Turbine Otter to be

jumbobum · Post by **jumbobum** » Fri Aug 05, 2005 4:14 pm

removed

dash2/3 · Post by **dash2/3** » Fri Aug 05, 2005 5:44 pm

curious, before i waste my terrible typing skills, where are you operating from?, what kind of environment are u operating? what configuration etc.?

twotter · Post by **twotter** » Fri Aug 05, 2005 11:19 pm

None of the above... I'd go with the Garrett.. More power, quicker response, lower operating costs, lower conversion costs, lower fuel consumption, better cruise performance..

Just my opinion..

CLguy · Post by **CLguy** » Sat Aug 06, 2005 8:29 am

I haven't had much to do with any of them, but was shown around a Walter and the one concern I had was there is a header tank in front of the firewall between the engine and pilot. Forget how many gallons but the engine will only pull fuel from it and all fuel from the belly tanks has to be transfered into it by the pilot.

I just thought there was a great opportunity for an OOPS! on an early morning or late evening when the pilot is not so alert and runs the header tank dry because he forgot to transfer fuel. We all know turbines don't fire back up quite like a piston after you run it out of fuel.

bush pilot · Post by **bush pilot** » Sat Aug 06, 2005 11:13 am

Garret Has a lower fuel consumption than P&W? Just wondering, but every garret driver I have talked to said that fuel consumption was higher at low alt but the ratio from low to high is better than P&W, where as P&W fuel flow is not bad at low alt but will not drop to a realy low amount untill you get above FL180. At least that is what it is like in the PAY2, maybe it is different for the type of garret they put on the Otter.

TFTMB heavy · Post by **TFTMB heavy** » Sat Aug 06, 2005 11:46 am

I've got DHC-2T time with a -27 and I've worked for an operator that had a DHC-3T with the PW, don't know what - on it and I've operated Garrett -10 (multi).

If I had to pick I'd really like to try the Garrett out on floats for the same reasons twotter pointed out. I think PW is fine but the Garrett would be my first choice if you can find a good AME that knows Garretts and you don't mind the noise!

Donald · Post by **Donald** » Sat Aug 06, 2005 9:32 pm

And don't forget Garrets can work in the really cold, but they are alot more work. You know what I mean?

dash2/3 · Post by **dash2/3** » Sun Aug 07, 2005 7:14 am

as far as P&W vs. Allison vs. Garrett vs. Walter goes...

P&W? you've got the name, customer support second to none, cool logo

reputation for reliability:unquestionable.

Allison? didn't know there was a conversion available with it.

Garrett? cheaper, more power, lower TBO than P&W.

Walter? heard of it as the throw-away turbine.

I haven't had much to do with any of them, but was shown around a Walter and the one concern I had was there is a header tank in front of the firewall between the engine and pilot. Forget how many gallons but the engine will only pull fuel from it and all fuel from the belly tanks has to be transfered into it by the pilot.

P&W -34 or -135
same sort of thing. difference is, engine draws off middle belly only. transfer from front and rear(or rears if you have extended range tanks.) not a big deal, a little different at first if your used to a R985/1340 system. middle tank size is 102 US gallons. leave transfer off for T/O & Ldgs. when middle gets to 80 gallons, start to transfer and transfer rate is slightly greater than consumption at cruise. on longer flights you can actually top-up middle. just like any other a/c. just fuel management.

fuel consumption, at lower altitudes, remember bush pilot, were talking otters here, you likely won't be above 12,000' anyway. the dash 34 conversion says sevice ceiling is 14,000'. at T/O, around 425-450 lbs/hr.
at cruise, again at lower altitudes in summer 360-385 lbs/hr. @ 50lbs torque/1900RPM usually at gross wt. of 9000lbs. giving you the limited speed of 125mph indicated. empty, at 43lbs/1900RPM 340-350 lbs/hr. start climbing and obviously this all goes down. we do our trends at 5500' indicated.

gotta go, maybe more later

JigglyBus · Post by **JigglyBus** » Sun Aug 07, 2005 7:08 pm

Texax Turbines has a nice little chart regarding this.

Doesn't mention anything about $ really, but has various performance numbers.

http://www.texasturbines.com/PagesPics/specs.htm

bush pilot · Post by **bush pilot** » Sun Aug 07, 2005 8:20 pm

Hey Dash I have heard you higher than that! My point was with P&W your fuel consumption only drops slightly with alt up to about FL180 and then dramatically drops after that(at least with my 135A), whearas the Garret has a higher fuel consumtion at lower alt but drops with a higher rate then the P&W.

rigpiggy · Post by **rigpiggy** » Mon Aug 08, 2005 9:45 am

Donald wrote:And don't forget Garrets can work in the really cold, but they are alot more work. You know what I mean?

ever tried to start one in the cold after a long heat/cold soak. w/o an APU, Good Luck

Not to mention the MTBF of the Pratt is much higher. For sheer economics the Garrett wins, for operation flexibility go w/ the Pratt

Rudy · Post by **Rudy** » Mon Aug 08, 2005 4:32 pm

What about the post shut down prop spinning I see garret pilots doing? That might be an annoyance with the metro but a major pain in the ass with the otter.

TFTMB heavy · Post by **TFTMB heavy** » Mon Aug 08, 2005 7:59 pm

rigpiggy wrote

ever tried to start one in the cold after a long heat/cold soak. w/o an APU, Good Luck

Not sure what you mean about the heat soak part? Never had a problem.

I agree with the cold, PW is good to -40, Garrett to -20. If you have an engine tent and you can plug in it's no big deal. Can't be worse than with the piston!

Garrett all the way. I think there is a Garrrett conversion in Whitehorse!

Brint · Post by **Brint** » Tue Aug 09, 2005 9:31 pm

Only flew an Otter with a Pratt. I've talked to a few guys running the Walter, and they only have good things to say about it. More power than the -135, and quieter with the shorter props.

bugspray · Post by **bugspray** » Tue Aug 09, 2005 11:54 pm

One thing everyone is overlooking is the flap restriction on the pratt. This would be the last choice for a conversion imo.....Take off and Landing is restricted to half flap.. Maybe dont matter in the ocean or large lakes of the Canadian Shield, but if you are working high altitude short mountian strips on wheels, you need full flap! Trust me i know after where i just came from. After all that is what makes the otter what it is, is the flap. From a pilots perspective you are much better off with a Walter or Garett. I see no advantage the pratt has over these two from a flying point of view. And if it aint gonna go where u want it to go, why have it....

dash2/3 · Post by **dash2/3** » Wed Aug 10, 2005 2:31 am

bugspray,

you are mis-informed. the otter with the vazaar -34 pratt does not have the flap restriction you speak of that most do if the baron stol kit installed. some argue that you don't need the kit. we opted for the 9000lb. up-gross in which case we had to install the baron anyway.

[/quote]One thing everyone is overlooking is the flap restriction on the pratt. This would be the last choice for a conversion imo.....Take off and Landing is restricted to half flap.. Maybe dont matter in the ocean or large lakes of the Canadian Shield, but if you are working high altitude short mountian strips on wheels, you need full flap! Trust me i know after where i just came from. After all that is what makes the otter what it is, is the flap. From a pilots perspective you are much better off with a Walter or Garett. I see no advantage the pratt has over these two from a flying point of view. And if it aint gonna go where u want it to go, why have it....[quote][/quote]

rigpiggy · Post by **rigpiggy** » Wed Aug 10, 2005 4:19 am

TFTMB wrote:rigpiggy wrote

ever tried to start one in the cold after a long heat/cold soak. w/o an APU, Good Luck

Not sure what you mean about the heat soak part? Never had a problem.

I agree with the cold, PW is good to -40, Garrett to -20.

heat/cold, there is no cold just a lower amount of heat, Kind of like there is no deceleration only negative acceleration. My high school physics teacher would be proud. Yes there is a garrett in YXY. Doesn't fly so much in the winter though.

Donald · Post by **Donald** » Wed Aug 10, 2005 9:34 am

There are a few Garrets around YZF, just not on Otters. They run all winter long, even down to -43. Just don't try to do an all-day hold at these temps.

bugspray · Post by **bugspray** » Wed Aug 10, 2005 10:13 pm

Dash..
Thank you very much for "kindly" informing me. However it sounds like i wasn't "misinformed" as if you do not have the -34 there IS a flap restriction. Please correct me if i am wrong. Thanks for the info on the -34 conversion though.
You say some don't need the Baron stol kit. I very much agree. However, if short field performance with high altitude hot days is an issue it makes a big big differnce in performance versus landing on floats in a large open lake or ocean or going runway to runway. All depends on the type of work involved.
Walter works fine in the cold weather. Runs at -40 as long as you put a tent over it with some heat like any engine should have. I know there is one in Whitehorse that ran all winter long. As far as the fuel issue with the Walter its as stupid proof as you can get. You can't run a tank dry (unless of course you are stupid). If you have the standard fuel system its a lot lot easier to blow a tank.
Also i might add the Walter is the ONLY turbine coversion with the upgross on "wheels". 8367 on wheels. Anyone with information otherwise please let me know. I know the garett does not have the upgross on wheels, and am sure the pratt does not have it. The Walter is a cheaper conversion, the Garrett has more power with less fuel burn and the pratt has the better customer support.
So the bottom line is you need to find the machine to fit your needs of the 3 conversion types.

dash2/3 · Post by **dash2/3** » Thu Aug 11, 2005 1:32 am

bugspray

i definitly have to agree that there is a difference between an swine with and without flap restriction strictly regarding landing performance only. yes, if you are at a higher altitude lake/strip or with a short strip the ability to select "landing" flap is, quite simply awesome. two years ago we leased a swine with the pratt -34 and no baron kit and you could see/feel the difference. yes with the normal flap travel that dehavilland designed into the otter you get better/steeper approach angle slower approach speeds equating to much better landing performance. throw in the ability for beta/reverse and were talking about some kick-ass short field work. just an example. at sea-level(350' asl

), landing at 8400 lbs. on a 1000' stip over a 50' obstacle is something we do on a very regular basis without the a/c breaking a sweat. unload/reload and t/o at 6900lbs over 50' obstacle and same deal, pretty much a non-event.we operate in/out of this same location on both floats and wheel/skis.

jumbobum · Post by **jumbobum** » Thu Aug 11, 2005 2:03 am

removed

rigpiggy · Post by **rigpiggy** » Thu Aug 11, 2005 8:43 am

So does Vazar http://www.vazar.com/turbineotterspecif ... opicspage/
The -40 to -10 start limitation on the pratt is specifc to the gearbox. SOP up north was for the F/O to hold the prop for a start" in feather", until the temps came up, around 3-5 minutes. Then you shutdown the engine had the F/O go to the other side and do the same. the engines were then available for start without blowing the gearbox or prop seals. The Pratt as long as the battery is warm will normally do a start w/o overtemp in the cold. the Garrett not so much. However our friend said that it is going to europe, so I don't think it matters as the Pratt seems to be the only available option.

rigpiggy · Post by **rigpiggy** » Thu Aug 11, 2005 8:46 am

bush pilot wrote:Garret Has a lower fuel consumption than P&W? Just wondering, but every garret driver I have talked to said that fuel consumption was higher at low alt but the ratio from low to high is better than P&W, where as P&W fuel flow is not bad at low alt but will not drop to a realy low amount untill you get above FL180. At least that is what it is like in the PAY2, maybe it is different for the type of garret they put on the Otter.

WRT the consumption using equal power setting the Garrett will burn about 100PPH less. at least that was the comparison for the metro to the 1900