard TBO, 3600 hours for a Pratt & 3000 hours for a Garrett, the Hot Section Inspection requirement is 1/2 the TBO. 1800 for the Pratt & 1500 for the Garrett. No start or cycle requirements. For operators that have received a TBO extension the Hot Section Inspection requirements are closer together. It depends on their approval. So, for an operator that gets an extension to 10,000 hours, they may be doing a HSI, Hot Section Inspection, every 800 hours. The company that I work for, Part 135, has an On Condition Program for our -34s & -135s. We have no TBO. We can run the engines for as long as we want, changing Life Limited components of course. To do so, though, we have to do borescope inspection of the Hot Section, which is the same as splitting the engine, every 400 hours. Quote Not to pick on you TOTTER, but the base TBO on the TPE331-12 engine is 5000 hrs non-commercial and 7000 hrs commercial with one hot at mid-life. An operator can get 1000 hour extensions on that per the service bulletin. I do agree that a hot on a 331 requires more disassembly than a typical Pratt hot, but not sure if it takes more skill. They both blow up if assembled wrong.

I am sure that I am going to drive everyone nuts with the replies, but I am just reading these comments from 2 years ago up to now. I just want to make sure that everyone has the right information and then they can make their own educated decision on what is the smart way to go.

This is another funny example of someone not knowing what they are talking about. The author states the Garrett grenades for the TPE331, but calls the TFE731 fan engine a very reliable engine. The nickname "garrett grenade" came from the early TFE731 engines that would have catastrophic high speed gearbox failures. The slogan had nothing to do with the TPE331. Garrett made changes to the gearbox design and it has become on of the most reliable biz-jet engines. All engines go thru there learning curve just as with the PT6 engines. Please review the AIN survey of actual operators that ranked the TPE331 engine the best in all categories. This was an independent survey of operators, not just people's opinions.

Now here is another example of speaking without understanding. There are numerous examples in aviation where the Garrett powered aircraft outperform there PT6 counterparts. Take for instance that most of the fastest and fuel efficient aircraft ever built were TPE331 powered. Examples, Conquest II, MU-2, 690 Commanders and up, Metros, Merlins, Cheyenne 400LS, and the B100 King Air just to name a few. On the Caravan, the 331 is definitely louder on the ground than the PT6, but is actually 3-4 dB(A) quiter for the same altitude in flyover. The noise is the cabin is noticeable less as well. As for more spool up time, you have obviously never flown a 331 engine. They are hands down the fastest responding. Don't know what you are talking about with shutdown problems. I have had more hot starts on PT6's in Twin Otters than with the 331. Do you run a PT6 and 331 overhaul shop? How do you know the wear and tear problems that you claim they have. "More shafts to turn"... The PT6 has two gearboxes and more accessory drives....that makes a lot of sense. I would bet that you have never flown a 331 powered airplane for any length of time. Anyone taking bets. If you have not, again, you may not want to comment until you have thousands of hours flying both engines. I have attached a head to head comparison between the 900 shp TPE331 and it closest Pratt counterpart the PT6A-42A. Please let me know if I missed any categories. (I don't have any legitmate numbers for the -42 in-flight shutdown rate or I would have included that as well).

Basically thats correct. The Garret has two shafts. One runs inside the other. One is for the Power Turbine, that drives the prop. The other is for the Compressor Turbine, which of course drives the Compressor. When the engine is shut down the outer shaft begins to cool down. The inner shaft stays hot. This causes the inner shaft to "Bow" and it will rub on the outer shaft. By pulling the prop through after shut down the pilot is running cooling air through the engine so that both shafts cool down equally or close to it. I do agree with everyone. Give me a Pratt any day. Even a R-985 radial is more reliable then a Garrett. This comment is the funniest one yet. This is a prefect example of someone that should not comment on the subject. He basically describes a free turbine engine (i.e. PT6, etc) The TPE331 is a single shaft engine meaning everything is coupled to the prop. There are bearings on each end of the shaft that support the rotating group. The shaft bow is mostly an issue with a fresh overhauled engine or new engine due the tight honeycomb seals between stages. The engine over time will cut into the seals as it breaks in and lessens the damage that can occur with shaft bow although it is always good to spin the prop after shutdown.