How to Preflight an Airplane (20+ things to check) -

What's Wrong with This Picture?

It’s hard to say at a glance

So before you strap on the airplane, you need to know it’s as eager to fly as you are.

Make sure — with a good preflight.

We all learn a little each time we fly!

Note: I’m not a flight instructor (CFI) and this information is for educational purposes only. Consult with your CFI for specifics about the particular airplane you are flying.

Knowing how to preflight an airplane is one of the most important things you can learn to prevent general aviation accidents. Flight planning is essential, checking the weather is essential, but making sure that the airplane is fit to fly is equally (maybe more) important.

First, follow the checklist. There’s nothing wrong with adding more detail to the checklist, but it’s there to guide you. You’ll not only want to catch the obvious but look for the not-so-obvious.

On several occasions, I’ve noticed things wrong with an airplane that the checklist didn’t specifically ask me to look for.

One time, the US Air Force Aero Club I flew with staged a pre-flight inspection contest. The club mechanics grounded the airplane and then logged and created a good number of problems for members to find in a mock-preflight inspection. Nothing major, but the same kind of things that a pilot could overlook. Things that would cause problems once airborne.

A few of them I recall:

Missing screw from the prop spinner
Tape over the static port
A missing light bulb from the wing nav light
Loose oil filler dipstick
Fuel tank cap removed
Circuit breaker manually popped (the older style you could pull out)

There were more, and I can’t recall all of them. They did a good job, though, and I was surprised when I won the contest, considering the number of seasoned pilots in the club. I was certain they’d notice everything.

So what do I do during preflight?

Here’s how I preflight an airplane – what I do and what I look for in a walk-around:

Interior

I walk up to the plane and open the door.

Once the door’s open I check the general condition and wonderful odor of the cockpit. It sounds odd, but I’m basically seeing if I smell any fuel. Ya never know.

If the plane has one of those stick-on carbon monoxide detectors, not what color the circle is. Anything darker than the original color (usually a yellow or orange tint) could mean there is an exhaust leak.

I also check the operation and condition of the pilot seat track rail and roller to make sure it engages in various positions, and I also check the aft end of the seat track to make sure the seat can’t roll aft too far. There’s usually a stop bar or something similar and I check to make sure it’s in place. I added that to my personal working copy of the Cessna 172 preflight checklist when I was flying that plane. I now expand that to the seat track on any airplane. There have been well-publicized accidents where the seat slid back unexpectedly during takeoff, causing the pilot to pull on the yoke to stop the aft seat travel. This led to a pitch up and stall with bad results.

I grab the checklist and read over the interior items. I’ll lower the flaps and make note of the sound and ensure that the flap indicator matches the actual position. If it’s a manual lever flap like on a Piper Warrior, I’ll try each stop and make sure the handle locks in position. I leave them down so I can check them better once outside.

There’s usually a power-on step to check the battery and gauge operations. With the power on, I open the pilot side window so I can hear the stall horn when I check the vane. I check the fuel gauges. I also turn on the exterior lights (including the taxi and landing light) then hop out. Walking around the plane, I quickly check the nav light on one side, the taxi/landing light, stall indicator vane, the other nav light, the rotating beacon, and the white taillight. I usually include a quick check of the pitot heat as well. You need to do all this safely but quickly since it’s putting a drain on the battery.

Inside again, I turn off any powered up items and shut down the power. Now I’ve checked for dead light bulbs, sound from the stall indicator, gauge indications that seem wrong, and initial fuel indication.

Exterior

Again following the checklist, I go around the airplane and make all the checks. I usually carry the keys with me to make sure the engine can’t be accidentally started by a passenger. This is what I look for outside:

General condition:

Everything, including skin dents, cracks, and anything that looks odd or broken.

Flaps:

Once down, I check to see that mechanical items like pushrods are in good shape, no corrosion, the motion of the rod end ball attachment is free, any bolt safety wires are in place and in good shape, and that the flap track has grease. Then I gently grab the flap trailing edge in the center and push up and down, listening for any strange noises or movement of the flap upwards through its locked position… anything that would indicate the flap may retract when the airstream pushes on it. I also make a note to see if both left and right flaps are matched in the angle of deployment. Either one could potentially be either damaged or mis-rigged and provide different degrees of deployment, which could be a controllability issue.

Landing Gear:

I look at the back and sides of the landing gear next. I want to see that the tires look properly inflated, no cord showing through, and that the brakes look good. Check for missing safety wire, rusty or cracked brake discs, brake fluid leaks, cracks in the brake hose, tire air valve has a dust cap (not mandatory but keeps the valve clean), and check that the axle nut is cotter-pinned.
I also look into the gear well on a retractable to check overall security, mechanical linkages, and that the gear position switches and wires look good (if visible).

Ailerons:

You want to make sure all the hinge pins are intact. Each one usually has a good bend at the end to keep them from sliding out. Make sure the hinges aren’t corroded. Grab the trailing edge of the aileron where the pushrod attaches and gently move it up and down to make sure the opposite aileron moves in the opposite direction. Also makes sure control yoke moves in the corresponding direction. (If the aileron doesn’t move you either have a problem or perhaps you forgot to remove the control lock.) When you move the aileron up, check to make sure any counterweights are in place and not coming loose.

Wingtip:

Check the navigation light with your hand. Make sure if you try to move it, it feels solid and the lens cover doesn’t come loose. Check the condition of any attaching screws. Also, gently grab the wingtip and move it up and down. You shouldn’t hear any cracking noises or feel the fairing move in your hand. I’m essentially trying to lift the wing just slightly and releasing it. This is just a sanity check to make sure I don’t hear any odd noises from the fairing or wing. It could tip you off to some structural problems or skin cracks that aren’t visible.

Wing leading edge:

I walk the length of the leading edge, dragging my hand across the surface lightly. I’m feeling for imperfections such as small dents or anything that might indicate a crack or surface irregularity. If there are fairings where the wing meets the fuselage, I check to make sure they’re intact and don’t move when pressed on. I also check any landing or taxi lights for security and damage to the lens covers.
Check the security of any stall strips.
Fuel caps: I check the security and function of the fuel caps. Do they remove and close cleanly? When closed, are the raised-grip handles (if equipped) aligned with the direction of flight? Is the safety chain intact? If the fillers are recessed into the wing, is there any water in the filler well? If so, you’ll want to be careful to not let any of it get into the fuel tank. This is also a good time to check the fuel level (overall and in relation to filler tabs if the plane had them.) I usually do this with a flashlight even in the daytime unless the sun is at a good angle. Check to see if the fuel level looks like a reasonable match compared to what the gauges told you earlier. You’ll need to make this determination on the other wing as well.
While there, you can check the fuel sumps for water, or do all of them at once. Follow the checklist for guidance.
I also take a look at the front of the main gear… brakes, wheel pants, etc.

Nose:

There are a number of things to check here!
- It’s a good time to take a look at the windshield and see how clean it is and if there are any cracks.
- Look at the outside air temperature probe if it goes through the windshield. Does it appear to have any damage?
- Check the cowl in general, all fasteners, and engine compartment dzus locks.
- Follow the checklist and check the oil level. You may need a flashlight here, especially if the cowl only has a small opening to fill the oil with. If you’re lucky enough to have swing-up cowl openings, you can get a much better look at things. A few items I make sure to check:
  - no oil leaks
  - oil dipstick is firmly closed but not overtightened
  - all wiring appears to be in good shape with no cracked insulation, frayed wiring, broken or missing connectors. Check for any burn marks that might indicate shorting.
  - no wires rubbing against metal (many times due to hold-downs missing.) This could wear away the insulation and cause short circuits.
  - engine mount bolts present, intact, and secured with castle nuts, cotter pins, safety wire, etc.
  - no evidence of animal nesting
  - flexible hoses and tubing in good shape
  - spark plug wires in good shape and attached
  - no cracks in the firewall
  - no oil leaks, exhaust system intact and no corroded components that could introduce exhaust gas into the cockpit
  - battery securely strapped in, no leaking, and cables attached tightly
  - carb heat cable and engine control cables secure
- Basically look at everything you can see and ensure it’s airworthy. When you close the cowl, check to make sure all fastener locks are locked. At this point, you can move to the front of the airplane. You want a flashlight here, too.
  - Take a look at the cowl openings for signs of nesting animals
  - Check the existence of, condition of, and tension of the alternator belt.
  - I usually check the prop spinner at this point. I’m looking for missing or loose attach screws and cracks or damage to the spinner. I will lightly hold the end of it and move it in different directions, listening for noises that could indicate cracks in either the spinner or its backplate.
  - Check the prop leading edge blades for knicks. Check with a mechanic if you have doubts, they may need dressing to file out the knicks before flight. Worst case, if they’re left untreated they can cause part of the prop to break loose.
  - Look at the landing and taxi lights if they’re on the nose to make sure they aren’t misaligned due to bracket failure.
  - Look at the air filter, make sure it’s not blocked or loose.
  - Visually check nose gear tire inflation, good tread and no cord showing, axle safety cotter pin, scissor and dampener for damage or leakage.
  - Check the exhaust pipe for cracks or looseness but don’t touch it unless you’re certain it’s cool.
  - Cowl flaps? Check the linkages. Open flaps also give you another chance to peak into the engine compartment.
  - Check the fuel sump for leaks. You can either do the fuel sump checks as you pass each one or do them all together before you finish inspection. Follow the checklist for your aircraft.
- This one, check with your instructor:
  - I was taught to look at the nose gear oleo strut and make sure it matches what the checklist says in terms of distance on the exposed strut. The problem here is that many times the strut pushes the nose up when the plane is empty or people may have pushed on the tail. One instructor told me to pull down on the prop and then let go so the strut compresses and then extends to its natural level.
    - The problem with this is you subject yourself to a little risk. In order to pull down with your body weight, you have to bend your knee(s) into the arc of the propeller and possibly extend one leg to be balanced. This is not a big deal as long as the prop is horizontal and you grab on each side of the spinner. However, since the prop is not always horizontal, if you pull unequally you may make the prop rotate slightly to the horizontal. If you must move the prop, have an instructor teach you the safe way to do it since there’s the remotest chance that the engine could fire. That’s another reason I said I always take the keys with me on preflight. That way I know I didn’t accidentally have the mags on… unless the key can be removed with the mags on… know your airplane!
  - Anyway, I’ve done this many times with no prop rotation at all and it gives you a good check on the strut extension. If you know a better way, please comment at the end of the post. Again, ask your instructor about the best-recommended way to check the nose strut.

Note, you do not want to pull down on the spinner. It’s not made for that and you could damage it.

Left Wing:

Following the checklist, I basically repeat what I did for the right wing, but add a check of the pitot tube.
- Look for blockage on the inlet and drain hole and anything that looks wrong. A solid bump on the pitot tube could introduce a bend. Especially on the basic bent-tube versions.
- Remove the pitot tube cover.
- Check any air inlet screens by the wing root for blockage.
- On a twin, makes sure the mirror on the side of the cowl is intact and clean. You need it to confirm gear down and in place.

Fuselage:

Here I’m looking at the fuselage aft of the wing. On one side of the plane (sometimes both) you’ll find the static port. You want to make sure it’s not covered or blocked.
Check antennas both on top and underneath the airplane. Make sure they’re not loose, improperly bent, or have cracks.
Check the vertical stabilizer fairing to make sure it’s not cracked or loose. You can grab it gently with your hand and apply a little pressure to it and listen for odd noises or movement.
Baggage Door: It’s usually on either side of the fuselage aft of the wing. Check its operation, especially the security of the latch. You don’t want to deal with it opening in flight! While you’re there, check the baggage compartment to make sure any loose objects are tied down and secure. Turbulence or crash landing could send objects flying. Examples are tow bars, plastic oil bottles, and luggage.

Empennage:

There’s a lot going on back here! With both the vertical and horizontal control surfaces and cables at work, there are several things to check.
Horizontal Stabilizer:
- As with the wing, I hold the end and give it a little up and down motion, listening for noise that might indicate cracks.
- I move the elevator up and down, full travel, and watch to make sure the control yoke moves appropriately. If it’s an “all-flying-tail” (aka “stabilator”) like on many Pipers, I make sure the trim tab moves in the same direction as the stabilator, but with increased travel.
- I look carefully inside the aft end of the plane where the control cables attach to the elevator and rudder assemblies. You want to make certain the cables are connected and safety wired. You can see them best when you’re moving the elevator up and down.

Unusual but True: When I was pre-flighting a Cessna trainer once, I did this check and found the upper stop bolt had come loose and backed out, hanging at enough of an angle that it kept the elevator from fully deflecting upward. You may not catch this during a yoke control check and it could keep you from rotating on takeoff. Part of knowing how to preflight an airplane is looking for the unexpected.

Vertical Stabilizer:
- Inspect the rudder hinge points to make sure all the attach points are in good shape and brackets are not cracked.
- Gently move the rudder with your hand to check the rudder cables and attach points, as well as check the rudder stop bolts. Pay attention to warnings on control surfaces. Any movements I attempt when I preflight do heed these warnings and any touch is very light. The intent is to see things better, not damage the plane!
- Check the rudder horn at the top and make sure it’s not damaged.
- Check any tail antennas and the overall condition of the stabilizer.

Finishing up from there is a walk back to the cockpit.

Nice job!

What’s left?

At this point, you’ve taken a good look at just about everything for a land airplane, and primarily single-engine. A seaplane, amphibian, or multiengine would have other specific items to check. No matter the plane, the preflight is important and should not be overlooked or done in haste or for show.

One final 2-step ritual I have, and it’s served me well on a few occasions, is to first walk far away from the front of the aircraft and just look at it. Then glance to each side as if you’re the final judge to release the plane for flight.

Do you see anything unusual from this perspective? Did you find a tow bar you left attached? That red remove-before-flight tag is still in place you say? Did you notice that after you drained the left wing sump, it started dripping fuel after you walked away?

The second step is one quick walk around the airplane to just look it over. Maybe in a level of haste to add oil that you didn’t expect to add, you left the baggage door open or unlatched. Maybe the tail tiedown rope is still attached. This final walkaround only takes a minute but could save an embarrassing, aggravating, or bad situation.

One last tip – the control check just prior to takeoff. I see a lot of pilots “stir the stick” and glance around to make sure they see deflection. Somewhere in the preflight, you really need to watch the direction of the control surfaces. Did the left aileron go up and the right aileron down when you turned the yoke left? What if the airplane just had some maintenance done? I may be going overboard here, but there is a slim possibility of crossed cables or broken pulley brackets, and you wouldn’t want to find out after rotation. I always check the full and correct deflection of all control surfaces during the engine run-up.

When you know how to preflight an airplane, you pave the way for a safer flight.