Carb issue.. maybe?

[irishfield]

Just the old gas wronghand! Don't think the impulse coupling or the mag really had anything to do with it.. but the couplings spankin new now!

 

[wronghand]

Well that's definitely food for thought. I know high octane fuel degrades fairly quickly but wow....

 

[tempdoug]

So Wayne, with your experience how long do you feel avgas can be stored before it breaks down?http://www.supercub.org/forum/showthread.php?39569-100LL-storage

 

[skywagon8a]

I have never felt that avgas breaks down unless it was mixed with oil for a two cycle engine use. Auto gas is another story.

 

[NunavutPA-12]

Last summer I found two drums of 80/87 abandoned on the tundra. They haven't made that stuff for about 30-years. I put a tank-full through the snowmobile and it ran just fine. Wouldn't use it in the 'plane of course.

 

[skywagon8a]

I've started up engines which were on an airplane abandoned in a dump for years (not 30) and it worked just fine with the 80 oct still in the tanks. I would not hesitate to fly with it.

 

[NunavutPA-12]

I think that in a sealed, steel drum avgas should last for a long, long time. In a vented tank or in a polyethylene gas can, or if mixed with oil.... not so long.

 

[irishfield]

I use to go through my 500 gallon tank every year, sometimes twice. With less on field customers and me flying less the last couple tanks lasted about 3 years and I monitor output from it pretty carefully. The first time I came up short I suspected someone was syphoning my tank, so at the next re-filled with 500US gallons I made sure the lids couldn't be opened, nor the nozzle used to syphon. By the time I got to empty I had only used about 435 gallons. Means I lost 65 gallons to evaporation. So presumably the more volatile stuff goes first and leaves behind the less volatile stuff.

As noted through this post... I also think it settles out with heavier and lighter substances in the fuel. What was in my gascolator wouldn't burn on the cement floor, but as I drained the fuel got lighter blue by the last few gallons and it burned just like car gas. SO.. if the airplane sits for a long time... shake your wings! lol

All my cans in camp are sealed... so they shouldn't get any worse and I will be mixing them 1 + 1 with fresh cans to use them up this summer.

I've always been of the opinion that 100LL never goes bad either.. but that has sure changed. In a sealed drum I'm sure it holds true, vented storage tank.. not so much!

 

[N86250]

I have never felt that avgas breaks down unless it was mixed with oil for a two cycle engine use. Auto gas is another story.

I believe the formulation of 100LL changed in the last 5-10 years. I know, it can't be, but after Irishfield's experience I'm sure it has. 4 years ago at 6G5 the FBO, who has since passed, sold two local guys most of the remaining 100LL in his tank at a big discount for their Cubs. Very unlike old XXXXX as he never ever gave anyone a break. When the active Cub with an A65 became hard to start the question of the cheap fuel came up. Ol' XXXXX finally admitted that his B&P supplier had advised him not to sell his remaining fuel as it was well over a year old and it should be disposed of and not mixed with his new fuel order. So maybe it was from a bad batch?? 6G5 didn't do much fuel sales as it was always priced high. Rather than dispose of the fuel at a total loss as recommended, he sold it cheap to the Cub guys, about 200 gallons, as he '' thought it would be OK in their old engines but he wouldn't sell it to anybody passing through in a Mooney or a Bonanza". The Cubs were very hard to start-handprop-but ran OK once running and the fuel was quickly used up once the fuel was determined to be the problem. Maybe not the best choice but that is what was done. My take on this is that fuel over 10 years old is probably still good but less than 10 is very questionable. Oh, yes, 6G5 has since implemented new storage tanks and creditcard pumps and is no longer the highest priced fuel in the area. jrh

 

[skywagon8a]

.... By the time I got to empty I had only used about 435 gallons. Means I lost 65 gallons to evaporation. So presumably the more volatile stuff goes first and leaves behind the less volatile stuff.

As noted through this post... I also think it settles out with heavier and lighter substances in the fuel. What was in my gascolator wouldn't burn on the cement floor, but as I drained the fuel got lighter blue by the last few gallons and it burned just like car gas. SO.. if the airplane sits for a long time... shake your wings! lol

I do know that the color is a die which can settle out. That seems like a high number for evaporation. Is your tank kept in the sun?

I believe the formulation of 100LL changed in the last 5-10 years.

Interesting, I wonder if this is so?

 

[irishfield]

Yes my tank gets the afternoon sun. After I was complaining about same, my son figured out the evap rate and said "that's about right over that time period", as he has to do so for the local airport (his job as finance chair on the committee) to be certain no fuel is being "given away". Why he was a tad pissed when the manager decided they should switch from underground tank to an above ground tank.

Giving serious thought to getting rid of my tank and just going to the local airport with my cans, but that removes some freedom and depletes spare time. I might see if they'll deliver 1/2 tanks when it's convenient for them on a multi fill run across the province... or I'll get a full tank and immediately can / seal the first 200 gallons or so and then use the tank first. I already have 30 x 5 gallon cans. Not a big deal to go to Walmart (by the way the only place we can still get the good old vented cans!) and get 20 more at $10 each. Evap losses alone will pay for them.

 

[skywagon8a]

What would happen to your evaporation rate if you built a roof over the tank to keep all sunlight away? How about some sort of a vapor collector on the vent to capture the "leakage"? A 65 gallon loss is well over $300, that does not sound acceptable to me. I keep my 100 gallon tank inside out of the sun and am not aware of any evaporation. The total amount pumped pretty much agrees with the amount purchased.

 

[irishfield]

I built a structure over my tank, way back when, and then never sheeted the roof after the first delivery guy told me they couldn't fill it if it was enclosed. Might be time to grab the steel from behind the hangar and finish that job, although the question will be what's worse... the white tank in moving air or inside a roofed structure. I guess if I leave the sides open as originally planned for air flow then at least the sun is off the tank.

$1.80 / litre at the airport the other day.. x 4 per gallon x 65 = $468 Cdn or $374 US right now. So I think I'll grab 20 more cans for $200, call the fuel company and get filled the next time they're doing the rounds.