Not very good things happen for sure. There are many reasons for this. Let’s have a look briefly (and technically);
As you can imagine, the plane that cannot fly cannot generate income. The first negative effect is of course the lost income.
Since the parking capacities of the airports are limited, it is necessary to fly the planes to distant airfields only for parking. Staff is also required to keep them safe there.
Unfortunately, the fact that the planes are not flying does not mean that their expenses are zero. Since planes are machines designed to fly, it is not very healthy in terms of their condition that they are on the ground for a long time. While the calendar-based maintenance requirements continue, parking and protection costs are added. There are many different systems in planes, so each of them needs to be arranged for a long time storage. The general procedure for a period of less than 1 year storage as follows;
– Putting the applicable protection equipment on all the probes and the sensors (pitot probes, static probes, Total Air Temperature (TAT) sensors, Angle Of Attack (AOA) sensors and ice detection probes etc.
– If the aircraft is parked or stored in high wind conditions, aircraft stability must be checked and moored if necessary.
– Similarly, if there is also cold weather conditions, special cold weather maintenance procedures must be applied such as draining all waters from water/waste lines etc.
– Cleaning of the aircraft externally and internally
– Parking the aircraft on a flat surface, making sure that the wheels of the NLG are on the aircraft axis and that the aircraft points into the wind.
– Installing the safety devices on the landing gears and putting the chocks in position
– Retracting all the flaps, slats, spoilers and thrust-reverser cowl doors
– Setting the Trimmable Horizontal Stabilizer (THS) pitch-trim control-wheel to two degrees aircraft nose up.
– Putting the warning notices in position to tell persons not to operate the systems during the aircraft storage procedure.
– Electrically grounding the aircraft.
– Applying protection of the Engines and the Integrated Drive Generator (IDG), APU, Fuel System, Landing Gears and the Wheels/Brakes, Water and Toilet System, Flight Controls, Cabin and the Cockpit, Doors, Windows, Oxygen System, Hydraulic System
– Flushing of the Air Data System
– Inspecting of the drains visually to make sure drain holes are not clogged by debris, dirt, bird nests, insects etc.
– Removing or Protecting of Some Critical Equipment such as Digital Flight Data Recorder (DFDR), Cockpit Voice Recorder (CVR) aka Black Box, if they are not solid state design, Emergency Locator Transmitter (ELT), Emergency Power Supply Unit (EPSU) and disconnecting batteries
– Removing the fire-extinguishing bottles from engines, APU, cargo, cabin and cockpit if the Outside Air Temperature (OAT) is more than 50 DEG celcius. This is because some aircraft internal areas can reach around 70 DEG celcius.
– Protecting the engines and the APU with specially adapted protection covers and equipment.
– Putting a cover on the top of the rudder to give protection from bird excrement.
– Sealing surge-tank overpressure protectors, ailerons to give protection from bird nests, air conditioning inlets and outlets, avionics ventilation inlets and outlets and battery venturi.
– Applying Corrosion Preventive Compound (CPC) to all the surfaces exposing the air.
There is a constant need for maintenance staff to do all these jobs.
Of course, all these steps (in other words, expense) must be reversed once again when the storage period is completed to return the aircraft to service.