As the pilot in command you are responsible to ascertain that the aircraft is an airworthy condition. As such you are required to check all papers as weight (mass) and balance, logbooks, licenses and limitations. And part of any flight is a thorough visual inspection of the airplane.
The visual inspection or walk around is done by the pilot as the final airworthiness check. In this section we describe were and what to look for when inspecting your aircraft. Any pilot who has build an aircraft will look much deeper and further than normally is required, as builders/pilots ourselves we will discuss this important part of the preflight and help you looking deeper and further.
In part one we looked at the cabin and cockpit during the preflight, here we continue outside of the aircraft.
Continued from part one.
Remove the gust lock and tail tiedown if any. Take a good look at the underside of the stabilizer and elevator. Make sure to inspect the hinges for any extra movement or unusual play. Grab the left and right stabilizer and try to move it up, down and left to right, it should not move other than normal movement. You can do the same for the vertical fin, it should be firmly attached to the fuselage and rudder cables.
Check the trim tab and rudder hinges for any flutter (less is better), take a good look at rudder stops and rudder cables. Verify that fairings are attached properly with all screws in place, sometimes, they have left the airplane without telling the PIC.
If you have an elevator which is constructed out of two halves (left and right), make sure they are still firmly attached. Grab them both and move them in opposite direction, no movement at the bolts is allowed. Check this regularly.
Verify that the beacon is operating and that the VOR antenna is firmly attached. The leading edges of the stabilizer are sometimes damaged by stones thrown up by the mail wheels. Walk back towards the cabin along the fuselage, do take a look at the underside, check to see if all antennas are in place (COM, NAV, Marker and or Transponder/DME antennas)
The flaps are now in the full down position, this gives us the change to inspect the tracks they move in. Again the hinges must have your attention. Visually look over the wing for dents or wrinkled skin (high load damage) or fuel stains (leaky fuel cap or other leakage). Proceed towards the wingtip inspecting the aileron. Move it carefully up and down and look at the left aileron, it must move in the opposite direction. Listen for any strange noises.
The wingtip must be firmly attached to the wing. Walk along the leading edge (make sure to look at the strut too) to check for damage and verify that the fuel caps are secure and closed. Now is the time to visually verify the quantity in the tank, drain fuel from the quick drains. Do not forget to look at the mail wheel, tire and brakes. Check the tire pressure, as sometimes its not readily visible that the pressure is too low.
If you can remove the top cowling, then do so. At least once a day before the first flight. I cannot count the times I lifted 'the hood' and found something loose or even missing. Be it Ty-wraps or exhaust springs (especially with Rotax engines) these tend to get loose or break, also check for other items like broken brackets near the ignition units or coolant hoses near hot spots (exhaust or turbo).
Check the propeller spinner too, inspect the propeller leading edge for nicks and dents. Have them dressed out by a qualified person (tip: clean the propeller after the last flight of the day, dead bugs eat away the paint and more and you will see any damage sooner and repairs will be cheaper). The same applies for the windscreen, clean it properly and you will see other traffic that much sooner.
Birds have sometimes nested in engine compartments. Especially in aircraft that haven't flown for (long) awhile. Be sure to remove all foreign material, which could have blown in there or left by these birds. Engine fires have resulted from the lack of this action.
Do not forget to visually inspect the battery and its connections. At this point do look at the ignition wires for any chafing which could cause a rough running engine. Look for stains around the lower cowling and on the floor. This could indicate exhaust system problems, oil leaks or coolant leaks in case of a liquid cooled engine. And while you are there: check the exhaust system for cracks indicated by stains. CO poisoning is not fun at all.
Be careful when checking the oil level if the engine has run previously. Keep the level between the min. and max. on the dipstick. Before checking the level in a Rotax engine: open the oil sump, ignition off/keys out and rotate the propeller until a murmling sound is heard at least a couple of times from the oil reservoir. Always carry an extra quart (0,946 liter) of right type oil in the aircraft.
Make sure to drain fuel from the gascolator (check for water and dirt), check the nose gear strut too and do not forget the tire pressure of all tires. The Aircraft Flight Manual (or Pilots Operating Handbook) has the details for the exact pressure.