At airports during late-night or early-morning hours, many airplanes remain parked at the gates for extended periods. These aircraft are typically undergoing what is known as a “remain overnight” service, which allows mechanics to perform essential maintenance checks and address any issues that have arisen during the day’s flights.
Jennifer Lasher, an aircraft mechanic who has also volunteered on The Museum of Flight’s 747 restoration project, describes the routine tasks involved in these overnight service checks. “When our assigned plane arrives, the first thing we do is add oil to the engines if needed. It’s a lot like adding oil to your car, except the oil costs about $20 per quart. We try not to spill.”
Mechanics then move to the flight deck to review the logbook for any problems reported by flight crews, known as “inbounds.” According to Lasher, these can range from minor issues such as a broken tray table to more complex electronic glitches in one of the engines.
The next step is a thorough walkaround inspection. Mechanics start at the nose of the plane, checking for dents or evidence of birdstrikes and foreign object damage. They ensure engine-driven generators have sufficient oil and clear filters. Tires and brakes are measured for wear and inspected for potential failures at takeoff or landing.
Other parts checked include wings, tail sections, landing gear wells for hydraulic leaks, static wicks that dissipate electricity buildup, cargo compartment integrity, lighting systems, and netting condition. Throughout this process, mechanics inspect the airplane’s exterior skin for dents or damage and verify that static and pitot probes are unobstructed.
After completing exterior inspections, mechanics return to the flight deck to test lights inside and out, run electronic diagnostics, check hydraulic fluid levels, replenish printer paper supplies if necessary, and clean windshields—especially important during bug season.
Inside the passenger cabin, they confirm all safety equipment is intact and operational. This includes exit signs and lighting systems as well as emergency slides. Lavatories are checked for functioning toilets and water systems along with fire prevention components.
Lasher notes that some nights go smoothly: “On an easy night, we check everything—it’s all good—and we sign it off.” More challenging nights involve addressing worn tires or brakes beyond acceptable limits or repairing birdstrike damage that may require extensive troubleshooting.
Once all tasks are complete and any required repairs made, mechanics sign off on their work before powering down batteries and main power systems so planes can rest until morning departures.
This article originally appeared in Aloft magazine published by The Museum of Flight.
