changeable,” Stowell says. “So if
an operator damages a winglet they
can quickly remove them and put
on a spare.” Winglets are common-
ly damaged by lightning strikes
or by bumping the wing against a
hangar or another vehicle.
Replacing a winglet usually takes
one to two hours, about the same
time it takes to replace a wing tip,
Stowell adds. Through an access
panel underneath the wing the
technician can loosen the 18 ten-
sion bolts and unhook the cannon
plug. Stowell compares the process
to “bolting the head of an engine on
the engine block.” There are barrel
nuts on the winglet side and the
bolt heads are on the wing side.”
Screws generally are used to
attach Winglets to smaller aircraft.
There can be as many as 40 screws
per wing, according to a BLR
Aerospace official, who adds that,
still, it takes no more than an hour
Winglets have been added to this Continental Airlines B757
to replace a winglet.
“There are some maintenance
requirements to winglets,” Stowell
adds. “I think if you look at a 757,
we probably add about 25 hours of
maintenance over a five year period.”
The Winglet Business
Even with all the benefits they
offer operators, the selection of
which aircraft get the aftermar-
ket winglet treatment is made
very carefully. “Every one of these
STCs, even the little jets are $10
million-plus dollars to certify,”
says Thompson. “So it’s not an
insignificant task.”
How does Aviation Partners
select its winglet candidates? “It’s
a bit of an informal algorithm,”
Thompson explains. “We look first
at very popular aircraft and then
see which ones can really benefit
from winglets.”
The company found, for exam-
ple, that winglets could greatly
benefit the Hawker 800s. Without
winglets, this business jet could
not fly from the U.S. main land to
Hawaii, but with winglets, it can.
In addition to the benefits,
Aviation Partners looks at the air-
craft wing structure when select-
22 Aviation Maintenance | avmain-mag.com | Oct/Nov2009
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56