Better Than You Found It

Shutting down the engine and flipping off the master switch, the pilot leaps from the aircraft, clutching his flight bag, headset, and GPS while digging for the car keys. Another flight is in the logbook; the airplane did its job well. But, is it ready for the next mission?

In the training syllabus, there's a lot of emphasis placed on doing a good preflight inspection, replete with checklist flow patterns and verifying movement, fluid levels, and airframe integrity. All of this is critically important because you're about to leave the ground in an aircraft, and you want to make sure it's airworthy. Unfortunately, students are seldom taught to look at the airplane before leaving it, after the flight. This may be because flight schools prefer to have their own staff keep an experienced eye on the equipment, but when the student becomes an airplane owner for the first time or purchases a share in a flying club, she may be putting the airplane away with deficiencies awaiting the next flight.

Begin your postflight inspection by tuning a communications radio to 121.5 MHz, to make sure your ELT is not activated or malfunctioning (top). If the aircraft will be left outside, assure that it's properly tied down (middle). Topping off the fuel tanks will help to prevent condensation--unless school policy, or the next flight's payload, dictate otherwise (above).

A postflight check doesn't require a lot of time. In some cases, the postflight can result in paperwork or shop contacts, generating reminders that something needs to be fixed before the airplane flies again. There should be a form in the airplane to record deficiencies that are discovered (the "squawk list," in common language).

On the way in

Your postflight inspection begins during the taxi after you've landed. Pay attention to atypical noises or vibration coming from landing gear. Are the steering and brakes operating normally? Do the brakes have equal pedal travel and resistance? In the absence of a crosswind, does the airplane track straight?

This is an excellent time to tune the radio to 121.5 MHz to check for an ELT signal, in case you or someone else has a malfunctioning emergency locator transmitter. Don't forget to put the local common traffic advisory frequency back in the active window and put the transponder in standby mode. It's often a good habit to reset your transponder to the 1200 VFR setting.

Before shutdown, perform a magneto grounding check at idle, by turning the ignition switch to Off briefly to see if engine firing stops. If the engine continues to run with the magneto switch Off, a grounding connection is broken. The propeller must be placarded with a large sign warning anyone passing by not to turn the "hot prop," which could cause the engine to fire as the magneto rotates. Some checklists call for this grounding check to be performed as part of the pretakeoff runup, but it makes more sense to do it at the end of the flight, just before putting the aircraft away, in case the P-lead came loose while airborne.

During shutdown at idle, watch the tachometer needle as the mixture knob is pulled back. It should rise about 25 rpm just before the engine quits; a larger rise means the idle mixture is set too rich, while no rise means the setting is too lean. If you see a discrepancy, put it on the squawk list to be attended to the next time the cowling is off for routine maintenance.

Take a moment to note the tachometer or hour-meter reading and check it against oil change or 100- hour inspection due times. If you're at or near the hourly interval for having the airplane serviced, this is the time to make an appointment with the shop--not when you're in a hurry to get off on the next trip. If it's a rental aircraft, a friendly reminder to the dispatcher will be appreciated.

Avionics faults need to be written up while they are still fresh in mind, taking particular note of the location and frequencies involved. Some faults may only occur under certain temperature and altitude parameters. Don't leave a broken radio to be discovered by the next pilot--or by yourself on your next flight.

After parking

At the end of every flight, consider what to do about the fuel level--take steps to see that the airplane is put away in a proper state of readiness, even though that's not always as straightforward as it seems. Minimizing condensation, particularly when stored outside, requires that the airplane be kept full overnight, but that's not always practical. A flight school's normal policy could be to have it topped off after each flight, but given a modern airplane's heavy equipment load and large fuel capacity, the tanks sometimes may have to be left down until the next trip's payload is determined.

Grab a rag or paper towel so you can safely remove the hot oil dipstick and take a reading. If a quart of oil is needed to bring the supply back up to dispatch level, this is the time to hunt one up, rather than when you're in a hurry to leave on the next flight. Bear in mind that a pint or so of oil might be retained in the galleries until the engine has been shut down for 15 minutes or so. Before you throw away the insulating towel, take time to wipe down any unsightly oil streaks while they are still warm; it's easier to remove them before they congeal. This postflight wipe-down can extend washing intervals, and it only takes a minute or two. You'll probably have more time to wash dirt off your hands after your flight than when you're trying to depart.

Before shutting down completely, perform a magneto check at idle (middle) by turning the ignition switch to Off briefly to see if engine firing stops. Check the Hobbs meter to see if maintenance is due (above). Check the oil--if it's low and you add more now, the next pilot will appreciate your consideration (top).

One of the older airplanes I fly has an oil cap that occasionally works loose. I like to verify its security after each flight to see if the problem is getting any worse. It never oozes out enough oil to be detectable on the dipstick, but such little annoyances shouldn't be allowed to grow, and you won't know if you don't check.

Look at the condition of the tire tread and inflation level, as well as the landing gear strut extension. If you have wheel fairings installed, you'll need to move the airplane to watch the tire as it rolls into view under the fairing. If this trip wore out the last remaining rubber above that brake burn spot (left by another pilot, of course), you'll want to write it up for "cord showing" in the maintenance request. Don't have such a form? Jot it down on the time sheet or leave a sticky note on the panel. The next pilot (or you) might not catch the bad tire on the preflight, and even if it's found, the moments before departure are no time to be seeking service.

Spring-gear Cessna airplanes tend to wear off the tread on the outboard side of the tire at touchdown, as the gear droops slightly in flight. Noting the wear progression and having the tires demounted and reversed halfway through the cycle can extend the tires'life considerably--if you catch it in time.

I gotta have it fixed...now

If you want to get on the shop supervisor's bad side, come up with an urgent tire change or inflation request when you could just as easily have caught it after the last flight. It's much easier for the mechanics to fit it into their day if some advance notice is given. Sure, they'll drop everything to help you get off on your trip, but it'll be reflected in the bill--and you'll likely get the least-experienced member of the crew, who can best be spared for your urgent problem.

Are the bugs on the windshield beginning to hold hands? Spread some approved windshield cleaner on the windshield (not glass or multipurpose cleaner, please) and let it be drying while you check over the rest of the aircraft. If you don't have windshield cleaner handy, use plain soapy water. Never wipe plexiglas dry, as the dirt under the cloth will gouge tiny scratches in the plastic.

Look for missing screws and loose fasteners as you walk around the airplane. Sure, they were OK on the preflight, but things usually work loose under vibration and flight loads, so this is the time to watch for backed-off fasteners. There's a screw that secures the aft end of a fairing above a Cessna's stabilizer; if that screw falls out, the fairing can trail outboard to contact the elevator at full travel. Keep an eye out for such things.

Turn the master switch back on briefly to check lights; you may not have noticed an inoperative anticollision light during the flight, but as a no-fly item it must be repaired before the next trip. And an unplanned night landing is no place to discover a burned-out landing light. While you're at it, have you checked your standby flashlight lately?

Securing the airplane should be part of every pilot's postflight ritual. Some schools have outside storage, which, of necessity, includes tying down the airplane. Others hangar their airplanes and spot them on the ramp for the scheduled flight. In each case, the aircraft must be left in proper condition; control lock in place, sunscreens installed, vents closed, wheels chocked, security devices (door locks, throttle or propeller locks) secured. Tiedown ropes or chains are to be tight and appropriately attached. Don't set the parking brake, which should only be used for temporary parking.

The overall external condition of the airplane should be given an inspection--antennas in place, fairings secure, no dents or skin ripples. The parts that are movable should move; the nonmoving parts should be solid. Nonstructural cracks should be noted and given attention to prevent further growth.

The postflight inspection is as important, if not more so, than the preflight. Save yourself the inconvenience of being faced with a broken airplane when you're ready for departure--put the squawks down after the flight, so there's plenty of time to have them fixed.

LeRoy Cook has been an active flight instructor since 1965 and has had more than 1,350 articles published. He is also the author of 101 Things to Do With Your Private License and Flying the Light Retractables.

Want to know more?
Links to additional resources about the topics discussed in this article are available at AOPA Flight Training Online.