Boeing 717 operators have been warned that there is a risk of uncontained failure of their Rolls-Royce BR 700s unless certain high pressure turbine (HPT) components are replaced early. The warning came in a 4 December US Federal Aviation Administration emergency airworthiness directive (AD).

In the USA 25 engine units with serial numbers from 13111 to 13193 are affected. The AD warns that a manufacturing process change on some BR 700-715 high pressure turbine discs has reduced their "maximum cyclic life".

Operators must replace the discs within the newly issued cycle limits, the AD states, explaining that some HPT stage 1 discs need replacing between 2,600 and 3,600 cycles, and some stage 2 discs need to be replaced before 3,800 cycles.

R-R says: "rig testing has revealed that the fatigue life of the BR700-715 HP turbine discs is more sensitive to a certain deburring process than expected. The life limit of a restricted number of affected discs has been reduced. These discs have not exceeded the reduced life. The AD is to ensure that operators remove the engines with the affected discs before the reduced life has been exceeded."

Source: Flight International