Planemaker "Surprised" With Hard Line Against Fueling With Jet-A

Owners of diesel-engined piston aircraft weren't the only ones "surprised" by the hard line adopted by ExxonMobil Aviation, which last week issued a letter to its distributors warning against fueling their planes with Jet-A. Diamond Aircraft -- which has sold more diesel-equipped aircraft than any other single manufacturer -- was fairly shocked, too.

"We are as surprised as you are by this circular and are contacting ExxonMobil Aviation to address the matter," reads a letter from Diamond to owners of DA42 Twin Star aircraft, powered by Thielert engines. "We are unaware of the reason for this circular and we are equally unaware of any jet fuel related service difficulties in any TAE powered Diamond airplane. There are of course several other certified and uncertified diesel aero engines in operation and there are also TAE installations in other than Diamond airplanes."

As ANN reported, ExxonMobil appears concerned about potential liability should a diesel-engined aircraft, fueled with Jet-A from one of its distributors, experience engine failure. The oil refining giant says it is concerned Jet-A doesn't have qualities that are vital to the operation of diesel engines.

While conceding the technical reasons cited by ExxonMobil are "valid general concerns for operation of diesel engine powered aircraft," Diamond adds "in the case of TAE and Diamond, all listed reasons, specifically ignition quality, freezing point and lubricity, have been addressed as part of the engine and aircraft certification process and approved by the responsible airworthiness authorities."

The planemaker also notes its TAE-125-powered DA42 was certified exclusively for operation on Jet-A and Jet-A-1 fuel -- not diesel fuel. Combined with the inherent fuel efficiency of diesel powerplants, the availability of Jet-A is a major selling point for many owners of diesel-powered planes... particularly overseas, where 100LL avgas is often unavailable.

ExxonMobil has required all its distributors of aviation fuel to sign indemnity agreements, as well as any customers who demand their planes be refueled with Jet-A at an ExxonMobil Aviation FBO. Diamond notes the company has not forbidden its distributors from selling Jet-A to pilots of diesel-powered aircraft.

"ExxonMobil Aviation does state that customers insisting on fueling their aircraft with Jet fuel must sign the indemnity agreement and as such it is clear that no fuel retailer should be refusing to fuel your airplane with Jet Fuel."

FMI: www.exxonmobil.com, www.diamondaircraft.com