Air ambulance flights across the UK using the same model of helicopter which crashed into a pub killing nine people have been suspended after a fault was detected on a flight.
Operator Bond has grounded its fleet of 22 EC135 helicopters as a precaution while the issue, discovered on an air ambulance in the north west of England yesterday, is examined.
The Association of Air Ambulances (AAA), which represents the majority of the air ambulance network, said 16 of its 36 helicopters in the UK were affected by the grounding and will be subject to safety checks this afternoon.
Areas affected include Dorset, Somerset, Thames Valley, the Isle of Wight, the Midlands, Scotland and Wales.
Eurocopter, the manufacturer of the grounded aircraft, said the decision taken by Bond did not apply to the rest of the EC135 fleet.
The Police Scotland helicopter that crashed into the roof of the Clutha bar in Glasgow on November 29 was a Bond-operated Eurocopter EC135 Type 2 aircraft.
An initial report from the Air Accidents Investigation Branch (AAIB) issued this week said there was ''no evidence of major mechanical disruption of either e ngine'' of the Police Scotland helicopter as it returned from an operation in Dalkeith, Midlothian, on the night of the crash.
A statement from Bond Air Services said: " During normal operations yesterday, one of our EC135 fleet has experienced an indication defect that requires further technical investigation.
"Therefore as a precautionary measure we have temporarily suspended service operations whilst we undertake detailed diagnosis. We commenced investigations overnight, are continuing this morning and are in close liaison with Eurocopter regarding this investigation."
Other air ambulances still in operation will be used to cover the areas currently affected by the grounding, AAA said.
Director Clive Dickin said: "Aircraft of all types occasionally are grounded for bad weather or routine maintenance. In these circumstances, other air ambulances and ambulance service providers work closely to ensure no patients are affected.
"Obviously, when an extremely rare incident like this happens, stresses can be placed on the services however these contingencies are planned for."
A Eurocopter spokesman said: "Eurocopter was informed by Bond that they decided to temporarily suspend flights with their EC135 fleet yesterday late evening. Based on an observation made on an aircraft engaged in medical services the decision was taken on their behalf for precautionary reasons.
"Eurocopter does not recommend any further action for the other EC135 aircraft in service around the world. The European Aviation Safety Agency has never issued an airworthiness directive to ground the EC135 fleet ever since its entry into service in 1996."
A spokesman for the Civil Aviation Authority (CAA) said: ''It is voluntary action by the operator. There is no official regulatory grounding of the type of helicopter so they are still free to fly if the operators wish to.
''If there were an official grounding, that would come from the European Aviation Safety Agency.''