Maybe they were used as substitutes for the grounded jets a few years ago:
“By March 18, every single Boeing 737 MAX plane (387 in total) had been grounded, which affected 8,600 weekly flights operated by 59 airlines across the globe. Several ferry flights were operated with flaps extended to circumvent MCAS activation.”
Similar to the old spare refrigerators, freezers, toasters and other items in the grandparents’ basements used as backups by the younger generation as their own new ones lasted 2-3 years before breaking down. That was in a newspaper column by Dear Abby or one of those. Actually heard cases of it being true.
Backup? The almost 70 year old fridge is in daily use in the garage mainly as a beverage cooler, but also used as overflow (can't really be depended on for long term storage of perishables in the summer when the garage gets well over 100 degrees). I replaced the gasket about 35 years ago or so. It's a pain to defrost it several times a year.