Like Mr. Gibbons, I'm not a technical expert, but there is in fact some basic preservation work that can be done to aircraft, and the airlines are doing this work to make sure that the fleet can fly when the time comes.
I would say that the most challenging thing in this regard is also keeping the certification of the pilots. Pilots need to fly so that they do not lose their qualifications to fly, so there is a rotation to ensure that. These are highly skilled workers. They need to work and we need to have a plan to make sure that they keep their certification.