nema
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Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 4:33 pm

Hi all,


I have a couple of questions on bird engine injestion as a friend of mine was delayed for 36 hours last week after this happened (Due to no other aircraft being available).

Brief story, my friend had just taken off, in a 737, and reportedly, two birds were injested into an engine. Bangs and flashes followed and an immediate return to the airport followed..

This brings me to a couple of questions as my friend couldn't answer these as he isnt an enthusiast or similar and basically took little notice or understanding of what was happening.

1) Do bird injestions ever happen and the flight can continue, if so what percentage are these less serious strikes? (is it 50/50 that you would need to land for example)

2) If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

3) Would this flight that my friend was on have to unload fuel weight before landing? He said they went straight back but it would be loaded for a 3.5 hour flight.

Thanks in advance for your input a.netters.
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YWG747
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 5:03 pm

1) That chances of continuing flight are very slim. Once you have an one of your two engine go out, I beleive you try and land as soon as possible.

2) If you get a bird in each engine you are landing with no engines. But if that were too happen, you better buy a lotto ticket.

3) As for your third question I really don't know. One would think you would need ot burn some of the fuel off, or dump it.
 
nema
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 5:29 pm



Quoting YWG747 (Reply 1):
That chances of continuing flight are very slim. Once you have an one of your two engine go out, I beleive you try and land as soon as possible.

Yeah, my question here was perhaps not so clear, i meant could you get a bird injested into engine and no significant engine damage occurring so the flight continues as normal. I wonder on a similar vein if there have been such accidents which never even got noticed by the crew.
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EMBQA
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 5:29 pm

1) It depends. If you have a compressor stall.. yea, you'll know it and land. If you have no issues, the crew may not know until they land and the next crew does a walk around and finds the evidance.

2) If it stalls out both engines you're in a world of hurt....

3) It depends on what you're flying on and what your Take Off weight and Max landing weight are.

Quoting NEMA (Reply 2):
i meant could you get a bird injested into engine and no significant engine damage occurring so the flight continues as normal

Actually pretty common. With newer High By Pass engines its pretty hard to get the object into the actual core engine...

[Edited 2008-08-12 10:33:40]
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SilverComet
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 5:35 pm

Quoting NEMA (Thread starter):
Do bird injestions ever happen and the flight can continue, if so what percentage are these less serious strikes? (is it 50/50 that you would need to land for example)

In general, if a bird got ingested into an engine, you would want to land back at least to have the engine inspected. Chances are there will be some damage. Even if you suspect minimal damage it is much safer to do that than to take it with you to destination and risk greater problems (engine fail, parts flying out of your engine and damaging other critical systems etc.) enroute.

Quoting NEMA (Thread starter):
If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

Just as fateful and unlikely as having all your engines fail on you on takeoff. You cannot plan for absolutely all possibilities or you would never take off. I think the probability of that happening is so low that you don't account for it. Besides, the geometry of the aircraft also protects at least one engine. I have experienced a few of instances of flocks of birds crossing in front of me on takeoff and landing (including one birdstrike) and also seen some footage of it happening to other aircraft and it seems to me that the birds are always flying more or less perpendicular to the direction of travel of the aircraft, never head on. Which means that the fuselage always protects one of the engines. That's the way it seems to me anyway.

Quoting NEMA (Thread starter):
Would this flight that my friend was on have to unload fuel weight before landing? He said they went straight back but it would be loaded for a 3.5 hour flight.

It depends on what weight the aircraft was at when it took off. In general, if the aircraft has to land and it's above its Maximum Landing Weight (and unless you're burning or other similar situation where you need to land right then) then you would want to jettison fuel before coming back to land. I have never flown a 737 so I don't have any typical MTOW/MLW figures or if the 37 has fuel jettison capability but I do know that overweight landings are possible. Maybe the crew opted to do that or maybe the aircraft wasn't even above its MLW (my guess).

[Edited 2008-08-12 10:52:46]

[Edited 2008-08-12 10:54:28]
 
pilotpip
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 5:43 pm

If I sucked in a bird, I'd be returning to the airport. Chances are that engine is pretty messed up if tweety went through the hot section. Flying around on one bad engine is just inviting something bad to happen to the good one. Get on the ground where everybody is safe.

Narrowbody aircraft typically don't have a dump option. There are typically overweight landing checklists in the Quick Reference Handbook which will outline greater distances, speeds and lengths required. Usually an overweight landing will result in a lengthy inspection of the aircraft structures after the event.
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Tristarsteve
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 7:32 pm



Quoting NEMA (Thread starter):
) Do bird injestions ever happen and the flight can continue, if so what percentage are these less serious strikes? (is it 50/50 that you would need to land for example)

On a modern high bypass engine probably 90pc of engine bird strikes are a non event. It is extremely unlikely that the bird will enter the power generator. It usually hits a fan blade and goes out the bypass duct. Fan blades are pretty strong and it would need a big bird to do damage.

If the bird goes into the IP compressor (or booster for the Americans) then it still depends how big it is. Small birds can produce a smell in the aircraft!!, or they may damage compressor blades. If the crew notice engine parameters shifting then they will report it and maintenance will do boroscopes to see what happened.

Quoting NEMA (Thread starter):
2) If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

There have been aircraft crashes caused by bird ingestion.
 
ThePinnacleKid
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 9:55 pm

I've often wonder if anyone on a.net was a passenger on a flight I worked between Memphis and Houston during June of '07... we hit a 30 to 40 lb hawk directly into the #1... ended up diverting and landing in Shreveport... if you were one of my passengers, would love to hear what you thought of the whole thing...

Quoting NEMA (Thread starter):
1) Do bird injestions ever happen and the flight can continue, if so what percentage are these less serious strikes? (is it 50/50 that you would need to land for example).

Yes, depends on if you know you hit something or not... a tiny bird hit on final for instance, you wouldn't notice, when I hit the huge hawk we were climbing and passing around 6000' just starting a turn... it hit and the capt. and I heard the thud.. but there was no "feeling" of anything odd, no eicas indications, and the plane flew great, even with the engine severely damaged... (we didn't even know how badly the engine was damaged until mx checked it out)

Quoting NEMA (Thread starter):
2) If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

Again, we didn't even realize how badly it was damaged, mx (when we talked to them in the air) actually left the decision to us whether to continue to Houston or divert... we decided after some discussion and progressing with the flight, that a diversion would be the best course of action as a "just in case" kinda thing (we had been noticing subtle degradation on the engines performance as we continued)... we had no clue how badly it was actually hurt (engine ran great... it shut down when we shut it down after landing.. and this was after it had lost parts or bent sections of every single fan blade, lost compressor blades, bent some compressor blades enough to be flush with the blade next to them, etc....)... from accounts of a friend that actually worked for airport Ops. at SHV (who was by the runway when we came in) said it was the loudest he has heard one of our planes.. sounded like a buzz saw from the engine... so audibly it was different, behaviorally it was doin' really quite well! That being said, we did know it had been hit, and from what we knew was working, but didn't know how long it would last, so we took precautions just in case it did die on us....



Quoting NEMA (Thread starter):
3) Would this flight that my friend was on have to unload fuel weight before landing? He said they went straight back but it would be loaded for a 3.5 hour flight.

I dunno about the 737.. but my aircraft (ERJ-145) we can't dump fuel... and in the situation that the engine "may" die... you don't want to just circle to get weight down... you go ahead and make those tough decisions we are required to make as a crew... which is more important... needless to say, we touched down in Shreveport 1300 lbs over MGLW... (mx inspection was not necessary due to vertical speed at touch down...)



On a complete side note, MX replaced the engine and we repositioned the aircraft back to Houston the next morning...

[Edited 2008-08-12 14:56:20]
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Dalmd88
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 11:52 pm

The last bird ingestion I've seen was about a month ago. 737NG, the crew never reported it. We found it on the nghtly walk. Like most have said nothing went into the core. We did have some significant blade damage. Two were easliy in limits, but the inital hit blade was bent pretty good. It might have been in limits, but it was so close to the limit we changed the blade.

I don't think the crew even knew they sucked it in.

The worst I've ever seen was a ANG C-130 that flew through a flock of geese on final. They bent a couple of props, dented the leading edge, broken windscreen, and even had one stuck in the APU inlet. The pilot said he thought they were being attacked by bowling balls.

[Edited 2008-08-12 16:56:05]
 
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Tue Aug 12, 2008 11:55 pm

As I understand it, losing an engine on a twin is an automatic emergency. So you're landing "as soon as practical". However as some have mentioned if you don't notice the bird strike. Well if you don't notice it why would you land?  Wink


I love this video:



Quoting NEMA (Thread starter):

3) Would this flight that my friend was on have to unload fuel weight before landing? He said they went straight back but it would be loaded for a 3.5 hour flight.



Quoting SilverComet (Reply 4):
. I have never flown a 737 so I don't have any typical MTOW/MLW figures or if the 37 has fuel jettison capability

No dumping facilities on the 737. In fact I don't know of any modern narrowbodies with fuel dumping capability.

All airliners can land at all weights up to MTOW. Even 747s. However you wouldn't want to do that unless an engine was on fire or something. Landing overweight, especially in a full long haul widebody, carries some risk. Better to dump, or barring that burn off (by flying around) the fuel if possible. Also landing overweight requires an inspection.
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 12:28 am



Quoting Starlionblue (Reply 9):
As I understand it, losing an engine on a twin is an automatic emergency.

As I understand it, even losing an engine on a 747 is an emergency... or at least an indication to land at your earliest convenience.

So here's my question: what happened in that cabin and cockpit when the birdstrike happened? I'm sure a bunch of alarms went off in the cockpit (engine performance not equal to commanded, etc.) but would the plane suddenly yaw? Roll?
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fr8mech
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 12:55 am

Birds go through the core all the time. Most of the time, the flight crew never knows it happened. During the spring and fall, we see bird strikes almost every night. Sometimes they go through the core, most times not.

Most maintenance programs require a borescope after a core ingestion. It's usually a progressive inspection. You check the first few stages of the compressor, if no damage found, no further required.

In 22 years, I've only seen one bird strike cause damage to an engine that did not have external signs of damage or a pilot report. In other words, only once, in hundreds of times, did the borescope result in a finding that required further evaluation.
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tdscanuck
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 2:39 am



Quoting NEMA (Thread starter):
2) If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

It's not a given that the birdstrike will shut down the engine. If the parameters start going flakey the crew will likely do a commanded in-flight shutdown. However, if both engines got hit I doubt they'd purposely shut down both engines...better to limp home on at least one that's dying than have nothing.

Quoting NEMA (Thread starter):

3) Would this flight that my friend was on have to unload fuel weight before landing? He said they went straight back but it would be loaded for a 3.5 hour flight.

On a 737, maximum landing weight is the same as maximum takeoff weight, so no problems. It's not considered an overweight landing. As far as I know, this is true of all transport aircraft that don't have a fuel dump system.

Quoting Starlionblue (Reply 9):
All airliners can land at all weights up to MTOW. Even 747s. However you wouldn't want to do that unless an engine was on fire or something.

Physically true, but you may be way out of certified limits on aircraft that do have a fuel dump system. If you don't have a fuel dump system, you're usually certified to land at MTOW.

Tom.
 
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 4:10 am



Quoting DocLightning (Reply 10):
As I understand it, even losing an engine on a 747 is an emergency... or at least an indication to land at your earliest convenience.

I have only the posts of our quad pilots to go by but as I understand it is not an emergency.

Quoting Tdscanuck (Reply 12):
However, if both engines got hit I doubt they'd purposely shut down both engines...better to limp home on at least one that's dying than have nothing.

Unless you're BMI.  duck 
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planewasted
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 4:59 am

Quoting Starlionblue (Reply 9):
I love this video:

Good one!

This is rather nasty:


[Edited 2008-08-12 22:00:45]
 
lowrider
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 5:27 am



Quoting DocLightning (Reply 10):
As I understand it, even losing an engine on a 747 is an emergency... or at least an indication to land at your earliest convenience

No, depending on circumstances we may elect to continue to our destination or some suitable intermediate point. British Airways did it with a planeload of pax on a 400. Losing two is always an emergency.

Quoting DocLightning (Reply 10):
So here's my question: what happened in that cabin and cockpit when the birdstrike happened? I'm sure a bunch of alarms went off in the cockpit (engine performance not equal to commanded, etc.) but would the plane suddenly yaw? Roll?

Probably felt the compressor stalls and saw a rising or fluctuating EGT, N1 variations, and possibly N2 variation as well. If the aircraft is equipped with vibration gauges you would start to see them climb. If there was damage to any of the engine driven accessories, the related systems would react accordingly. There were probably minor yaw excursions until the engine was shut down. The engine would not be secured without the concurrence of two pilots (there may be an IRO in the cockpit). There might be an alarm for the oil pressure falling as the engine shuts down. Someone checked out on type might be able to give more detail.
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 5:35 am



Quoting PlaneWasted (Reply 14):

This is rather nasty:

As Eddie Izzard says: "It's not a bird strike. It's an engine suck..." At no point were those seagulls actively aiming for the engines.  Wink

Quoting Lowrider (Reply 15):
(there may be an IRO in the cockpit).

A who?
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lowrider
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 5:43 am



Quoting Starlionblue (Reply 16):
A who?

An International Relief Officer. Basically a relief pilot for long flights. Some companies have them sit in the jumpseat for take off and landing.
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 5:54 am

I see thanks. My guess is that the "International" part is a US term. No European country besides Russia has anything but international flights long enough to warrant relief pilots. No Asian country either for that matter.
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lowrider
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 6:03 am



Quoting Starlionblue (Reply 18):
My guess is that the "International" part is a US term.

I think I first heard it from an Asian carrier. But you are right, most countries aren't large to warrant a relief pilot. You might see it on some flights from the Eastern US to Hawaii or Anchorage.
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HAWK21M
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 8:13 am

It depends on the Type of bird & the Type of Engine [high/low bypass],depending on the location of the strike.
Many times the birds are small enough to pass through the Bypass section of the High bypass engine & only Indications would be a smell in the AC ducts to the crew.

In case a Bird strike is reported.Mx action as per approved schedule is followed & if all items are within limits the aircraft is declared airworthy & back to service.

Low bypass engines have chances of more serious damage also the damaged blade would need a shop visit to rectify,unlike a high bypass fan blade damage in the Bypass section.

The Advantages of night ops is that the Bird hit chances are less compared to day.

regds
MEL
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 9:27 am



Quoting Lowrider (Reply 19):

I think I first heard it from an Asian carrier. But you are right, most countries aren't large to warrant a relief pilot. You might see it on some flights from the Eastern US to Hawaii or Anchorage.

Ah yes. Forgot about the colonies.  Wink
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ThePinnacleKid
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 1:14 pm



Quoting Tdscanuck (Reply 12):

On a 737, maximum landing weight is the same as maximum takeoff weight, so no problems. It's not considered an overweight landing. As far as I know, this is true of all transport aircraft that don't have a fuel dump system.

I don't personally know about 737's so I can't comment on that part... but as far as all transport aircraft w/o the ability to dump fuel... that couldn't be further from the truth... If it were you would never see a plane circle to burn fuel off... furthermore, just read my prior post.. In my incident we landed 1300 lbs overweight... I can assure you the aircraft is transport category.. that day we had 50 passengers and 1 lap child... (a full boat for our 145)
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SilverComet
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 4:39 pm



Quoting Tdscanuck (Reply 12):
On a 737, maximum landing weight is the same as maximum takeoff weight, so no problems. It's not considered an overweight landing. As far as I know, this is true of all transport aircraft that don't have a fuel dump system.

I used to fly the A319. It did not have a fuel dump system. And the MLW was not the same as the MTOW and I assure you if you landed at anything above MLW it was considered an overweight landing.
 
BAE146QT
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 4:44 pm



Quoting NEMA:
Bird Injestion - How Significant Is It?

I would like to point out that although a single birdstrike is usually not terminal for the average airliner, the experience is pretty significant for the bird.
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point8six
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 7:14 pm

Depends on the size of the bird!
A bird-ingested engine shutdown is not an emergency, nor does it require "land at the nearest suitable airport".(B747)
Landing over-weight is allowed (B747-400) up to Max. landing weight, under certain conditions, (approved by Boeing and subject to individual airline approval).
Sometimes you feel/hear it (birdstrike) and sometimes you are told about it by ATC (carcasses on runway) and by ground engineers, who spot the damage on arrival.
One instance a few years ago, concerned a BA 747 Classic, which ingested a Swan during departure from LHR. The collision caused the fan to disintegrate and the engine suffered severe damage. Snow geese have been known to fly at high altitudes and a collision with such a large bird at altitude could be very unfortunate  Wow!
 
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HAWK21M
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 9:48 pm



Quoting BAe146QT (Reply 24):
I would like to point out that although a single birdstrike is usually not terminal for the average airliner, the experience is pretty significant for the bird.

 biggrin 

Quoting Point8six (Reply 25):
Snow geese have been known to fly at high altitudes and a collision with such a large bird at altitude could be very unfortunate

Some hard boned structured birds like the vulture are equally destructive.
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tdscanuck
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RE: Bird Injestion - How Significant Is It?

Wed Aug 13, 2008 11:24 pm



Quoting ThePinnacleKid (Reply 22):
I don't personally know about 737's so I can't comment on that part... but as far as all transport aircraft w/o the ability to dump fuel... that couldn't be further from the truth...



Quoting SilverComet (Reply 23):
I used to fly the A319. It did not have a fuel dump system. And the MLW was not the same as the MTOW and I assure you if you landed at anything above MLW it was considered an overweight landing.

I got some bad data...the 737 has the same restriction. The A319 actually has a smaller gap between MTOW and MLW than the 737NG.

Should have checked the TCDS...

Tom.
 
nema
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RE: Bird Injestion - How Significant Is It?

Thu Aug 14, 2008 2:29 am



Quoting Starlionblue (Reply 13):
Unless you're BMI

Hmmm, that mention i guess was from the BMI incident at my local airport, (hence my a.net username), and next week i will be flying with BMI.

As for the topic, gotta thank all for such informative input. Some really interesting replies, thanks again all..
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Thu Aug 14, 2008 3:28 am



Quoting NEMA (Reply 28):
Hmmm, that mention i guess was from the BMI incident at my local airport, (hence my a.net username), and next week i will be flying with BMI.

Meh. Not to worry. If we avoided airlines that had crashed because of bone headed mistakes at some point few of us would fly at all.  Wink
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SEPilot
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RE: Bird Injestion - How Significant Is It?

Thu Aug 14, 2008 1:37 pm

One of the big worries for GA pilots is birds building nests in engines (they rarely do it in flight, however.) I had it happen when I was only on the ground for a couple of hours; my preflight did not discover it, as it was to the rear of the engine and not visible through the cowling openings. I removed the top cowl after I returned for some reason and discovered it. Not a good situation-a bird's nest will significantly affect cylinder cooling. After this incident I did not leave the plane even for a short time outside without the cowl plugs installed.
As to jet engines, the severity of the encounter will be directly related to the size of the bird. As others have mentioned, a small bird can cause little or no damage; a large bird is probably going to cause quite a bit of it.
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HAWK21M
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RE: Bird Injestion - How Significant Is It?

Fri Aug 15, 2008 12:25 pm



Quoting SEPilot (Reply 30):

One of the big worries for GA pilots is birds building nests in engines

Common occurances on the B737 rudder hinge balance weight area of the classic,if not flown for more than 24hrs.
regds
MEL
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josekmlb
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 5:23 am



Quoting HAWK21M (Reply 20):
The Advantages of night ops is that the Bird hit chances are less compared to day.

Well I saw a first for me at the airport over here at night. We had a CRJ200(ASA) land at night around 2100 about a month ago and had a bat strike the nose gear of the a/c. It was pretty cool to see that when he pulled into the gate to see a little head and bat wings hanging by a thread.
 
kris
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 9:38 am

This has probably been asked before - but wouldn't it be possible to have a mesh in front of the engine to stop any bird/FOD ingestions? Every time I fly forward of the wings I look back and think that!

[Edited 2008-08-22 02:39:57]
 
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 10:35 am



Quoting Kris (Reply 33):
This has probably been asked before - but wouldn't it be possible to have a mesh in front of the engine to stop any bird/FOD ingestions?

Interesting idea. However at the speeds we are talking about such a mesh would either:
- Be too weak to stop the bird, at which point you have bird AND mesh in the engine.
- Be strong enough to "stop" the bird, in which case it would slice the bird up. The bird in minced form would still get inside the engine.


I have heard of three practical FOD protection methods (apart from a clean runway)

- The MiG-29. Given the realistic expectations the designers had about runway conditions, these aircraft have doors that close the intakes during taxi and take-off. Air comes in through vents above the main intake. This kind of solution is neat, but far too costly and heavy for an airliner.
- Chined tires or splash guards on the 727 and DC-9 and it's children. Simple and cheap solution but not workable with wing mounted engines.
- The gravel runway modded 737s have vortex dissipators in the front of the engines to scare FOD away. Not needed unless you are on a gravel runway.

You can see the intake doors clearly here:

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Photo © Piotr Marek (EPGD Spotters)



737 with dirt runway equipment. Note the gravel deflector on the nose gear and the vortex dissipators on the engines:

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Photo © Aaron Hall

"There are no stupid questions, but there are a lot of inquisitive idiots."
 
kris
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 11:05 am



Quoting Starlionblue (Reply 34):
Be strong enough to "stop" the bird, in which case it would slice the bird up. The bird in minced form would still get inside the engine.

But surely slices of bird would do less damage that the whole thing, which would rely on the fan to do the mincing!
 
XT6Wagon
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 11:31 am



Quoting TristarSteve (Reply 6):
On a modern high bypass engine probably 90pc of engine bird strikes are a non event. It is extremely unlikely that the bird will enter the power generator. It usually hits a fan blade and goes out the bypass duct. Fan blades are pretty strong and it would need a big bird to do damage.

yah modern high bypass engines are very good at chucking even metal and other not very engine friendly stuff past the core and thus with minimal damage.

On the other hand, you can have a golden BB where you win the lottery and something that shouldn't have done anything at all.... makes it all go bad.

Quoting Kris (Reply 35):
But surely slices of bird would do less damage that the whole thing, which would rely on the fan to do the mincing!

Mesh strong enough to stand up to the bird would be very very heavy. And block much of the airflow. Its just better to put the wieght into stronger compressors and turbines if you expect alot of this kind of thing. No engine likes having anything but air moved through it, but if you have to you can make them very tolerant to abuse. That said since people don't buzz wildlife sanctuaries at low altitude in thier 737's designing engines for large and constant bird strikes hasn't been needed.
 
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Starlionblue
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 1:51 pm



Quoting Kris (Reply 35):
Quoting Starlionblue (Reply 34):
Be strong enough to "stop" the bird, in which case it would slice the bird up. The bird in minced form would still get inside the engine.

But surely slices of bird would do less damage that the whole thing, which would rely on the fan to do the mincing!

That's fair, but that would mean massively strong and heavy mesh. Also you've got a pretty good mincing system already, the fan.
"There are no stupid questions, but there are a lot of inquisitive idiots."
 
2H4
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 2:27 pm



Quoting XT6Wagon (Reply 36):
since people don't buzz wildlife sanctuaries at low altitude in thier 737's

Ah, but we're getting one step closer with the P-8A....



 Wink

2H4
Intentionally Left Blank
 
SlamClick
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 3:43 pm



Quoting NEMA (Thread starter):
2) If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

I recall two such incidents but can't give much info. Seems like there was a Lear at ATL and an Electra in New England somewhere but beyond that, I don't remember. Some airport bird removal programs likely trace from these events.

Quoting TristarSteve (Reply 6):
(or booster for the Americans)

?? - I don't think so.

Quoting ThePinnacleKid (Reply 7):
we hit a 30 to 40 lb hawk directly into the #1

Wow! That is some hawk! Red-tail hawks, one of the larger, may reach 4 pounds and have a four foot plus wingspan. California condors have weighed in at 23 lbs and had a ten foot wingspan. I've seen a 40 lb turkey in the grocery store but those are raised on the ground. I'm guessing your bird had at least the wingspan of a young Cessna!

Quoting Starlionblue (Reply 9):
All airliners can land at all weights up to MTOW

This seems to imply that if a plane is heavy enough you will be unable to get it down at all.  Smile

Quoting Tdscanuck (Reply 12):
On a 737, maximum landing weight is the same as maximum takeoff weight, so no problems.

Not on any 737 I've been trained on. (300, 400, 700)

Quoting Tdscanuck (Reply 12):
It's not considered an overweight landing.

Any landing at a weight greater than maximum certificated landing gross weight is an "overweight" landing. Action required is determined by how much over the weight was and severity of the impact. A hard landing at a higher weight being the worst of both.

Quoting Tdscanuck (Reply 12):
As far as I know, this is true of all transport aircraft that don't have a fuel dump system.

That is not the criteria. Transports certificated under US FAR 25 which includes Boeing but with which Airbus is compliant, the criteria is CLIMB performance with an engine inoperative. FAR 25.1001 states that unless a plane can meet the performance criteria cited [FAR 25.119 and 25.121(d)] at maximum takeoff gross weight it must have a fuel jettison system.

Structural landing weight limits are just that, and they consider damage to the aircraft structure but do not consider aircraft performance.

Quoting Tdscanuck (Reply 12):
If you don't have a fuel dump system, you're usually certified to land at MTOW.

Not correct. See 25.1001 above.

Quoting Lowrider (Reply 15):
No, depending on circumstances we may elect to continue to our destination or some suitable intermediate point.

Correct under US rules. If you lose not more than one engine on a plane having three or more engines you may continue to destination if that is "as safe as" landing at the nearest suitable airport. I've been on the jumpseat of a 727 that did a precautionary shutdown of #2 for oil strainer clogging. They overflew dozens of suitable airports and proceeded to destination where the filter was cleaned.

Quoting Starlionblue (Reply 16):
A who?

A who? A SlamClick for a while, to name but one. "Heavy crew" permits more flying time on a two-pilot airplane than just the two required pilots could fly. In some cases it is done just so the same crew can bring the flight home without a layover, in some cases the flight could not be flown at all without three pilots. One by one they will rotate through the 'crew rest' seats or bunks and spend time off the flight deck. At my company all the widebody f/o's were type-rated. One was f/o the other IRO on any given flight.

Quoting Lowrider (Reply 19):
But you are right, most countries aren't large to warrant a relief pilot.

The heavy-crew provision can be applied in the domestic (48 contiguous) area as well, but only under Supplemental rules. I've seen a DC-9 fly with a heavy crew so that three pilots could get it through an 8-hour plus day that did not return to crew base. It was legal and the only alternative would have been to pre-position a second crew at one of the intermediate stopovers.

Quoting HAWK21M (Reply 20):
The Advantages of night ops is that the Bird hit chances are less compared to day.

I've had three bird strikes in jets; one half an hour after sunset and the other two full dark. One of them after midnight.

Quoting Point8six (Reply 25):
Landing over-weight is allowed (B747-400) up to Max. landing weight,

Hmm. Wouldn't "up to Max landing weight" be UNDERweight? Wouldn't overweight mean beyond max LGW?

Quoting Tdscanuck (Reply 27):
The A319 actually has a smaller gap between MTOW and MLW than the 737NG.

Again, that is not relevant to whether they would have a fuel jettison system.
Overweight landing is a structural consideration.
Fuel jettison capability is performance driven.

Quoting SEPilot (Reply 30):
a bird's nest will significantly affect cylinder cooling

Yes, but it is such a nice warm place to build a nest a couple hours after shutdown. I found two in engines and one in the rudder balance in the course of a single week.

Quoting Starlionblue (Reply 37):
Also you've got a pretty good mincing system already, the fan.

More effective than Gallagher!
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
point8six
Posts: 44
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 7:25 pm

SlamClick - yes, well-spotted! Just a small piece of "finger-trouble"!
 
SlamClick
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 7:27 pm



Quoting Point8six (Reply 40):
SlamClick - yes, well-spotted! Just a small piece of "finger-trouble"!

I suspected as much.  Smile The dreaded FFS. (fat finger syndrome)
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
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litz
Posts: 1849
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 9:45 pm



Quoting Point8six (Reply 25):
Snow geese have been known to fly at high altitudes and a collision with such a large bird at altitude could be very unfortunate

check this thread : http://www.airliners.net/aviation-forums/tech_ops/read.main/220562 for some more information ...

The highest reported birdstrike is apparently FL370 (yes, 37000 feet) involving a turkey vulture.

Extensive googling did not yield airline, airplane, or date however ...

As for the dangers? At that height the chances of a double-ingestion are next to nil, so if one engine goes offline, you just land ASAP.

Low down, there have been several (4-5) actual crashes caused by birdstrike damage that affected most or all of the various accident planes' engines.

- litz
 
tdscanuck
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RE: Bird Injestion - How Significant Is It?

Fri Aug 22, 2008 11:26 pm



Quoting Kris (Reply 33):
This has probably been asked before - but wouldn't it be possible to have a mesh in front of the engine to stop any bird/FOD ingestions?

That's basically what the inlet guide vanes on the JT8's do...they at least slice the squishy FOD into pieces. They also help mechanics just lose limbs, instead of their lives.

But, as noted, on a high bypass fan you'd pay a big weight and drag penalty for not much benefit.

Tom.
 
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HAWK21M
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RE: Bird Injestion - How Significant Is It?

Sat Aug 23, 2008 9:34 am



Quoting SlamClick (Reply 39):
I've had three bird strikes in jets; one half an hour after sunset and the other two full dark. One of them after midnight.

Guess Unlucky or maybe the Birds have a hidden agenda against you....Ever went bird hunting in the past wink 

Out here...Just before Sunrise or after sunset are critical times.After rains have stopped,the birds come to feed on insects & that adds to the confusion on the Airside.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
curlyheadboy
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RE: Bird Injestion - How Significant Is It?

Sat Aug 23, 2008 12:40 pm



Quoting NEMA (Thread starter):
2) If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

The only air crash of which I witnessed the immediate aftermath in my life (though from a distance) was at the airport close to my home (LIN). A Learjet 45 sucked pigeons in both engines and the outcome was a deadly crash.

In addition, I seem to remember that an E-3 AWACS crashed after ingesting birds and that's a 4-engined plane, So I guess it's rare but still possible, and if it's on T/O after V1 you are in a very nasty situation.
If God had wanted men to fly he would have given them more money...
 
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HAWK21M
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RE: Bird Injestion - How Significant Is It?

Sat Aug 23, 2008 4:10 pm



Quoting NEMA (Thread starter):
If the flights generally have to land after a bird injestion, what happens, if in the unlikely event, you get one in each engine? seems pretty fateful to me.

you got to have real tough luck to encounter such a situation.....Not Impossible though but very rare.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
ThePinnacleKid
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RE: Bird Injestion - How Significant Is It?

Sat Aug 23, 2008 7:31 pm

Quoting SlamClick (Reply 39):
Wow! That is some hawk! Red-tail hawks, one of the larger, may reach 4 pounds and have a four foot plus wingspan. California condors have weighed in at 23 lbs and had a ten foot wingspan. I've seen a 40 lb turkey in the grocery store but those are raised on the ground. I'm guessing your bird had at least the wingspan of a young Cessna!

I'm taking hawk in the not so literal confining definition but in the other variation (#2)...

1. any of various accipitrine birds having short, rounded wings and a long tail and legs, as Cooper's hawk, goshawk, and the harriers

2. loosely any of various other birds of prey, as falcons and ospreys


I have photos of the engine (post raptor and prior to cleanup... should you care to see nothing but blood patterns, feather pieces, and remains...)

It was a large enough bird to take chunks of fan blades, bend fan blades, and bend/break compressor blades to be virtually laying against the next blade...

that being said, I have no idea the actual weight of the thing... just it was huge, very large wingspan, and after that, it was gone... I do not know, nor did my captain know, nor did anyone on the ground know about avg bird weights... all we could do is guess by size and approximation on weight range... so 30-40 lbs could be way off real world physical weight... but that was the guess to relative size and judging by damage... (so in reality who knows what it actually weighed)

[Edited 2008-08-23 12:39:55]
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wingscrubber
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RE: Bird Injestion - How Significant Is It?

Mon Aug 25, 2008 12:07 am

I was told a story once about a bird strike test using rolls-royces' 'chicken cannon'.
I googled 'rolls royce, frozen chicken', and found this account-

British Rail once borrowed the infamous chicken cannon; however, they had a lot of trouble with it - they were trying to use it to test the effect of a bird strike on High Speed Trains. They were worried that drivers could get hurt, and wanted to ensure that birds couldn't penetrate the trains windows.

Unfortunately, every time they used it the bird would smash through the window, through the seat and embed itself firmly in the rear bulkhead. Proof positive, they thought, that bird strikes were ultimately lethal.

They asked, however, how aircraft survived such strikes - and were told that birds rarely penetrated the windows of aircraft flying at any kind of speed - including supersonic jet fighters!

Rolls Royce asked BR where they were getting their chickens from. Tesco was the reply.

Ahh, said Rolls Royce - try thawing them out first or buy fresh chickens - not frozen!!!


Also found youtube of the 'chicken cannon' in action-
http://www.youtube.com/watch?v=rSafRuLB0c0&feature=related
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Viscount724
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RE: Bird Injestion - How Significant Is It?

Tue Aug 26, 2008 1:25 am



Quoting CURLYHEADBOY (Reply 45):
In addition, I seem to remember that an E-3 AWACS crashed after ingesting birds and that's a 4-engined plane, So I guess it's rare but still possible, and if it's on T/O after V1 you are in a very nasty situation.

The only two E-3 AWACS hull losses to date werre both caused by bird strikes on takeoff.

USAF E-3 at Elmendorf AFB, Alaska in 1995 (all 24 aboard fatal)..
http://aviation-safety.net/database/record.php?id=19950922-0

NATO E-3 in Greece in 1996 (no fatalities).
http://aviation-safety.net/database/record.php?id=19960714-0

Photos of the aftermath of the incident in Greece.
http://www.aviationpics.de/military/1999/awacs/awacs.html

Transport Canada link with some interesting photos of birdstrike events (the first two of the USAF E-3 in Alaska).
http://www.tc.gc.ca/civilaviation/Ae...WildlifeControl/tp13549/Plates.htm

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