How you change an Airbus A380 engine

Just before landing at London's Heathrow Airport, you're likely to see a complex of enormous hangars flash by your window. Along with offices and parking space for stored aircraft, the complex houses the engineering division of British Airways, which is charged with keeping the airline's fleet in the air.

The largest two hangars, which are adjacent to its crew training center (where I piloted a Boeing 747 simulator two months ago), are big enough to house BA's biggest aircraft, the Airbus A380. First built in the 1950s during the days of the British Overseas Airways Corporation, BA's predecessor airline, they have been enlarged several times as commercial aircraft grew continually bigger. Before the airline's first A380 arrived in 2013, crews had to cut a slot at the entrance of each hangar to accommodate the aircraft's 79-foot (24-meter) tail fin.

On June 21, the day before BA accepted delivery of its twelfth A380 (and the last in its original order), I had the chance to tour the hangar as one of the airline's massive A380s was undergoing an engine change. The airliner had arrived at Heathrow that morning from Johannesburg, but was pulled from service temporarily to fix a non-critical oil pressurization issue.

Keep clicking for a walk around and inside.

The maintenance hangars are on Heathrow's eastern edge, well away from the terminals where you spend your time as a passenger. The Boeing 777 in the background is parked in a penlike structure that allows engineers to run engine tests while limiting jet blast and noise to the surrounding area. Just above a Cathay Pacific 777 from Hong Kong is about to land, just one of the continuous stream arrivals that roared overhead during our visit.

As technicians inside the hangar prepared to remove the faulty engine and send it it away for inspection and repair, the replacement Rolls-Royce Trent 900 engine sat on a wheeled cradle on the the hangar floor. Rolls-Royce will deliver a new engine right to your door if you like. That would be one hell of a present to unwrap.

When parked inside, the A380's 261-foot (80-meter) wingspan makes for a snug fit. And you thought parallel parking was hard.

Robert Crew, BA's engineering head for the airline's A380, A350 and Boeing 787 fleet, stands in front of one of the A380's four engines.

The airline's Heathrow and London Gatwick bases only handle light and routine maintenance. Heavier jobs such as "D Checks", when almost the entire aircraft is taken apart and inspected, occur at separate facilities in Glasgow in Scotland and Cardiff in Wales.

Each engine can produce between 70,000 and 80,000 pounds of thrust. That's more than enough to lift a 575-ton aircraft into the air.

Opening the engine gives you an awesome full view of all the parts inside.

To remove the engine, technicians open the nacelle on either side. Then, they lower the engine onto the yellow wheeled cradle on the left.

It's delicate job that takes about two and a half days. We visited on a Tuesday and the aircraft was scheduled to fly out again Thursday night.

BA also uses the engine replacement time to make other, noncritical repairs.

For example, each of the 22 landing gear tires is checked to make sure that it has the correct pressure. If needed, the tires will get a boost of nitrogen.

These "pink pigs" are ground support equipment used during maintenance jobs. The nozzles lining each side are used to provide air line connections to the aircraft from a single point inside the hangar.

Considering how big and complex the A380 is, its cockpit is much simpler than you might expect. LCD screens have replaced mechanical gauges and there are fewer controls than in older aircraft like the Boeing 747.

The bumps on either side of the throttles on the console house trackballs for controlling the computer screens. Like all newer Airbus aircraft, the A380 uses controls sticks (the joysticklike things next to either seat) instead of controls columns.

Just behind the cockpit on the lower deck is the First Class suites. BA's premium class lacks the bars and showers you'll find on other A380s, but it's still the most luxurious place on the plane to spend 12 hours. During our tour, workers cleaned the cabin and readied it for its next flight.

The business class section on the upper deck isn't quite as posh as First, but it's still a world away from economy. In business class, BA uses a staggered arrangement between standard and rear-facing seats.

Seats and personal TVs get smaller in premium economy, also on the upper deck.

And in the very back on both decks is the economy section. Each BA A380 has seats for 469 passengers.

Did I mention how big the A380 is? The fuselage is 238 feet (72 meters) long and 23 feet (7 meters) wide and the total wing area is 9,100 square feet (845 square meters).

The A380 is so high I could stand under it without ducking my head. Here you can see the 20 wheels of the main landing gear.

The wings support four Trent 900 engines, each of which is almost 10 feet (3 meters) wide and weighs almost 7 tons. The spirals in the center of each engine fan let ground crew know the engines are running.

The outlet on the A380's tailcone is the APU, or auxiliary power unit, which starts the engines and powers the airliner when the engines are shut down.

Though it's a tight fit for the aircraft inside the hangar, there's enough room to to play catch.

And in case you were wondering, a typical A380 will cost you a cool $432 million (about £321 million or AU$580 million). Start saving now.