BMI squashed radome
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Old bird strikes, the go-slow mitigation effort
That photo shows the radome merely dented, or crushed. Maybe that's a safer damage pattern than the usual fracture-shatter.
Some bird-strike investigators suggest pilots fly at the slow-speed Noise Abatement Profile CLB-Spds, until above 3000'. There have been numerous cases of cockpit penetration of a goose, eg, at 6000 Feet / 250KIAS. Still have some guys want to exceed 250 below 10,000 Ft. USAF B-52 had bird penetrate front spar during a low-level mission.
-- Bird (starlings) ingestion caused crash of EAL Electra at BOS 4Oct60. [birds]
-- United Viscount 745-D / 23Nov62 \\ bird collision \\ inflight breakup at 6000', near Ellicott City MD. Uncontrollable "following separation of the left Horizontal Stabilizer which had been weakened by a collision with a whistling swan." Carcass of swan found 10' from the severed left Stab. FDR showed descent from 6000' to impact in less than one minute,
-- Sep87 B-1B crashed. Bird strike, fire (ingestion? impact?)
-- Ethiopian Airlines ET-604 / 15Sep88 , B737-200 ET-AJA; T/O at Bahar Dar, birds ingested, surges, internal destruction of engines, double engine failure, crash landing. Sob = 104, fatal=35, serious injuries = 27. /// F/O’s T/O, at V1, flock of pigeons rose from rwy ...
AAR Sec 2.5 --- Normal spatial density of birds: “one half of ingested birds caused no damage.” Based on engine damage, calculations estimated LHS engine ingested 14 to 16 birds, RHS engine ingested 10 to 12 birds.
AAR Sec 2.8, “Analytical assessment of Engine Surge Mechanism.” Fan damage results in losses of Fan efficiency and fan-flow capacity. (P&W study mostly based on PW2037 data base of fan-damage.)
Findings and Conclusions ---
... #8 “The analytical assessment also suggested that a power reduction ... would be necessary to clear the surges.... to 60% of Takeoff Thrust for the left engine and 30% of Takeoff Thrust for the right engine.”
#9 “The turbine melting and failures ... resulted from cessation of airflow due to rear compressor destruction that was caused by the repetitive surges.”
Cause: “The accident occurred because the airplane could not safely return to the runway after the internal destruction and subsequent failure of both engines ... from multiple bird ingestion by both engines during takeoff.”
Some bird-strike investigators suggest pilots fly at the slow-speed Noise Abatement Profile CLB-Spds, until above 3000'. There have been numerous cases of cockpit penetration of a goose, eg, at 6000 Feet / 250KIAS. Still have some guys want to exceed 250 below 10,000 Ft. USAF B-52 had bird penetrate front spar during a low-level mission.
-- Bird (starlings) ingestion caused crash of EAL Electra at BOS 4Oct60. [birds]
-- United Viscount 745-D / 23Nov62 \\ bird collision \\ inflight breakup at 6000', near Ellicott City MD. Uncontrollable "following separation of the left Horizontal Stabilizer which had been weakened by a collision with a whistling swan." Carcass of swan found 10' from the severed left Stab. FDR showed descent from 6000' to impact in less than one minute,
-- Sep87 B-1B crashed. Bird strike, fire (ingestion? impact?)
-- Ethiopian Airlines ET-604 / 15Sep88 , B737-200 ET-AJA; T/O at Bahar Dar, birds ingested, surges, internal destruction of engines, double engine failure, crash landing. Sob = 104, fatal=35, serious injuries = 27. /// F/O’s T/O, at V1, flock of pigeons rose from rwy ...
AAR Sec 2.5 --- Normal spatial density of birds: “one half of ingested birds caused no damage.” Based on engine damage, calculations estimated LHS engine ingested 14 to 16 birds, RHS engine ingested 10 to 12 birds.
AAR Sec 2.8, “Analytical assessment of Engine Surge Mechanism.” Fan damage results in losses of Fan efficiency and fan-flow capacity. (P&W study mostly based on PW2037 data base of fan-damage.)
Findings and Conclusions ---
... #8 “The analytical assessment also suggested that a power reduction ... would be necessary to clear the surges.... to 60% of Takeoff Thrust for the left engine and 30% of Takeoff Thrust for the right engine.”
#9 “The turbine melting and failures ... resulted from cessation of airflow due to rear compressor destruction that was caused by the repetitive surges.”
Cause: “The accident occurred because the airplane could not safely return to the runway after the internal destruction and subsequent failure of both engines ... from multiple bird ingestion by both engines during takeoff.”
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That's not a bird strike...
This is a bird (or lightning (see below)..damn you Ppruner's I always thought it was a bird!) strike
This is a bird (or lightning (see below)..damn you Ppruner's I always thought it was a bird!) strike
Last edited by Wombat35; 26th Nov 2007 at 22:31. Reason: Not a bird strike after all !!
Had an old instructor at USAir nicknamed Snowgoose, had a goose go right thru the forward spar on the F27, the engine flamed out almost immediately due to fuel venting overboard.
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Just as a point of interest (I'm interested SLF btw), how aware would the flight crew be of a bird strike like this? I'm assuming there would be no warning whatsoever of what was coming...the poor people at the pointy end must sh!t themselves in such a situation as I'm guessing it would be quite a bang - I've had a direct windscreen hit on a smallish bird at 80mph in a car and that was scary enough!! Would it also be apparent further back in the cabin that something had been hit?
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Perkin
I understand that it was a collision at 250 kts at around 6000 feet. Don't know whether "bird type" has been identified. A couple of bangs when the left side of the radome was hit and later on a further large bang when the right side collapsed. Yes, the cabin crew would have heard it and felt the airframe vibration.
Extremely experienced skipper now has grey hair.
Extremely experienced skipper now has grey hair.
Rotate on this!
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Can someone tell me wtf all that stuff is in the F-111 photo. There seems too much of it to be part of the internal gubbins of the a/c itself.
The USAHAS site just has the picture captioned 'Bird strike at Cannon AFB' without any gen and I have googled me socks off to no avail.
Edit: My first thought was some kind of composite 'ribbing' but there just seemed too much of it...Many thanks
The USAHAS site just has the picture captioned 'Bird strike at Cannon AFB' without any gen and I have googled me socks off to no avail.
Edit: My first thought was some kind of composite 'ribbing' but there just seemed too much of it...Many thanks
Last edited by SLFguy; 26th Nov 2007 at 12:48. Reason: Cheers Dozy...
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some general comments about stuff that dents aircraft
It makes a difference whether you get hit on a composite or a metal leading surface. the metal is more likely to permanently dent before fracturing, while the composite trampolines inward and then splits at the bottom of the trampoline. The soft object that causes the trampoline effect oozes through the split on the downward stroke. However it's often the rebound of the trampoline that finishes off the stucture. In the cases of bird guts you can actually get them inside a perfectly good looking composite radome, engine nose spinner, aircraft leading edge, which on closer inspection whill be shown to have cracked due to the trampoline effect.
Regarding metal denting, the dent size is more a function of the speed of the collison rather than the size of the object. To judge the dent size you need to have some idea of either the speed or the size of the object and then you can assess the missing parameter.
It makes a difference whether you get hit on a composite or a metal leading surface. the metal is more likely to permanently dent before fracturing, while the composite trampolines inward and then splits at the bottom of the trampoline. The soft object that causes the trampoline effect oozes through the split on the downward stroke. However it's often the rebound of the trampoline that finishes off the stucture. In the cases of bird guts you can actually get them inside a perfectly good looking composite radome, engine nose spinner, aircraft leading edge, which on closer inspection whill be shown to have cracked due to the trampoline effect.
Regarding metal denting, the dent size is more a function of the speed of the collison rather than the size of the object. To judge the dent size you need to have some idea of either the speed or the size of the object and then you can assess the missing parameter.
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Some more to think about...
1. At 250 knots IAS your TAS in a standard atmosphere at 6,000 feet is 273 knots.
2. The impact standard under FAR 25 does not contemplate "no" damage. It only discussess "continued safe flight and landing" and is based on a SINGLE 4 lb bird not a flock.
3. A typical goose weighs far more than 4 lbs and due to a more sedentary and non-migratory lifestyle they are now in many cases over 10 lbs.
4. Large bird populations (i.e. greater than 4 lbs) are increasing at a very high rate due to an abundamce of food and a lack of predators.
5. Managing migraotry waterfowl populations is challenging due to public concern over wildlife preservation.
6. When you hit birds above 1500 feet or so they will most likely be raptors or migratory waterfowl.
7. Twin engine aircraft are more prevalent today and the horizontal distribution of birds in a flock creates some very interesting risk scenarios not contemplated by FAR 33 & 25.
1. At 250 knots IAS your TAS in a standard atmosphere at 6,000 feet is 273 knots.
2. The impact standard under FAR 25 does not contemplate "no" damage. It only discussess "continued safe flight and landing" and is based on a SINGLE 4 lb bird not a flock.
3. A typical goose weighs far more than 4 lbs and due to a more sedentary and non-migratory lifestyle they are now in many cases over 10 lbs.
4. Large bird populations (i.e. greater than 4 lbs) are increasing at a very high rate due to an abundamce of food and a lack of predators.
5. Managing migraotry waterfowl populations is challenging due to public concern over wildlife preservation.
6. When you hit birds above 1500 feet or so they will most likely be raptors or migratory waterfowl.
7. Twin engine aircraft are more prevalent today and the horizontal distribution of birds in a flock creates some very interesting risk scenarios not contemplated by FAR 33 & 25.
Last edited by Canuckbirdstrike; 26th Nov 2007 at 15:11. Reason: correct minor error "250" knots
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Lomapaseo,
Correct me if I'm wrong, but your analysis sounds to me like what happened to the Space Shuttle 'Columbia' - distortion and splitting at the maximum distortion (of course the problem in that case was that the split then allowed heat ingress rather than a foreign object).
IGh,
You could also include the E-3 Sentry that went in after taking in a flock of geese on departure from Elmendorf with loss of a/c and all aboard.
Wombat35,
Apparently not (from that link) - hail or other storm-related.
Amazing pic, though! I think many would've just said "sod this" and punched out... How the blazes did they see the strip well enough through all that, to get it down?! One goooood bit of airmanship.
I do love Mary Shafer's title on that link - "SR71 Flying Qualities Lead Engineer" - the ultimate anorak!
Correct me if I'm wrong, but your analysis sounds to me like what happened to the Space Shuttle 'Columbia' - distortion and splitting at the maximum distortion (of course the problem in that case was that the split then allowed heat ingress rather than a foreign object).
IGh,
You could also include the E-3 Sentry that went in after taking in a flock of geese on departure from Elmendorf with loss of a/c and all aboard.
Wombat35,
Apparently not (from that link) - hail or other storm-related.
Amazing pic, though! I think many would've just said "sod this" and punched out... How the blazes did they see the strip well enough through all that, to get it down?! One goooood bit of airmanship.
I do love Mary Shafer's title on that link - "SR71 Flying Qualities Lead Engineer" - the ultimate anorak!
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"Quote" forgive my math, (500X5280)/3600)X(500X5280)/3600)2.2) 733*733X2.2=1183110 ft/lbs roughly. Had an old instructor at USAir nicknamed Snowgoose, had a goose go right thru the forward spar on the F27, the engine flamed out almost immediately due to fuel venting overboard.
Very good with the maths there (one exception) BTW F27's engines are fed fuel from a collector tank (aprox 40 litres usuable in the smaller varieties fitted) so instant flame-outs ???
Very good with the maths there (one exception) BTW F27's engines are fed fuel from a collector tank (aprox 40 litres usuable in the smaller varieties fitted) so instant flame-outs ???
The need for speed
In Australia it's all the go to keep up high speed below 10
)Whilst it's great fun to go tearing along at 320kn <10, 250 is the safer option:
a) Energy when striking other flying objects (almost hit a paraglider once but I'm sure I said that before)
b) Lookout and avoidance.
You save very little time and, if you cock it up, you lose a lot of time.
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Just for info the details given earlier were quite correct. The strike did happen at approx 6000ft and yes the aircraft returned to LHR on a Full emergency with Vibration problems.
The Identity of the bird has been found and needless to say he will not be flying into any more aircraft in the foreseeable future.
And for those twitchers out there it was song thrush. Now you might say a thrush will not cause that amount of damage but at 6000ft at approx 250 knots it probably would. The Song thrushes were actually on migration from Northern Europe which is why they were at 6000ft. They also showed up on the Met weather radar ! although we believe only one actually hit the aircraft.
The Identity of the bird has been found and needless to say he will not be flying into any more aircraft in the foreseeable future.
And for those twitchers out there it was song thrush. Now you might say a thrush will not cause that amount of damage but at 6000ft at approx 250 knots it probably would. The Song thrushes were actually on migration from Northern Europe which is why they were at 6000ft. They also showed up on the Met weather radar ! although we believe only one actually hit the aircraft.
