i was on a plane yesterday and i was watching the wing and the engine to see if any birds flew in. its pretty big and it has a big opening, i dont see how birds never fly in there and damage anything. anyone know what would happen if a bird did fly into the engine?
isis
Favorite Answer
This is a few of the FAA's bird strike reports ...........
" compiled over 46,000 strike reports from 1,400 airports, 1990-2002 (about 6,000 strikes in 2002), but estimate that this represents only about 20% of the strikes that have occurred. The following examples from the database are presented to show the serious impacts that strikes by birds or other wildlife can have on aircraft.
FK-100
Aircraft struck a flock of geese and ingested one after takeoff. Engine vibration caused crew to reduce power to idle Nose was damaged. Several blades were deformed. Engine was replaced. Bird was identified by the Smithsonian. Cost of repairs and lost revenue totaled $654,000. Aircraft was out of service for 8 days.
Regional Jet
Aircraft struck wild turkeys. One shattered the windshield spraying the cockpit with glass fragments and remains. Another hit the fuselage and was ingested. There was a 14 inch by 4 inch section of fuselage skin damaged below the windshield seal on the flight officer’s side. Cost of repairs estimated at $200,000. Time out of service was at least 2 weeks.
Cessna 172
Vulture smashed through the windshield and the right side door blew open. The instructor’s headset flew out the open door. Bird ended up in baggage compartment. Student pilot was cut on face and arms, instructor cut on face and arm. Time out of service was 48 hours and cost to repairs was $1000. Loss of revenue unknown at time of report.
OUCH
rickpoleway
Despite being an aerospace engineer, I feel a bit out of my depth, especially with contradictory answers from people claiming to be aircraft technicians.
I'll try to stick to facts and no speculation, I'm sure all the examples given above are right-on.
Fact 1
Bird-strikes continue to constitute a SERIOUS problem and represent a SERIOUS component of the risk of on-take-off engine-failure, take-off in turn is the critical engine-failure requirement for airliners. So the bird-strike risk is at its highest at basically the worst time for the engine to fail.
Fact 2
It matters if you hit the bird at 5 knots or 500 knots.
Fact 3
In cases when damage IS done, the broken-off fan-blade going through the rest of the engine causes a significant proportion of the damage, the idea that a fair-sized bird hitting the engine, especially near the rim of the fan wouldn't cause credible damage at take-off speed isn't realistic, the developments have been to change it from a major explosion of turbine-blades out of the back, to a violent judder allowing easier recovery and landing.
Fact 4
Full Authority Digital Engine Control plays a real role in controlling the engine after it sustains serious damage, and the flight control computer of a modern airliner immediately compensates for the change in flight characteristics reducing risks.
Fact 5
Yeah before you say anything, I know, if the bird is smaller it makes it way less dangerous. I don't know what the critical size is, it will vary with the size of the engine and its RPM too, it seems safe to assume that developments will push this threshold in a favourable direction.
Fact 6
Not only is resistance to damage more of a priority of military engines, when compared to weight and even reliability but military engines are way narrower than airliner engines, that means that the bending moments incurred when an object hits the end of a blade are easier to deal with. A lot of the time the bird's speed (kinetic energy I mean here) will have been absorbed largely by the intake duct, in the case where there is some bend in it, so the bird hits the wall.
The comment on priorities is justified because the effectiveness of a military plane is less dependent on its economy than its resistance to damage by small debris from explosions and anti-aircraft shrapnel, airliner engine reliability is orders of magnitude higher, partly because the reliability of a fighter in general flight plays second fiddle to its ability not to get knocked on it's bum, whereas airliners need just fly back and forth at 36000ft all day practically forever and not fail. Plus, the fighters obviously fly at bird-altitude more of the time, again making it more worthwhile to seriously harden them.
JET_DOC
Depends on the size of bird and size of engine. Its going to be a return to gate with an engine change. The replacement so it can be sent out to be fully inspected. You don't know the extent of the damage unless you take it apart. Tests are done in engine development to see how it holds up to a bird ingestion. You don't want the N1 fan to come apart and blades to go into the cabin. I've seen a pigeon stuck in the inlet of a GE 701C that came off a blackhawk. Messy! I doubt any substantial size peice would make it even half way through. Being the speed everything spins at, the occurence would result in no flying that day, even if just precautionary.
Anonymous
I have heard all the stories, watched video tapes of bird and human ingestion, both accidental and with purpose. I can only tell you this from my personal experience. I took what was believed to be a duck into the left engine of my F-111 one day and it destroyed the engine. Since the plane has two engines, it was not a major problem and I landed without incident. That's a long time ago and perhaps they've improved the engines' survivability these days.
Late note for Steve O: The 111 did in fact have problems with compressor stalls. They finally solved it with the triple plow intake mod. It wasn't all that bad,anyway. As much pilot technique as anything else. The TF-30 was not fond of birds,though.
Anonymous
Steve's right about the certification. The test used to be done by shooting a frozen turkey into the inlet with the engine operating. Then it was inspected to ascertain the extent of damage. The test was called the Canadian Frozen Turkey Test or words to that effect since it originated in Canada.
A friend of mine was flying an F-101 Voodoo in the pattern when it hit and ingested an adult Canada Goose. The collision was so severe, he thought head had hit a smaller aircraft. But the engine suffered no major damage and continued to operate normally.