On Oct 16, 3:32 pm, Scott Skylane wrote:
Newps wrote:

Jay Honeck wrote:

You have to remove the interior panels of a 172 to do an annual
inspection?

No, usually just the front two panels because that's where the fuel
lines run and there's some control cables in there. The front seats
have to come out but not the rear.

Actually, on the 172, the aileron cables run up the rear door posts, as
do flap cables on the manual flap models. If you don't remove the rear
seat, accessing these areas can be very difficult.

Happy Flying!
Scott Skylane

There are elevator and rudder cables and pulleys under the
entire length of the 172's floor. If you don't yank the rear seat, you
can't get the carpet up and take the inspection panels off. Every time
we get another second-hand 172 we find the pulleys under there seized,
cables worn, an incredible amount of junk including mouse nests and
droppings (corrosive), dirt, oil, small stones (tracked in by people),
rags and lost hardware (risk of cable/pulley fouling), and so on.
Sometimes even tools.
The bottom end of the aft doorposts (immediately ahead of the
aileron cable pulley in that corner) has a tendency to crack in the
angle cutout. It's difficult enough to see the area with everything
pulled out, impossible without it. Any 172 with more than two or three
thousand hours is likely to be cracked in that spot, both sides, and
certainly cracked if it has seven or eight thousand. Cracks sooner if
operating off rougher surfaces. Cessna sells a reinforcement kit, but
it's a stinker to install. They say it's 20 man-hours per side, and
we've found that not far off. After we do a couple more we'll get that
down.
If you don't drop the headliner at least partway you can't
inspect the rubber fuel line connections. They harden and crack with
age and start leaking. Guess what you'll find someday when you go to
fly your airplane? Or maybe they'll start leaking in flight. Had that
happen once in an old 180. And the aluminum lines are often not
properly located and are chafing against the holes in the doorpost on
their way from the wing root, down past the aileron cable and into the
floor.
The bulkhead at the back of the forward baggage compartment
(or the back of the only compartment if it's a 172L or earlier) has
cracking problems, usually in the lower corners near floor level. Got
to take all the plastic out of there to get a good look.
If you don't take the rudder bar covers out, you can't get a
look at the bar bearings (they need lubing) or the fuel line where it
goes through the firewall (the RH steering rod comes awful close and
can chafe it. Could create nasty surprises in flight). Some airplanes
have had trouble with loose bar bearings or broken brake master
cylinder bracketry.
If you don't remove the side panels forward of the door you
can't see inside those doorposts. They like to crack around the door
hinge attach points and you can't see it on the outside. It's the
doorpost itself that cracks, inside the skin, in the bend radius by
the rivet line. Bottom hinge is worst, 1975 and later is worse, too.
Don't know why.
If you don't take the plastic console off you can't get a good
look at the trim mechanism, the aileron, trim and rudder pulleys (more
seizures, possibly fraying cables) and the fuel valve u-joints, which
have stupid little rivets that gradually wear out and could leave you
with no fuel control.
The skin and internal structure at the little fuel access step
forward of the door sometimes cracks. Got to have the rug up and
panels out to see that.
There's no substitute for taking the time to do it right. We
do it, it takes a couple hours longer, but we seldom have any snags in
between inspections. And we're always surprised, even though we
shouldn't be, at how easily all the controls move after we've cleaned
everything, freed up all the pulleys and bellcranks, and set all the
cable tensions to spec.

Dan