Planemaker "Surprised" With Hard Line Against Fueling With
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
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
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."