C177 Fuel Problems
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C177 Fuel Problems
Recently, I was flying a round trip in a C177. When I departed the home airfield I had around 3 hours fuel on board (I forget the exact tank figures but it was spread fairly evenly).
Upon arrival at my destination the aircraft was left on a slight slope, which, in retrospect may have caused some fuel to crossfeed from the left tank into the right. (I don't know, it's equally likely from later events that there was a crossfeed issue and only the left tank was being emptied.) Anyway, prior to departure I dipped the tanks and discovered I had 10L in left, 50L in right - about 2 hours for a 30 minute flight. In retrospect I should have considered the imbalance strange and investigated further but I have seen similar imbalances in Cessna's and as previously mentioned, there was a slight lean to the right).
About 10 minutes after departure, with fuel selector on "both", the engine almost stopped. A quick change to the right tank (which I remembered having more fuel) prevented a complete failure and in air restart.
So, my question is, what could be the issue? A friend has advised that the Cessna manual advises that there may be fuel feed issues when one tank is low but this is not described well and goes on to contradict itself. Could it be a crossfeed issue? Or maybe a breather valve problem? Any thoughts welcome.
Upon arrival at my destination the aircraft was left on a slight slope, which, in retrospect may have caused some fuel to crossfeed from the left tank into the right. (I don't know, it's equally likely from later events that there was a crossfeed issue and only the left tank was being emptied.) Anyway, prior to departure I dipped the tanks and discovered I had 10L in left, 50L in right - about 2 hours for a 30 minute flight. In retrospect I should have considered the imbalance strange and investigated further but I have seen similar imbalances in Cessna's and as previously mentioned, there was a slight lean to the right).
About 10 minutes after departure, with fuel selector on "both", the engine almost stopped. A quick change to the right tank (which I remembered having more fuel) prevented a complete failure and in air restart.
So, my question is, what could be the issue? A friend has advised that the Cessna manual advises that there may be fuel feed issues when one tank is low but this is not described well and goes on to contradict itself. Could it be a crossfeed issue? Or maybe a breather valve problem? Any thoughts welcome.
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With regards to taking off with the imbalance - on reflection I'm surprised I did as well! I guess I just assumed (always a bad idea) that it would just crossfeed as usual.
The cap seel is a good point. I've since been told there have been issues in the past with water getting into the tank and I suspect this may have caused the imbalance in the first place.
The cap seel is a good point. I've since been told there have been issues in the past with water getting into the tank and I suspect this may have caused the imbalance in the first place.
A long time ago, I had a problem with a 172 that had a faulty tank selector. With it set on both, the feed from one tank was shut off. Turned to either tank it worked fine. Your symptoms match that sort of scenario. I don't know what the engineer did to the valve in my case (replaced or stripped down) but it worked fine the next time I was in the aircraft. It could be a venting problem as well but you need to look at the fuel system diagram in the manual to see which is more likely. I can think of some ways to check it out on the ground but only looking at the manual will show what is the best for you. I would not fly the aircraft if I suspected a faulty fuel selector.
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from here 172 vs 177? - CESSNA 172 FORUM - Cessna 172 talk 24/7
In cruise flight, the Cardinal is a steady IFR airplane—if you can get it trimmed out laterally and keep the fuel balanced. Several owners reported gross fuel-flow discrepancies when the fuel selector is on “both,” with the tendency for fuel to flow from the left wing. Left-right switching every half hour may be necessary to maintain good lateral trim or a few seconds of uncoordinated flight to clear the liquid from tank vent system, which is what causes the imbalance.
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Crablab. I have had a similar incident in a C177 RG. It had been parked on a slope left wing low. It had not flown for a couple of weeks and there had been some heavy rain. I took off and the engine soon started running very roughly. I did a tight circuit and landed. After parking I found substantial amounts of water in the left hand wing fuel drain. When I did my preflight it was definitely all fuel in the sample and no water at all.
Closer inspection revealed the rubber seal on the left hand fuel cap had perished and was letting in water. Because of the slope the rain water would have gone into the tank and flowed down to the wing tip. Once the plane taxied out and had taken off the water made its way from the wing tip down to the centre where it affected the engine running.
I suspect you may have had water in the wingtip and your engine nearly stopping was the result of water not fuel imbalance. With the fuel tank selector on both and no water in the tank the engine will run regardless of any imbalance or even an empty tank.
Closer inspection revealed the rubber seal on the left hand fuel cap had perished and was letting in water. Because of the slope the rain water would have gone into the tank and flowed down to the wing tip. Once the plane taxied out and had taken off the water made its way from the wing tip down to the centre where it affected the engine running.
I suspect you may have had water in the wingtip and your engine nearly stopping was the result of water not fuel imbalance. With the fuel tank selector on both and no water in the tank the engine will run regardless of any imbalance or even an empty tank.
