Most of the historic aircraft that make up the Battle of Britain Memorial Flight (BBMF) have been grounded due to an engine issue.
A Lancaster bomber, two Hurricanes and three Spitfire planes are all affected by the problem.
The BBMF has three other Spitfires with different engines which are currently unavailable for other reasons.
The RAF said it had "taken the decision to temporarily pause flying of our aircraft powered by Merlin engines".
A spokesperson said: "A routine engine inspection has highlighted a fault with one of our Merlin engines. We are currently investigating the fault."
The decision to halt flying was "purely as a precaution" but safety was "paramount" and the unit was still operating its Griffon-engined Spitfires, they added.
'A great shame'
RAF Coningsby in Lincolnshire, where the unit is based, confirmed an appearance at Weymouth Carnival had to be cancelled on Wednesday afternoon.
The BBMF has also cancelled its appearance at Eastbourne Airbourne. A Spitfire, a Hurricane and a Lancaster bomber were due to appear at the air show later.
Organisers are waiting to see if it will be able to appear on another day as the show runs until Sunday.
Meanwhile, organisers of Biggin Hill's Festival of Flight, which is taking place this weekend, said: "The Battle of Britain Memorial Flight will not appear this weekend unless we're told otherwise."
The air show takes place at the site of an airfield south of London that played a central part in the Battle of Britain in 1940.
Colin Hitchins, of the festival, added: "It's a great shame. But we'll see what happens. If they can make it, great, but if not, we'll see them next year."
The festival is due to feature other Spitfires and Hurricanes, he added.
The RAF states the mission of the BBMF is "to maintain the priceless artefacts of our national heritage in airworthy condition in order to commemorate those who have fallen in the service of this country, to promote the modern day air force and to inspire the future generations".
The aircraft can regularly be seen in the skies at air shows and military events.
The RAF spokesman was unable to say when they would be back in action.
One of the planes is the last remaining airworthy Spitfire which flew in the Battle of Britain, and the Lancaster is one of only two left flying in the world.
The news comes before the first ever airshow at RAF Scampton, which is due to be held in early September and include planes from the BBMF.
In July, the Duke of Cambridge attended an air display marking 60 years of the BBMF. Prince William, who is the flight's patron, also spoke to veterans at the event.
Battle of Britain Memorial Flight
- The Battle of Britain Memorial Flight was formed on 11 July 1957 by Gp Capt Peter Thompson, a former Battle of Britain Hurricane pilot
- He set about collecting and preserving examples of the main aircraft involved in the conflict to honour the RAF's defence of the UK against German attacks at the end of 1940
- The BBMF has 12 historical aircraft, including a Lancaster - one of only two left flying in the world; the other is in Canada
- It also has a Dakota, six Spitfires, two Hurricanes, and two Chipmunks, which are used for training
- The flight has been displayed or flown at thousands of events as a tribute to those who have served in the RAF
- 11 July 2017
- 4 July 2017
- 4 July 2017
- 7 August 2014