Two of the three air ambulances in Wales have been grounded.
The Welsh air ambulance based in Welshpool is currently the only operational aircraft left in Wales as one based in Caernarfon and the other based in Swansea have been grounded over safety concerns.
It follows a routine check of an EC135 aircraft in Europe, where a small crack was detected similar to a defect found on the same aircraft type in Scotland in February.
Wales Air Ambulance has leased two EC135 helicopters, pilots and engineers from Bond Air Services since 2009.
As a precautionary measure, Bond has made the decision to temporarily ground its EC135 fleet while additional rigorous checks are carried out.
BAS is currently awaiting further comment from manufacturer Eurocopter on its investigation to identify the cause of this crack.
Wales Air Ambulance is still operational in Wales with the use of its third helicopter, which is a different model and not subject to the investigation.
This aircraft is currently operating on extended hours to optimise its coverage across Wales.