AvGas in jet tanks

[ToiletDuck]

Is it common practice for you jet guys to put some AvGas in there from time to time to clean the system? I was suprised to find that you could run a jet on avgas.

 

[Big Duke Six]

Not sure about "cleaning the system", but they can be run on avgas if the need arises. If I remember right, most engines require a logbook entry if they are run on a certain percentage (or higher) of avgas. It is not the best thing for a jet engine however, so there is a limit on how much avgas can be run.

 

[MTpilot]

P2-V jets always burn avgas.....and quickly.

 

[avbug]

True, the p2v burns avgas...but it also dirties up the jets in a big way, and yes, it burns a lot. Each jet on a typical drop burns as much as both 3350's put together. Lighting off the jets triples the fuel consumption.

Why would one put avgas in a kerosine jet A tank to "clean it?" What do you think avgas does? How do you imagine it might "clean" a system?

If one intends to run avgas in a turbine engine, the fuel controller should be reset, and the time the engine is operated on avgas needs to be closely watched. Most have a very limited life operating on alternate fuels. Cut fuels, perhaps...but alternate fuels can severely limit engine life.

 

[Diesel]

our old company the boss would run avgas through the engines to clean the blades off of the pt-6. personally i thought this was more of an old wives tale than anything else.

I have run avgas through king air's when i've been in a jam. Landed at a place that said they had Jet A. They just didn't tell me which day they would have jet A.

In the king air if I remember correctly the boost pumps have to be operational to run avgas. If they aren't you were limited to 18,000 Feet.

It's been a while since I've needed to do it. I was never really comfortable with the idea. They say you get higher ITT's from the avgas but I never saw a difference. Probably because the avgas was "cut" so much by the Jet A.

 

[erj-145mech]

Back when I was working on the King Air's, we would put about 10 gals of av gas in the aux tanks (Center section) to keep them from drying out. We only used them for long flights with no pax on board. When we filled the tanks, the gas would dilute with the Jet A. The gas would keep the rubber nipples on the tanks from drying out and cracking/leaking.

The PT6A's could burn av gas for a total of 150 hours between overhauls. This was because of the lead build up in the hot section.

 

[Flying Illini]

Yep, in the King Air you can use avgas but the boost pumps must be operational, you're limited to 17,000' (I think), and you have to keep track of the engine operating time b/c the engines are limited to 150hrs on avgas (or something close to that).

 

[avbug]

Yes, they can burn avgas, but if you'll look in the maintenance manual for the Pt6A, you'll find that the fuel controller must be reset; merely pumping the avgas abaord and flying isn't acceptable. Nor is there any good reason to pump avgas into a cell when you could merely fill it with jet, or lubricate it...or maintain it properly. I know of no recommendation by any manufacturer producing turbine equipment to fill kerosine tanks with avgas to preserve the rubber.

As far as running avgas through an engine to clean it...that's what compressor washes are for. Distilled water and turbine wash...not avgas.

 

[Donsa320]

our old company the boss would run avgas through the engines to clean the blades off of the pt-6. personally i thought this was more of an old wives tale than anything else.

I have run avgas through king air's when i've been in a jam. Landed at a place that said they had Jet A. They just didn't tell me which day they would have jet A.

In the king air if I remember correctly the boost pumps have to be operational to run avgas. If they aren't you were limited to 18,000 Feet.

It's been a while since I've needed to do it. I was never really comfortable with the idea. They say you get higher ITT's from the avgas but I never saw a difference. Probably because the avgas was "cut" so much by the Jet A.

What would make one expect higher ITT's on Avgas....it has lower energy. You'd have to burn more Avgas to get the same power as JetA since it weighs less per gallon.

This oughta get something going. <grin>

~DC

 

[ToiletDuck]

Well when I was getting my Commercial the examiner who flew jets said that they figured it up they could burn around 750gals per overhaul of avgas. That they did it everyone once in a while because Jet A was kerosene based and algae or something like that could grow in the system. So they would put avgas in there to clean out the algae. I just didn't know if this was common practice or not.

I figured it might be some "old backwood" trick. Our cropduster who has about 30-40k hours,quit logging but he's been doing it since he was 18, says that sometimes when they refuel on the ranch and there is a ton of dust from the machinery sometimes it gets in the tank. So he'd take a waterhose and burst high pressure water in the tank. Said it sinks to the bottom and traps all the dirt with it. Then he'd sump it out. I was always a little freaked out about it but I don't know if he's had any serious accidents..... I have seen them "hydroplane" them on the canals though to wash the cow poop off the body though... lol.

 

[bugchaser]

I know of several Ag operators who put a little avgas into their jetA tanks to keep the algae growth down, and add some to the airplane tanks at the end of the season to keep things clean during the winter. .5-1% is the mix if I remember correctly. Maybe its just an old wives tale? We have never had any problems. As for running avgas in the Pt6, not a good idea but it can be done as detailed above. Don't see anything in my aircraft ops manual that states anything about adjusting the fuel control. This is only meant as an emergency type of deal. If there is no JetA available, probably no tools etc. to adjust the fuel control either. Hey you could always go to town and get some diesel, that runs pretty good, just smokes a little more than kerosene.

Anyone have any pics of airplanes "hydroplaning" or skiing on the water? Having a hard time convincing some people that this is possible. I have seen it done many times. Pretty cool. Of course I would never do something like that.

 

[ToiletDuck]

I think I took some pics I'll go look. I remember seing them disappear below the horizon and thinking "OH MY GOD HE CRASHED", I've seen 3 crashes when walking rice fields, and my grandpa came back "nah he's just rolling the wheels in the water over ther' to wash the plane off" lol.

 

[ToiletDuck]

Here's a pic on another forum. I don't have a way to post mine.

http://www.aviationforum.org/forums/showthread.php?s=&threadid=772&highlight=hydroplane

 

[Lead Sled]

Not sure about "cleaning the system", but they can be run on avgas if the need arises. If I remember right, most engines require a logbook entry if they are run on a certain percentage (or higher) of avgas. It is not the best thing for a jet engine however, so there is a limit on how much avgas can be run.

That is true for some turbine aircraft and not true for others. There will be a section in the flight manual detail what fuels can be burned and with what limitations. It was permissable in some of the airplanes I've flown in the past, but with some restrictions. It's not permissible in the airplane we're flying now. Most jetfuels are blended with a biocide to keep the green things from growing in the tanks.

'Sled

 

[Lead Sled]

Anyone have any pics of airplanes "hydroplaning" or skiing on the water? Having a hard time convincing some people that this is possible. I have seen it done many times. Pretty cool. Of course I would never do something like that.

Check out www.supercub.org There are a bunch of photos there.

'Sled

 

[EMB145XR]

Plain jet fuel (Jet-A) does not contain any biocide. Fuels with added Prist (those with anti-ice inihibitor) does contain biocide, if I remember correctly. There is an additive called Biobor than can be added to jet fuel to keep any microorganisms at bay. We used it all the time and never had a bit of algae. Of course, if you fly your aircraft regularly, there shouldn't be any worries whatsoever.

 

[bugchaser]

Thanks for the pics guys. Your right, the best thing would probably be to add a commercial biocide to the storgage tanks.

 

[NookyBooky]

There was some great video of guys hydroplaning right up to very narrow beaches in AK on www.airviolence.com, but the website is no longer...