The Thames Valley and Chiltern Air Ambulance was grounded yesterday by Bond Air Services after a fault was reported with the fuel indication system in another one of its aircrafts.
Some of Bond's fleet have been cleared to fly, but the TVACAA vehicle's remains grounded while investigations continue.
"Bond Air Services took the decision following a reported indication defect on one of their EC 135s that needed further technical investigation," said TVACAA chief executive Mark McGeown.
"As a result of that investigation we have been advised that our helicopter cannot be returned to full service at present.
"Bond Air Services are working with Eurocopter to rectify the defect and return our aircraft to full service at the earliest opportunity.
"We fully believe that the safety of patients and air ambulance staff is the number one priority."
Hampshire and Isle of Wight Air Ambulance will provide support to across Berkshire, Buckinghamshire and Oxfordshire until normal service is restored.
In addition, the air ambulance medical crews will be able to respond to calls in an emergency response vehicle provided by the South Central Ambulance Service NHS Foundation Trust.
A Bond Aviation EC135 helicopter leased to the police dropped from the sky onto a pub in Glasgow, on November 29, killing three crew and seven others.
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