The company is under pressure from airline customers due to parts not lasting as long as expected on the Trent 1000 which powers the Boeing 787 Dreamliner, meaning it has to make regular checks on the parts, which has led to some planes being grounded.

"The good news is that we've gone through the peak of that and the incidence of aircraft on the ground turned out to be less than we feared and the incidence of failure on the repeat inspections...so far is going better than we had anticipated," CEO Warren East told investors on Friday.

The company said on Friday the engine issue could lead to additional cash costs of 100 million pounds in 2018.

(Reporting by Sarah Young; editing by Kate Holton)