Editor’s Note: This article originally appeared on FreightWaves.com.
Delta Air Lines parked 571 aircraft from its primary fleet across the country in 2020 when the COVID-19 pandemic wiped out most passenger air travel. Airlines still have about 70 percent of their pre-pandemic international capacity in hibernation, but Delta is returning aircraft to the skies because the U.S. domestic market is recovering faster than in other parts of the world.
Parking a transport category jet and bringing it back to life after months of inactivity isn’t as simple as shutting engines down and restarting them again. It takes a lot of effort—including maintenance line checks and other operational systems checks—to keep an aircraft in a ready state for future use.
Heat, Bugs, and Critters
As the pandemic reached the U.S. in March 2020, Delta began parking aircraft at its storage facilities in:
- Blytheville, Arkansas
- Kansas City, Missouri
- Marana, Arizona
- Birmingham, Alabama
Each location had separate challenges, such as humidity, desert heat, or bugs and small animals nesting in various parts of the airframes and engines.
In some regions of the world, for example, pitot tubes and other external sensing equipment would get clogged with mud thanks to mud dauber wasps. Maintenance technicians are instructed to regularly check probe covers for damage.
The Search for Space
So many aircraft were flown into the Birmingham airport that Delta technical teams ran out of the chocks placed by the wheels to hold the aircraft in place. Workers bought 6-by-6 skids of wood from local hardware stores to hand-make replacements, the airline said in a recent blog post.
Finding airports and fields that had room for aircraft was a big undertaking itself. In San Bernardino, California, a designated parking area wasn’t usable after a Boeing 757 began sinking into the pavement. And runways in Kansas City and Victorville, California, were only temporary, so the planes eventually had to be moved again.
Airplanes in long-term storage also require extensive engine covers, and all fuel must be off-loaded if the aircraft are hangared.
Other Logistical Headaches
Delta TechOps scheduled maintenance work for each aircraft at seven, 14, 30, 60, 100 and 180-day intervals. Coordinating the checks and spreading out the work required extensive planning, according to the airline. The engineers developed flexible “job cards” for each aircraft specially tailored to the climate conditions where they were parked, while conserving supplies and manpower.
“Putting an aircraft to sleep really hasn’t been done in the Delta world before. Some of the tasks have never been written for a lot of these airplanes because they were fairly new,” a maintenance program manager in Atlanta said in a Delta video.
The pandemic complicated the storage efforts. Most mechanics commuted to different storage facilities for periods lasting a few days to a month and couldn’t eat at restaurants because they were closed. At one location, a chief used the hotel kitchen to make meals for his team.
Many stored aircraft were stripped of certain parts to help repair those airplanes still in service. When it was time to reactivate them, mechanics had to find and reinstall new parts.
All airplanes reentering service had systems activated and reviewed, with special attention paid to lubricating landing gear systems and other components. Then they had to undergo a test flight before flying to a repair facility for a complete maintenance overhaul, according to Delta’s blog.
Smaller aircraft can take about 10 days to two weeks to rehabilitate. Larger aircraft can take two to three weeks to fix up. The process is longer for airplanes stored 180 days or more, especially if there are components that need programmed replacement.
When maintenance line checks are finished, pilots arrive to fly the airplane to the first airport at which it will rejoin operations, and pick up passengers and cargo.
So far, Delta has returned 493 aircraft to the active fleet. The company expects to be reactivating aircraft into 2022.
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