The Bird Ingestion Hazard to Commercial Aircraft Engines and How It Is Addressed

A MISCONCEPTION Turbofan engines are huge vacuum cleaners - birds are sucked in from everywhere REALITY They are only ingested if they are in line with engine HOW FLEET SAFETY IS ASSURED •Certification regulations for bird ingestion are designed to achieve required safety goals •Manufacturers design engines to meet the rules with safety margins •The technology and rules have been evolving, it is a learning process RULE CHANGES WITH TIME BIRD RULES ARE BASED ON WEIGHT CLASSES Small (flocking) \u3c4ozs Medium (flocking) \u3e0.75 – 2.5lbs Large Flocking \u3e2.5 – 8lbs Large (single) \u3e4lbs 1960\u27S - 1974 FAR 33.13/19 , details in AC 33-1, -1A, -1B Foreign Object Ingestion (ice, birds, tire, gravel etc.) small birds (2-4ozs) medium birds (1-2lbs) large birds (4lbs) Takeoff power and initial climb speed Medium/Small run-on at least 5 minutes at desired minimum 75% thrust with no indications of imminent shutdown 4lb large bird, safe shutdown The run-on capability is “advisory” 1974 – 1990 FAR 33.77 (amdt 6) Established bird requirements in FOD rule and adopted details similar to AC 33-1B 1.5lb medium birds, up to maximum of 8 birds 5 minute run-on, 75% thrust 1984 FAR 33.77 (amdt 10) Medium (and small) birds aimed at critical areas Significant change, thrust & run-on MUST be demonstrated 1990\u27s In the mid-80‟s, industry & regulators recognized that 1.5lbs was not enough, we were meeting flocks of large gulls, the “Bird Committee” was formed and created a separate bird rule •FAR33.76 (amdt20) •Substantial rewrite of requirements •Medium birds increased to 2.5lbs for mid- & large-sized engines •Mix of 1.5 & 2.5lb, up to 5+6 dependent on engine size •Ingest at critical conditions •75% thrust capability •20 minutes run-on with throttle excursions to simulate go-around and baulked landing. •Law in 2000 but becoming effective mid-90‟s •Large single bird 4/6/8lbs safe shutdown Another significant increase in requirements 2000 - 2008 1990‟s - Elmendorf accident, goose populations on the rise •Bird II formed, 2000-2002 added Large Flocking Bird Rule for larger engines –4.1 to 5.5lbs demonstration at takeoff power –50% thrust capability –20 minutes run-on with throttle excursions to simulate go-around –Law in 2007 but becoming effective ~2001 A further significant increase in requirement