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Fuel smell on takeoff

JackinMichigan

Well Known Member
We took our RV-10 on it's second flight today. Both flights were 45 minute long circles around the airfield at 2,400 AGL.

On takeoff, between right when the wheels leave the ground to about 700 ft, I'm getting a distinct and unmistakable odor of fuel in the cockpit. It goes away once I reach 1000 ft, but it's happened both times. Takeoff is, of course, full rich, full throttle and prop governor all the way in. Apart from that both flights have been quite uneventful.

I really want to know where this fuel smell is coming from. We pressure tested the fuel system to 20psi (the most pressure the fuel valve can handle) and it stayed rock solid for days. Anyone else experience this?
 
I had the same thing happen to me after refueling. Really got my attention! It dissipated shortly after I reached pattern altitude. I attribute the odor to the tanks being full.
 
Either fuel level sending unit or B nut is loose on fuel vent line inside the tank. Open the lower intersection compartment and take a look for stains. If no fuel stains around sending unit, then fill tank and watch fo fuel to flow out of the vent. http://www.vansairforce.com/community/showthread.php?t=74258&highlight=Fuel+vent


You should not smell fuel even when you over fill the tank..... Here is a good thread to read on a similar issue

http://www.vansairforce.com/community/showthread.php?t=78318&highlight=Fuel+smell
 
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One thing I discovered during my Phase I testing was that every single B-nut on the entire aircraft needed re-torquing. Vibration, I guess...
 
Wrap all your fuel fittings with white tissue or napkin and tape. Take it around the pattern and check them all for the telltale blue stains. It is known that the vents sometimes will purge a bit of fuel and you can smell it in the cockpit. Knowing this I took great care to seal out any air entering from the wing roots by fabricating flexible control rod boots and sealing up any wire/fuel line holes with a little silicone. Never had a fuel smell problem and I always kept the tissue wrapped on the fittings and inspected at every condition inspection.
 
Either fuel level sending unit or B nut is loose on fuel vent line inside the tank. Open the lower intersection compartment and take a look for stains. If no fuel stains around sending unit, then fill tank and watch fo fuel to flow out of the vent. http://www.vansairforce.com/community/showthread.php?t=74258&highlight=Fuel+vent


You should not smell fuel even when you over fill the tank..... Here is a good thread to read on a similar issue

http://www.vansairforce.com/community/showthread.php?t=78318&highlight=Fuel+smell

I think that turned out to be it. The left tank was dripping fuel out of the overflow and leaking in several places, in spite of the fact it was a quick build and these tanks were guaranteed not to leak. In the process of pulling the tank off and sending it back to Vans.
 
If you don't keep the ball in the center during climbout and the tanks are anywhere near full and you DONT smell fuel you aren't using all your available senses.
 
Jack,
You can make a tool to tighten the B nut through the sending unit hole. Easier than removing tank and sending back. It?s in one of my prior posts
 
If you don't keep the ball in the center during climbout and the tanks are anywhere near full and you DONT smell fuel you aren't using all your available senses.

???
The tanks and/or hardware should not leak during slips/skids.
 
in a slip or skid you might be forcing fuel out of a vent if your tanks are full. The end of the vent tube at the top of the tank would be submerged.
 
in a slip or skid you might be forcing fuel out of a vent if your tanks are full. The end of the vent tube at the top of the tank would be submerged.

It's especially bad if you've just filled up an -8....the underwing air vent really picks up the fumes of anything that spills from the fuel tank vents!
 
I guess they fixed this in the -10: the cabin air intake is forward of the fuel vents. I?ve never smelled any gas in a slip.
 
I had a customer who mentioned he smelled fuel at takeoff and climb out as well in his RV-10. Looking at all of the usual culprits identified in this thread produced no telltale blue stains. With the cowling off, I pressurized the fuel system. Using a bright light and my finger I felt every fuel line and finally noticed a teeny crack in one of the injector lines that was just leaking enough to be wet, but not even wet enough to leave a blue stain. It only showed up when moving the mixture control to full rich. It could have been quite serious if left to propagate.

The moral of the story is to throughly check the lines from the tank to the cylinder, and pressurize them where possible.

Vic
 
Any chance you are over priming a bit? I see this on my plane occasionally (a Cozy). If I boost a bit too long fuel runs down and out the air filter, hits to cowl floor and I’ll smell it for several seconds on takeoff. You may find staining on the bottom of the air filter.
Agree with Vic also though, just had a friend who caught an injection line beginning to crack.
Tim Andres
 
I had a customer who mentioned he smelled fuel at takeoff and climb out as well in his RV-10. Looking at all of the usual culprits identified in this thread produced no telltale blue stains. With the cowling off, I pressurized the fuel system. Using a bright light and my finger I felt every fuel line and finally noticed a teeny crack in one of the injector lines that was just leaking enough to be wet, but not even wet enough to leave a blue stain. It only showed up when moving the mixture control to full rich. It could have been quite serious if left to propagate.

The moral of the story is to throughly check the lines from the tank to the cylinder, and pressurize them where possible.

Vic

Shoot fire! Good example of tenacity to believe your indications unless you prove them false.

Carl
 
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