Aero-Tips!
A good pilot is always learning -- how many times have you heard
this old standard throughout your flying career? There is no truer
statement in all of flying (well, with the possible exception of
"there are no old, bold pilots.")
Aero-News has called upon the expertise of Thomas P. Turner,
master CFI and all-around-good-guy, to bring our readers -- and us
-- daily tips to improve our skills as aviators. Some of them, you
may have heard before... but for each of us, there will also be
something we might never have considered before, or something that
didn't "stick" the way it should have the first time we memorized
it for the practical test.
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Aero-Tips 10.31.06
I was with a student teaching the preflight inspection on the
six-passenger, retractable-gear airplane he'd just purchased.
Looking in the left-wing wheel well I pointed out a broken spring
on the landing gear uplock mechanism. It was a small, thin, wiry
spring, partially obstructed (as is normal) by a fabric cover.
I declared the airplane rejected for flight (I don't want to
have to write about by own gear-up landing, especially if it
results from a previously noted mechanical cause). But with a lot
of new ground-time on our hands we continued the "teaching"
preflight. Wouldn't you know, the corresponding spring in the right
wheel well was broken also.
It looked the same on both sides of the airplane... enough to
make me wonder if I had misdiagnosed the problem.
Symmetry
Admit it, you know what I'm talking about. You get a little pain
on one side of your body, but if you feel it on the other side too
you declare it "normal" and move on. In our airplane example, my
student and I saw something we thought was wrong on one side of the
airplane, but comparing the "mirror image" on the other side
revealed the same picture. It would have been very easy to declare
the airplane airworthy because the discrepancy was symmetric. No
doubt this is why it wasn't found by the pilots who had flown the
plane before us, or the mechanic that had inspected the airplane
before my student bought it (although he/she should have known
better). There was no "right" configuration to compare it two and,
in airplanes, two wrongs do not make it right.
Aero-tip of the day: Check the airplane against
informed expectations -- not just against the airplane itself.