Post Failure Questions

When problems turn up in your airplane, you need to be concerned — whether the problem is large or small — because may just be the tip of the iceberg. Usually, the problems are trying to tell you something, and if you don’t listen, that something could cost you your life.

LETS TAKE BOB FOR EXAMPLE… Bob has a really nice, older plane that he has been fixing up for years. A few years ago, Bob had the entire fuel system of the plane reworked. He did the job right, having the tanks inspected and sealed, and even had all the fuel lines replaced with new ones. The old fuel lines were in fairly good shape, but were a little stiff (from 25 years of age), so he made the right decision.

A FEW YEARS LATER, BOB’S PLANE HAD A BIT OF A MISHAP. A wing was grabbed by the wind. The result left one wing bent, and the plane in storage. It was a year later when the damage was being repaired that the ticking time bomb inside Bob’s plane was found.

A MECHANIC WAS REMOVING THE WING FOR REPAIRS. This involved disconnecting the wing at the fuselage, and carefully moving it to a jig for repairs. When the wing was being disconnected, the mechanic loosened the clamp on the fuel line to the tank, and went to pull the hose off of the tank nipple.

Imagine the mechanic’s surprise when the hose broke off in his hands, under light pressure as he started to loosen the clamp!

HOSES COME IN TWO TYPES — CONTINUOUS CONTACT, AND INTERMITTANT CONTACT. While the hose installed on Bob’s fuel system was Mil-Spec hose, it was not rated for continuous contact. This line had been incorrectly used as fuel line and had started to break down due to the higher level of exposure. The inside of the line was literally covered with cracks. The fuel attacked and broke down the elastomer. When the mechanic grabbed the hose, the structure, gooey from decades of exposure to fuel, pulled free from the nipple.

Look at the internal structure of this fuel hose – how much longer do you think it would have lasted in flight?

TALK ABOUT GOOD LUCK — If Bob had been flying the plane, and had to make a high G turn, or even bounced a landing, who can say whether the hose would have held, or failed. Consider the consequences of the failure — 100-octane gas, flowing into the cockpit from the tank, with no way to isolate it. The outcome wouldn’t be good, no matter how lucky the pilot could be.

FIND A PROBLEM, FIX IT, LOOK FOR MORE. Bob’s mechanic informed him of the problem, and then checked the rest of the fuel system. In doing so, he confirmed his suspicions: the entire system had been incorrectly refitted with the wrong material!


  • Hoses
  • Belts
  • Fasteners
  • Accessories
  • Electrical connectors

While these checks do not necessarily need to open every access plate from nose to tail, they should AT LEAST cover anything that you could possibly suspect. When Bob found the first hose was bad, he suspected that the rest of them might be bad as well, since they were all replaced at the same time.

Keep up your questioning attitude. It is important to understand why components fail in your airplane, so take a moment to think about anything that goes wrong on your plane. If there are signs — or even suspicions — that the issue extends past the current problem, LOOK FURTHER. With this approach, you will be less likely to be greeted with a cockpit full of high-octane fuel, and more likely to have a safe and uneventful flight.