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How Simply Switching Fuel Tanks Led To This Accident

Ronnierob

When fuel starvation happens in flight, it usually happens at the worst possible time. Like when you're low, in the traffic pattern.

And while you may not have caused the problem directly, there's a lot you can do to prevent it.

This accident is a perfect example:

The pilot stated he had an uneventful cross-country flight and on the downwind leg of the destination airport traffic pattern, he switched the fuel selector from the right tank to the left tank and turned on the boost pump. While on short final approach, the engine started losing power as the airplane was approximately 75 feet above ground level. The airplane subsequently impacted terrain about 600 feet short of the runway and came to rest upright. The pilot further stated that at the time of the engine power loss, he pushed all the controls, mixture, propeller, and throttle full forward and the engine rpm started to increase, but then quickly decreased again. The pilot then shut-off the master switch and walked to the fixed based operator to get help. He then walked back to the airplane, shut the ignition off and took his keys and headset out of the airplane. The pilot added that he did not touch the fuel selector.

Examination of the wreckage by a Federal Aviation Administration inspector revealed damage to the wings, landing gear, and stabilator. The inspector also noted that although adequate fuel remained in both fuel tanks, the airplane fuel selector was in the "off" position. The pilot further reported that there were no preimpact mechanical malfunctions with the airplane.

View the full report here.

Follow The Checklist, Unless...

Checklists are ingrained in our flying. And at some point, all of us have found ourselves flying through a checklist, moving through each item almost automatically. Which is how an empty fuel tank gets selected, or the fuel selector gets turned to the "off" position.

No one looks at the fuel selector in flight and says "hey, let's turn that off!" You're working the checklist, or that little GPS scheduler message pops up and says "switch fuel", and you do. Without even looking.

There Are Good Times To Switch Fuel Tanks, And There's This

We're flying over Maroon bells. We're only a few thousand feet above the peaks. There are 14,000' mountains in all directions. It's an incredible view, and it's also a really bad place to switch tanks.

Boldmethod

If we select a bad tank position, or if the valve fails to open, we've set ourself up for a real problem. And remember, it takes time for the problem to show up. So thirty seconds after we've switched tanks, we're a glider.

Even if the checklist says switch tanks, if you're not in a safe spot for an engine failure, defer it. In this case, we switched tanks once we crossed the peaks.

Look, Change, Wait

Besides selecting an empty tank or turning the valve to "off", a valve could stick, or a pump could fail.

So, there's a great rule-of-thumb to follow. When you change tanks or turn off a fuel pump, monitor for thirty seconds. Look, change, and wait. Make sure the fuel flow is steady, and the engine's running smooth. If it's not, undo what you just did.

Boldmethod

The fuel selector is often your point of failure.

  • 1) You select a bad tank. Either an empty one or one that's contaminated.
  • 2) The valve fails and you can't feed from the tank.
  • 3) You keep burning a tank until it's empty.
  • 4) You don't move the selector all the way over to a tank, or you inadvertently select the off position.

Which goes back to our earlier rule about changing the fuel system. Don't do it unless you can make a safe power off landing, of you have lots of time to restart the engine.

Upwind? Bad idea. The beginning of downwind? Bad idea.

Change Tanks At The Right Time, Not Just Because Your Checklists Says So

There are a lot of issues that can cause fuel starvation. Broken lines and clogged filters are just a few reasons. Those can be hard to diagnose, and may not be solvable in-flight.

But most of the time, fuel starvation is caused by something we do to ourselves. Forgetting to switch tanks, or changing to a bad fuel system configuration are two of the most common reasons.

If you take one thing away from this, it's that you never want to reconfigure the fuel system out of habit. Always look, and make sure you're selecting a tank or setting that has fuel. Then after you make the change, wait. Make sure that your fuel flow and engine operation remains steady, and if it doesn't, undo what you just did.

And no matter what the cause, here's the best way to prevent an emergency: don't touch the fuel system unless you have time, and altitude, to fix the problem.

Aleks Udris

Aleks is a Boldmethod co-founder and technical director. He's worked in safety and operations in the airline industry, and was a flight instructor and course manager for the University of North Dakota. You can reach him at aleks@boldmethod.com.

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