When you open the hangar door, however, you notice the faint but unmistakable smell of avgas. Looking over your Skywagon, there are several droplets of blue avgas on the trailing edge of the right wing.
You sump the right-wing fuel tank, hoping that the sump drain is the source of the fuel leak—but it’s not. You climb onto the wing and shine a flashlight into and around the right fuel tank, hoping to find the source of the drip—but it’s not obvious. You had filled both tanks shortly after arriving at this airport, and now the right tank has lost an estimated three gallons of avgas.
You consult a local aircraft mechanic on the field, and he suspects the tank is cracked. Repairing it will involve removing the tank from the airplane and sending it to a weld shop, then reinstalling it. He estimates the entire process will take two weeks.
It’s a gorgeous day and you and your spouse are only 90 minutes from home by Skywagon. You can easily cover that distance using the fuel in the left wing only.
By Dave Hirschman
I’m choosing option one: Fly home using the fuel already in the airplane.
The fuel leak is small, and it’s located in a place where it’s not a fire hazard. Prop blast will likely blow it into the slipstream all the way home. I’ll select the intact left tank for takeoff and climb, then switch to the right tank during cruise to use up as much fuel as possible from the leaky tank on the way home. The faulty tank is going to be sent out for repairs as soon as we get home, anyway, and this will help empty it.
This leak is an annoyance, and it could be costly to repair—but it’s not an immediate danger. If we only flew mechanically perfect airplanes, we’d seldom get off the ground. Just about every airplane at the flight school where I did my initial training had squawks, inoperative systems, and idiosyncrasies that pilots were told about and worked around. This fuel leak is in the same category. This Skywagon is nearly 60 years old and it shows its age with leaks and creaks.
Would I make the same decision to fly if I wasn’t desperate to get away from my in-laws? Yes, I think I would. Aviation is a constant balance of risk and reward. What’s the benefit to any course of action? What’s the downside? Here, the risk seems like it’s worth the reward.
By Ian J. Twombly
As with any decision involving the mechanical status of an airplane, there are two questions you must answer before deciding what to do: Is it safe, and is it legal?
In this scenario, the second choice, while not the safest, is practical and reasonably safe. By draining the fuel we’re reducing the extremely low likelihood of fire, taking away any risk of the fuel contaminating bits inside the wing we can’t see—and perhaps most important, being a steward of the environment. Avgas is nasty stuff. No need to throw it carelessly to the wind.
The harder question to answer is one of legality. The pilot in command is the only person who can determine if the aircraft is airworthy for the flight. So, what is airworthy? The definition says to be airworthy the aircraft must conform to the type certificate and be in a safe condition for operation. Which brings us back to the first question.
I think you could make a logical argument that with plenty of fuel for the short flight in the other wing tank and no fuel running overboard, safety is not compromised. That said, I would have a long talk with the mechanic to get his or her input, and possibly request the fuel selector be blocked from the empty tank and a placard be added.