Spend enough time in a hangar and you will no doubt hear many flying-isms, many of them pithy sayings warning pilots against making poor decisions. A few warn against running out of fuel, an unforgivable mistake for any pilot. “The most useless things in aviation are the runway behind you, air in the tanks, and the altitude above you.” Truer words were never spoken.
Pilots run out of fuel for myriad reasons, but inaccurate fuel gauges leading to mistrust is historically a big problem. Twin Commander expert technician Mike Grabbe described the various types of fuel systems in a Flight Levels article in 2020. He wrote:
It doesn’t matter if your aircraft fuel quantity indication system is as simple as a cork float and a marked stick poking out the top of the tank, one with floats driving potentiometers, a system that has an AC- or DC-powered transformer using a float with an iron slug or a capacitance type system. All fuel quantity systems need to be calibrated every so often, to ensure you are seeing an accurate indication in the cockpit.
Grabbe’s point about calibrating and servicing the system is well taken. We can’t expect an aircraft that was manufactured many years ago to operate free of maintenance, and that includes the fuel system. Continuing to rely on aging gauges can lull a pilot into a false sense of security.
Then there’s the issue of leaks. Even if we assume the gauges are accurate, pilots often base their fuel operating principles on time, and a leak, a missing fuel cap, or other anomaly can lead to a much lower fuel level than predicted. Without a visual sweep of the gauges, it’s possible a pilot could never know.
Unfortunately, the problem hasn’t gotten any better. Respected Twin Commander instructor and broker Gary Gadberry recently gave a presentation at the recent gathering at Hancock Aviation in Tennessee addressing continuing fuel management issues.
Many years ago Twin Commander Aircraft developed a low fuel warning light specifically to address this issue. Custom Kit 110 adds a low fuel level warning system to earlier piston models, except the 680T, 680V, 680W, and 681.
CK 110 includes new parts for the fuel transmitter that is installed in the center fuel tank, and a warning light installed in the cockpit, to alert the pilot when fuel quantity falls below 31 gallons. If the light illuminates, you have adequate time to identify and fly to a nearby airport to take on fuel. In addition, Gadberry has developed an aural system to complement the light.
According to Ontic, the factory is also working on a new Vendor’s Kit with their part number as identified by an Ontic/Twin bulletin. This will upgrade the transmitter as part of an overhaul process to ensure the integrity of the wire between the resistor and the float. When that breaks the fuel quantity indication goes with it.
Contact your preferred Twin Commander Factory Authorized Service Center to learn more about CK 110 and how it can improve your airplane’s fuel system.
