flight testing
4
5
32 SEPTEMBER 2019 \\ AEROSPACETESTINGINTERNATIONAL.COM
petroleum, and gas operators; Search And Rescue (SAR)
outfits; and VIP carriers. An aircraft de-icing system for
the helicopter blades and inlets has been designed but
not yet installed on the Flight Test Vehicles. The de-icing
kit will be tested after the basic aircraft in 2020 or 2021.
The cold weather test plan Bell flew in Yellowknife
collected data for Model 525 initial Type Certification.
“Fundamentally, it’s driven by the FARs Federal Aviation
Regulations you have to show compliance to for civil
certification,” said O’Neil. “They require you to
demonstrate the aircraft has positive stability
characteristics, has no objectionable
vibrations, and starts in cold weather
after soaking.” He added, “It is up to
you how cold you certify your
aircraft. You set your target. That’s
what drives your data collection.”
Yellowknife on the north side of
-40 to
+58°C
operating
temperature range
Great Slave Lake is one of the coldest
cities in Canada with average January
lows around -32°C (-26°F) and dips of
around -50°C (-58°F). Relentless FTVs 2 and
3 were ferried 3,550 km from Arlington to Yellowknife in
two days with stops in Kansas, North Dakota, and South
Dakota in the US, and Saskatoon and Fort McMurray in
Canada. Both helicopters were already instrumented.
O’Neil explains, “Three has quite a bit more
instrumentation for gathering information throughout
the aircraft for loads and stresses. Other than that, they
are very similar.”
of Bell 525
Relentless instrumentation was integrated and
installed by Bell engineers. “It is all built by us,” says
O’Neil. “Obviously hard drives, electronic cards, and
who offer expertise associated with suppliers and
pricing. And of course we will also promote the tourism
activities for off-duty cold weather testing groups
or individuals who wish to explore our unique
northern environment and communities across the
Northwest Territories.”
TRAVEL FOR DATA
Since first flight in July 2015, the Model 525 test program
has centered on the Bell Flight Research Center in
Arlington, Texas. Specialized testing has nevertheless
taken instrumented helicopters and testers to off-site
environments. Two deployments to Alamosa, Colorado
put Model 525 prototypes through high-altitude tests in
cold and warm conditions. Hot-weather, high-altitude
testing took the Relentless to Yuma, Arizona in August
2018. While Flight Test Vehicles (FTVs) 2 and 3 were in
Yellowknife for intense cold, Relentless No. 4
documented inlet/engine performance in heavy
February snow around Griffiss International Airport in
Rome, New York. O’Neil says, “We flew in conditions that
were extreme blizzard conditions to the point that the
local airport was wondering who those crazy people out
there flying were.”
The Model 525 will be certified in Federal Aviation
Regulation (FAR) Part 29 criteria and marketed to oil,
“It’s not really the
maximum speed that
sets your limitations,
it’s margins with
control surfaces”
4 // The Bell 525 will be
certified as the first
commercial helicopter with
fly-by-wire flight controls for
added safety in degraded
visual environments
5 // Bell sent two Relentless
Flight Test Vehicles to
Yellowknife – the fully
instrumented FTV 3 was
used to document loads and
stresses through the flight
envelope (Photos: Bell)
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