This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
During preflight, my co-pilot and I did a thorough walk around, including checking oil and adding oil and sumping the tanks for water. No discrepancies were found and no water was found while sumping the Piper PA-28.
We took off towards the north and started our initial climb out. My co-pilot talked to Regional Departure.
We started heading to ZZZ when at 4,048 feet (starting our cruise climb), the engine lost power entirely for five to six seconds.
We quickly cycled the throttle, engaged the fuel pump, and switched fuel tanks.
After the engine started back up, it felt unreliable so we made the collective decision to land at ZZZ1 airport after querying ATC. We landed safely at ZZZ1 and parked doing a thorough run up.
We collectively decided to have a mechanic look at the aircraft before having it airworthy again. Later that day, the mechanic found water in the fuel tanks that possibly starved the engine.
Primary Problem: Aircraft
ACN: 2076945
Cessna bladders often have wrinkles on the bottom. Cars don’t have fuel caps facing the sky, that’s why no water. Check the o ring on your caps, that’s where most water comes from.
Why doesn’t this problem happen
with automobiles? I’ve never had to sump my gas tank on any of my cars.
Caution should be advised if sump check is made very soon after refueling. If water is in the new fuel, it might take 20-30 minutes or more to settle down into area where sump drains are located.
The fuel may have had water in it but it didn’t come from condensation. Do the math. An empty 25 gallon tank at 120F and 100% humidity when fully condensed will produce only a teaspoon of water or less. If the tank is not completely empty or the atmosphere is less humid or the air in the tank doesn’t exchange completely, or….. you’ll get even less. The water he saw came from some other source – not condensation.
I’ve experienced this in a humid environment where water condenses on the inside surface of fuel tanks that are not full. Sumping produced only fuel until vibration caused the water droplets to shake off into the fuel. It took more than two full cups of dumped water per tank after that to get back to fuel. I’ve added a good wing shake to my preflight now, and occasionally find I fair amount of water, especially on a cool morning after a hot day.
Sometimes water in the tank doesn’t migrate to the sump due to adhesion between the water and the aircraft skin. If my airplane is parked outside for any length of time (especially overnight), or after it has been raining, I always give the wings a good shake before sumping. I have found many times that while the initial sump did not yield any water, after shaking and waiting a short while, I have gotten water out the drain. This has been true in a C150, C152, C177 and C177RG. ‘Regional’ Departure sounds like the Dallas area. A warm humid day in Dallas followed by a cool night would result in a vast amount of condensation inside the wing tank if the fuel was not full. This condensation would not appear during a normal sumping, unless the wings were shaken vigorously. During flight due to fuel sloshing and normal flight attitudes, the adhered condensed water would break free and could find its way to the engine.
Sometimes water in the tank doesn’t migrate to the sump due to adhesion between the water and the aircraft skin. If my airplane is parked outside for any length of time (especially overnight), or after it has been raining, I always give the wings a good shake before sumping. I have found many times that while the initial sump did not yield any water, after shaking and waiting a short while, I have gotten water out the drain. This has been true in a C150, C152, C177 and C177RG. ‘Regional’ Departure sounds like the Dallas area. A warm humid day in Dallas followed by a cool night would result in a vast amount of condensation inside the wing tank if the fuel was not full. This condensation would not appear during a normal sumping, unless the wings were shaking vigorously. During flight due to fuel sloshing and normal flight attitudes, the adhered condensed water would break free and could find its way to the engine.
I had found in the past that parking on an uneven tie-down area, such as turf, could result in the aircraft being nose low, not allowing tank sumping to remove all water. Might this have been the case?
I always top off my tanks and use low flow prist while fueling. Some call it over kill, but never had ice or water contamination-issues.
It is possible water could have settled in an area away from the sump and migrated to the carb during the flight. They also say they checked the tanks but what about other areas of the fuel system. It also doesn’t say anything about possible carb ice or what fuel they were using.
Makes no sense to me that water was in the tanks if they sumped the tanks properly.
Possibly flying through rain with the fuel filler cap ajar or missing?
Regards/J
It is possible for water to be present but not show depending on the size of the sample.
Maybe their sample was small and all water, not providing a fuel/water contrast, and appearing to be water free.
That sounds very possible. The pilots involved seem to be well versed and safety focused. If the AC was sitting at some angle the sump drain may have also been above the lowest point in the tank
Their fuel should have had a light blue tint indicating 100LL. I was taught to have the background of the sample be the white of the plane to see this. Holding it up to the sky gives the illusion of bluish and can make you believe you have no water when in fact you have all water in the sample.
See Chris M’s reply.