Forums: Skydiving: General Skydiving Discussions:
Supervan 900 - Caravan engine mod

 

First page Previous page 1 2 3 4 Next page Last page  View All

pilotdave  (D License)

Apr 20, 2007, 10:22 AM
Post #1 of 78 (7858 views)
Shortcut
Supervan 900 - Caravan engine mod Can't Post

http://www.texasturbines.com/caravan/ttci_c.htm

This'd be nice for a DZ. 900 hp for a caravan. Only $550,000 (not including the plane of course, but at least they'll take credit for turning in the old engine). 13 mins to 14,000 feet on a 95 degree day. 5000 hour TBO (for part 91 operators).

Dave


Premier billvon  (D 16479)
Moderator
Apr 20, 2007, 10:37 AM
Post #2 of 78 (7814 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

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.


mgattini  (D 40947)

Apr 20, 2007, 11:12 AM
Post #3 of 78 (7785 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

He doesn't have the STC on it yet and has been working on it for years....


howardwhite  (C 3896)

Apr 20, 2007, 12:38 PM
Post #4 of 78 (7739 views)
Shortcut
Re: [billvon] Supervan 900 - Caravan engine mod [In reply to] Can't Post

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


Beerlight

Apr 20, 2007, 3:19 PM
Post #5 of 78 (7677 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Looks like they'll do an Otter conversion also..... but I'll take a P & W.


angrypeppers  (B License)

Apr 20, 2007, 5:14 PM
Post #6 of 78 (7647 views)
Shortcut
Re: [howardwhite] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Our mechanics used to call it "shaft bow". We'd have to spin the props on the Dorniers and Metros after the engines shut down...maybe twenty blades or so. If I remember correctly, the prop shaft would get so hot that they could bend in the space between the bearings that supported them. A&P's feel free to correct me!


diablopilot  (D License)

Apr 20, 2007, 8:39 PM
Post #7 of 78 (7601 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Garrets are a fucking nightmare!


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


diverdriver  (D 19012)

Apr 21, 2007, 6:10 PM
Post #8 of 78 (7515 views)
Shortcut
Re: [angrypeppers] Supervan 900 - Caravan engine mod [In reply to] Can't Post

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.

Oh yah, Garretts....ewwwwwwww!!!!

Had a skyvan not come off the start locks after starting and the pilot tried to takeoff. Ran off the side of the runway and instead of aborting then he tried to keep going, tried to rotate and realised he wasn't going anywhere THEN he aborted. Over ran the runway at SDC (2000) and snapped the nose gear off.


riggerrob  (D 14840)

Apr 23, 2007, 9:35 AM
Post #9 of 78 (7376 views)
Shortcut
Re: [Beerlight] Supervan 900 - Caravan engine mod [In reply to] Can't Post

STCed turboprop conversions for single Otters have been available for many years.
The first was Vazar installing a Pratt & whitney PT6A-? in the 1970s.
A Garret/Honeywell conversion is available from Texas Turbines.
Finally, there is an STC to install Walter's copy of a PT6


riggerrob  (D 14840)

Apr 23, 2007, 9:43 AM
Post #10 of 78 (7367 views)
Shortcut
Re: [diablopilot] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Funny!
That is exactly what Ray Ferrel said - after giving us a ride in a PAC 750 - during the 2007 PIA Symposium.
Pratts may be gas-guzzlers, but there is a reason they dominate the skydving fleet (Bandierante, Turbo-Beaver, Caravan, Cresco, PAC 750, Porter, Turbo DC-3, Twin Otter, Westwind Beech, etc.): reliability.


Unstable  (D 28930)

Apr 24, 2007, 8:13 AM
Post #11 of 78 (7285 views)
Shortcut
Re: [riggerrob] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Quote:
That is exactly what Ray Ferrel said - after giving us a ride in a PAC 750 - during the 2007 PIA Symposium.
Pratts may be gas-guzzlers, but there is a reason they dominate the skydving fleet (Bandierante, Turbo-Beaver, Caravan, Cresco, PAC 750, Porter, Turbo DC-3, Twin Otter, Westwind Beech, etc.): reliability.



Help me understand something please....If the PT-6 is significantly more reliable - then how do we explain the TBO difference between the PT-6 and the Garrett we are comparing it to? How does the Garrett get off with have a 5,000 hour TBO?


Premier billvon  (D 16479)
Moderator
Apr 24, 2007, 9:47 AM
Post #12 of 78 (7268 views)
Shortcut
Re: [Unstable] Supervan 900 - Caravan engine mod [In reply to] Can't Post

>then how do we explain the TBO difference between the PT-6 and
>the Garrett we are comparing it to?

The Garretts have a 5000 hour TBO, but they often blow before that. We've lost a significant number of Garretts before they reach TBO.


riggerrob  (D 14840)

Apr 24, 2007, 11:58 AM
Post #13 of 78 (7248 views)
Shortcut
Re: [billvon] Supervan 900 - Caravan engine mod [In reply to] Can't Post

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.


(This post was edited by riggerrob on Apr 24, 2007, 1:00 PM)


RMURRAY

Mar 31, 2009, 9:12 AM
Post #14 of 78 (7072 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

In reply to:
http://www.texasturbines.com/caravan/ttci_c.htm

This'd be nice for a DZ. 900 hp for a caravan. Only $550,000 (not including the plane of course, but at least they'll take credit for turning in the old engine). 13 mins to 14,000 feet on a 95 degree day. 5000 hour TBO (for part 91 operators).

Dave

if all goes right, Parachute School of Toronto (Baldwin, Ontario) will have one the first of these Caravan conversions (for skydiving) from May to Oct 2009. Not sure of the owner of the plane but it is based at STL in PA. Pilot of the fastest climbing jump Caravan on the planet is Jason Fisher.


mdrejhon  (C 3268)

Mar 31, 2009, 11:22 AM
Post #15 of 78 (7001 views)
Shortcut
Re: [RMURRAY] Supervan 900 - Caravan engine mod [In reply to] Can't Post

I'm looking forward to jumping Canada's fastest climbing skydiving Caravan. (err.... World's fastest climbing skydiving Caravan)

I also hope Skydive Gananoque gets to borrow this plane for one of their Turbine Boogies. They borrowed this same Caravan once last year (if I remember correctly, pre-engine conversion). Fingers crossed.


totter

Mar 31, 2009, 1:17 PM
Post #16 of 78 (6941 views)
Shortcut
Re: [diverdriver] Supervan 900 - Caravan engine mod [In reply to] Can't Post

In reply to:
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.


CSpenceFLY  (D 25252)

Mar 31, 2009, 2:07 PM
Post #17 of 78 (6918 views)
Shortcut
Re: [totter] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Garrets are just too freakin' noisy


chutejump  (D 6919)

Mar 31, 2009, 5:40 PM
Post #18 of 78 (6835 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

 

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"!!!!!!!!


yjumpinoz  (D 13167)

Apr 1, 2009, 7:24 AM
Post #19 of 78 (6711 views)
Shortcut
Re: [chutejump] Supervan 900 - Caravan engine mod [In reply to] Can't Post

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


vpjr  (D 14158)

Apr 1, 2009, 5:43 PM
Post #20 of 78 (6577 views)
Shortcut
Re: [billvon] Supervan 900 - Caravan engine mod [In reply to] Can't Post

 
The Garretts have a 5000 hour TBO, but they often blow before that. We've lost a significant number of Garretts before they reach TBO.
Pilgrim airlines (Twin Otters with PT6-20s) had TBO extensions to 10,000 hours. My question is what are the hot section requirements? Starts? Hours? and who can preform the Hot Section inspection on the Garrett? If an A&P can preform the hot section inspection are such special tools requried that only a repair facility can do the inspection? FAR Part 91 requires compliance with Hot section inspections and life limited parts, ADs, but not Overhaul. Your aircraft inspection program may.


totter

Apr 2, 2009, 1:39 PM
Post #21 of 78 (6467 views)
Shortcut
Re: [vpjr] Supervan 900 - Caravan engine mod [In reply to] Can't Post

In reply to:
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.
In reply to:
If an A&P can preform the hot section inspection are such special tools requried that only a repair facility can do the inspection?
An A&P can due a Hot Section on a Garrett. If they have the money they can buy all the tools the need.
I would make sure that that A&P has lots of experience on Garretts before I let them dig into it.
In reply to:
FAR Part 91 requires compliance with Hot section inspections and life limited parts, ADs, but not Overhaul.
There is no requirement under Part 91 to comply with Hot Section Inspections. It is a manufactures requirement. Under Part 91 (i.e. Skydiving, General Aviation) you do have to comply with all life limts. TBO is not a life limit.


vpjr  (D 14158)

Apr 2, 2009, 5:11 PM
Post #22 of 78 (6409 views)
Shortcut
Re: [totter] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Your right I dont see Hot section inspection in 91.409


RMURRAY

Apr 3, 2009, 5:11 AM
Post #23 of 78 (6339 views)
Shortcut
Re: [pilotdave] Supervan 900 - Caravan engine mod [In reply to] Can't Post

here is a link to FAQ and an explanation why they picked the engine over P&W....

http://www.texasturbines.com/caravan/ttci_faq_c.htm#20

6. Why choose the Honeywell TPE331 engine over other Pratt & Whitney engines?
Texas Turbines spent an extensive amount of time researching the best engine to mate to the Cessna Caravan. We considered several engines and knew that it would be an easier sell to put another Pratt and Whitney engine on the airplane, but we could not justify a PT6 when the TPE331-12JR beat the engine in all operating aspects. The following engines were considered:

Pratt & Whitney: PT6A-135A, PT6A-34, and the PT6A-42A
Honeywell: TPE331-10 and TPE331-12JR

The PT6A-34 and PT6A-135A were ruled out early for a multitude of reasons. The -34 was eliminated because of the higher prop rpm and noise level for takeoff, dual exhaust issue, and the lower thermodynamic rating as compared to the -114A, although it did have a higher gearbox limit (750 shp). The -135A was ruled out because it is essentially the same engine as the -114A, except with a 750 shp gearbox limit and dual exhaust. Thermodynamically the -135A has the same power as the -114A at altitude unless you want to run it hotter, which will cost more to overhaul if it makes it there. There have already been enough CT blade issues with the PT6 engine. Running the engine hotter will only cause more issues.

The PT6A-42A was ruled out mainly because of the operating cost. The Honeywell TPE331-10 and -12 engines can typically be operated less than the PT6A-114A on the same TBO. The dual exhaust, specific fuel consumption, and 850 shp gearbox limit were other contributing factors.

The Honeywell TPE331 engine was chosen for superior fuel specifics, faster power response, higher base TBO, and lower operating cost per horsepower. The engine has proven its reliability in commercial operations around the world and has an in-flight shutdown rate as good, or better, than any engine on the market today. It just makes economic and pilot sense to choose the TPE331-12JR to power the Caravan.


downwindray  (D 28874)

Apr 22, 2009, 1:32 PM
Post #24 of 78 (6096 views)
Shortcut
Re: [RMURRAY] Supervan 900 - Caravan engine mod [In reply to] Can't Post

You are correct. Sky's The Limits' Grand Caravan is there now being converted and will in Toronto with Jason flying next month.


riggerrob  (D 14840)

Apr 23, 2009, 8:10 AM
Post #25 of 78 (5946 views)
Shortcut
Re: [Beerlight] Supervan 900 - Caravan engine mod [In reply to] Can't Post

Texas Turbines has been converting single-engined Otters - with Garrett engines - for about a decade now.
The problem started with the basic design of the dHC-3 single-engined Otter. Great airframe for short lake take-offs and landings, but it never had enough horsepower to climb out of mountain valleys surrounding small lakes.

Now that the original 650 horsepower radial engines are 60-plus years old, reliability is also a problem.
The first attempt at re-engining Otters involved installing 1,000 horsepower PZL radial engines made in Poland.
Single-engined Otters have also been "turbinized" with Pratt & Whitney turbines and Walter turbines.

Just the other day, I was watching turbine (P&W) single Otters land and take off from Vancouver harbour.


First page Previous page 1 2 3 4 Next page Last page  View All

Forums : Skydiving : General Skydiving Discussions

 


Search for (options)