The Royal Navy's first £3 billion aircraft carrier is taking on 200 litres of water an hour.
A problem with one of the seals around one of its propeller shafts was first identified during sea trials.
The ship is scheduled for repair and a Royal Navy spokesperson said the fault will not prevent her from sailing again early in the new year.
HMS Queen Elizabeth was commissioned into the Royal Navy by her namesake on December 7, 2017.
But she arrived at her new home in Portsmouth on August 16, 2017 amid a comprehensive sea trial programme.
Around 100,000 people lined the seafront to welcome HMS Queen Elizabeth, the soon-to-be Royal Navy flagship.
It was the culmination of years of work, rebuilding the Princess Royal Jetty and commissioning the SD Tempest just for the carrier, as her giant size required an extra powerful tug.
The team responsible for controlling the vessel's future strike force have also taken part in a US-UK exercise.
Saxon Warrior 2017 saw more than 60 Royal Navy and Royal Marine personnel direct carrier strike operations from the deck of the USS George HW Bush to practise for the arrival of HMS Queen Elizabeth.
The biggest warship ever built in Britain has been undergoing sea trials since setting sail from Rosyth dockyard in June.
The Royal Navy live streamed the 280-metre, 65,000-tonne vessel leaving the Rosyth on the Firth of Forth at the end of June.
A Merlin helicopter was the first to land on the ship's flight deck, piloted by 26-year-old Lieutenant Luke Wraith.
However, flying trials with helicopters and the F-35B Lightning II will start in 2018.
HMS Queen Elizabeth can be thought of as a base like RAF Marham at sea and could carry up to 72 aircraft at maximum capacity.
During her estimated 50-year working life, HMS Queen Elizabeth could be pressed into action for various work such as high-intensity war fighting or providing humanitarian aid and disaster relief anywhere in the world.
The carrier has been subject to criticism due to its computer system, which reportedly runs on the same operating system that was hit by a cyber attack in May, and to its security measures, which were challenged after an unauthorised drone landed on her dock.
The Key Numbers:
- The project to build HMS Queen Elizabeth and sister ship HMS Prince of Wales cost more than £6 billion.
- The aircraft carrier weighs 65,000 tonnes and has a top speed of 25 knots.
- Its flight deck is 280 metres long and 70 metres wide - enough space for three football pitches.
- The ship is the second in the Royal Navy to be named Queen Elizabeth.
- The ship will have a crew of around 700, increasing to 1,600 when a full complement of F-35 jets and Crowsnest helicopters are embarked.
- There are 364,000 metres of pipes inside the ship.
- Both HMS Queen Elizabeth and HMS Prince of Wales will keep 45 days' worth of food in its stores.
- The entire Ship's Company of 700 can be served a meal within 90 minutes - 45 minutes when at action station.
- Leaving the Rosyth dock was among the most difficult manoeuvres in the sea trials, with just 50cm between the bottom of the ship and the seabed in the port.
The History Of British Aircraft Carriers
The Royal Navy has seen 16 different classes of aircraft carriers take to the sea since 1918, with between one and 10 ships commissioned for each class.