How are jet engines certified against birdstrikes?

Danny Beckett
  • How are jet engines certified against birdstrikes? Danny Beckett

    I recall that during US1549's birdstrike incident that resulted in it landing on the Hudson, a large amount of migrating geese weighing upto 20lbs each were sucked into the A320's engines — far bigger and heavier than previously certified.

    I believe that at the time the engines were tested & certified by throwing small chickens or similar, one at a time, into the engines. Has this certification process been improved at all since this incident?

  • There are hundreds of tests that need to be performed for certification of a turbine engine.

    The FAA requirements and tests are listed in CFR part 33 E and F.

    Amongst them are:

    • Maximum static thrust tests
    • Vibration tests
    • Endurance tests
    • Water ingestion test
    • Hail ingestion test
    • Ice cloud test
    • Bird strike test

    A number of them can be seen in this video of the GE90-115 Engine

    The specific requirement for bird ingestion are described in §33.76. The number of birds to be used and their weight depends on the area of the engine inlet.

    There have been several changes to the bird ingestion requirements for certification since the A320 engine was certified in 1996. However, once an engine is certified there is no need to demonstrate compliance to the updated requirements; the engine remains certified as it was.

    The latest update to these requirements was in 2007, prior to the Hudson accident. To answer your question: no, there have not been any changes to the bird strike testing requirements of engines in the aftermath of the Hudson accident.

  • There are multiple various requirements, for instance:

    • After "swallowing" a fat already goose (formally up to 3.65kg) the engine must still pull at least half of the thrust for at least 14 minutes, and must not become dangerous for the plane (no fire, no uncontained failure).
    • After ingesting a whole flock of sparrows (16 birds no more than 0.85kg each) the engine must still work for about 20 minutes.

    There are also requirements for various sizes and number of birds in between, and some requirements depend on the inlet size. In general, seems that after the bird strike the engine is required to stay safe and even work for some time, but not for long.

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