Clipped wings

“We carry out maintenance checks every seven days,” explains Virgin Atlantic’s Matt Sharp, Senior Manager for Aircraft Maintenance at the airline’s London Heathrow hub. “This is quite a simple inspection where the aircraft is powered up and a few checks are carried out, fluid levels, battery power and any status messages. We also perform a walk around, both internally and externally, to check for any leaks or damage to ensure the aircraft is still correctly blanked.”

Blanking is the process by which all external openings of the aircraft, everything from engine intakes to pitot tubes and beyond, are covered up.

Further checks are then carried out at 14, 30, 60 and 180 days. The 30-day checks include removing blanks, running the engines at idle, turning the air conditioning system on, and moving the aircraft in order to rotate the wheels and power up the brakes. These checks take some 60 person-hours to complete.

At 180 days, the aircraft enters a maintenance hangar for a full check and inspection: lubrication of flight controls, removal of wheels for axle inspections, and so on, taking some 300 person-hours.

This can be complex logistically, Virgin Atlantic’s maintenance staff in Manchester have been travelling to parked aircraft in Glasgow and Doncaster every seven days.

Airlines scrambled to park and store

Inside company war rooms and emergency strategy sessions, airlines were forced to respond to the Covid-19 crisis in ways that few had prepared for, both in terms of grounding their aircraft and then reactivating them to serve urgent needs like skeleton essential services and medical cargo transportation.

A tale of two parking cities

“At a time in which the global pandemic had an unprecedented impact upon the aviation industry, our home bases of Manchester and London Heathrow (were) incredible in supporting our parking requests,” says Virgin’s Brailsford. “However, with the majority of the European fleet grounded, tarmac was limited, resulting in parking at a number of locations. Doncaster immediately stood out as a perfect match, allowing us to park our aircraft while using our maintenance teams from Manchester to perform periodic parking checks.”

The two cities’ airports are separated by roughly an hour and a half by car: important, says Brailsford, so that engineers “can regularly perform checks to ensure our fleet is airworthy and ready to return to service when required. Further maintenance requirements are another factor, while we had all seven of our B747 fleet on the ground in Manchester is a great example of this. They underwent a programme of engine changes and other activity in readiness for them to retire from our fleet. It was necessary to reunite engines with their original airframes ahead of the sale or return to the lessor of each aircraft. “

“There are a number of considerations that need to be taken into account when storing aircraft. Key factors include humidity and weather conditions,” Brailsford explains. “For example, the dry air at Ciudad Real (CQM, the somewhat infamous ‘south Madrid’ airport) where we have stored some of our 747s and A330s, is ideal.”

Finnair / Finnair

A finnished fleet

Finnair parked the majority of its fleet, including most of its Airbus narrowbody aircraft, while serving strongly reduced domestic Finland demand for urgent travel – some 5% of normal – with its fleets of Embraer E190 and ATR 72 aircraft. Internationally, meanwhile, it operated both its widebody types, the Airbus A350 and A330, with varying mixes of passenger and cargo payloads.

“For our long-haul fleets,” Finnair’s A350 Programme Manager Sara Mosebar explains, “we have our newer A350 fleet which, of course, is more fuel-efficient, more economical to operate and with a larger cargo capacity. The A350 was the obvious choice for most of our cargo operation. It’s highly dependent on the distances you’re flying and then the size and capacity of what you’re carrying. It is like any normal operation but then it’s highly specific: where could we fly our customers? Where was the cargo demand?”

The A350 operated with belly cargo and, for the most part, passengers in the passenger cabin but some flights were in an EASA-approved all-cargo layout, where lightweight freight – usually Covid19-related items like personal protective equipment (PPE) – was shipped in boxes on passenger seats in the main cabin.

For those missions, Mosebar says; “we primarily focused on hubs where we already had established route structures, because there is a lot that goes into an aircraft to any hub. Do you have the appropriate maintenance personnel available? Is there someone available to service the aircraft? Do we have all the flight permissions to go to certain airfields? All of that is already in place when we focus on places where we are already operating.”

Some of Finnair’s A330s, meanwhile, saw passenger seats removed to become all-freight aircraft, allowing the transportation of even more lightweight cargo in the passenger cabin. “The seats were removed, carpeting put down over the rails that you would normally have exposed, and then points were made for the attachment points for netting, so that way everything could be secured,” Mosebar explains. “One of the interesting things about that is that in the cargo hold of a normal commercial aircraft there are smoke detection systems installed. In the interior of the aircraft, it’s mostly reliant on the fact that people are present most of the time, so the smoke detection is only in the lavatories and in specific areas in the passenger compartment. So we had to have someone monitoring the interior of the cabin and the load during the flight for smoke detection purposes.”

Which to store?

Nonetheless, almost every Finnair aircraft, including the widebodies, have been stored at some point, with only three A350s flying at the nadir of operations. But how does an airline decide which aircraft to store?

“For the A350s, there’s a lot that goes into it,” Mosebar says. “Some of the aircraft are heavier than the others, so obviously that immediately impacts fuel efficiency. The older aircraft, specifically our first three aircraft, are line numbers 18, 19 and 20, so they’re something like four tonnes heavier than the latest standard of the A350s coming off the line. So those were some of the earliest aircraft parked, and will continue to be parked until we return to full long-haul operations for the A350s.”

The question of whether aircraft are owned or leased also comes into play. “We think about the leasing conditions we have for certain aircraft, we see costs of utilisation but primarily one of the things we took into consideration with the A330 modification was that we have half of our A330 fleet as owned and half of it as leased,” Mosebar notes. “For Finnair, it was easier to do the cargo modification in terms of changing the passenger configuration into cargo for the aircraft that we own versus those that we lease. For the A350 there were a lot of fuel conditions, weight savings, leasing terms – while, on the A330 it was primarily the lease conditions we were looking at.”

As the crisis continued, it became clear that a key part of the puzzle is not storing any one aircraft for too long. Aircraft are, after all, made for flying and, the longer they sit on the ground, the more maintenance they require, both to be kept in readiness and to return to service. As a result, Finnair had a crack team of specialists deciding which particular tail numbers would be passing in and out of service.

“At the very beginning,” Mosebar explains, ‘it seemed as though it would be as simple as ‘okay, we’re going to store those, we’re going to operate these three. Then it very quickly evolved into a regular process of trying to rotate the tails as much as possible to minimise the amount of manpower utilisation from the maintenance perspective.”

A giant task

So, how do you park an aircraft? Finnair’s Sara Mosebar jokes: “very carefully! One of the revelations that we had during this period is that not a lot of consideration has gone into the parking of aircraft historically, because normally you don’t see this scale of parking anywhere. The world has never seen this scale of parking for this period of time.”

“Airbus – and any OEM (original equipment manufacturer) – has published storage and parking procedures for every aircraft as part of their maintenance documentation but it’s not something we generally would have used. It’s not as though we just had these regular job card templates available in our system: we had to develop all of that on our end, review all the procedures and figure out exactly what does go into parking.”

An immense amount of work was needed to review every task required, both for operators and airframers, and to optimise processes to park an unprecedented number of aircraft, at speed.

“When you park an aircraft, the first thing that you have to consider is maintaining the asset value and protecting the aircraft, as well as maintaining the safety,” Mosebar says. “In terms of the initial parking procedure, depending on the aircraft type, you can choose your parking period at the beginning. For instance, the A320s and A330s, you can choose up to 15 days or one month procedure, and then you can choose to park it for three months. For the A350, there’s a single parking procedure that allows you to store for up to three months. There’s not too much difference in terms of what’s involved.”

ECTran71/WikipediaCommons

External protections

That list is certainly extensive. “External protections have to be applied, every part of the engine covered – engines, thrust reversers, inlets, all of that. APU protection is installed. The doors need to be lubricated. Every external probe is capped and covered. Landing gears are checked and protected in terms of lubrication. Fuel samples are taken from the fuel tanks to make sure there is no present microbial growth, and that’s monitored throughout the parking period as well. The waste system is cleaned and drained. The potable water system is drained. Everything is checked, preserved, and then ready for storage,” Mosebar explains.

Finnair estimates that some 30 person-hours of work are required to store a widebody aircraft per calendar day, with teams working at pace to park an aircraft.

But few airlines were prepared to park their entire fleets at once. Airline schedules are designed to keep aircraft in the air and most hubs do not have space for all the aircraft notionally based there to be parked normally. That is both a delicate ballet of parking on aprons, taxiways and runways – especially those in unusual places, as the various pictures of aircraft sinking through the surface of taxiways show – and a need for hardware.