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."
More top news
Henley Royal Regatta will be available to view around the world via a live stream in 2015, it's been announced.
Wednesday morning's weather for the east of the region
Wednesday morning's weather for the west of the region