Fuel vent ice protection

[vic syracuse]

I am sharing this as a solution that I have found, not as a recommendation. I have always been concerned about inadvertent ice accumulation on the RV's. It can happen no matter what time of the year due to the capabilities of these aircraft. I managed to get about a 1/4" of mixed icing over the Sierra's this past Fall while at 14K'. The 10 climbed fine to 16K' so I could get out of it. The main thing bothering me was the fuel vents, so I decided to try something. I asked at Van's if we really needed the ram air into the tanks, and since the answer was no, I decided to put one of the cable fairlead covers like we use where the rudder cables exit the fuselage ahead of the fuel tank vent. The vent line does not protrude below the depth of the cover. I have made many flights now, at all pwer settings and altitudes, and I have not noticed any difference in fuel flows or pressures. There are no fuel stains by the vent, so it is not syphoning fuel out in flight. At this time I elected to cover only one, and will feed from that tank if I ever should encounter icing again.
Maybe others have tried this already. I know there was a thread a while back and I didn't remember if we had found a solution.
Just for the record, I am NOT equipping my RV-10 for flight into known icing. I just want time to get out of the icing it my way (with a running engine).

Vic

 

[Kyle Boatright]

The fuel vent icing issue is one that all of us need to be aware of. Sharp shapes (like our fuel vents) ice faster than blunt shapes, so those vents would seem to be fairly prone to icing.

Some builders <not me> have looped and terminated their fuel vent tubing inside the wing/fuselage intersection to simplify the routing. I'd think this would also keep the vent(s) dry and ice free.

Just something to consider.

 

[vic syracuse]

Hi Kyle. Hopefully they have just looped the vent tubing, but actually terminated it outside the wing. Otherwise, that could be a very serious issue when the fule in the tank expands. One change I would make for the vents on the 10 is to route the outlet aft of the spar. Right now, the weay they are called for in the plans, when the fuel expands it drips out of the vents, and if the wind is just right it blows it back just enough such that it runs down the gear leg and into the wheel pants. It has the potential for a brake fire if one starts taxing without noticing this, given we need to use brakes for turning.
I talked to Ken at Van's, and he has no problem with us drilling one hole in the spar with a grommet to run the fuel vent aft.

Vic

 

[tacchi88]

Fuel vent

Have QB wings, but not started yet. You guys brought a good point about venting, and dripping on a hot brake would be "exciting". Had a Piper and wing tanks similar as out 10s, they run the vent on the outer extremety of the tank, at the highest point. Fuel can still drip out on a hot day when full but very little. Will have a look when ready. Any thoughts if it can be done?
TT

 

[gmcjetpilot]

C-172 tank vents

Notice the tank vents on a C-172 are behind the lift struts. Vics blocking shield sounds like a good idea; ice will form on the shield and not the vent tube? It may even be a drag reduction and add 0.00005 kts.

For me flying in icing conditions is tooooo scary , I flew freight over the cascade mountains in light twins years ago and saw all the ice I want in a little plane to last me for the rest of my career. Single engine, single pilot IMC, ice.... no thanks, good luck.

Just for the record you can only get icing in IMC (vis less than 1 mile) and freezing temps, right. Stay out of cloud you are OK, or move to warmer climates.

Vic is right and you can get trace ice any time not forcast or reported (thus unknown until you found it) if flying IMC. I also agree if you get it you need to get out of it. So for any IFR RV this mod sounds like standard equipment.

George

 

[rvbuilder2002]

Just for the record you can only get icing in IMC (vis less than 1 mile) and freezing temps, right. Stay out of cloud you are OK, or move to warmer climates.

George

No, you can be VFR and still get Ice.
Clear ice accumulation can be caused by rain that freezes on contact with the airframe such as flying just below a cloud layer in temps just below freezing. Precip is falling but not yet frozen. This type of ice can build up a lot of weight very quickly.

Scott

 

[w1curtis]

icing in VMC

Just for the record you can only get icing in IMC (vis less than 1 mile) and freezing temps, right. Stay out of cloud you are OK, or move to warmer climates. George

From my PP (or was it IP) written, I think this was any type of visible precipitation at or below the freezing level. So you can be VMC in rain and still experience icing.

 

[dan]

Icing in VMC

Learned to fly in the northeast (Boston area). Had icing in good VMC due to light precip on a few occasions when I was younger and dumber. 10 miles visibility turns to 2 feet when your windscreen ices over. It happens.

)_( Dan
RV-7 N714D
http://www.rvproject.com

 

[gmcjetpilot]

Ice Ice Ice

No, you can be VFR and still get Ice. Clear ice
accumulation can be caused by rain that freezes on contact with the
airframe such as flying just below a cloud layer in temps just below freezing.
Precip is falling but not yet frozen. This type of ice can build up a lot of
weight very quickly.

Scott

Yes you can be in temps above 32F/0C and get ice, however it's very
avoidable. Other than the weather phenomena of freezing super cooled
rain/drizzle falling from higher altitudes into warmer temps at a lower altitude,
if you are clear of visible moisture and freezing (ambient) temps, as a rule
you don't get icing.

You are very correct, you could be flying or sitting on the ramp in temps
above 0C or 32F and have liquid (super cooled) water drops fall from freezing
temps above your altitude, super cooling the water, to freeze on contact,
even in warmer temps below, BUT you have moisture at or below freezing,
thus ice, the criteria for ice. This can happen when a warm front over takes
freezing air mass (aloft) or more likely a cold front moves under warmer wet
air aloft. http://www.criacc.qc.ca/villes/verglas98_e.html


If you are under freezing perception (rain, drizzle or fog), chance is the
visibility is not good or even 3 miles, but it is possible. As Dan said, ice over
the windscreen makes vis short indeed. VFR in freezing weather would likely
be marginal. It happened to me on the ground at Atlanta. I was in a B737 and
had light to moderate freezing drizzle, turning the plane into a Popsicle in 10
minutes. The condition on the ground was just under freezing and the
visibility was marginal VFR to IFR. It took three hours and two trips to the
deice pad before I could depart.

Getting into freezing precip, even light, with a light plane, you are in deep
doo-doo and no amount of fuel vent ice protection will help. A good weather brief would make avoiding this straight forward.


Except for freezing fog, drizzle or rain, light moderate or severe, falling into
lower warmer temperatures........, you can NOT GET icing unless you are in
VISABLE moisture (cloud, fog, rain defined as vis 1 mile or less) and
temperatures below freezing.

Stay out of clouds at freezing temps you will not get ice. Also stay away
from warm fronts overtaking cold air masses below freezing (at some
altitude.)

Again all of you are correct and I am wrong again. Gee can't get nothing buy
you guy's.

George