An aircraft that is not flying

Not flying is an operating state, not a pause

An aircraft that has stopped flying has not stopped costing, and more to the point it has not stopped changing. Seals dry, batteries discharge, corrosion starts, fluids settle, and the calendar items that ground an aircraft keep expiring on exactly the schedule they always did. The difference is that nobody is opening the hangar every week to notice.

The failure this guide is written against is not dramatic. It is an owner asking in March for an aircraft that stopped flying in November, and the answer taking six weeks and a number nobody expected.

Where the aircraft is managed under an operator's certificate, that operator's approved procedures govern how it is stored and returned to service. The manufacturer's maintenance manual has a storage section and it is the authority on preservation. Confirm what applies with your maintenance provider rather than assuming it from a general checklist.

Decide which kind of not-flying this is

The single most useful thing you can do is name it, because the three are different jobs:

• Short, a few weeks. Little more than the usual, plus ground runs and covers.
• Extended, a month to several. The manuals usually have a defined preservation state, with tasks at entry and at exit.
• Indefinite, where nobody knows. The expensive one, because it tends to be managed as a series of short pauses and therefore never gets the preservation a long one would have had.

If the honest answer is indefinite, treat it as extended. The cost of preserving an aircraft that then flies next month is small. The cost of not preserving one that sits for a year is not.

The airframe while it stands

• Covers and blanks on pitots, static ports, intakes and exhausts, with a removal checklist that someone actually follows. A blanked pitot that flies is a serious event, and it is prevented by procedure rather than by memory.
• Wildlife. Birds and rodents are the most common cause of damage to a standing aircraft, and they get in through the places a walkaround does not look.
• Tyres and gear. Pressures fall, and a tyre standing on one spot flat-spots. Moving the aircraft periodically is the usual answer.
• Batteries, whose discharge is the most common reason a standing aircraft will not start when wanted.
• Fuel, its quantity and its condition, and water drains on a schedule rather than on suspicion.
• Humidity, if the hangar has any. It is the whole corrosion story.

The clocks that do not stop

This is the part that surprises people, because it is administrative rather than mechanical, and it is where the six weeks usually goes:

• Calendar maintenance items run on dates, not hours. An aircraft that flies nothing still reaches them.
• Emergency equipment with service lives: beacons, rafts, extinguishers, oxygen.
• Registration and airworthiness documents.
• Insurance. Tell the insurer the aircraft is in storage. Cover for a stored aircraft is a different conversation and sometimes a cheaper one, and a policy that assumes operation may carry conditions you are no longer meeting.
• Navigation databases and subscriptions, which lapse quietly and are needed before the first flight, not after it.
• Hangar agreement, and whether its term outlasts the storage.

Crew currency decays on its own schedule

Nobody is flying, so nothing is being maintained: licences, medicals, recurrent training and type currency all run down while the aircraft sits. The aircraft can be returned to service faster than a crew can, and training slots are the item you cannot buy at short notice.

If the aircraft may be needed at short notice, currency is what actually determines whether it can go, and it should be tracked whether or not anyone is flying.

A monthly rhythm beats an annual scramble

Whatever the manuals require, a short monthly pass is what keeps a stored aircraft honest: walk it, check tyres and battery, look for wildlife and water, run what the manual says to run, and record the date and what was seen. Ten lines a month.

The record is the point. A stored aircraft with twelve monthly entries is a known quantity when it comes back. One with none is an inspection.

Coming back

Work backwards from the first intended flight, and expect the long poles to be administrative and human rather than mechanical: the calendar items that came due during storage, the crew currency, and anything on order. Plan a return to service check flight before the trip that matters, for the same reason a season starts with one.

What to hold on file

One record should hold the storage decision and its date, the preservation tasks done at entry, the monthly checks, every calendar item with its expiry, the insurer's acknowledgement of the storage, and the return to service tasks outstanding. See how the operations view works, or read a pre-season readiness check, which is the same aircraft on the way back up.