Avionics News September 2016 - 26

EAA STCS ACCESSIBLE SAFETY
Continued from page 25

FAA "knows how we got there," he said. "What the
FAA cares about is meeting the ultimate requirements.
The testing process does not include every variable
that any smart person can come up with. Testing every
corner case drives up the cost of software, but it's not
why airplanes come to unfortunate ends. The testing is
reasonable. How critical is the display to safety? The
display of outside air temperature isn't as critical as attitude, so you test them differently."
There was no specific aha moment that led to the STC
project. "It evolved from the collaboration between the
EAA, the FAA and Dynon," Hamilton said. "All of us
were frustrated that we have all these airplanes, about
100,000 of them, using 50-year-old vacuum technology, and no aircraft owner wants to spend $100,000 on
avionics for a $20,000 to $30,000 airplane."
Dynon has shipped roughly 15,000 units, "equipment
that is critically safe and offers pilots a lot of advantages over the installed Part 23 equipment," Hamilton
said. Bringing these advantages to certificated aircraft
"was a matter of going through the list of requirements
and showing the FAA that we met them." With long and
documented history of reliability, the FAA accepted it as
commercial-parts STC, Jordan added. In other words, it
does not need part manufacturing approval.
From start to almost finished, the STC project took
six months, said Tom Charpentier, the EAA advocacy
specialist who scheduled the project's tasks and coordinated its documents. As president of the EAA Employee
Flying Club, he was pilot in command for the seven
hours of FAA flight tests in the club's Cessna 172. The
EAA submitted the final document, the STC's instructions for continued airworthiness, in early July and
expected FAA approval by EAA AirVenture 2016.
Conducted in March 2016, the flight tests demonstrated to the FAA that what the EAA and Dynon was
doing was reasonable, Jordan noted. "The maneuvers
were basically those in a commercial pilot flight test,
because they are more stressful than those in IFR
flight. The FAA added some maneuvers that previous EFIS certification experiences have tripped up
the equipment. Those maneuvers, like a chandelle,
involved a lot of airspeed change. To simulate failures,
Charpentier made a test flight with the pitot source disconnected and another that relied solely on the D10A's
battery backup."
"The ultimate goal of the STC project, which we
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2016

achieved, is that the installation of EFIS-D10A does
not affect the certification of a Part 23 airplane," said
Paul Dunscomb, Dynon's vice president of engineering.
"If the airplane was certified for IFR flight before the
installation, it is IFR-approved after the D10A replaces
any vacuum-driven attitude indicator installed in the
airplane."
While the D10A installed under the STC is the same
unit amateur builders install in their experimental aircraft, some of its features, such as the built-in autopilot,
are not available because the STC does not cover the
installation of the necessary servos. And it will not display the horizontal situation indicator because the STC
does not cover the connection to a navigation source,
like a GPS.
The EAA picked the initial makes and models on the
STC's approved model list, the Cessna 150/152 and
172, and the Piper PA-28 Cherokee and PA-38 Tomahawk, because these aircraft represent the majority
of the 100,000 aircraft that can benefit from the STC.
Other makes and models will join the AML in due time,
said Elliott. One day before AirVenture in late July, the
EAA added the Cessna 175, 177 and 182 to the AML,
and expanded the STC to include the Dynon EFISD100, which has a 7-inch display.
Aircraft owners will buy the STC from the EAA.
The EAA also paid close attention to the installation instructions, employing a format that will be easily
understood by any avionics technician or airframe and
powerplant mechanic.
With the STC in hand, aircraft owners will work with
Dynon dealers on the installation. The STC lists a single
kit number on the STC, Jordan added, but owners can
install any subset of the kit, with the part numbers listed
deeper in the STC paperwork.
"The primary instrument is the same EFIS that we've
sold for more than a decade, and its prebuilt wiring
harnesses connect it to the aircraft connections," Jordan
said. "The STC options are a remote compass, OAT,
which also delivers density altitude and true air speed,
and an angle of attack pitot probe."
If there is a sure sign that the EAA plans to continue
its Affordable Innovations STC efforts, the EAA is
seeking the donation of a Cessna 172 or 182, or a Piper
PA-28, which will be its dedicated STC test bed aircraft. The members of the EAA Employee Flying Club
got their 172 back after the FAA flight tests, when its
vacuum attitude indicator replaced the Dynon EFISD10A, but once the FAA issues the final STC approval,
said Elliott, it will again fly with the D10A. q

Table of Contents for the Digital Edition of Avionics News September 2016