London - The blades of the Trent 1000s are wearing out faster than expected, causing more Dreamliners to be grounded.

Around 120 Trent 1000 engines should be affected from the new finding, which to hamper efforts for diminishing the number of grounded planes.

Air-safety regulators are expected to publish a directive about the issue in the coming weeks.

We continue to proactively manage a number of known durability issues within our Trent 1000 fleet and have made good progress in redesigning and replacing affected parts,
Rolls-Royce said.

The issue concerns a minority of 787 engines that haven't already had the relevant blades replaced and may cause additional short-term disruption,
The British engine manufacturer also added on an email to Bloomberg news agency.

EASA, The European Aviation Safety Agency did not comment yet while the FAA (The U.S. Federal Aviation Administration) declared that it was working on it.

Airlines who operate Dreamliners with Trent 1000 turbines had to ground some of their aircraft because of the several design failures on the engine. Some operators such as British Airways, Virgin Atlantic and Norwegian Air Shuttle were forced to lease additional jets to compensate the gap caused by their grounded 787s.

With the new finding, the affected Dreamliners started to go to the maintenance hangars for corrective work. The previously estimated cost of 1.3 billion pounds ($1.5 billion) for emergency maintenance might not change, but the engine manufacturer could face a fresh bill for flight disruptions.