You can go a long time in flight training and never touch a fuel selector switch, activate an electric fuel pump, or decide which fuel tank to tap next. You can keep that streak alive if you stay with the kinds of airplanes you trained in after you move on to the next certificate or rating, or when you join the ranks of aircraft owners. Some pilots get their first training hours in aircraft that demand pilot participation in fuel management.
This obligation to take positive steps to keep the fuel flowing often seems like just one more nagging detail to worry about for a novice trying to keep the wings level, hobbling through slow flight, or preparing to land. But later many look back on those days and conclude that the experience helped from the perspective of developing habit patterns and stamping fuel management consciousness into their pilot thinking.
Running a complex fuel system only works if you know how much fuel you have, and where you have it. Only then can you figure out the proper way to deliver it to the engine. When you move up to a different make and model, the fuel system is sure to be one of the first things you’ll study. But don’t just take the book’s word for it—check the aircraft’s paperwork and placards, too. Its fuel system may have been modified in ways that are uncommonly tricky.
Last October 2, the pilot of a Cessna 180 with a modified fuel system that reduced the aircraft’s total fuel capacity faced a forced landing in Mitchell, Oregon, over what the National Transportation Safety Board accident summary described as “rugged terrain.” One serious injury and one minor injury resulted. “Examination of the airplane wreckage revealed minimal evidence of fuel,” noted the report. “The airplane had a modified fuel tank system through a supplemental type certificate (STC). The STC changed the fuel capacity of the two fuel tanks from 30 gallons to 28.2 gallons each.
“The installation information for the STC noted that to determine the usable fuel for the airplane, the airplane’s type certificate data sheet (TCDS) should be referenced and the unusable fuel amount listed therein should be subtracted from the new total fuel capacity. The TCDS for the airplane stated that 5 gallons of fuel were unusable, making the total usable fuel capacity on the airplane 51.4 gallons.
“As a part of the STC, the airplane flight manual (AFM) and the fuel selector valve placard were to be updated with the revised usable fuel quantity. The pilot had purchased the airplane several years prior to the accident and the previous owner told him that all of the fuel (56.4 gallons) was usable. The pilot reported that there was no AFM supplement for the STC included in his paperwork, and that he did not ever look at the quantities indicated on the fuel selector valve placard in the cockpit due to its location between the seats.”
Probable accident cause: “The pilot’s lack of understanding of the airplane’s fuel system, which resulted in a loss of engine power due to fuel exhaustion.”
A pilot giving 15-minute rides to prospective young pilots should be on his best behavior. But giving multiple short flights while managing a complicated fuel system got the better of a Piper Comanche pilot in Highgate, Vermont, on October 3, 2009. “Improper fuel management” resulting in fuel starvation was the NTSB’s probable cause determination for the engine stoppage and subsequent forced landing that ran the PA-24-260 off the end of the departure runway during the fifth demo flight. The aircraft made it 300 feet off the ground before the power loss. “The pilot switched fuel tanks and verified that the fuel pump was on, but to no avail. He then force-landed the airplane on the departure end of the runway. The airplane continued off the end of the runway and through a grassy overrun for about 100 yards, until it impacted a fence, substantially damaging both wings,” said the NTSB report.
“The pilot noted that there were two main fuel tanks and two auxiliary fuel tanks on the airplane, and that during the first four flights, he only utilized fuel from the left main tank. Prior to the fifth flight, both auxiliary tanks and the right main tank were full, and the left main tank indicated one-quarter full. The pilot initially switched fuel feed to the right main tank, but then decided to utilize the remaining fuel in the left main tank, and switched back to that tank before takeoff. Postflight examination of the left fuel tank revealed no fuel in the tank.”
Many pilots like to burn the fuel in a tank down to empty before switching. It’s a pity that a takeoff was attempted with that goal given higher priority than departing on the fuller tank—and many checklists advise pilots to “use the fullest tank” for takeoff and landing. Just the uncertainty about the fuel quantity remaining in that tank argues against making the gamble. These reports invite us to second-guess the decisions made—those made in the moment about a takeoff, and those made over time, about studying a modified fuel system—and resolve to find a better way.
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