AOPA Pilot Magazine - July 2022 - 52

Diamond Aircraft Industries originally found its
niche in the general aviation market selling motorgliders
and light piston singles-the DA20 and
DA40-to North Americans and Europeans.
By 2004, it expanded its offerings to twins with
the debut of the Thielert Centurion diesel-powered
DA42 Twin Star line; it started making its
own Austro line of turbodiesel engines in 2007;
and followed up in 2012 with the larger, sevenseat
Austro-powered DA62. Along the way
came the D-Jet, a 2006 twinjet design intended
to capitalize on what at the time seemed like a
vast market for very light jets. Today, all the aircraft
are still in production (save the D-Jet) and
selling well to both private owners and flight
schools around the world. That's quite a product
line, but Diamond lacked a big-cabin single
that could one-up the DA40.
Until the DA50 RG came along in 2020. It
was a long time coming, with the first DA50 prototype
appearing in 2007. But after trials with
no fewer than six different engines (a turbocharged
piston, a turboprop, and four diesels)
and a switch to retractable landing gear, the first
DA50 RGs were sold to European customers in
2021. By this summer, the DA50 RG should have
earned its FAA certification and begun a demonstration
tour in the United States.
Systems basics
The airplane has a 300-horsepower Continental
CD-300 dual-channel full authority digital
engine control, intercooled twin turbo turbodiesel
engine, liquid cooled and arranged in
a V-6 configuration. Fuel is fed to injectors at
the pistons via a dual common rail fuel injection
system that operates at 23,000 psi thanks
to high-pressure fuel pumps. The FADEC controls
ensure that the proper amount of fuel is
delivered to each cylinder at the proper time,
ensures that no limitations are exceeded, and
controls the turbochargers and propeller, which
is driven through a gearbox.
With all that fuel pressure there's no way
the engine can consume the volume of fuel
being fed into the cylinders. So, the unused
fuel is returned to the main and auxiliary fuel
tanks. Along the way, the heat of the returning
fuel is cooled on its way to the left (main)
tank, while warm fuel returning to the right
(auxiliary) tank keeps fuel temperatures from
52
AOPA PILOT / July 2022
reaching the freezing point at altitude. In
another quirk, fuel is normally delivered to
the engine from the main tank only, so there's
a fuel-transfer rotary button to send fuel from
the aux tank to keep fuel tank imbalances
below the 9-gallon limit. If there's a problem
with the fuel feed from the left tank, fuel can
be drawn from the aux tank by moving the fuel
selector to the Emergency position.
Thanks to the automated functions of the
FADEC, a single-lever power control governs
both engine and propeller functions, so there's
no need for separate propeller and mixture controls.
A small sliding switch at the front of the
The arm rest contains flip-up multifunction display
and other controls for easy access (below). VGs at
the wing tips, plus the huge gull-wing doors and
interior (facing page, above), are distinguishing
features-and the reinforced structure surrounding
the cabin gives the DA50 exceptional crashworthiness.
Continental's CD-300 twin turbodiesel uses
intercooled intake air from the twin turbochargers
and a common rail fuel injection system (facing
page) to push true airspeeds as high as 181 KTAS.
Incoming, intercooled air is fed to the engine via the
two large parallel tubes atop the engine. A single
power lever and FADEC controls mean maximum
power with modest fuel burn and low workload.
AOPA Pilot Magazine - July 2022

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