Maintenance Matters

August 2007 Issue

Wet Vacuum Pumps: Reliable, Durable

So why aren’t they more popular? Cost, mainly. At five times the price of a dry pump, many owners balk. The oily belly argument is bogus, in our view.

In free markets—or so the theory goes—good products rise to the top like cream and bad products are weeded out and tossed aside to wither and die. In the real world, it’s messier than that, thus we have VHS instead of BetaMax, PCs dominate Macs and the overwhelming majority of airplanes have failure-prone dry vacuum pumps instead of bulletproof wet pumps. What happened here? The precise details seem to be lost to the sands of time but the short version is this: Dry pumps appeared in the mid-1960s, they were substantially cheaper than wet pumps and by the time owners realized how unreliable dry pumps were, the aircraft manufacturers had established them as the defacto standard. And because the OEMs could get away with that, the two wet pump manufacturers—Pesco and Garwin—got out of the wet pump business and eventually disappeared entirely.

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