Air accident investigators are examining the possibility that the helicopter involved in the incident at the Salthill air show on Sunday was tampered with while it was open to the public throughout the day.
A man and two women were injured when an emergency door fell about 150 feet from the RAF Merlin helicopter as it took off. They were discharged from hospital yesterday after being treated for minor injuries.
Four investigations have begun: by the British ministry of defence, the Irish Aviation Authority, the Air Accident Investigation Unit and the Garda.
One theory is that the emergency door was interfered with, accidentally or otherwise, as hundreds of people inspected it throughout the afternoon. The helicopter was taken to Galway airport overnight but was allowed to return to Britain yesterday after being inspected.
Supt Noel Kelly, who is heading the Garda investigation, said that all aspects would be examined.
Air show organiser Brian McGrath said it was an unfortunate incident but one outside the control of the voluntary committee which staged the event each year. He also said that the future of the air show was in doubt - not because of the incident, but because of a financial shortfall.