Training and Safety Tip: Sweat the details
During preparation for a recent flight, a pilot colleague ahead of me experienced a minor crisis when his aircraft began to spew fuel on its departure run.
The aircraft looked normal during its runup, and the pilot took to the runway for his takeoff roll. As he accelerated and lifted off, a cloud appeared just above his right wing.
When a gas cap pops off while the wing is generating lift like it did in the case of this Bonanza, the low-pressure air flowing over the top of the wing will siphon fuel out of the tank. Depending on the aircraft’s fuel system design, a pilot may not notice the loss of fuel immediately. The gauges may not show the loss, and by the time it does become noticeable, there's probably already less usable fuel left.
In the case of two separate wing tanks, the leaking fuel from just one side could also lead to a weight imbalance. If the tanks are connected and the cockpit fuel switch is set to “both,” that could create a far greater emergency as the fuel is rapidly sucked out of both tanks, leading to unexpected fuel exhaustion and, eventually, a possible engine failure.
An additional risk of an unsecured fuel tank is contamination. A popped fuel cap will allow water, dirt, or any other external debris into the tank, leading to blocked fuel lines or other obstructions in the fuel system, which can, in turn, cause engine roughness or failure. A missing cap can also disrupt the venting system that is designed to maintain proper fuel flow and can lead to vapor lock.
On that Thursday afternoon, the pilot returned to the field and landed uneventfully. The airport closed the runway until a ground patrol found the lost fuel cap.
It turned out to be a mechanical problem—a worn-out part—not a human-induced one. But it was a good safety reminder that minutiae matter, and can make or break an entire flight.
It’s easy to overlook small details like a loose wire, or a missing rivet, or a peskily malfunctioning fuel cap. You’ve probably topped up the tanks, and you want to launch while the day is young. One extra check to make sure the cap(s) is/are on tight is a good habit to get into, even if you’re anxious to get in the sky.
One of my instructors always told me, “Slow and steady wins the race.”
I say it’s the details that win the race.
