Sigma-Tek’s new piston vacuum pump replaces standard 200-series pumps. Upper section houses a crankshaft and connecting rod.The double-acting piston is in an isolated chamber at the bottom of the pump.

Aircraft owners aren’t likely to agree on much but few would argue the point that vacuum pumps are the least reliable and most likely-to-fail component on the airplane. To its credit, the aftermarket industry has gotten busy recently and developed improved pump designs or back-up systems intended to either minimize the likelihood of inflight failure or provide an alternate vacuum source if a pump does fail.

The latest idea comes from Sigma-Tek, a well-known and respected builder of instruments, pumps and other aftermarket accessories. Sigma-Tek’s new pump has a novel design approach. Instead of vanes or an impeller, it returns to an idea of yesteryear: A piston cycling air through a…