Bird Strike Committee Proceedings

 

Date of this Version

9-2011

Document Type

Article

Citation

Presented at 2011 Bird Strike North America Conference, September 12-15, 2011, Niagara Falls, Ontario, Canada.

Comments

Copyright 2011 Leslie McVey

Abstract

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) <4ozs
Medium (flocking) >0.75 – 2.5lbs
Large Flocking >2.5 – 8lbs
Large (single) >4lbs

1960'S - 1974

FAR 33.13/19 , details in AC 33-1, -1A, -1B
Foreign Object Ingestion (ice, birds, tire, gravel etc.)

  1. small birds (2-4ozs)
  2. medium birds (1-2lbs)
  3. 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's

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 requirements

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