The Royal Navy flagship HMS Queen Elizabeth is set to sail into its home base of Portsmouth later following four months of repairs in Scotland.

In February, the £3 billion aircraft carrier had been due to take part in Steadfast Defender – Nato’s largest military exercise since the Cold War – when the problem with the starboard propeller coupling was discovered shortly before it was due to sail.

At short notice, its sister aircraft carrier HMS Prince of Wales, which itself suffered a propeller shaft problem in August 2022, was called in to form the heart of a carrier strike group in the exercise, with helicopters and F-35 fighter jets on board.

The 65,000-tonne warship returned to the Rosyth dockyard where it was assembled. It departed from Rosyth last week after the repairs were completed.

A Royal Navy spokesman said: “The ship emerged sooner than initially forecast from repairs and, after sailing under the Forth Bridges, has spent the last seven days at sea being put through her paces on trials to test her systems to the maximum.

The Royal Navy aircraft carriers HMS Queen Elizabeth and HMS Prince of Wales alongside at HMNB Portsmouth
The setback came 18 months after sister ship HMS Prince of Wales broke down off the Isle of Wight after it sailed for the US having suffered a malfunction with a coupling on its starboard propeller (Andrew Matthews/PA)

“This has included marine engineering trials, sailing at high speed for extended periods of time and manoeuvring as aggressively as possible to give the command team full confidence in her systems following the docking period.”

The ship’s commanding officer Captain Will King said: “Whilst no warship wants to find itself spending unscheduled time out of the water, I am enormously proud of the work that has gone on in Rosyth.

“Everybody on board is looking forward to getting back to sea, where we belong, and picking up a busy programme in the autumn.”

Before heading into Portsmouth harbour on Tuesday evening, the aircraft carrier will carry out a sail past of the Isle of Wight, exchanging gun salutes with the Royal Yacht Squadron as the Cowes Week regatta continues in the Solent.

Having returned to Portsmouth, the crew of HMS Queen Elizabeth will begin preparations for operations to be resumed in the autumn.