Improving nacelle designs to reduce engine-failure risks
Credit: Sean Broderick/AWST
Minimizing the risk of air transport engine failures has been a focus for decades—work that has paid off. The failure of an engine designed after the first generation of late 1960s high-bypass turbofans has never resulted in what regulators define as a “catastrophic” event involving multiple fatalities or loss of an aircraft. Most of the risk mitigation has focused on uncontained failures, defined by the FAA (Advisory Circular AC 33.5) as incidents in which fragments are released through the engine structure. The reason: debris exiting through the engine’s sides presents the highest risk to the cabin and flight-control surfaces, which puts passengers, fuel and critical controls in danger. But a recent series of engine failures underscores that even when debris is technically contained, risks can be high. As a result, industry is re-examining certification requirements and moving to correct model-specific risks on in-service aircraft.