Thursday, April 1, 2004
The Ultimate Preflight
The assumption that the airplane has always worked in the past is no excuse for a hasty inspection
Look for signs of rust, corrosion or any indications that any of the bolts or rivets have been working. Especially look for nicks or dings in the struts where they’ve been hit by something.
Eyeball the leading edge for damage and continue down around the wingtip, looking for the same thing. Gently push the wingtip, looking for movement. One of the factors we’re constantly looking for everywhere on the airplane is relative motion between two parts where there isn’t supposed to be any. Examine nav-light lenses for security.
Push the aileron full up so you can see the hinges. Examine where they attach to both the wing and aileron, looking for corrosion/rust, signs they’ve been working and/or cracks. Put the palm of your hand against the bottom of the leading edge of the aileron at each hinge and push up. You’re looking for vertical movement, which indicates the hinges are loose on the wing or aileron spar. If it has external counterweights, e.g., a Cherokee, check the mount points inside the outboard end of the aileron for cracks. Repeat the same check for the flaps. When the flaps are up and locked, jiggle them and see if they’re truly locked. Most modern airplanes are. Some older ones aren’t supposed to be.
Fuel Level, Fuel Tanks
Everyone should have graduated fuel sticks for their tanks, which are readily available for most popular models of airplanes. If you can’t feel the fuel with your fingertip, it’s critical that you have an accurate way of measuring exactly how much fuel there actually is. It’s a lousy place to be guessing and don’t trust the fuel gauges, which are the most frequently inaccurate part of an airplane (that is, if you don’t count the pilot claiming how fast his or her airplane is).
Also look for fuel stains under the wing around the tank. These are sure signs of leaks. At the same time, look at the tank vents to make sure insects aren’t building hotels in them.
If it’s a stabilator, peek down inside the fuselage and/or tail cone and try to see the pivot point. Again, you’re looking for cracks, rust or indications that it’s been wearing against something. Move the surface up and down at the tip to see if there’s any sign that it’s moving independent of the fuselage.
On a normal, two-piece tail, rock the stabilizer to see that it has no movement and push the elevator down so you have a clear view of the hinges. Check them the same way you did the ailerons: Push up on the elevator spar and see if there’s any vertical movement relative to the stabilizer.
If there are any wires or struts for the tail, check them carefully for nicks and chips, and examine the ends, both the top and the bottom, for signs of rust or movement.
Trim-tab hinges and actuating mechanisms seem to wear more than most parts of an airplane, and a loose or broken trim tab can cause flutter. Flutter is serious stuff and can tear the tail clean off an airplane, which isn’t good. Just wiggle the trim tab. It’s okay if it has a little movement, but it shouldn’t have much.
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