HMS Queen Elizabeth took part in flight trials last year off the coast of the United States (Picture: Royal Navy).
They are the largest and most powerful ships ever built for the Royal Navy.
Last year, HMS Queen Elizabeth returned to the UK after conducting flight trials with the F-35 in the United States.
More than 500 takeoffs and landings were conducted over a four-month period and at full capacity, the ship will be able to carry 72 F-35s at once.
The aircraft carrier is expected to undertake its first operational deployment in 2021.
The second Queen Elizabeth-class carrier, HMS Prince of Wales meanwhile could be ready for sea trials later this year.
Prince of Wales turned on its engines for the first time last November, with Captain Stephen Moorhouse taking charge of the ship in September.
They are the first new carriers built since HMS Ark Royal was scrapped in 2010.
HMS Queen Elizabeth has returned to Scotland for routine maintenance work at the same dry-dock at Rosyth where she was assembled.
12 Key Facts On The Carriers
1) The project to build HMS Queen Elizabeth and sister ship HMS Prince of Wales cost more than £6 billion.
2) Each aircraft carrier weighs 65,000 tonnes and has a top speed of 25 knots.
3) The flight deck of Queen Elizabeth is 280m long and 70m wide - enough space for nearly three football pitches.
4) The ship is the second in the Royal Navy to be named Queen Elizabeth. A ship of the same name was planned in the 1960s but never constructed.
5) Prince of Wales is the seventh ship to carry the name, with the first being launched in 1765.
6) Each carrier will have a total crew of 679, increasing to around 1,600 when a full complement of F-35 jets and Crowsnest helicopters are embarked.
7) There are around 364,000 metres of pipes inside each ship.
8) Each vessel has two 33-tonne propellers (one at each end of each carrier).
9) Both HMS Queen Elizabeth and HMS Prince of Wales will keep 45 days' worth of food in its stores.
10) The entire Ship's Company of 700 can be served a meal within 90 minutes - 45 minutes when at action station.
11) Each Queen Elizabeth-class aircraft carrier has a total of 16 decks, comprised of nine decks from the hull to the flight deck and a further seven in each of the two islands.
12) There is more than 250,000 km of electrical cable and more than 8,000 km of fibre optic cable in each of the ships.