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.