Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Rolls-Royce plc RB.211-524 series turbofan engines. This proposal would require initial and repetitive borescope inspections of the head section and meterpanel assembly of the combustion liner, and replacement, if necessary, with serviceable parts. In addition, this AD would propose an optional installation of a front combustion liner with a strengthened head section as a terminating action to the inspection requirements. This proposal is prompted by reports of engine fires due to premature engine combustor distress. The actions specified by the proposed AD are intended to prevent engine combustor liner deterioration due to thermal fatigue, which can result in combustor liner and case burn-through and engine fire.