Rolls Royce said it is making progress in its investigations into an engine failure that resulted in a forced landing of one of Qantas's planes last week and has forced the Australian airline to keep its fleet grounded.Rolls said that the problem was specific to the Trent 900 engine.'A series of checks and inspections has been agreed with Airbus, with operators of the Trent 900 powered A380 and with the airworthiness authorities,' Rolls said. 'These are being progressively completed which is allowing a resumption of operation of aircraft in full compliance with all safety standards.'Shares in the company immediately jumped after the announcement, which came as Qantas said it found "slight anomalies" on three Airbus A380 engines, forcing it to keep its fleet grounded.Engineers are making further checks after finding "oil where oil shouldn't be on the engines".The carrier has been giving all its Rolls-made Trent 900 engines the once over after one of the super-jumbos had to make an emergency landing in Singapore on Thursday."These are new engines on new aircraft and they shouldn't have these issues at this stage, so it's given us indication of an area for us to focus into," chief executive Alan Joyce told the Australian Broadcasting Corporation."We are keeping an open mind on it but... We think it could have been a materials issue on the engine, or a design issue."The six A380s will be out of the skies for at least another 72 hours, Joyce said"We still believe with the progress we are making - this is days not weeks - but we will take as long as it needs to in order that we are absolutely comfortable the aircraft is safe to fly."