Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG (Type Certificate Previously Held by Rolls-Royce plc) Turbofan Engines

The FAA is superseding Airworthiness Directive (AD) 2008-22-24 for certain Rolls-Royce Deutschland Ltd. & Co KG (RRD) RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4-B-75 model turbofan engines. AD 2008- 22-24 required initial and repetitive ultrasonic inspections (USIs), both on-wing and during overhaul, to detect cracks on the installed low-pressure compressor (LPC) fan blade roots. AD 2008-22-24 also required re-lubrication of the fan blade roots according to accumulated life cycles. This AD retains the requirements of AD 2008-22-24 and extends these requirements to engines operating under additional flight profiles and adds the RB211-535E4-C-37 model turbofan engines to the applicability of this AD. This AD requires initial and repetitive USIs to detect cracks on the installed LPC fan blade roots, both on-wing and at engine overhaul, and replacement of certain blades that exceed the criteria established by the manufacturer. This AD was prompted by small cracks found in the LPC fan blade roots on the concave root flank during an engine overhaul. The FAA is issuing this AD to address the unsafe condition on these products.