In the first part of this series, Preflight: Step 1 – The Cockpit Check, we talked about starting your preflight in the cockpit.

But the exterior check in step 2 actually starts even before step one.  Confused?  Let me explain:

Every preflight really should begin as you are walking out to the plane.  Or – if you’re lucky, as you enter your hangar, before you even touch the plane at all.

Is the plane leaning to one side or the other?  Does it look very tail-low or tail-high? Are there puddles of fluid under the engine cowling or at the main gear?  Are there stains on the wings or anything new that you never noticed before? Do you always lock the plane, but the door was open when you first look?  If you don’t own your plane, some of the above things may not apply, but even if you rent, there are probably processes and patterns where if something is different, you’ll notice.  If you ever have a question, grab a flight instructor and ask!

After this first look, do your cockpit check, and when that is complete, move on to the exterior check!  Because the exterior check is the longest part of the preflight, we’ll break it up into 3 sections – wing, tail, and engine.

NOTE: the specifics in this series apply to Cessna 172 aircraft, as that is what I instruct in most – in any case, always use the Pilot Operating Handbook (POH) for your aircraft to confirm that you have not missed anything on your preflight!

I tell my students to step forward and out, putting them in front of the plane, to the left of the engine cowling.  From here, they can start by checking the cowling itself for loose or missing screws, checking the static port to make sure it is not blocked or covered by anything. This is also a good vantage point to look at the wind screen – is it dirty? Does it have bugs splattered all over it? Clean it before you go!

Now look up – at the leading edge of the wing at the wing root.  There is probably a vent here – check to make sure it is not blocked. Now run your hand along the leading edge of the left wing, looking for big dents that might change the wing’s ability to create lift.  As you move from the wing root toward the wing tip, you’ll run past the pitot tube – check all the openings/vents to make sure they are not blocked by anything (including a pitot tube cover).  Keep going to reach the stall warning opening – check to make sure it is not blocked.  If you have a suction tool, you can test whether it is working or not as well.  Keep moving toward the wing tip and check to make sure that the fuel tank vent is also not blocked, and the fairing for the wing strut is secure and in relatively good shape.  While checking all of this and the leading edge, you should also be checking the bottom of the wing for loose rivets or loose or missing inspection covers, or anything else out of the ordinary.

Once at the wingtip, just check the plastic tip cover for any major cracks (you may find small cracks that have been stop drilled, but those are okay), and make sure it is secure.  Now on to the trailing edge.

You removed the control lock during the cockpit check, right? If not – go remove it now, because we’re going to check the ailerons.  First, push the left aileron up, and look over to the one on the right wing to make sure it is down. Also, if you can see it, check that the yoke turns toward the left while the left aileron is up (the yokes should always turn toward the up aileron).  Now push the left aileron down, and check the other aileron (which should be up now), and the yokes (which should be turned to the right now – toward the up aileron).

Now, hold the aileron up with one hand, and duck under the wing and turn around so you can look between the wing and aileron at the following:

1. There should be three counterweights on the outside of the aileron, securely attached
2. Three hinges, all of which should have secure bolts and safety wires, and none of which should be cracked or broken in any way.
3. A pushrod, which will rotate a little, but the bolt should be secure – it should not be loosened or turned by your fingers.

Make sure you hold the aileron up with one hand and do these checks with the other! Even if the aileron seems to stay up on its own, even a slight wind could push it down and pinch your fingers – consider this the voice of experience telling you that THIS HURTS. Avoid this by learning from my mistake and holding the aileron up with one hand anytime you have your fingers in the gap between the wing and aileron!

You may also see one or two wires coming out of the back of the aileron – these are called static wicks, and they help protect the airplane and its electronics from static electricity and/or lightning strikes.  Just make sure that if the plane has any, that they are all there, secure, and in good shape.

Now continue moving inboard to check the left flap.  Push on it – it will give a little – maybe an inch or so.  Too much is a cause for concern.  If you are in doubt, ask your instructor or a mechanic.  Check the tracks – there will be two (one on each side of the flap).  Look at the rollers for cracking, wear, or other issues (including being gone completely!).  The tracks should have a little grease on them – not necessarily sopping in grease, but enough to let the rollers move smoothly.  Check the pushrod on the flap just like you did with the aileron.

Now that we’ve completed the left wing, let’s check the left main gear.  Is it fully inflated? Are there bald or flat spots or belts showing from excessive wear?  Now roll the plane forward or back to see under the tire, too.  What about the brakes? Is there fluid leaking? Check the rotor for wear, and both pads (each pad should be at least as thick as two quarters pressed together).  Check the brake line for security, and the “bolt” to make sure it is not loose.

Once you are done checking the main gear, it’s time to move back toward the empennage (tail). We’ll talk about the tail in the next post in the series!

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Do you have anything to add to the preflight series so far? Add your tips to the checklist by leaving a comment below!

Andrew Hartley is a Certificated Flight Instructor in Columbus, Ohio.

Preflight Series:
Preflight Step 1: The Cockpit Check
Preflight Step 2: Exterior (Wing)
Preflight Step 2: Exterior (Tail)
Preflight Step 2: Exterior (Engine)
Preflight Step 3: Fuel