Jay Honeck wrote:
Here's a true but all-to-common sad tale of my owner-assisted
annuals: As I was reinstalling the gas tank (by finger screwing in
the 3.2 million stainless steel screws that hold it in the wing) all
was going well -- until the VERY LAST SCREW.

Uh-oh. Before you said you took out 6.3 million screws. There are 3.1
million screws floating around loose somewhere... did you look at your
A&P's biplane to see if he "borrowed" some of your screws? If not you
might have to re-do your weight and balance.

That one just fell in the hole, and would NOT tighten. This couldn't
possibly ever happen on the FIRST screw, or even the 20th screw -- it
HAS to be the last one. So, I had to take them all out, jostle the
tank a bit, and start over.

This is why you leave everything really loose - like, each screw only
engaged a couple of turns - until you've got all the screws in. You
might pick two screws on opposite sides of the thing and run them all
the way down just to keep the panel basically in place, but then you've
only got two screws to back all the way out if you can't get one started.

It may also be helpful to have a tapered drift handy to get things to
line up - use steel carefully, or brass, aluminum, plastic, or wood if
you're being really careful of the threads. Or, use a little pick or
hook to reach up in the hole and poke the nut plate or Tinnerman nut
into place.

The same thing goes for putting in bolts or putting nuts on studs when
there is more than one. Start them all, then tighten each one a little
at a time. Sometimes the manufacturer will have a recommended order
and torque. If not, doing something like tightening to finger tight or
until the nut or bolt head seats, then to maybe two-thirds of the final
torque, then to the final torque works well. This kind of thing tends
to be associated with "bigger" stuff like engines, so it might not be
the kind of thing you get to do on the plane, but it works just as well
on your car or around the house.

Matt Roberds

Disclaimer: This is based on experience with ground vehicles and in
fixed installations. I don't have an A&P; I don't even have a TG&Y.
Some of this may not be allowable owner maintenance. Your mileage
may vary.