First A380-related airworthiness directive orders Trent vane check

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European safety regulators have drawn up the first airworthiness directive relating to the Airbus A380, mandating checks for cracking of vanes in Rolls-Royce Trent 900 high-pressure turbines.

The directive, issued by the European Aviation Safety Agency, states that development testing and flight tests of the Trent 900 have revealed evidence of cracking on some nozzle guide vane surfaces.

EASA says that not all nozzle guide vane assemblies are affected and that the problem would become apparent on affected engines within 1,000 cycles.

"Analysis of test data and review of the manufacturing process has revealed compounding effects that may contribute to a shortfall in component life and an increased likelihood of premature cracking in this region," it states.

Excessive cracking on the vanes' convex surface could, it says, lead to possible fracture of high-pressure turbine blades - and subsequent engine damage - if vane material is released. Turbine gas flow could also be blocked, it adds.

EASA is instructing operators of Trent 900 engines to inspect the nozzle guide vane surfaces before 400 cycles, and to repeat these inspections at least every 100 cycles. If no damage is detected by 1,000 cycles, it adds, normal inspection maintenance can be resumed. The directive takes effect from 2 December.

Rolls-Royce states that the Trent 900 last month clocked up one year's airline service and, in that time, accumulated 8,000 cycles across seven aircraft.

Singapore Airlines and Qantas both operate Trent 900-powered A380 aircraft, while Emirates' A380s are fitted with Engine Alliance GP7200 powerplants.