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Fuel tank vent tube leaking in wing? Advice?


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Vent tube leak problem in Bravo.

 

Bravo has a slight gasoline leak pretty much near the right wing tip. Not huge, just an occasional drip/stain...particularly if right tank is more than and three fourths full or conducting maneuvers that puts right wing low. Likely that the vent tube has become disconnected. Hard to see exactly what's going on in there too limited access panels. We found an invoice from previous owner's service where a service mechanic has a note saying reconnected right-wing vent tube. Was one hour labor.

 

It looks to us like the likelyway to see and repair this would have involvinvolvedremoving the rivets to remove the wingtip. But it does not appear that has been previously done. That is rivets and wingtip show no traces of having been removed and replaced ...and we can't believe that if the had been and then perfectly meticulously professional repainted the charge would have been only one hour labor.

 

This is on the P2004 bravo. I presume the tube situation may be very similar on the other bravos.

 

So here are my questions:

 

Has anybody else here experienced this or heard of it? (One mechanic we spoke to said he had heard of this not being uncommon and they had done some repairs of that in the past on Tecnams.)

 

Any thought or solutions?

 

I also appears possible that the small plastic external vent fittingson both wingtips may have been broken off , and is not clear. It appears possible that they used to have small protruding plastic tubes trailing backwards that may have been snapped of. So can anyone look at their vent exits on their tecnam wingtips and described them, or better yet post a photograph here?

 

All help appreciated, as this is the most annoying puzzling and frustrating minor problem that could lead to significant repair work.

 

Al

 

Sent with 100% recycled electrons

 

 

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Vent tube leak problem in Bravo.

 

Bravo has a slight gasoline leak pretty much near the right wing tip. Not huge, just an occasional drip/stain...particularly if right tank is more than and three fourths full or conducting maneuvers that puts right wing low. Likely that the vent tube has become disconnected. Hard to see exactly what's going on in there too limited access panels. We found an invoice from previous owner's service where a service mechanic has a note saying reconnected right-wing vent tube. Was one hour labor.

 

It looks to us like the likelyway to see and repair this would have involvinvolvedremoving the rivets to remove the wingtip. But it does not appear that has been previously done. That is rivets and wingtip show no traces of having been removed and replaced ...and we can't believe that if the had been and then perfectly meticulously professional repainted the charge would have been only one hour labor.

 

This is on the P2004 bravo. I presume the tube situation may be very similar on the other bravos.

 

So here are my questions:

 

Has anybody else here experienced this or heard of it? (One mechanic we spoke to said he had heard of this not being uncommon and they had done some repairs of that in the past on Tecnams.)

 

Any thought or solutions?

 

I also appears possible that the small plastic external vent fittingson both wingtips may have been broken off , and is not clear. It appears possible that they used to have small protruding plastic tubes trailing backwards that may have been snapped of. So can anyone look at their vent exits on their tecnam wingtips and described them, or better yet post a photograph here?

 

All help appreciated, as this is the most annoying puzzling and frustrating minor problem that could lead to significant repair work.

 

Al

 

Sent with 100% recycled electrons

 

 

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Take the strobe / light thingy off the wing tip and have a giz in there ............ assuming there is no vent disconnect - just pushed in

 

There should be say 10 mm of black plastic vent tube protruding out rear of wing tip fairing - sounds like vent tube has been pushed in ?

 

 

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Take the strobe / light thingy off the wing tip and have a giz in there ............ assuming there is no vent disconnect - just pushed in

 

There should be say 10 mm of black plastic vent tube protruding out rear of wing tip fairing - sounds like vent tube has been pushed in ?

 

 

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  • 3 weeks later...

Well, after finally going to the extreme of deriveting and removing both wingtips, discovered that both vent tubes were loose in the wings flopping around and all too often spilling fuel into wing spaces.

 

Based on other reports, it appears that this is not an uncommon issue in tecnams with wing tip vents.

 

I'd call it a design or workmanship flaw. If this were a car it would be treated IMO as an urgent safety recall paid for by the manufacturer.

 

I note that in their newer models Tecnam has gone to putting the vents in the fuel cap.

 

I would suggest anyone with the wingtip vents on their Tecnam check carefully the whole wing , especially trailing edges and tips for post flight fuel stains.

 

Al

 

 

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If the tank vent tubes simply go from the end of the wing tanks to the adjacent wing tip, then they are a cheap and nasty effort, and the manufacturer should be kicked in the testicles for it. The ONLY reliable wing tank vent system has a cross-over to the other wing, so when one wing is low (in terms of effective angle of gravity), the vent exit is higher than the highest level of fuel in the 'low' tank. It's called 'lean', and it happens for all but the 100% perfect pilot. Also- they need to exit in a neutral air pressure area.

 

Yacht cockpit drains have been able to manage lean, by using cross-over, for at least the last 100 years. When aircraft designers don't have the wit or intelligence to understand basic fluid dynamics, they need to be treated with a disproportionate response... We are talking a serious comprehension re-alignment session out the back of the shed here.

 

 

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  • 3 weeks later...
It's worth submitting a defect report, if the Tech manager considers it a safety issue he might raise an airworthiness notice.https://www.raa.asn.au/wp-content/uploads/2012/02/Defect-Report-November-2014_Fillable.pdf

I agree. If there is spare fuel in the wing space, that sounds like quite a hazard to me. One spark and things could become really bad.

 

 

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