AIRFRAME TECHNOLOGY
Low Plasticity
Burnishing
One solution to eliminate cracks
in landing gear
Y
By Doug Hornbach
Doug
Hornbach is
the president
and laboratory
director for
Lambda
Technologies.
He has been
with the
company since
1992.
ears of research have shown
that high strength steels used
in the main landing gear of
aircraft are prone to stress
corrosion cracking (SCC) and
fatigue. Operators can spend millions each
year on inspection and repair to ensure
safety and remain compliant with airworthiness directives (AD). In certain cases,
landing gear may even need to be completely replaced to solve the problem, adding a
costly unscheduled maintenance cycle.
The combination of SCC with vibration during braking or "gear walk," can be
particularly problematic. On some popular
models, landing gear is currently inspected
every 450 landings, costing an estimated
$2 million annually for the industry.
Redesigned braking systems and constant
sanding and repainting have done little to
offset the issue.
A main landing gear
fitted with robotic
LPB system.
Low Plasticity Burnishing
A solution to cracking in landing gear that
is cost-effective, reliable and permanent is
Low Plasticity Burnishing (LPB). Created by
Lambda Technologies, LPB is a mechanical
means to combat fatigue initiating damage,
including foreign object damage (FOD), corrosion pitting, fretting-induced cracking,
Robotic LPB systems can be used
in a hangar environment, allowing
landing gear components to be
processed without removal from
the aircraft and increasing time in
service.
16
April 2013
and SCC. LPB induces a deep, stable layer
of residual compression in the surface of a
part, mitigating fatigue crack initiation and
growth. Because SCC requires surface tension above a certain threshold level, LPB
compression can eliminate SCC in high
strength alloys.
Extensive work was done on LPB treated
landing gear steels to determine the influence of many pre and post processing operations, like repeated shot peening, plating,
stripping, and other MRO functions. Tests
show that LPB eliminates SCC and the
adverse effects of FOD, restoring fatigue
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