Fuel vent deflector

A

aifreeman

New member
Does anybody know the CORRECT reason for this odd device? Silly answers happily received . Andy freeman. UK. One very happy Decathlon owner. :?
 
Andy-

It's an FAA requirement that the fuel vent be protected from impact icing to prevent engine failure. If you got caught in freezing rain it would build on the deflector. This is the same reason that most high wing Cessnas have the vent just aft of the lift strut.

Tom-
 
Thanks. That`s what I thought. I just get blank stares when I tell people that. Maybe we get warmer freezing rain over here!
 
Jerry-

This should be better publicized, I just saw a set of your replacement wings with it missing. The owner had rigged a short tube on the vent to prevent the tank from getting pressurized and was then complaining about uneven fuel flow??????????

Tom-
 
Jerry-

His comment was that the old one got lost, and since it was just to assure ambient, rather than impact, pressure to the vent his arrangement would suffice. It was easy to see that his "mod" actually provided a slight decrease from ambient and caused the fuel flow imbalance because it affected the near tank more.

Of course he discounted my advice, after all who would be concerned about ice on a Citabria?

Tom-
 
Tom, with respect, dont use my thread to have a bash at ACA. When I list the zillion reasons for owning a Decathlon top of it is the fact that it`s still in build and every part is available by post off the shelf direct from the manufacturer (Mandy!) 3000 miles away. Try that with a Boeing. Andy
 
Andy-

"Bash at ACA", how so? If I was "bashing" anyone it was the ACA customer who failed to follow the directions ACA supplied with his replacement wings. My comment was simply that the importannce of the deflector should be better publicized, if that's "bashing" we've got an extremely low threshold of acceptable vs. unacceptable discourse in this forum.

There is no doubt that it's GREAT to have ACA still available to support the fleet, and Jerry posting the (semi) official word here, But blindly ignoring legitimate airworthiness issues, questions, is foolish.

Please explain why you think I was "bashing".

Tom-
 
Well, there should be a slightly higher pressure region at that point under and airfoil. So, in theory it should still function 'okay' but not as good. If you factor 3D flow into it, the accelerated flow around the windshield likely reduced the pressure in that area. How much one cancelled the other? Well, this is 3D fluids we are talking here... :p

He is probably better off than the guy I saw at Oshkosh a few years ago where he put the vent deflector OVER the vent...you know.....to seal it up. :shock:
 
Jerry-

What he did was install a short piece of tubing facing downward to prevent impact airflow from pressurizing the forward facing vent, thinking incorrectly that the deflector was for that purpose. It was obvious that the angle of the downward facing opening in his extension caused a slight decrease in pressure. He was then complaing that his LH tank wasn't feeding correctly, it's obvious that the decreased vent pressure would have a greater effect on the nearest tank.

Your OSH experience confirms my initial comment that the deflector is poorly understood and deserves better publicity.

Tom-
 
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