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  #31  
Old 05-11-2010, 06:30 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
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Default Dick Rutan

I will reread the Rutan article but I think the fuel leak was on the positioning flight to Alaska or on a test flight in Alaska. He did say something like, close your eyes, put your fingers in your ears and turn off the battery switch with your elbow. I think this was actually an old Air Force joke.
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  #32  
Old 05-11-2010, 06:35 PM
TSwezey TSwezey is offline
 
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I don't think it's just a tunnel issue there are plenty of openings in the tunnel for vapors to get out. And as it builds slowly you really don't smell it.
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  #33  
Old 05-11-2010, 06:40 PM
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Phil Phil is offline
 
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Location: Waco, Texas
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Quote:
Originally Posted by TSwezey View Post
I don't think it's just a tunnel issue there are plenty of openings in the tunnel for vapors to get out. And as it builds slowly you really don't smell it.
Todd, it sounds like your first overall pick is for the vapor warning device more than any other?
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  #34  
Old 05-11-2010, 06:40 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default not just gas

There are things to be learned from accident/incident reports on large airplanes as well as small. Fires other than fuel fed can kill you just as quickly.
Nascar Cessna310, Orlando, July 10, 2007, electrical fire
Swissair 111, wiring, electrical/oxygen fire
Fedex, Sep 5, 1996, unknown cargo fire
Air Canada DC9, Cincinnatti, OH, lav motor/wiring, electrical fire
Beech Debonair, Pittsburg PA, electrical fire consumed cabin. Pilots aborted takeoff and escaped.
The Fedex accident occurred a few months after the Valujet accident. The Fedex accident is a textbook example of the crew making an almost instant decision and doing everything nearly perfect.
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  #35  
Old 05-11-2010, 08:33 PM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
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Default Vibration can be bad news aft of the firewall.....

I've been thinking, asking, what causes a fuel leak in the cabin?

We assume the area aft of the firewall is ok for solid aluminum lines. No transition to the engine (a vibrating mass) so it should be safe. Up front we use teflon hose and fire sleeve and feel all right about it.

But there's a lot of floor vibration aft of the firewall (at least there is with my airplane). The area going forward from the spar is progressively more "alive" in flight, place your foot on it sometime to get a feel of it if your floor is not carpeted. It is especially so with an auto engine. Seems there may be a harmonic issue going on here, perhaps from exhaust pulses. Generally the high rpm six cylinder engine was very smooth - except at that floor area. I was so concerned about it with possible lower skin failure, I go rid of external mufflers and installed an internal muffler. It did not eliminate all floor vibration but it was better. With Lycoming it is not as pronounced but the forward cabin floor area definitely is not smooth and calm.

This has to have an affect on aluminum fuel lines mounted on the floor running to the firewall. The lines coming through the fuselage sides from the wing tanks along the spar are in a relatively calm area, but forward of the valve and pump toward the firewall, vibration is on the increase. That's where aluminum can become brittle and crack, IMHO.

It's been a year since I installed the Lycoming and have not gotten around to building a new tunnel cover where 2 batteries used to sit above fuel lines and fuel pumps - all enclosed (the single battery now resides forward of the firewall). Everything is currently exposed. The cabin has major air leaks around the canopy and there is a lot of air moving through. It has been on a list of things to work on, the tunnel cover and excess ventilation, but it will stay as is for now.

One thing we don't need in the cabin are poorly ventilated bomb containers with fuel lines, electric wires and arching motors.
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  #36  
Old 05-11-2010, 08:59 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
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I have been following both RV10 incidents with great interest, this is specially that I have been thinking about both scenarios even before they happened.

I have a RV7A and since I built it little over a year ago, occasionally I would smell a bit of fuel. I kept looking for it and could not find it till just recently when I found that my transducer (floscan) was weeping a bit of fuel thru the place that wires come out. As a result I was thinking of moving it FWF, of course the replacement one as the old one is not fixable, or I don't know how to fix it. Anyway after long consideration I thought if that was going to fail, there are greater chances to smell the fuel and do some thing about it then not knowing and let it completely fail. Of course a complete failure is not just engine out, the fuel in FWF to me is perhaps far more dangerous then some (emphasis on some) in the cockpit. I was quite surprise to be able to smell the gas as little as it was coming out judging based on the stain that it left behind but then again, Todd's incident is having me rethink that idea.

At the present, I just like to get others thoughts and ideas about this and thinking of replacing the aluminum lines with the stainless steel.
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  #37  
Old 05-11-2010, 09:49 PM
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Cfrisella Cfrisella is offline
 
Join Date: Aug 2008
Location: Sun city, Ca.
Posts: 255
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If a little airflow will help in the tunnel. How about running an airhose from a radio stack cooling fan.(If one's installed)
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  #38  
Old 05-11-2010, 11:25 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default Tunnel

All Piper Commanches have a tunnel. In the Twin Commanche it is quite crowded. The Commanches have no history of fire or explosion originating from the tunnel area. In the later airplanes, fuel lines, fuel selector, flap motor and boost pump, along with a lot of electrical wiring.
Some automotive electric pumps are installed inside the fuel tank. Various fuel gage senders are installed inside fuel tanks. These do not cause fire/explosion.
This raises the question: are the electrical components in the tunnel of the RV 10 adequate for the installation. A modern flap motor simply should not be a source of ignition. Likewise the electric boost pump.
I believe strobe light power supplys to be very high risk as ignition sources. It would be best to install strobe light components as far as possible away from any fuel. There have been a few cases of strobe components causeing explosions in GA aircraft.
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  #39  
Old 05-11-2010, 11:32 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default Fuel lines

I believe that 5052 O aluminum tubing is the MINIMUM standard for standard category ga aircraft. 5052 is almost twice the strength of the 3003 tubing supplied by Vans. More important, if the 5052 is properly flared with a quality flaring tool, there should not be any significant "tool marks" left by the flaring tool. Fabrication of hard stainless lines is probably beyond the capability of most homebuilders, except in very small diameters.
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  #40  
Old 05-12-2010, 05:08 AM
TSwezey TSwezey is offline
 
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Location: Savannah, GA
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Guys I don't think this is just a tunnel issue. I think this an entire fuel system issue. Who's to say the fumes didn't fill the cabin when I put it into a slip. Or should I say did the slip block the airflow that was pushing these fumes away. I think this is the first time I have slipped it with the flaps down in a while. I have four overhead vents that pump air into the cabin.
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RV-10 Vesta V8 LS2/BMA EFIS/One formerly flying at 3J1 Hobbs stopped at 150 hours
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