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Fuel Vent Lines

S

stickandrudder1

Member
I'm a 7A builder, and am presently fabricating the fuel vent lines. I plan the 7A to be IFR capable, and while I don't plan on deliberately flying into icing conditions, it think it's nonetheless prudent to plan for the possibility. My question is whether anyone has considered the possiblity that the forward facing vents become clogged due to icing, and opted to add an inboard valve to the existing line that could be opened if necessary? I'm not sure this is a good idea or not. I'd appreciate any feedback.

Thanks
 
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Alternative solution

Cessna puts their fuel vent right behind the strut which is a clever way to prevent ice in the opening. So you might consider putting something in front of the vent rather than an inside vent. Venting a tank inside the cockpit is IMHO risker than the chance of ice being a problem.
 
Drill a 1/32" hole on the back side of the vent line. This will allow for venting if the front gets clogged with ice or a bug. Drill the hole outside of the skin though, if (when) you over fill your tanks the drips will just hit the deck.
 
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I teed a one-way check valve into the right vent line at the high point inside the cockpit. With pressure in the tank it is closed off, but if the vent should become clogged by mud duabers, ice, etc. the check valve automatically opens up to vent the tank. Take off is always on the right tank, and switched if accidentally encountering icing conditions.

Vic
 
Vic, do you have a part number of the check valve you used. Where did you get it, and did you test it to insure it could deliver enough displacement air. This sound exactly like what I'm after. Something automatic, that will keep the fan going when the unexpected happens.
 
I'm traveling, so I don't have the part number with me, but I think they are in the Spruce catalog as well as the Summit Racing catalog. They have AN-6 fittings on them, so I know they will certainly flow enough air for the -4 vent line.

Vic
 
Vent issue

Just make sure that it is vented in some form. This is from Aviation International News Today: :eek:

First Major-damage VLJ Returns to Service
The first very light jet to suffer major damage, Cessna Citation Mustang S/N 049, returned to service on February 29 after enduring the collapse of its left fuel tank and two broken wing spars on a December 19 ferry flight. According to the FAA, the twinjet received ?substantial damage? during the flight from Cessna?s Independence, Kan. factory?where owner Spectator Grupa of Croatia took delivery of the aircraft earlier that day?to Allegheny County Airport (AGC) near Pittsburgh for a planned fuel stop. The crew, a Spectator Grupa pilot and a contract ferry pilot, heard a bang at 18,000 feet during the descent into AGC, which was followed by a left-engine low fuel pressure warning. They then noticed distortion on top of the left wing and heard a second bang. The crew continued the descent and landed safely at AGC. FAA inspectors found that Cessna workers inadvertently blocked the left fuel tank vent with adhesive vinyl, which covered the Croatian registration numbers while the aircraft carried a temporary N-number. This blockage prevented the inflow of air to replace fuel drawn from the tank by the engines, and the tank deformed. Cessna technicians disassembled the twinjet before trucking it to the Independence plant, where new wings were installed at Cessna?s expense.

John Clark
RV8 N18U "Sunshine"
KSBA
 
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