Flaperon washes up on Reunion Island
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WingNut60:
The aircraft was in final approach, initiated a go-around at 20 ft height - too late. It hit the water in a slight nose-down attitude at a vertical speed of about 1000 ft/min. The fuselage broke aft of the wing but remained attached.
As I said above: the vertical speed breaks the airplane.
I would just about guarantee a nose well up attitude as he hit the water, especially with the sea wall filling the windshield.
As I said above: the vertical speed breaks the airplane.
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I wonder whether a native English speaker with no flying experience would understand "The aircraft rotated at one hundred and sixty knots"?
), but that is a bit more specific than "floating in the sea" - basically it was not on the surface.Rob
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Just about anybody living in Toulouse is an "aeronautical expert" in the eyes of the reporter of a local newspaper. The article doesn't say that the individual has any connection to the investigation conducted in the vicinity, nor what expertise he has regarding the flotation characteristics of a B777 flaperon which, in all probability, is not designed or manufactured in Toulouse.
Last edited by Gysbreght; 24th Aug 2015 at 11:27.
Quote from ZeBedie:
"Which may explain why it's the only item to be found?"
Or, as 172driver and I have discussed above, because this flaperon - assuming it's from MH370 - happened by pure chance to be washed up on this relatively-tiny, well-populated island after floating on or beneath the surface for about 16 months.
Is there anything unique about the floating capabilities of a flaperon, as compared with other primary or secondary flight controls made of composites? Or, for that matter, belly fairings, landing-gear doors, fan cowlings, etc,? If not, there may be large quantities of other nearly-submerged pieces that missed the tiny island on their way west.
The reported theory at Toulouse is that the flaperon was the only part to detach from the a/c before the entire airframe sank to the ocean floor. It's been suggested here that it might have detached in a very high-speed descent. However, unless a pilot managed subsequently to regain control of the a/c and perform a textbook ditching in calm waters, there would be lots of debris. Some of that might still be afloat near the western shores of the Indian Ocean, or already ashore.
"Which may explain why it's the only item to be found?"
Or, as 172driver and I have discussed above, because this flaperon - assuming it's from MH370 - happened by pure chance to be washed up on this relatively-tiny, well-populated island after floating on or beneath the surface for about 16 months.
Is there anything unique about the floating capabilities of a flaperon, as compared with other primary or secondary flight controls made of composites? Or, for that matter, belly fairings, landing-gear doors, fan cowlings, etc,? If not, there may be large quantities of other nearly-submerged pieces that missed the tiny island on their way west.
The reported theory at Toulouse is that the flaperon was the only part to detach from the a/c before the entire airframe sank to the ocean floor. It's been suggested here that it might have detached in a very high-speed descent. However, unless a pilot managed subsequently to regain control of the a/c and perform a textbook ditching in calm waters, there would be lots of debris. Some of that might still be afloat near the western shores of the Indian Ocean, or already ashore.
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Variation in water desity is a secondary effect
A 777 flaperon is constructed with upper and lower aerodynamic surfaces that meet at a sealed training edge. This hollow structure is vented in order to allow internal pressure equalization with the ambient during flight. Whether it floats or sinks initially will depend on how much of that internal volume of air escapes and is replaced by sea water.
If the flaperon looses enough of its trapped air to start sinking, the volume of the remaining trapped air will be halved when depth reaches 10 meters and halved again (down to 1/4 that on the surface) when depth reaches 30 meters. Surely this rapid change in trapped air volume will have a much higher impact on buoyancy than variations in water density that will be only a fraction of a percent.
There are only four states that the flaperon can be in at any point in time with regard to floating/sinking:
1. Floating on the surface with sufficient trapped air/gas to provide positive buoyancy.
2. Sinking toward the bottom at an increasing rate as it buoyancy decreases due compression of trapped air/gas resulting from increasing water pressure.
3. Resting on the bottom with negative buoyancy thus not able to float.
4. Rising to the surface with increasing rate as its buoyancy increases due to expansion of trapped air/gas resulting from decreasing water pressure.
Note that none of these four involve being suspended at a finite depth below the surface, yet above the bottom for any period of time.
Now consider changes that could occur to move from one state to another.
State 1 (floating) to State 2 (sinking) could occur from:
- loss of trapped air/gas due to wave action.
- loss of trapped air/gas due to venting enabled by damage or corrosion.
- loss of trapped air/gas due it being dissolved into the sea water.
State 3 (on the bottom) to State 4 (rising) could occur from:
- accumulation of trapped gas due to a chemical or biological process.
- detachment of a particularly dense portion of the flaperon due to corrosion rendering the buoyancy of the remaining system sufficient to initiate floating.
As for the Frechman and his 777 flaperon in a swimming pool, he could show that it sinks to the bottom or floats on the surface depending on how much of the interior volume he floods. There is no way he could end up with it fully submerged, half way down, neither rising or sinking further.
If the flaperon looses enough of its trapped air to start sinking, the volume of the remaining trapped air will be halved when depth reaches 10 meters and halved again (down to 1/4 that on the surface) when depth reaches 30 meters. Surely this rapid change in trapped air volume will have a much higher impact on buoyancy than variations in water density that will be only a fraction of a percent.
There are only four states that the flaperon can be in at any point in time with regard to floating/sinking:
1. Floating on the surface with sufficient trapped air/gas to provide positive buoyancy.
2. Sinking toward the bottom at an increasing rate as it buoyancy decreases due compression of trapped air/gas resulting from increasing water pressure.
3. Resting on the bottom with negative buoyancy thus not able to float.
4. Rising to the surface with increasing rate as its buoyancy increases due to expansion of trapped air/gas resulting from decreasing water pressure.
Note that none of these four involve being suspended at a finite depth below the surface, yet above the bottom for any period of time.
Now consider changes that could occur to move from one state to another.
State 1 (floating) to State 2 (sinking) could occur from:
- loss of trapped air/gas due to wave action.
- loss of trapped air/gas due to venting enabled by damage or corrosion.
- loss of trapped air/gas due it being dissolved into the sea water.
State 3 (on the bottom) to State 4 (rising) could occur from:
- accumulation of trapped gas due to a chemical or biological process.
- detachment of a particularly dense portion of the flaperon due to corrosion rendering the buoyancy of the remaining system sufficient to initiate floating.
As for the Frechman and his 777 flaperon in a swimming pool, he could show that it sinks to the bottom or floats on the surface depending on how much of the interior volume he floods. There is no way he could end up with it fully submerged, half way down, neither rising or sinking further.
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Prior METRON Analysis
The drift study linked by AirLandSeaMan (24th Aug 2015, 15:58) is from the same company that did the Bayesian (conditional probability) analysis that was instrumental in finding AF447.
From the BEA's summary of sea search operations:
http://www.bea.aero/fr/enquetes/vol....11.2012.en.pdf
"The BEA asked METRON to analyse the results of previous searches in order to produce a probability map for the location of the wreckage. METRON used the SAROPS(21) tool and a distribution based on studies by the BEA and its Russian counterpart (MAK) focusing on nine aircraft accidents that had occurred in cruise.
An updated distribution of probabilities of the presence of the wreckage was produced taking into account the efficiency of the sonar searches during phases 2 and 3, and the unsuccessful searches in phase 1. The lack of results from the air and sea searches conducted from 1 to 6 June 2009 was also taken into account.
On 20 January 2011, the BEA published the results of the METRON study on its website. It mentioned an area where there was a high probability of the wreckage being present near the centre of the circle.
The summary of the analysis of the results from the previous phases, reinforced by the findings of the METRON study, helped define the search strategy for phase 4. This involved a systematic search starting from the centre of the circle, with the exception of areas already explored using sonars during phases 2 and 3, for which a re-exploration with the same type of resources was deemed unnecessary."
That study is here (5.8 MB):
http://www.bea.aero/fr/enquetes/vol....h.analysis.pdf
Good track record.
From the BEA's summary of sea search operations:
http://www.bea.aero/fr/enquetes/vol....11.2012.en.pdf
"The BEA asked METRON to analyse the results of previous searches in order to produce a probability map for the location of the wreckage. METRON used the SAROPS(21) tool and a distribution based on studies by the BEA and its Russian counterpart (MAK) focusing on nine aircraft accidents that had occurred in cruise.
An updated distribution of probabilities of the presence of the wreckage was produced taking into account the efficiency of the sonar searches during phases 2 and 3, and the unsuccessful searches in phase 1. The lack of results from the air and sea searches conducted from 1 to 6 June 2009 was also taken into account.
On 20 January 2011, the BEA published the results of the METRON study on its website. It mentioned an area where there was a high probability of the wreckage being present near the centre of the circle.
The summary of the analysis of the results from the previous phases, reinforced by the findings of the METRON study, helped define the search strategy for phase 4. This involved a systematic search starting from the centre of the circle, with the exception of areas already explored using sonars during phases 2 and 3, for which a re-exploration with the same type of resources was deemed unnecessary."
That study is here (5.8 MB):
http://www.bea.aero/fr/enquetes/vol....h.analysis.pdf
Good track record.
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METRON Analysis
No attempt is made to perform high resolution modeling of separate wind and current forcing or leeway modeling to predict the resultant differential movement due to the different sizes of individual pieces of debris.
Until such time as there is a better understanding of how the Flaperon floated, it may or may not fit neatly into this study. I personally suspect that its behaviour will fall outside that of a general field of floating debris.
Time will tell.
Quote from mm43:
"Until such time as there is a better understanding of how the Flaperon floated, it may or may not fit neatly into this study. I personally suspect that its behaviour will fall outside that of a general field of floating debris."
Thanks, mm43, for responding to the question I posed 42 hours ago:
"Is there anything unique about the floating capabilities of a flaperon, as compared with other primary or secondary flight controls made of composites? Or, for that matter, belly fairings, landing-gear doors, fan cowlings, etc,?"
I see my question was poorly phrased. Instead of "floating capabilities", perhaps it should have read something like "floating capabilities, characteristics, and sailing performance"?
"Until such time as there is a better understanding of how the Flaperon floated, it may or may not fit neatly into this study. I personally suspect that its behaviour will fall outside that of a general field of floating debris."
Thanks, mm43, for responding to the question I posed 42 hours ago:
"Is there anything unique about the floating capabilities of a flaperon, as compared with other primary or secondary flight controls made of composites? Or, for that matter, belly fairings, landing-gear doors, fan cowlings, etc,?"
I see my question was poorly phrased. Instead of "floating capabilities", perhaps it should have read something like "floating capabilities, characteristics, and sailing performance"?
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FCeng84
Would you happen to know what the total density of a flaperon would be? Composites commonly float in water (especially when in a honeycomb structure), but I guess the 777 flaperon is not made only from composites - am I mistaken here?
Unless we know the density of a 777 flaperon, we can not say conclusively that the "drifting below the surface" scenario is wrong, imho.
Would you happen to know what the total density of a flaperon would be? Composites commonly float in water (especially when in a honeycomb structure), but I guess the 777 flaperon is not made only from composites - am I mistaken here?
Unless we know the density of a 777 flaperon, we can not say conclusively that the "drifting below the surface" scenario is wrong, imho.
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MrSnuggles,
Well, the notion of drifting below the surface, i.e. "neutral buoyancy" is a bit of a fallacy. Things float or they don't. What can happen is that temperature effects can cause objects to rise or fall, e.g. in a thermocline, but for 2,500 miles - no!
My examination of the B777 Flaperon construction ( Boeing is not helpful in this regard) tends to lean toward a familiar spar, rib, stringer construction but using CFRP materials. The unknown area is what is actually happening between the forward spar and the aft spar? What the construction was on the trailing edge is fairly obvious from the many photographs available. There is also an obvious drain hole located just forward of the aft spar on the underside and outboard of the inboard rib - [if that makes sense].
There must be a way for any void compartments to "breathe", otherwise pressure differentials will cause damage.
My assumption is that the Flaperon floated topside down, with its center of buoyancy about 25% aft of the forward spar.
Unless we know the density of a 777 flaperon, we can not say conclusively that the "drifting below the surface" scenario is wrong ...
My examination of the B777 Flaperon construction ( Boeing is not helpful in this regard) tends to lean toward a familiar spar, rib, stringer construction but using CFRP materials. The unknown area is what is actually happening between the forward spar and the aft spar? What the construction was on the trailing edge is fairly obvious from the many photographs available. There is also an obvious drain hole located just forward of the aft spar on the underside and outboard of the inboard rib - [if that makes sense].
There must be a way for any void compartments to "breathe", otherwise pressure differentials will cause damage.
My assumption is that the Flaperon floated topside down, with its center of buoyancy about 25% aft of the forward spar.
I live in a coastal area and see neglected mooring buoys sink then float. The weight of barnacles and mussels eventually causes the buoy to sink. Then after a few months some of the barnacles and mussels drop off and the buoy surfaces again. Then the cycle starts again. Maybe better nutrients near the surface causes the barnacles and mussels to grow again and then it sinks again.
Looking at the photos the CG and centre of buoyancy would be close together so odds are it floated flat down with a significant proportion submerged. The effect of wind will surely be whatever effect the wind has on the top few inches of the water, ie how the surface of the water moves relative to the body currents rather than direct wind effect on the body. Doesn't sound prone to accurate calculation given the variation over time and space. However at least we know it floated on account that it didn't sink. If by some circumstance I can't imagine, it floated feet below the surface then I can't see why it would make it to the beach rather than be grounded as the bed shelves.
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Difficulty in proving flaperon came from MH370
Article in the French press today concerning the problems that the experts are having in definitively identifying the flaperon as a component of MH370. The component ID plate is missing and apparently the maintenance tasks reported to have been carried out by Malaysia Airlines don't tie in exactly with what the investigators are seeing on the flaperon.
They are reported to be waiting for the end of the holiday period when they might be able to get data from a Spanish sub-contractor that supplied a numbered component within the flaperon. If this sub-contractor has data on the history of this component then they might be able to tie the flaperon back to MH370.
Vol MH370 : la difficile identification du morceau d?avion trouvé à La Réunion
They are reported to be waiting for the end of the holiday period when they might be able to get data from a Spanish sub-contractor that supplied a numbered component within the flaperon. If this sub-contractor has data on the history of this component then they might be able to tie the flaperon back to MH370.
Vol MH370 : la difficile identification du morceau d?avion trouvé à La Réunion
The Le Monde article mentions that parts are recovered from retired airframes and that the authorities want to ensure that the flaperon is not lost inventory 
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... and apparently the maintenance tasks reported to have been carried out by Malaysia Airlines don't tie in exactly with what the investigators are seeing on the flaperon.
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Metron Analysts
The co-authors of the 24 Aug 2015 memo:
J. Van Gurley
Metron | About Us | Management | Lawrence D. Stone
J. Van Gurley
Metron | About Us | Management | Lawrence D. Stone