"Vaughn Simon" wrote in message
...

"Mike" wrote in message
news:2Rrbk.459$713.307@trnddc03...
Nonsense. If you are human, and especially if you lack x-ray vision,
you can miss damage on a preflight.

The chances of any such 'invisible' damage being a safety of flight issue
are pretty much nil. Someone might crinkle a firewall with a wheelbarrow
landing or overstress the airframe, but the chances of that being a
safety of flight issue in the near term are next to nothing. But if
someone bangs up a wing or a tail against a hanger, flat spots a tire, or
has a prop strike this is going to show up during a proper pre-flight.

Obviously, you haven't seen some of the things I have seen. One of the
more tender, and more invisible spots on some airframes is where the
horizontal stabilizer connects to the fuze. Many designs allow a
tremendous moment arm for any non-balanced load on the stabilizer to
stress the attachment points. This shows up as cracked spars on Cessnas,
and I have seen stressed and cracked fittings from another airframe. How
can this happen? Well on Cessnas it happens from folks using improper
procedures to back the plane into a parking spot. It can also happen from
innocent (but ignorant) bystanders, mowers, animal activity, or any of
thousands of other posibilities.

I always give each side a good heave up and down for this very reason, so
such can easily be checked on the preflight for impending failure.

Also, you don't know what happened on the last flight. Excessively
hard landing? Botched manuver? These and countless other things can
cause difficult-to-detect damage to an airframe.

Certainly. But that's what pre-flight and annual inspections are for. My
A&P found a cracked bulkhead in the tail on my first annual after I bought
the plane. It had probably been that way for years. Such problems you
mentioned are common, but how many airframes do you see breaking up in
flight because of it?

One list item: The standard for passing a preflight inspection is not
"safety of flight in the near term". I would hope that you would consider
an airplane not airworthy long before that.

The preflight is just a simple way to find out if the aircraft is airworthy
to the best of the pilot's ability. I never suggested it was anything else,
so you should go back and check your inference for any degree of
reasonableness.

So what trick do you use to get them to do the runup?

The most polite thing I can say is that was an unnecessary comment.

(I don't want this to turn into a flame war so you may have the last
word.)

Vaughn

So why do you take a simple statement and take it to the nth degree? The
previous poster (who has no flight experience, btw) condemned partial
ownership because another owner might "damage" the airplane and not tell
anyone. It was a ridiculous statement to begin with because a proper
preflight and regular inspections make such a non issue to the safety of
flight. That was the context of my statement. Instead you want to turn
this into some obscure situation. Is it possible to have damage that goes
undetected during a preflight? Yes. Is such damage a concern? The
statistics suggest you should be more concerned about being hit by
lightning. If you don't want to get flamed, try working your way up the
thread and figuring out what the context is before you jump on a comment and
try to make it something it isn't.

My "comment" was far more valid than yours, BTW. If you have a student that
you can't even trust to do a preflight, how are you going to trust them to
do anything else that can save their lives? If you have such students you
can't trust to perform basic safety of flight tasks, you shouldn't let them
solo until they mature.