The challenges of storing large fleets of aircraft.

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SARS-CoV-2. It seems unbelievable that something so small has managed to put so many economies, so many industries, in check. With closed borders and blocked tourist destinations, commercial aviation has been one of the hardest hit, and the major companies only have two options: Retire the older planes, and store the rest. Putting an obsolete model in a cemetery doesn’t sound so complicated, but what about those planes that have to be returned to the sky?

The COVID-19 pandemic caught us in a wicked dance. Countries open, close, relax and adjust according to the number of cases detected. As expected, these manoeuvres conflict with activities that depend on mass transport of people… and so we come to commercial aviation.

The airlines are in crisis, there’s no doubt about it. Some are trying to restart their structures with offers and future ticket purchases, but today they are basically a shadow… and they have thousands of planes on the ground. That sets up several questions: Where are they stored? What kind of care do they require? How long can they be kept out of the circuit? Basic questions on the surface, but they need more detailed exploration.

The first step is to find a good location. The vast majority of traditional airports were not designed for long-term storage, and there are also climatic demands that must be considered. The “ideal location” for an aircraft is dry, and relatively cold. There are two reasons for this: On the one hand, humidity accelerates the corrosion process, stimulates microbial growth and the appearance of fungi both inside the aircraft and in specific elements (e.g. fuel tanks). On the other hand, excessive temperature damages everything based on rubber and adhesives, and ultraviolet light can cause additional damage.

If that “cold and dry” combination is not available, airlines are willing to accept regions with higher temperatures, as long as maintenance personnel are nearby to work on the aircraft if necessary. For example, Qantas decided to rest its Boeing 787s at the Victorville airport, since humidity in California is lower than in Australia, and the company has an engineering team stationed in Los Angeles.

Another important fact is that there is a big difference between “active parking” and “deep storage. Aircraft that are actively parked are essentially ready to fly, stored at airports or very close to their routes. Under this configuration, an aircraft would take no more than 48 hours to return to service. Landing gear is lubricated, and all openings are covered, with special attention to the engines. They are also “walked” to prevent deformation of the tires, and electronics and hydraulics are periodically reactivated.

Deep storage demands a different kind of work. Engine lubricants are replaced with anti-corrosion agents, and in more extreme cases, they are completely removed for return to the manufacturer. If a break is too long, some airlines will probably prefer to remove or recycle the aircraft before continuing to pay for storage. That’s one reason why they’re pulling 747s around the world.

By Lisandro Pardo – Neoteo, Hackaday