Composite Airframe Outlasts Metal Testing Rig
It may not be the prettiest
piece of hardware ever to come from Bend, OR... but
a Columbia airframe -- complete with more than 100 sites of
deliberately inflicted unrepaired damage, a host of structural and
nonstructural repairs plus as many as 25 intentional manufacturing
defects -- was recently subjected to a punishing fatigue analysis
equivalent to 25,000 flight hours at loads exceeding the
Columbia’s Utility Category certification levels.
The result was astounding, representatives with the planemaker
told attendees at this week's Lakeland Fly-In. The Columbia
airframe absorbed the loads, stress and punishment while the
testing fixture, made of high-strength steel, was beginning to fail
due to metal fatigue.
“This test should unequivocally quell any lingering
misconceptions that somehow a composite airframe isn’t as
durable as an aluminum airframe,” said Columbia Aircraft
Manufacturing Corporation Vice President of Engineering Tom Bowen.
“The load spectrum applied to the Columbia airframe during
the test was 20% - 40% greater than what would have been required
to simulate the same test on a Normal Category airframe. As far as
we know, no other personal aircraft airframe, composite or
aluminum, has ever successfully completed such an exhaustive and
severe fatigue testing program.”
Listen To Bowen's Comments On Composites Durability
Testing Here
Bowen pointed out that the 25,000 hours simulated by the test
program is equivalent to 123 years of aircraft life if flown an
average of 200 hours per year, twice as many as has been documented
by the known competition. The test was originally intended to
simulate 12,500 flight hours, but once the airframe achieved that
milestone with no signs of fatigue, the test engineers decided to
start the test cycle again and go a full 25,000 hours. Upon
arriving at 25,000 hours, it seemed pointless to continue the
test.
“We were curious to know just how far this airframe could
be pushed,” said Jake Ruhl, lead structural test engineer for
the project. “This test provides irrefutable evidence that
the Columbia can go far beyond the designed service life even under
extreme conditions with countless flaws, repairs, and damage while
demonstrating no signs of fatigue or wear. In my mind, this test
program -- equivalent to 166,695 cycles -- shows that the Columbia
350 and 400 airframes are likely the strongest, most damage
tolerant and robust in the industry.”