VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-12
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 04-14-2017, 06:56 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 636
Default How to Find Source of Fuel Smell?

I just did the Fuel Tank Attach Modification Service Bulletin 13-12-19. I accomplished the modification by carefully removing the tank lid to gain better access to the lower front edges of the tank. All went well and tank was resealed with ProSeal. Tank was filled with 20 gallons 93E10 to calibrate the fuel gauge. The airplane sat for a full week with completely full fuel tank and no fuel odor was noticed when canopy was raised. I even left the fuel shut off valve in the open position to static test the fuel lines up to and including the gascolator. Very good.

Now I have flown the plane three times for roughly an hour each flight and have 5 gallons remaining in the tank. On the first flight I noticed fuel smell occasionally on climb out and occasionally in cruise flight with a fair amount of turbulence. Second flight was a little less fuel smell and the third flight was still less but smell was occasionally still there. I suspect the leak to be very small, and of course, difficult to find.

I see no evidence of a leak at the tank. It might be carb float bowl overflow but I donít see evidence of residue in the drip pans. I have searched VAF and found a thread for RV-12 Fuel Tank Leak thatís not much help.

My question isÖ has anyone used a dye solution specifically made for detecting fuel leaks? I found a UV dye additive for auto fuel that fluoresces under black light. Anybody try anything like this?
__________________
-
Jim Stricker
Hinckley, Ohio
PPL - 1970
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 275
Reply With Quote
  #2  
Old 04-14-2017, 07:45 PM
KALEWIS's Avatar
KALEWIS KALEWIS is offline
 
Join Date: Nov 2009
Location: Jackson, OH
Posts: 454
Default

Run a tank of 100LL .... it has blue dye in it

A few gallons of avgas is ok for the Rotax
__________________
Airspeed, Altitude, or Brains...you need at least two

RV-12 #328
At 260 Hrs on the Hobbs

http://unicom12.blogspot.com/
Click on above for build site
Reply With Quote
  #3  
Old 04-14-2017, 09:04 PM
Mark Albery's Avatar
Mark Albery Mark Albery is offline
 
Join Date: Jul 2007
Location: Redwood City CA
Posts: 560
Default

I'm not sure about the -12, but with the other RVs completely filling the tank can allow fuel to enter the vent tubes with their opening near the filler neck. Then when you fly the expanding air in the tank (not being used) pushes that fuel out of the fuselage vent outlet and you can often smell it in the cockpit.

Possibly the turbulence could allow fuel to splash down the vent in a similar manner.

When the tank is less full there is less likelihood of fuel getting into the vent.

Whether this applies for a single tank set up will depend if the air expands in the climb at a greater rate than fuel is being drawn from the tank.
Reply With Quote
  #4  
Old 04-15-2017, 12:41 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 636
Default

I forgot to mention that tank is an early design with visual sight gauge on the side and vented fuel cap. I elected not to install the new vent line and instead stay with the vented fuel cap. The vent holes in the cap are fully open.

Also, as for carb bowl overflow possibility, during last condition inspection I weighed the floats and they are within spec. Both carbs were overhauled by Lockwood prior to my purchasing the plane.

Another data point - while doing the fuel tank modification the carbs sat for five months and most likely the fuel evaporated from the float bowls. I'm wondering if gaskets may have dried out.
__________________
-
Jim Stricker
Hinckley, Ohio
PPL - 1970
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 275
Reply With Quote
  #5  
Old 04-15-2017, 05:29 AM
Pat Stewart Pat Stewart is offline
 
Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,075
Default

Check the carb floats especially if you get this smell on climb out.
__________________
Built, RV 8, RV8A, RV 10, RV12, Purchased RV7A
Restored J3Cub and PA28R180
Pecan Plantation
Eagles Nest Mentor
Reply With Quote
  #6  
Old 04-15-2017, 07:17 AM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 431
Default

Jim-

Five months is a long time for auto fuel to sit in a carb bowl compared to aviation fuel. You just may want to pop off the carb bowls and have a good look for gunk.

If you look carefully at the flight data recorder you may see a small indication of what is going on ... I would think if you are smelling fuel and it is coming from the float bowls, there should also be a small change in RPM, EGT, fuel pressure and fuel flow at the time of the "event" when you are smelling the fuel. If you can see the "event" reflected in the flight data, it would indicate you are not getting the fuel smell from your repaired tank ... its coming from under the cowl from a carburetor(s) overflowing.

As another data point, you may want to place 30% or more 100LL in the tank and make a test flight. You just may be seeing the results of winter blend auto fuel being used in the spring when the temperatures are warming up.

Keep us posted as to what your findings are.
__________________
John
www.dogaviation.com
RV-12 Wings, Empennage, Fuselage, Finishing, Avionics and Powerplant kits all completed
Now Flying!!

Dues paid until September 2017
Reply With Quote
  #7  
Old 04-15-2017, 09:06 AM
DHeal DHeal is offline
 
Join Date: Sep 2006
Location: Windsor, California
Posts: 585
Default

The only time I get a whiff of fuel odor in my RV-12 cockpit is during climb-out with what was later to be determined were over-weight fuel bowl floats. You may or may not see any evidence of fuel residue in the carb overflow trays.
__________________
David Heal - Windsor, CA (near Santa Rosa)
EAA #23982 - EAA Technical Counselor and Flight Advisor; CFI - A&I
RV-12 E-LSA #120496 (SV w/ AP and ADS-B) - N124DH flying since March 2014 - 530+ hours (as of August 2017)!
VAF donation through June 2018.
Reply With Quote
  #8  
Old 04-15-2017, 05:41 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 636
Default

I checked my engine log book and carb floats were weighed 8 months ago as follows - 6.1g (R) 6.2g (L). So the floats are less than the 7.0 gram spec set by Rotax for SB-912-065UL. I guess I'll have to re-weigh the floats now that I'm having a problem.
__________________
-
Jim Stricker
Hinckley, Ohio
PPL - 1970
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 275
Reply With Quote
  #9  
Old 04-15-2017, 05:55 PM
Dave12 Dave12 is online now
 
Join Date: Oct 2010
Location: Elkton, Md.
Posts: 1,261
Default

In almost 600 hrs. of 12 time, the only time I have smelled fuel was when the floats were heavy.k
__________________
Proud Dad of a Navy Corpsman
FMF "Devil Doc" 2nd Marines
N588DF RV12 #336 Sold
N73DF RV12 #244 Flying
Reply With Quote
  #10  
Old 04-15-2017, 07:09 PM
snopercod's Avatar
snopercod snopercod is online now
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 676
Default Combustible Gas Detector?

Amazon sells Combustible Gas Detectors.
__________________
(2017 dues paid)
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 03:12 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.