Summary
We propose to adopt a new airworthiness directive (AD) for all Rolls-Royce plc (RR) RB211-524 turbofan engines with certain part number (P/N) low-pressure turbine (LPT) stage 3 turbine blades installed. This proposed AD was prompted by reports of LPT stage 3 turbine blade failures, release of blades, and subsequent in-flight shutdowns. This proposed AD would require implementation of a life limit for certain P/N LPT stage 3 turbine blades and replacement of affected blades that reach or exceed the life limit. We are proposing this AD to prevent failure of LPT stage 3 turbine blades and subsequent release of blade debris, which could lead to failure of one or more engines, loss of thrust control, and damage to the airplane.