Preflight Checklists - Everything You Should Prepare For

‍Preflight checks are the most important phase of every flight. It is the last opportunity you have to determine a go or no-go decision.

As the pilot in command, the responsibility of life, limb, and property of all those on board, and sometimes even those beyond rests on your shoulders. Preflight checks are your first line of defense against any eventuality that may arise, from inconvenient to fatal.

As a flight instructor for the last twenty-five years, I teach this to all my students, from those stepping into their first plane to those stepping into a jet.

‍Weather

Preflight checks should not be limited to superficially checking the aircraft - walking around it to look for obvious dings and problems. Rather, it should be like preparation for a mission.

Your preflight checks should begin the night before the scheduled flight. Turn on the weather channel and get an overall view of what the weather is like along your route of flight. If I am flying from Philadelphia to Boston, I take a moment to get a feel for what's going on with the entire northeast.

The Weather Channel has good narratives about the big picture that is dominating a particular weather system. Their graphics are also good enough to leave a searing imprint in my head.

Next, I’d recommend going to this website and printing out the outlook briefing for your route. You should get pretty much the same information that was presented on the Weather Channel, except with more granularity.

With that in your hand, call 1-800-WV-BRIEF. The number reroutes to the closest Flight Service Station.

They will pretty much tell you the same thing you had printed out, but the benefit of calling them, aside from putting it on the records that you are well prepared for a flight, is that briefers are well versed with the area they are located and can brief you on nuances of what the data you have printed in your hands means.

Give them your tail number and ask for an "Outlook Forecast". An outlook forecast is a forecast for flights that are more than six hours into the future.

This preflight step does two things for you. It gives you a heads-up on what to expect in the morning, and, more importantly, it gives you a feel for the bigger picture as you prepare for your flight.

When you get to the airport, the following day, print out the full standard briefing from the website then give the briefer a call. The entire printout will be part of your kneeboard package. Take notes on your printout as he goes through the data. make sure to include NOTAMs and PIREPS for your route of flight.

This is not the last briefing. Obtain an Abbreviated Briefing just before boarding and departure. And if you are on a long trip, get an enroute briefing as well.

Aircraft Performance Checks

It is important that the pilot in command perform preflight checks that include calculating weight and balance, and fuel requirements for the flight.

Just because a Cessna 172 has four seats and a baggage compartment does not mean that it can be filled up with four passengers and crew along with baggage and wings filled with fuel.

Plan where you are going, and what you are carrying, then fill your fuel accordingly. If necessary, call the FBO where you are renting the aircraft and tell them not to fuel the plane. Most places will not unload the fuel once they have been filled.

Administrative Checks

If you are new to the environment where you are flying from, you should include the log books as part of your verification checks. Make sure you verify the 100-hour inspection, the annual, VOR checks, pitot/static inspection, transponder, and altitude encoder checks.

As part of the preflight, make sure you have your medical and your license with you. You should also have all your necessary qualifications current - for example, your BFR. If you are making an IFR flight, make sure you have the necessary approaches and flights to allow you to be PIC on an IFR flight.

On the Apron

As you walk to your aircraft, study it from top to bottom. Flat tires are obvious from a distance as the plane tilts to one side. Just look at the plane, and if you've been around them enough, anything that's not right will strike you from a distance if you are paying attention.

Cockpit Preflight

Your first point in the physical preflight check process is the aircraft cockpit.

Here, it's time to check the paperwork that is in the aircraft and required for the flight by FAR.

The acronym you should be familiar with at this point is the acronym, ARROW - Airworthiness Certificate FAR 91.203, Radio License, Registration FAR 91.203, Operating limitations FAR 91.9, and Weight and Balance information FAR 23.2620.

Remember you cannot fly without any of these documents being on board.

This is also a good time to check the Squawk sheet. and review the panel for any inoperative components. Make sure that what is working equals or exceeds your Minimum Equipment List appropriate for the flight you are making.

If you are on a VFR flight, but the weather up ahead has the potential to turn to IMC, you should make sure the minimum equipment for IFR flight is operational. The aircraft you are about to fly will also have a prescribed preflight checklist, this would be a good time to refer to that checklist for checking the thing you need to review in the cockpit.

There are a number of ways you can do preflight checks. The first is to follow the checklist in detail, line by line.

The second, and my preferred way, is to use the line-by-line checklist as a guide, but first do a visual checklist that comes from a flow pattern. Once that is done, review the checklist to see if you have covered everything that is listed.

In the cockpit, take your time.

Begin by removing the gust lock from the yoke. Then make sure all the switches that should be in the off position, are in the off position.

Check that there are seat belts and shoulder harnesses in the aircraft and that they are in working order. Inspect the windshield, make sure there are no cracks or physical damage, and be certain to have it cleaned to keep visibility at its best.

Slide the seat forward to adjust it to your comfort then lock it in place. Push it back and pull it forward to make sure it does not slide forward and that the locking mechanism is secure. Having something so simple and often forgotten, fail, is a flight hazard.

Then turn on the batteries.  Keep your ear out for the sound the electric motor for the directional gyro makes. If your flight is at night, make sure you satisfy all night flying requirements.

Verify all the panel and cabin lights are operational.

As part of your preflight check, you should also inspect the cabin and the floor of the aircraft under the seats. Make sure there is no trash. I had an empty soda can once roll forward and jam itself behind the rudder pedal in flight.

Also, look at the fuses and make sure they are all in place. You also want to make sure that you have spares to use in case they burn. I always carry spare fuses in my flight bag for the aircraft I regularly fly.

If the aircraft has retractable landing gear, make sure that the three green lights are illuminated. Do not move the landing gear lever.

Once verified, turn them off and step out of the cockpit. Verify that the strobes, landing light, tail light, and position lights are all working. Check your stall horn at this time as well.

Return to the cockpit, shut off the lights, and check the voltmeter. make sure there is enough juice in the battery. Shut off your master at this point and go over the cabin portion of the checklist to verify you have already done everything that is on the first part of the list.

Walk Around

Take the checklist with you and exit the cabin. Your first item here is the wing and the flaps. Whether you are in a high-wing or a low-wing aircraft, piston prop, or jet, the logic of this preflight checklist is that you spend your time methodically inspecting the plane.

First Wing

When inspecting the flap, look at the sheet metal, the surface, and the hinges, as well as the control arm. Different aircraft have different flap mechanisms, check whatever is visible and make sure there are no obstructions and that its path is unobstructed.

It is also wise to inspect the sheet metal that covers the wings. Observe all the rivets. If you are flying in a flight school environment and there is heavy aircraft usage, you should keep an eye out for wrinkles in the sheet metal as it is a characteristic of hard landings that might have damaged the spars. Hold the flap and gently shake it to see if it wiggles and stays in place.

From the flaps move on to the ailerons and the winglets if there are any. Inspect the hinges on the ailerons as well as the free movement of the control surfaces can be performed at this point. Make sure no obstructions are present. It is also wise to look for bird nests if the plane has been on the ground for more than a day.

Raise the ailerons and make sure they are unimpeded from full travel. Look at the yoke when you do this. When the aileron is up, it means the wing, in flight will go down, which means you are turning toward the wing. Your yoke should reflect that.

Never assume that the rigging is correct. It is possible for the aircraft to have just come back from maintenance that necessitated the un-rigging of the controls, and the mechanics put it back incorrectly.

It's a good time to remove the wing tie-downs at this point.

Inspect the fuel vents. There should be no obstruction visible. Inspect the fuel and take samples. Check for color and condition. Take at least three samples from each port.

Walk around to the leading edge and check for damage then come under the wing, if you are flying a low wing, and check the strut. If you are on a high wing, this is the point you climb up and check the upper surface of the wing.

Next, check the wheels, and the brakes. If the aircraft has retractable gear, check the limit switch and the mechanism in the gear well. Be sure to note that there are no obstructions inside the well.

Pay attention to the height of the strut. It's not good if it's too low, and not good if it's too high. In smaller planes, push on the wing and see if there is sufficient travel and return on the strut.

If it goes down but doesn't come up, get a mechanic to look at it. Also, make sure that is not too high off the ground. That means that there is too much gas in it and may cause a problem in the event of a hard landing.

When you check the brakes there are two things you are specifically looking for. The caliper mechanism and the disk.

If you haven't refueled, measure the fuel in your tanks before filling up, and compare that to the fuel indicator. The indicators on small aircraft are hardly ever accurate, but you can get a sense of what levels in the wing and indicator correspond to how much the tanker tops you off with. After years of flying, I can look inside the wing of my aircraft and have a good idea of how much fuel there is in it.

Engine Cowling

When you get to the cowling, it's a good time to inspect the windshield. Keep this as clean as possible for the best visibility. Most students and new pilots forget to clean the windshield and window.

The engine cowling presents a lot of clues to the condition of the aircraft. If the engine cowl is on the wing, or in the nose, it does not matter. You will still be looking for the telltale signs of a problem.

There are a number of things to do at the cowling. Inspect it for overall signs of oil or heat damage. Normal oxidation discoloration around the exhaust vent is normal. There should not be any other signs of heat or damage.

The inlets should be free from debris. Birds like building nests here in the winter, so be aware of that, it can be a fire hazard. It should also be free from any oil drips or excessive oil flow.

Check the engine compartment. Make sure bolts that are supposed to be locked are secured, and that seals are not leaking in any way. The engine compartment should be dry.

Check the engine oil and make sure that there is sufficient quantity on the stick. If the plane just landed, it's okay for there to be a quart or two low on the stick as most of the oil is still in the upper compartments. But if the plane has been on the apron all night, there’s no reason for the oil level to be low.

Tighten the oil cap after topping off the engine oil and make sure they are firmly secured. Visually inspect the cables for ware and that the spark plugs look like they are seated properly. The spark plug leads should not show any signs of fraying or cracks.

Propellers

Begin with a visual inspection. Make sure there is no visible damage. Nicks and cracks are the typical damages that props face.

Once the visible checks are complete, run your finger along the leading and trailing edge of the blade.

Inspect the spinner. Look to make sure that all the fasteners are in place and snug. Look inside the spinner. Make sure there are no foreign objects inside the spinner and no oil in the immediate area below the spinner. Oil leaks behind the spinner are an indication of a problem with the prop control mechanism.

Follow the shaft from the prop to the engine and inspect the seal. There should be no oil stain on this seal. It is supposed to be dry.

Nose Gear

Once the engine compartment is checked, it's time to look at the nose gear. There are a number of differences in the nose gear compared to the main gears. The nose gear has the shimmy dampener and the steering links. Inspect these to make sure they are secure.

There are also a few things about tires that you should think about. When checking the tire you have to look for thread ware and bald spots. Bald spots are indicative of locking the brakes on landing and are indicative of a larger problem.

It is not sufficient to look at the tires where the plane stands. You should untie the aircraft and push it back to expose the thread that is in contact with the tarmac.

Aside from wear, look at the air pressure, and if there are cracks on the tire walls. Do not fly with damaged tires under any circumstances.

Depending on your aircraft, the static port should be in the nose section of the fuselage, or the empennage. Make sure you see that it is clear from obstruction. I once had a place come back from the paint shop where they painted over the static port.

There is also a static port inside the aircraft. It's the alternate static port in case of icing. Check that one too.

Second Wing

Come around to the second wing and repeat the checks that were conducted earlier. Always look closely and look from afar. One of the reasons I do not recommend burying your head in the checklist is that it becomes very easy to look for what is only on the list and to miss obvious damage that may indicate a serious problem lurking below.

Remember to remove the tie-down.

The main gear on the second wing should be next, following the same procedures as the other landing gear.

Empennage

The empennage is the tail section of the aircraft. Check the sheet metal and the rivets that go all the way back to the elevator. This will be a good time to remove the tie-downs.

Check the sheet metal just as you did with the wings. There should be no wrinkles or buckling of the skin.

One main difference between the tail and the wing is that the tail section is susceptible to hard landings where the tail hits the runway on poor takeoffs or landings.

Next check to see if there is free travel of the elevator and that the elevator trim connector is connected. There should be no damage to the elevator surfaces and the horizontal stabilizers.

Finally check the vertical stabilizer and free travel of the rudder.

Continue the walk around and take a look at the baggage compartment that there is nothing there that shouldn't be there and that the door is secure.

Once you reach the door from where you began, take out the checklist and go over everything here, to make sure that everything on it has been completed. Use that list to check the things that you have accomplished.