British Airways (BA) has apologised to passengers who were caught up in the ordeal which began on Tuesday last week.
The flight time from London to Athens is less than four hours, but this journey lasted eight times longer.
A faulty cockpit warning light caused the first flight, due to depart at 1.15pm, to be cancelled at Heathrow.
But that was just the first in a long line of problems for passengers.
The second plane couldn’t take off at its scheduled time of 5pm because cabin crew had exceeded their working hours.
Passenger Geoff Lye said the pilot told them it was “the most embarrassing PA announcement” he had made.Related articles
GETTYBritish Airways: A flight from London Heathrow to Athens took 33 hours instead of four
Passengers behind me said they could see flames kicking out from the engine
British Airways passenger
After an hour on the plane due to “security issues”, passengers were allowed to disembark.
BA gave them vouchers for a night’s stay in London, before the travellers returned the next day to board another plane.
This flight did depart at 1.40pm, but just moments later the starboard engine caught fire.
Mr Lye told the Evening Standard: “We just took off and there was a bang and it was the engine next to me. There was this huge noise and a judder, and then there were about six more bangs. It was one bang after another.