European safety regulators are ordering checks on Rolls-Royce Trent 1000 engines after inspections of intermediate pressure turbine blades discovered missing rear seal fins.
The Trent 1000 is used to power the Boeing 787. All 787s have been grounded since mid-January over a continuing battery safety issue.
But the European Aviation Safety Agency is ordering checks on the rear seal fins because, it says, release of the components could result in secondary damage and possible engine power loss.
For affected aircraft the EASA directive instructs checks before 450 cycles and further inspections every 200 cycles.
EASA says the instructions are an interim action, adding that a modification is being developed to "enhance the capability of the engine to sustain non-uniform loads".