Twice a week. On average, thats how often GA pilots run out of gas. One reason for this-we surmise-is that pilots either don’t know how to manage fuel or they just do it poorly. The iffy gas gauges found in typical legacy airplanes aggravate the problem.

Although the real reason for fuel exhaustion lies between the pilots ears, there’s a not-too-expensive upgrade that can help: a fuel totalizer. It will provide instantaneous fuel consumption data along with fuel remaining, endurance and, perhaps most important, a reliable indication of lean state. With gas at $6 a gallon, you need all the help you can get.

When connected to a loran or GPS, a totalizer can supply distance-to-empty and reserve-at-destination information, along with your real-time mileage. Most fuel totalizers are stand-alone products; others require either a compatible GPS or an installed engine monitor to do their thing. Either way, none will guarantee you wont run out of fuel, but you’ll have to work at it.

How They Work

Totalizers count the impulses generated by a fuel-line mounted transducer and convert the information into fuel consumption. Presuming the device knows how much fuel is aboard, is configured properly and there are no leaks, any totalizer worthy of the name will display the real-time gallons, pounds, liters or other measurement unit per hour flowing into the engine.

It will work with mogas, avgas or Jet A, although a higher-capacity transducer may be required for larger or turbine engines. A totalizer should display the endurance remaining until empty tanks, expressed in time, but its still up to the pilot to enter into the unit the correct fuel amount aboard and to switch tanks as appropriate to ensure the available fuel gets to the engine.

A standalone totalizer installed in a non-pressurized single requires only a suitable cut-out in the instrument panel, passing three wires through the firewall and connecting them to the transducer, bolting the transducer to the top of the engine and installing a hose and appropriate fittings in the fuel line. A dedicated circuit breaker and appropriate wiring may also be necessary.

But some aircraft-those with pressure carburetors, for example, and some fuel injection systems-return a variable amount of excess fuel to the tanks. Since this happens past the point in the system where the transducer can be installed, the totalizer wont know about the returned fuel, displaying greater consumption than the engine is actually burning. The fix is to install a second transducer in the return line, subtracting from the total, but some totalizers cant do the math.

Most totalizers accommodate only one engine. For twins, manufacturers offer an upgrade path, ensuring the totalizer counts all the gallons burned and subtracts them from the fuel onboard, while allowing the pilot to view an individual engines flow. One system, Sagems FC-10, requires an add-on box, the FT-10, to handle twins. Shadins totalizers work just fine with two engines. Then comes connecting the totalizer to the avionics. Many products can receive serial data from a loran or GPS to calculate real-time mileage, fuel remaining at destination or fuel required to the next fix. Others send their fuel flow data to the navigator, allowing it to make its own calculations. Most totalizers are available in either a standard or optional configuration, allowing them to send and receive such data.

All of the totalizers we looked at come with a supplemental type certificate for at least one aircraft; many are STCd in hundreds of aircraft types through an