Supervan 900 - Caravan engine mod

The plane is stripped down, has a gross weight increase kit, and the 331 engine. The plane is under max TO weight, with-in CG limits, has the required amount of fuel(3 loads plus 45 minutes of reserve), and uses "live"weights of the jumpers as produced by manifest.

As for king airs being faster, why of course they are but they burn more fuel, require more maintenance, have small doors, and are generally hated by fun jumpers.

PT6 VS Honeywell

That debate will always continue, however the Honeywell is a nice engine and provides the Grand Caravan with the power and speed it deserves.

Seat Belts

The number of seat belts is part of the STC for the jump mod.

Engine Out on takeoff

Any aircraft including Otters and Skyvans having an engine out after takeoff sucks and usually ends badly. I have flown them all and you take a young low time pilot and put them in a Otter/skyvan you are more likely to get hurt than in a caravan, heavy or not.

The SuperVan fully loaded is not that bad, it still is in Cessna's Envelope and they tested it, ALOT. the type of engine has nothing to do with it.


TBO

The 331-12JR-702TT has a 5000 TBO for part 91 operators ans 7000 TBO for 135 guys. The engine has autostart and a torque/Temp limiter which is helps the pilot not to over stress the Engine. Skyvans do not have this. Thats why they go boom. Bad pilots not the engine.

Lastly NOISE

on the ground the Supervan is louder but by electronic measurement is still quieter than a SUPER OTTER at all phases of flight.

The Supervan prop turns at 1591 RPM all the time. We have more noise complaints from rotax powered ultralights than the Honeywell powered Supervan.

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How does one determine the max number of seatbelts that are allowed on a jump plane?

In the States it is all part of the 337 Major Alteration process that every operator has to go through to install the jump mods.
There should be a seperate Form 337 just for the seatbelt install. For an aircraft like the Caravan, you show where the belts will be placed (Stations), how many belts there will be, how they will be installed, how they will be inspected and how they will be replaced. You work up "Sample" weight and balances to show compliance. If the FAA Inspector agrees with your work, they approve the 337 and your good to go.

One thing to keep in mind, When did they have the 21 jumpers on board? Was it the first load after fueling or the 3rd?
The Grand Caravans that I used to work on, PT6A, we would put 15 on after fueling, 17 max on the next load and 19 max for the 3rd load after fueling.
We did run the numbers and you could put 21 on board for the 3rd load after fueling. We did not do it though. That extra 2 people just killed the climb performance it was not worth it. We also did not do it because of comfort. If 19 in a Caravan is comfort.

We would let one person sit on the rear cargo deck, but only after the forward part of the aircraft was full and that person would be one of the smallest on the load.

Hypothetically speaking, you could install 10 seatbelts in a 182 if you could show on paper that the aircraft would remain in W&B limits.

The Honeywell engine is heavier than the PT6 which helps the CG issue that some poeple thinks exists.

We have been flying with 21 after the first load of fuel has been burned.

It truly is wonderful machine and is liked by all.

no doubt...

come and visit us sometime, fish.


jmy

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The Skyvan has Garrett engines. They're a pain in the butt. Direct gearing, so the prop is always spinning at a fairly constant RPM even at idle. (noisier.) They are always breaking down - last summer one had an uncontained turbine failure and peppered the fuselage with shrapnel. Left a big hole in the top of the wing. The pilot was (fortunately) able to land it.

I'll take a PT6 derivative any day over a Garrett.

These forums are a great to gather information about products or experiences, but many times they are are great way for people to spread a lot of bad information that they portray as factual. Many of the comments throughout this thread are not correct.

The fact is that both the PT6 and the TPE331 engine are very reliable engines. It is funny how that no one, except for one person (johanW) discussed the failures on the PT6, because there have been many in skydiving. Actually, there were at least 7 PT6A-114A failures on Caravans alone last year that I know about and 3 were in skydiving airplanes. Most were uncontained CT blades failures which caused catastrophic damage to the engines.

It is very difficult to argue a reliability equation in an industry that varies dramatically in how the engines are operated and maintained. Some DZ's do an exceptional job on maintenance and then others scrape by just making payments on airplanes. Again, they are both reliable engine, but both only get that reliability from regular maintenance.

The main benefit of the Supervan 900 conversion to the Caravan is to provide the DZ's with airplane that will revolutionize the industry just as the -27 engines did for the Twin Otter. This airplane provides a lift capacity unmatched by any aircraft in the industry for the same operating cost. That equates to a lower operating cost to the DZ and eventually to the skydivers.

As for the numerous comments on this thread, I would recommend that several of you not comment unless you know the facts. Many people in this thread just spout off quotes that someone else told them and portray them as fact. I do not want to pick on any one individual, but I do feel that I should comment on some of the quotes to set the record straight.

For the record, I am the one that designed, built, and test flew the Supervan 900, so I think I have a pretty good grasp of what the engine and airplane are capable of doing. I have also been around skydiving and aircraft maintenance for 20+ years.

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In addition, you have to let them cool down for a while before you can shut them down.

Actually it is recommended to cool down all turbine engines prior to shutdown to prevent blade tip rub on the turbine wheels due to the tight tolerances.

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Garrets are a fucking nightmare!


For the same price why not buy a shiney new PAC750XL?

I would be happy to show how much more revenue and jumps you can produce with the Supervan 900 over the PAC750XL. A converted caravan can be purchased for several hundred thousand less and will end up with a better market and re-sale if you ever have to get rid of it. We are already converting a Caravan for a DZ in Australia and should be able to get one in New Zealand shortly. That should tell you what they see in the airplane versus a new 750XL.

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Meanwhile, many PT6 engines operate "on condition" long past 5,000 hours.

Bureaucrats - who write TBOs - are not always in touch with the nitty-gritty of airplane maintenance.

Actually the TBO's on the Pratt and the Garrett are determined by the manufacturer and approved by the FAA using historical operating data to show that the engine is capable and reliable enough to achieve the TBO. It is definitely not a hap-hazard number pulled out of the air. The TBO for the TPE331-12JR if 5000 hours non-commercial and 7000 hours commercial with one hot at mid-life. Honeywell is having such good reliability that they are considering a 7000 TBO with no hot section.

Don't comment about engine reliability if you don't have the actually in-flight shutdown or failure rate of the engines. What happens in your world doesn't necessarily mean that is the industry standard.

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Close, the wouldn't bend while in use. They would heat up during use and since the shaft is so long it would bow slightly after shut down. That's why you see pilots pulling the props through after shutdown. This pulls cooling air through the engine which cools the shaft bringing it back straight or preventing it from bowing to begin with. Not sure how much myth is associated with it but that's what I understand.

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.

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Hummmm? that is strange! Like putting a suit on a pig? Sorry I never saw a Garrett that could hold its own against a Pratt!

Garretts are screeching loud! require more to spool up! have had shut down problems! are shaft driven throughout, more bearing wear, more shafts to turn, more rotating parts to lube and fail! But! Yes! If you want to cruise at higher altitudes for long distances and burn less fuel, it is a better beast, but if you want a balls out, down dirty in the mud brut! the name is! Pratt & Whitney!!!!

Now put a 900 shaft HP pratt on a Caravan! and you got a "MACHINE"!!!!!!!!

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).

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This comment is the funniest one yet.

You like that one. I was waiting to see how long it would take for someone to catch that.

Actually shaft bow happens because the shaft has few bearings to support it in relation to its length.
It can happen to any 331 regardless of age. Anyone who has listened to a Casa or Skyvan start and heard a distinctive little pop right after light off, that's due to shaft bow.

The Garrett was the logical choice for the Caravan. The PT6A-114A is under powered for the aircraft and with all other PT6 models having dual exhaust going to the Garrett makes sense.
A local operator here uses the first Texas Turbines conversion on amphibs.

I still stand by my ideals of the PT6 being a better engine. The PT6 is just more forgiving to pilot mistakes and for lack of a better term, maintenance malpratice. The SRL on the -12, though, does take a lot of pilot error out of play.

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Thats why they are called Garrett grenades. The Garrett (Honeywell now) TFE 731 series jet engines are very reliable though.

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.

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.

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My question is what are the hot section requirements?

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.

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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.

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Dude, The thread was dead for four months. This is like the old Ford/Chevy agrument. You are beating your head on a brick wall. Carry on.

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.

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.

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TOTTER Check out the video on Youtube.

I watched it every day, PT6A-34 Single Otter/TPE331-12 Caravan.
Before the operator started flying out of the airport he kept the aircraft on our ramp. So, I have had the opportunity to watch this Caravan take-off multiple times. It still takes 3 times the distance for the Caravan to get on step then our -34 powered Otters. This has nothing to do with the engine, though. It's the Caravan wing design.
Once the Caravan was airborne then it won hands down. It does haul ass in the air. But this, compared to the Otter is because of wing design. Plus, the turbine otter is limited to 134 knot IAS. Airframe limitation.
The stock Caravan is no comparison to the Garrett Caravan. The PT6 Caravan would easily eat up a mile of water to get on step.

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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.

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.

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.

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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.

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.

here is an interesting (and seems balanced) point of view from an aviation forum. will need to dig up the link....

Ahh yes...Pratt vs. Garrett (well, Honeywell now, but most people still call them Garretts) - one of the great debates of general aviation. I've seen several reasonable people resort to shouting at one another over this topic. Thing is, both these engines are so good at what they do that it really comes down to which characteristics are preferred by the aircraft operator.

The Pratt is a very good engine - it's biggest advantages, in a nutshell, largely stem from it's unique design. Because the airflow reverses itself
several times within the engine, it makes the gas generator and power sections into compact, self-contained units. This allows them to be broken
apart for easy inspections and maintenance. Secondly, the design makes the PT6 a very smooth (there aren't any long driveshafts in the PT6), compact and lightweight engine when compared to it's competitors - a PT6A-135A (a new variant that is quickly becoming the standard install in many aircraft) weighs in at only 338 pounds (153 kg), yet produces 750 shaft horsepower. Finally, as mentioned above, the PT6 is, by nature of it's design, a very durable engine. It is not very susceptible to FOD ingestion (the air enters
the engine at the far end and even then it makes a very tight turn from the duct to the inlet), and if the propeller were to strike the ground, the
inspections and repairs would be substantially less expensive than comparable engines.

However, the PT6 has a number of drawbacks. First of all, the PT6 doesn't respond quickly to power setting changes; all turbine engines have some lag
as we know, but the PT6 has a LOT of lag, whereas the Garrett will respond virtually instantaneously to power changes. Secondly, the PT6 has a fuel
burn penalty as mentioned above (it isn't huge - maybe a few percent overall), mostly due to the losses associated with turning the airflow
through 720 degrees within the engine. Also, due to the long intake duct, the PT6 is very sensitive to intake icing - even small amounts of ice and
frost can have dramatic effects on performance with this engine. As such, all PT6 installations I've ever seen continuously route some engine exhaust
around the inlet lip for ice protection. Finally, the PT6 seems to be fairly susceptible to hot starts. Again, this has to do with the airflow reversing
several times, which makes the job of cooling parts of the engine much more difficult under certain conditions.

As for the Garrett, it's advantages lie mostly in the performance department. From a pilot's perspective, the Garrett is vastly superior - better power response, more fuel efficient and much easier to handle overall. However, the Garrett is not a particularly compact engine (especially in the high-power versions) when compared with the PT6, and
maintenance is a royal pain in the ass on them. What's worse is that the Garrett sucks anything and everything into it's air inlet, which in turn attempts to make it's way through the gas generator - and as we all know, FOD can ruin a gas turbine engine. The Garrett also requires a huge amount of battery power to start - because the propeller is connected directly to the engine, you're spinning that on start as well, unlike the PT6 - so starting a Garrett without ground power can be a bit iffy if the aircraft has cold-soaked on a ramp at -30 all night. Finally, the Garrett is not a "good neighbour" engine - it's always running at 98% RPM (unless it's in ground fine - 70% or so), and as such it is tremendously noisy inside and outside the aircraft, making it unpleasant to work around (or in, for that matter) and unpleasant for people living near an airport or under the approaches to an airport.

http://www.airliners.net/aviation-forums/tech_ops/read.main/260832/

Everything is fairly spot on except the bold statement. I don't know the exact number, but Garrett engines are several times more likely to suffer damage from a hot start than Pratts. Having to turn all of the mass of that engine from the back to the prop reduction gearbox requires a great deal more from the starter and battery.

This is why Garretts start on stop locks in a flat pitch configuration and why some aircraft manufacturers (Commanders for example) have electical systems designed to run in either parallel or series mode to deliver more juice to the starter and keep things cooler.

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here is an interesting (and seems balanced) point of view from an aviation forum. will need to dig up the link....

Ahh yes...Pratt vs. Garrett (well, Honeywell now, but most people still call them Garretts) - one of the great debates of general aviation. I've seen several reasonable people resort to shouting at one another over this topic. Thing is, both these engines are so good at what they do that it really comes down to which characteristics are preferred by the aircraft operator.

The Pratt is a very good engine - it's biggest advantages, in a nutshell, largely stem from it's unique design. Because the airflow reverses itself
several times within the engine, it makes the gas generator and power sections into compact, self-contained units. This allows them to be broken
apart for easy inspections and maintenance. Secondly, the design makes the PT6 a very smooth (there aren't any long driveshafts in the PT6), compact and lightweight engine when compared to it's competitors - a PT6A-135A (a new variant that is quickly becoming the standard install in many aircraft) weighs in at only 338 pounds (153 kg), yet produces 750 shaft horsepower. Finally, as mentioned above, the PT6 is, by nature of it's design, a very durable engine. It is not very susceptible to FOD ingestion (the air enters
the engine at the far end and even then it makes a very tight turn from the duct to the inlet), and if the propeller were to strike the ground, the
inspections and repairs would be substantially less expensive than comparable engines.

However, the PT6 has a number of drawbacks. First of all, the PT6 doesn't respond quickly to power setting changes; all turbine engines have some lag
as we know, but the PT6 has a LOT of lag, whereas the Garrett will respond virtually instantaneously to power changes. Secondly, the PT6 has a fuel
burn penalty as mentioned above (it isn't huge - maybe a few percent overall), mostly due to the losses associated with turning the airflow
through 720 degrees within the engine. Also, due to the long intake duct, the PT6 is very sensitive to intake icing - even small amounts of ice and
frost can have dramatic effects on performance with this engine. As such, all PT6 installations I've ever seen continuously route some engine exhaust
around the inlet lip for ice protection. Finally, the PT6 seems to be fairly susceptible to hot starts. Again, this has to do with the airflow reversing
several times, which makes the job of cooling parts of the engine much more difficult under certain conditions.

As for the Garrett, it's advantages lie mostly in the performance department. From a pilot's perspective, the Garrett is vastly superior - better power response, more fuel efficient and much easier to handle overall. However, the Garrett is not a particularly compact engine (especially in the high-power versions) when compared with the PT6, and
maintenance is a royal pain in the ass on them. What's worse is that the Garrett sucks anything and everything into it's air inlet, which in turn attempts to make it's way through the gas generator - and as we all know, FOD can ruin a gas turbine engine. The Garrett also requires a huge amount of battery power to start - because the propeller is connected directly to the engine, you're spinning that on start as well, unlike the PT6 - so starting a Garrett without ground power can be a bit iffy if the aircraft has cold-soaked on a ramp at -30 all night. Finally, the Garrett is not a "good neighbour" engine - it's always running at 98% RPM (unless it's in ground fine - 70% or so), and as such it is tremendously noisy inside and outside the aircraft, making it unpleasant to work around (or in, for that matter) and unpleasant for people living near an airport or under the approaches to an airport.

http://www.airliners.net/aviation-forums/tech_ops/read.main/260832/

Cessna just announced (July 2012) the Grand Caravan EX model with an up-rated Pratt & Whitney PT6A-140 engine. Horsepower is increased from 675 to 867 horsepower. This increases rate of climb by 20 percent.

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PT6A-140 engine

?

Is this an uprated -114 or is this the Blackhawk -42 mod?