every time I fly my 170 b a little fuel will be on top that comes out of the fuel vent. is there a check valve or anything that can be done. with vented caps does it really need the vent on top of the cabin?
thankyou in advance for any suggestions.
fuel vent
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This topic was moved from the MX Library (where documentation is kept) to the Hangar (where maintenance discussions are held.)
This subject has been discussed at length, and a "search" may be used to look at the discussions. (Short answer: Yes a check valve was issued, then rescinded in a service bulletin. If you have the check valve it should be removed.)
This subject has been discussed at length, and a "search" may be used to look at the discussions. (Short answer: Yes a check valve was issued, then rescinded in a service bulletin. If you have the check valve it should be removed.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
How To Keep Fuel Off of The Top of C-170B Airplanes.
!. Do not fill the tanks really full.
2. Keep the Ball Bank Indicator perfectly centered.
3. Do not lower the nose before tanks are down to half full.
4. Never make a really,really steep approach.
Violation of any of the above will probably cause the cross cabin vent line to flood with fuel which will pi-- all over the "roof".
Sometimes, even if you're very ,very careful, it will do it anyway!
Personal experience causes me to suggest that the hoses on that
cross cabin vent line should be known to be in good condition. They're not called out on any inspection that I'm familiar with so they well may be very old and in bad shape. If that is the case, if or when the vent line floods you likely will get a cockpit full of fuel.
I did, and I sure don't want to do it again.
P.S. For the uninitiated, the above rules are facetious.(but true)
!. Do not fill the tanks really full.
2. Keep the Ball Bank Indicator perfectly centered.
3. Do not lower the nose before tanks are down to half full.
4. Never make a really,really steep approach.
Violation of any of the above will probably cause the cross cabin vent line to flood with fuel which will pi-- all over the "roof".
Sometimes, even if you're very ,very careful, it will do it anyway!
Personal experience causes me to suggest that the hoses on that
cross cabin vent line should be known to be in good condition. They're not called out on any inspection that I'm familiar with so they well may be very old and in bad shape. If that is the case, if or when the vent line floods you likely will get a cockpit full of fuel.
I did, and I sure don't want to do it again.
P.S. For the uninitiated, the above rules are facetious.(but true)
BL
Blu Elder ( 
) is correct. And another way to get fuel out of the "gooseneck" vent is to do a wheel landing full of fuel and get on the brakes hard. It was a problem reported by test pilot WD Thompson in his book, and the original reason for the check (ball) valve (which was later found to introduce it's own icing problems and was required to be removed, and a vented fuel cap put on the right filler neck.)
) is correct. And another way to get fuel out of the "gooseneck" vent is to do a wheel landing full of fuel and get on the brakes hard. It was a problem reported by test pilot WD Thompson in his book, and the original reason for the check (ball) valve (which was later found to introduce it's own icing problems and was required to be removed, and a vented fuel cap put on the right filler neck.)'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
I think I ordered the check ball system from Cessna around 12 years ago. It consists of a cotter pin, a small neoprene ball and a cap to fit over the end of the vent pipe. The ball floated between the cotter pin and the cap. The pin is placed approximately 1/2" behind the vent opening and the ball then inserted into the vent tube and the cap slides on the end of the vent. The system solved 95% of all leakage around the vent and continues to do the same for me today. Still get a little leakage when I'm topped off but for the most part it's gone. Dual vented caps did nothing, I still got a LOT of fuel out the gooseneck. Seems like any icing problems with the gooseneck vent would be backed up by the redundant vent on the cap.
JJH55
JJH55
When installing a Continental IO-360 engine in the C-170 IAW the STC from XP Mods, the " roof top" vent is removed and both tanks are outer end vented with the vent line terminating under the wing just behind the lift strut/wing juncture on each side.
What I'm getting at is that if you want to eliminate the "wet roof",
install that engine with that STC and ,"VIOLLA", your problem is solved for a lousy $30,000, or so.
What I'm getting at is that if you want to eliminate the "wet roof",
install that engine with that STC and ,"VIOLLA", your problem is solved for a lousy $30,000, or so.
BL
Anyone who's ever flown a Cessna with the under-wing vents will attest to the fact that they also occasionally spill fuel out the vents. The problem is when the tanks are full or nearly full fuel can enter the vent lines and a bubble can slow it's return to the tank. Additional splashing of fuel can have a surging effect and force the fuel captive to the bubble to exit the vent.
Moving the vent to under the wing solved the smell and stain of fuel on the cabin roof and onto the windshield in a hard-braking wheel landing.
Many operators of airplanes with the check ball still complained of vented fuel out the cotter-pin holes onto the roof anyway.
Moving the vent to under the wing solved the smell and stain of fuel on the cabin roof and onto the windshield in a hard-braking wheel landing.
Many operators of airplanes with the check ball still complained of vented fuel out the cotter-pin holes onto the roof anyway.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.