If you’re ever at the airport late at night, or early in the morning, you may have noticed that a lot of planes spend the night at the gates. Have you wondered what is going on with these airplanes?
Usually they’re on what’s called a “remain overnight,” where they sit on the ground long enough to have some work done on them.
As a mechanic for a major airline I’m responsible for taking care of planes on their overnights. In this article, I’ll walk you through an airplane’s typical night. (If you’re curious, an atypical night would be when the plane has been damaged in some way or there is a major mechanical that has grounded the plane.)
On a typical night at a hub airport, the airplane will undergo some level of standard “check.” A common check that every overnight airplane gets at my facility is known as a “service check.”
The first thing we do on a service check is check the engine oil and add some if needed. Often this is done while passengers are still getting off the plane. It’s a lot like adding oil to your car, except the oil costs about $20 per quart.
Then it’s up to the flight deck to check the logbook for “inbounds,” which are problems written up by the flight crew. Often there’s nothing, but when there’s something it can range from a broken tray table to an electronics glitch in one of the engines.
Then, we turn on hydraulics and set the brakes, and make a circuit around the outside of the plane, in a process known as the “walkaround.” This is a way to proactively find any problems that could delay the plane on its first flight in the morning.
Starting at the nose, we look at the radome for dents or damage. We check the wings and engines for evidence of birdstrikes or other foreign object damage. We open a panel in the engine cowling to check the generator to make sure it has enough oil and that the filter isn’t clogged.
We measure the tire tread to make sure it’s deep enough. We then inspect them for cuts, missing tie bolts (the bolts that hold the two halves of the wheel together) and exposed body fabric. The brakes are inspected for hydraulic leaks and cracks to the braking surfaces, and to make sure that there’s sufficient brake thickness left until the next service check.
We look at the landing gear wells, wings, and tail for hydraulic leaks. We make sure that the wicks that pass static electricity buildup harmlessly into the atmosphere are present and intact.
As we’re checking all these items, we’re also inspecting the airplane’s skin for any dents or damage, making sure the static air measurement ports and pitot ports are clear and that we don’t see evidence of oil leaks or hydraulic leaks anywhere else on the airplane.
Then we look inside the cargo compartments. Here we’re looking for holes in the sidewalls, and to make sure the lighting and cargo nets are in good shape.
Some planes are chatty and will tell us things via screens in the cockpit. Some are quiet, but low to the ground and easy to inspect. Some are tall and aloof, and in this case, we climb on ladders and lifts to look inside compartments and check gauges.
Once the outside of the plane is taken care of, it’s on to the inside (or, upstairs, as mechanics call it). In the flight deck we turn off hydraulics and unset the parking brake (don’t worry, the wheels are chocked). Then we make sure all the lights, inside and out, are working properly, run a few electronic tests, and check hydraulic fluid levels. Also, depending on the airplane, we might look at other measurements that are indicated in the flight deck (remember how some planes are chatty?). Finally we make sure there’s paper for the printer, and that the windshields are clean. There are disadvantages to working in the winter (rain and wind, mostly) but one thing I like about winter work is that the windows are not covered with dead bugs.
In the passenger cabin, we check the integrity of all the safety equipment and exit signs, lights and slides. We make sure the toilets flush and the water runs and that the anti-smoking/anti-fire components in the lav are present and working.
Sometimes we find headphones, IPads and Kindles. When this happens, it’s a mad dash up the jetway to try to catch a gate agent before they leave, so they can either get the item to its owner, or enter it in the lost and found system. In my experience people (me) don’t usually realize something is missing until they arrive home or at their hotel, so the lost and found system is the best bet for getting it back.
The goal of the service check is to find problems, and wear and tear, before they become delays. On a good night, we check everything, it’s all good, and we sign it off. On a hard night, we find tires and brakes that are worn past the limit, or birdstrike damage in an engine, or inbounds that require hours of troubleshooting and repairs.
Once we have confirmed that the plane is happy, or have fixed anything that was making it unhappy, it’s time to sign it off and put it to bed. We turn off the battery or batteries (so they don’t run down if power gets dropped) and turn off the main power bus to the airplane. The plane goes dark and settles in to nap until the first flight of the morning.