Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan Engines

We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires initial and repetitive borescope inspections of the head section and meterpanel assembly of the combustion liner, and replacement if necessary. This new AD requires those same inspections, and replacement. This AD also expands the applicability to include part numbers (P/N) of additional combustion liners. This AD was prompted by an inquiry submitted by an operator, which resulted in RR performing a complete review of the affected front combustion liner part numbers. We are issuing this AD to prevent deterioration of the engine combustion liner, which can result in combustion liner breakup, case burn-through, engine fire, and damage to the airplane.