Black box data is the ne plus ultra of aircraft accident investigation. But it is not the only kind of physical evidence. Pieces of debris—in particular, their dents and fractures — can tell a vivid story by themselves.
There are five basic ways that an object can break. The two most important for our present discussion are tension and compression. A tension failure occurs when something is pulled apart—think of pulling the ends of a piece of string until it snaps. Compression is the opposite; it’s what happens when something is crushed by a weight or smashed in an impact.
When a plane crashes, it’s common for all different parts to exhibit different kinds of failure. Imagine a plane whose wingtip hits a tree. The impact would crush the leading edge of the wingtip—compression failure—and then wrench the wing backwards from the body of the plane, causing a tension failure at the forward wing root and compression failure at the aft end.
By collecting many pieces of debris after a crash, investigators can place the mechanical failures in a chronological order to tell a story that makes sense, much as you might arrange magnetic words on a refrigerator. This is how the mystery of TWA 800 was solved. When the fuel tank exploded, the pressure pushed the fuselage skin outward so that it came apart like a balloon popping. The plane broke into two major parts that smashed apart when they hit the ocean. Thus tension failures predominated in the first phase of the catastrophe and compression failures predominated later.
So now let’s turn to the issue at hand. What story do the pieces of MH370 debris tell?
In April of this year the Malaysian government published a “Debris Examination Report” describing the 20 pieces of debris that were deemed either confirmed, highly likely or likely to have come from the plane. For 12 of them, investigators were able to discern the nature of the mechanical failure. Some key excerpts:
Item 6 (right engine fan cowl): “The fracture on the laminate appears to be more likely a tension failure. The honeycomb core was intact and there was no significant crush on the honeycomb core.”
Item 7 (wing-to-body fairing): “The fibres appeared to have been pulled away and there were no visible kink on the fibres. The core was not crushed; it had fractured along the skin fracture line.”
Item 8 (flap support fairing tail cone): “The fracture line on the part showed the fibers to be ‘pulled out’ showing tension failure. Most of the core was intact and there was no sign of excessive crush.”
Item 9 (Upper Fixed Panel forward of the flaperon, left side): “The fracture lines showed that the fibres were pulled but there were no signs they were kinked. The core was intact and had not crushed”
Item 12 (poss. wing or horizontal stabilizer panel): “The carbon fibre laminate had fractured and appeared to have pulled out but there was no crush on the core.”
Item 15 (Upper Fixed Panel forward of the flaperon, right side): “The outboard section had the fasteners torn out with some of the fastener holes still recognizable. The inboard section was observed to have signs of ‘net tension’ failure as it had fractured along the fastener holes.
Item 18 (Right Hand Nose Gear Forward Door): “Close visual examination of the fracture lines showed the fibers were pulled and there was no sign of kink.”
Item 20 (right aft wing to body fairing): “This part was fractured on all sides. Visual examination of the fracture lines indicated that the fibers appeared to have pulled away with no sign of kink on the fibers.”
Item 22 (right vertical stabilizer panel): “The outer skin had slightly buckled and dented but the inner skin was fractured in several places…. The internal laminate seems to be squashed.”
Item 23 (aircraft interior): “The fractured fibres on the item indicated the fibres were pulled out which could indicate tension failure on its structure.”
Item 26 (right aileron): “The fitting on the debris appeared to have suffered a tension overload fracture.”
Item 27 (fixed, forward No. 7 flap support fairing): “One of the frames was completely detached from the skin. It may be due to fasteners pull through as the fasteners’ holes appeared to be torn off with diameters larger than the fasteners.”
Note that all of these but one failed under tension. The exception is item 22, which came from the tail—specifically, from near the leading edge of the vertical stabilizer.
It’s particularly remarkable that Item 18, the nose gear door, failed under tension. (Image at top) If, as the Australian authorities believe, the plane hit the sea surface after a high-speed descent, this part of the plane would have felt the full brunt of impact.
Bill Waldock, a professor at Embry Riddle University who teaches accident-scene investigation, says that if MH370 hit the water in a high-speed dive, you would expect to see a lot of compression, “particularly up toward the front part. The frontal areas on the airplane, like the nose, front fuselage, leading edge of the wings, that’s where you’d find it most.”
I spoke to a person who is involved in the MH370 investigation, and was told that officials believe that that observed patterns of debris damage “don’t tell a story… we don’t have any information that suggests how the airplane may have impacted the water.” Asked what kind of impact scenario might cause the nose-gear door to fail under tension, it was suggested that if the gear was deployed at high speed, this could cause the door to be ripped off.
This explanation is problematic, however. According to 777 documentation, the landing gear doors are designed to open safely at speeds as high at Mach 0.82 — a normal cruise speed. The plane would have to have been traveling very fast for the door to have been ripped off. And to be deployed at the end of the flight would require a deliberate act in the cockpit shortly before (or during) the terminal plunge.
The experts I’ve talked to are puzzled by the debris damage and unable to articulate a scenario that explains it. “The evidence is ambiguous,” Waldock says.
In a blog post earlier this month, Ben Sandilands wrote, “Don Thompson, who has taken part in various Independent Group studies of the mystery of the loss of the Malaysia Airlines in 2014, says some of these findings support a mid-air failure of parts of the jet rather than an impact with the surface of the south Indian Ocean.”
A mid-air failure, of course, is inconsistent with the analysis of the Inmarsat data carried out by Australian investigators. So once again, new evidence creates more questions than answers.
UPDATE 5/24/17: Via @ALSM, here’s a diagram of the front landing gear and doors:
UPDATE 5/25/17: In the comments, we discussed the possibility that the front gear door could have come off in the process of a high-speed dive. @ALSM speculated that the loss of engine power upon fuel exhaustion could have led to loss of hydraulic pressure, which could have allowed the gear doors to open spontaneously, and then be ripped off in the high-speed airstream. But he reported that Don Thompson had dug into the documentation and confirmed that following a loss of hydraulic power the gear would remain stowed and locked. Thus it seems unlikely that the gear door could have spontaneously detached in flight, even during a high-speed descent.
UPDATE 5/25/17: There’s been some discussion in the comments about flutter as a potential cause of inflight breakup, so I thought it would be apropos to add a bit more of my conversation with the accident investigator involved in the MH370 inquiry.
Q: Does the MH370 flaperon look like flutter to you?
A: In a classic sense, no, but where you would be looking for flutter would be on the stops, on the mechanical stops that are up on the wing, so the part of that piece that came out. And in looking at that piece, you’ve got different types of failures of the composite skin that don’t appear to be flutter.
Q: What does it look like?
It just looks like kind of an impact-type separation. So it looks like you’ve drug that thing either in the water or on the ground or something. But it’s a little hard with that one because you don’t have any other wreckage, so, one of the keys — you don’t base anything on one small piece, you’re trying to look at kind of the macroscopic view of all the wreckage to make sure that, “Oh, if I think this is flutter do I see the signatures elsewhere on the airplane?” Typically we won’t base it on one piece like the flaperon.
To provide some context, we had earlier talked about the phenomenon of flutter in general:
Q: I can think of a couple of cases where there was flutter, where the plane got into a high speed descent and stuff got ripped off.
A: Yup.
Q: Where would that fall in the bestiary of failures that we talked about earlier?
A: So flutter’s kind of a unique thing, and it’s based on aircraft speed and structural stiffness. So, you know, when those two things meet you get this excitation, an aerodynamic excitation of a control surface which will become dynamically unstable and start going full deflection. So for a flutter case you generally look at the control stops—so there’s mechanical stops on all the flight controls—and you look for a hammering effect on the stops. So repeated impacts on the stop will tell you that, hey, maybe you’ve got a flutter event.
Q: But if you see the piece—there was a China Airlines incident, the elevator was shredded, or part of it was ripped off. What would that look like?
A: Mm-hmm. You know, it’s going to be different for every single case. Sometimes that flutter will generate the load in the attachment points, break the attachment points, and other times it will tear the skin of the control surface, and so you’ll see this tearing of the skin and the separation of rivet lines, and everything. I’ve seen both. I’ve seen a control surface that comes apart at the rivets, and flutters that way, and I’ve seen them where it generates loads to break the attachment points. It depends on the loads that are created and how they’re distributed throughout the structure.
For his part, Bill Waldock told me that the tensional failure of the collected debris implies a shallow-angle impact. Both experts, in other words, believe the debris is most consistent with a more or less horizontal (rather than high-speed vertical) entry into the water.
This is not consistent with the ATSB’s interpretation of the BFO data unless we posit some kind of end-of-flight struggle, à la Egyptair 990, or last-minute change-of-heart by a suicidal pilot. Either seems like a stretch to me.
Below is part of a post from @Andrew on Victor I’s site.
Is this anomaly significant?
It is very familiar information continuously reviewed, yet I do not recall a definitive answer of how unusual the redundancy was. If 50 pilots were queried, how many would find it very unusual, somewhat unusual or relatively normal? Does the information become more relevant if the majority of pilots see the unsolicited repetition from someone in the cockpit as highly unusual?
“Lumpur Radar (132.6) cleared the MH370 to climb to FL350 at 1650:08. That call was acknowledged by MH370 at 1650:11 and the aircraft reported maintaining FL350 at 1701:17, which was acknowledged by Lumpur Radar at 1701:21.
It’s not clear why MH370 again reported maintaining FL350 some 6 ½ minutes later, at 1707:56. There was no requirement to do so.”
@Nederland
Nice work on your path, and the write-up is great. I took a look at your proposed flight path from Arc2 to Arc6 on PSS777.
The first thing I had to do was add waypoints to the PSS777 data base for UPROB, BEBIM, and Wilkins. For Wilkins I used 55S04 as a surrogate point along the BEBIM/YWKS path. PSS has a fairly large waypoint data base, but not those waypoints, for what it’s worth.
The big thing of course is you are changing speed and direction to Wilkins between Arcs 3 and 4 at BEBIM. You get a good match to BTO/BFO with that assumption, and further assuming no winds, but that’s a pretty big assumption.
Check out Richard Godfrey’s Wilkins path spreadsheet (if you have a copy). You will see the strong wind after about 20S adds approx. +10 to your ground speed, so I hit Arc6 about 5 min early by adding that wind. so I think you end up needing to adjust your speeds a little. You can use Richard’s data to estimate wind impacts between Arcs, but I think it’s the high wind below 20S that is the most important in your case.
@Jeff Wise:
I just thought about a “coincidence”:
The pilot – oddly, because totally unneceesarily – repeats his flight level (17:07:56 UTC) a mere 8 seconds (!) after the last ACARS transmission (17:07:48 UTC)
I raised the issue on V’s blog but was shrugged off, as ACARS transmissions (including their timing) would not be known to the pilot.
Agreed. Still, I can’t shake the nagging feeling, that something is not right here.
I mean, think of it:
• only 8 seconds after last ACARS message: pilot places odd (because completely unnecessary) ATC call
• only 5 seconds after passing IGARI and only 1 minute after last ATC comm: transponder shuts off
• only 3 minutes after MH370 vanishes from primary radar: SDU re-logs on to Inmarsat
When contemplating this pattern of “coincidental” timings, I get the feeling that this was all planned exactly punctual to the minute/second.
…
OR this is, what we are being made to believe.
(Maybe someone missed to add some buffer time to the “story”, forgetting that the pilot could neither have known precisely when leaving radar coverage nor when the last ACARS message was sent.)
What do you think ?
[BTW: Here are 2 different theories for the unnecessary ATC call at 17:07:56 UTC repeating the flight level (fishing for hand-off or rattled by disposal of co-pilot).]
@ Susie Crowe
Good point Susie as it is important to re-evaluate ALL clues.
The repeated radio call is considered very unusual (by active and retired pilots) and has raised the following explanations:
1. Hypoxic confusion as even relatives of Z fail to recognised his voice at that time and slurring is noticeable.
2. A coded signal to those listening that “the plan” was “on track”. Maybe one pilot had disposed of the other by that time.
@TBill
Thank you for this. Yes, for this version I haven’t taken into account any wind effects. If I add +10 kts to ground speed after 20S, then it very much looks like the initially proposed route (BEBIM to NOBEY) would be a better match in terms of BTOs (the BFOs are roughly the same for either route).
Is there a copy of Richard Godfrey’s spreadsheet online?
Referring to my previous post to @ventus45, how could I calculate possible ground speeds at different altitudes (such as FL200 or FL150/130) for the segment around Sumatra? How much would that change (roughly)?
@Peter Norton, Even back in March 2014 it seemed to me that the timing of the going dark, coincident with the turn back, strongly indicated that someone had carried out a sophisticated, aggressive plan. And the timing of the SDU re-boot–together with the fact that is almost inconceivable that it could have come back online in any other way except deliberately–also indicates intentionality, as well as sophistication. However, I’m not very convinced by the timing of the call to ATC to repeat the flight level. Its significance is just too vague.
@Nederland
I believe Richard posted his spreadsheet to Victor’s blog a while back, if I recall Brock asked for it. I have a question on the data in there, which I may have corrupted myself not sure.
@TBill
This one?
http://mh370.radiantphysics.com/2017/03/02/radar-maybe-captured-fighter-jet-chasing-mh370/#comment-913
@Cargo Handler, @Susie Crowe :
As Jeff pointed out, this has been “up there” from Day One, but I have not yet seen any explanation of the repeated FL that feels like it settles the matter once and for all. It appears as if it would be hard to get any further in that end, though Jeff’s general observation of the communications’ events being too “convenient” to suggest anything else than pilot/hijacker input of course weighs pretty heavily.
It struck me now that it could be of interest to see what this communications radio looks like and where it is placed in the cockpit. I recall seing a close-up photo or digital rendering of such a radio a while back. And also cockpit photos. Anyone who knows right away where to find that?
There are 2 good ones in my link.
@Cargo Handler
Thank you for understanding my point. IMO, regardless of cause, this is a significant indicator something was amiss in the cockpit. If that indicator is sequenced with the last ACARS transmission it should become even more significant.
@Nederland
Excellent you found it!
That would be a good base case for Wilkins, but I am a little confused about some of the numbers in there. Do you see why speed went up at 2241? I am thinking it should be constant speed.
@ Susie @ Jeff
Fully agreed. The three major early clues are:
1. unnecessary FL call,
2. diversion (with transponder off) without communicating and
3. reboot of SDU.
To his credit, JW has highlighted these significant events from the very start.
Plain pilot suicide does not require events 1 & 3.
Simple hijack or serious fault requires item 2 only.
Nation-state sponsored hijack requires 2, 3 (and possibly 1 for ground support).
The only other evidence I trust are eyewitness accounts, the Curtain boom and serious interpretation of “debris ” – the remainder is plausible but tainted.
@All,
We all know what it’s like when you repetitively undertake the same actions regularly, such as driving a car and forget whether you undertook a certain action or not. These automatic routes we take without thinking or actually registering what we do. The double FL350 call, 6 minutes apart, could simply have been because the PIC did not remember executing an action he has performed a million times before.
@KK
Very valid comment Karen however many professional pilots flag this behaviour as unexpected and very unusual. Perhaps its the way pilots are trained – do something, move onto the next point … always knowing where you are in your process chain.
@Susie Crowe,
Your comments are always intelligent and perfectly written, IMO.
A few posts back you wrote “In my opinion there is only 1 person who definitively knows whether Captain Zaharie was responsible. Why that individual has remained silent could point either way and could also be attributed to fear. I have put myself in her position many times, but cannot simulate fear of safety, if one exists. Without doubt, I know what I would have done if my husband was innocent, which is not, what has been done. In considering his guilt however, I would likely mimic her response in saying nothing and trying to disappear from it all.”
Like you, I have placed myself in her shoes many times. They too, are victims in this whole tragedy perhaps more so given that ZS was the PIC on this flight. Whether her verbal insistency of innocence of her husband would have swayed the public opinion from thumbs down to thumbs up, is doubtful IMO. Would she have been believed? Perhaps it was a lose/lose situation for her, doomed if you do and doomed if you don’t.
How many couples wake up one day, kids grown, and realize they have become strangers in their own marriage and grown apart. ZS becoming more atheist and fighting for democracy, Faisa perhaps embracing religion more fervently and taking a conservative stance. It happens. Would a broken marriage weigh heavily on both of them if this were so? Of course. Does it make ZS a suicidal mass murderer? Of course not. IMHO, every single word uttered by Faisa would likely have been twisted by the media to further crucify her husband.
The proverb “silence is golden” is believed to date back as far as Ancient Egypt. The poet Thomas Carlyle wrote; “Silence is the element in which great things fashion themselves together; that at length they may emerge, full-formed and majestic, into the daylight of Life, which they are thenceforth to rule”.
@CH, No doubt it would be flagged as such by many pilots but that does not mean it doesn’t happen and is completely benign.
@Peter Norton:
You cut my quote a little short and the link doesn’t work for me…
Provoking early hand-off is good, the other one I have not seen any elaborated interpretation of. Another shot at the link?
@Sunken Deal
Have to come back to you for I was probably a bit to harsh on your comment about the Quran.
Excusse me if I offended you or anyone else. It’s just that so many horrible crimes are committed in recent times which are justified (mis)using the Quran.
Going that way just triggers my sence of injustice and fear of blog-sites getting infiltrated with all kinds of vague Quran-statements which imo only add confusion and possibly a platform to radical Muslims to post their messages this way too.
As far as we know Z. does not fit the profile of a radical Muslim at all. On the contrary I would say.
Anyway, looking for clues, evidence or justification in the Quran has no use imo regarding MH370.
If you start going this way you can as well use the I Tjing or the Bible or another ‘orakel-book’.
I think we better stick to more logical assumptions and facts. That’s difficult enough.
@TBill
By the way, I read your latest flight-path paper. The good thing is imo also yours is leading to an end-point in the Northern region. Although yours ends at 33.1S and West of the 7th arc (inside).
But I think this doesn’t fit the latest drift-studies well (too far South) and requires a right turn after second engine flame-out which is, according the simulations, more unlikely.
There’s also no specific deep trench in the vicinity of 33.1S which I think would have been one of the goals if the flight was all planned by Z. (which I still think it was).
I’d rather opt for ~1 degree more North at around ~32.2S/96.5E as an end-point reached by a (partial) glide from a right engine flame-out point even more North around ~31S.
@KarenK:
Hi Karen, I think your suggestion concerning the FL repetition pinpoints that there is actually very little to go on and reminds us that interpretations often can go either way, and that it, with a little effort, is easy to come up also with innocent scenarios. Even if it was a provocation of an early hand-off, there might theoretically be perfectly innocent reasons for that. However, with the events then unfolding, explanations will most likely have to encompass them too.
About the innocent repetition: since calls to ATC as a rule are connected to changes in the machine’s path through the air, i.e. leaving or reaching FL etc., these calls would probably be less prone to forgetting if the pilot still has his or her wits, and would, I assume, be checked against the instruments and reality before a call if there was doubt. “Maintaining FL” does seem to need a context of some kind, doesn’t it?
If one pilot has been out of the cockpit for a while and meets the other one in the door when he returns, then I see a context. And reasons for distraction.
You do get a “sense” that whoever says this is alone in the cockpit. (But any “sense” would in the end need to be analyzed to rule out the arbitrary from what realistically could be said to be intented, which is hard in 1.5 second calls with some static and garbling; which suggests that much of what one may “sense” need to be ruled out as such.)
My next thought is that it, at least from the point of view of the ATC, is about a pilot trying to provoke conversation, but it is not important enough to warrant a full call. When and if you find time, we would save some fuel / avoid a cloud, if we are allowed to descend… Close to the idea of a provoked early hand-off. But could it be a pilot at gunpoint, or were there other systems to signal a hijack?
Lastly, noting that Z (I assume it is) is skidding on the flight-no. in his calls all the way, one might conclude that he is either so tired from lack of sleep or distraught that the reason for repetition you suggested might be valid after all.
@TBill
A ‘right engine falme-out’ should be a ‘second engine flame-out’..
Hold on to your socks:
When the Captain (if him) skids on the flight-no., starting “Malaysia One (Sev…)” he is not only giving a crypto for his full name, but also alluding to the sister aircraft shot down over Ukraine, MH17.
Malaysia ONE SEVEN ZERO would correspond to Ahmad (First letter of alphabet), Shah (S-even), Zaharie (Z-ero).
Funny isn’t it?
(Flight MH170 would take us to Katmandu. I am not sure of the significance of that here if but it is in the heart of the Himalayas of course.)
@TBill
As far as I can see, all previous route suggestions require some (manual) change in speed to make them fit with the distances between the arcs (like here at 22:41). I therefore think my model needs fewer assumptions.
I can see that the spreadsheet indicates unusual winds while crossing the 6th arc. If you say that means arriving at the 6th arc five minutes earlier (or aspeed greater by 10 kts for most of that segement, south of 20S), then I’d say BEBIM – NOBEY is a better fit for constant mach speed.
I can try and recalculate this, giving the two alternatives (can I quote your PS9 trial?). It will take a while, however (not very much time at the moment).
@Ge Rijn
Re: navigating to a deep trench, I have not investigated making end-of-flight maneuvers (eg; turn to the East) to hit a specific spot. I suspect that is “easy” because the BFO math is not very sensitive to heading when you get so far away from the satellite.
So I still think MH370 could have headed East at the end, if the flight was piloted. So that potentially gets us over to 32S.
@Nederland
You do not have to change your calcs, as it is just a minor speed adjustment. The main thing I was planning to point out was that the Wilkins path has a BFO problem (per Richard’s calc BFO’s) but then I realized maybe the calc BFO’s are not quite right in that spreadsheet. Wilkins is close to 180S so there should be a fairly good match.
good catch
you have to click on the word “here” in the penultimate line of my posting above (unfortunately Jeff’s blog color scheme doesn’t decorate links in any way, no underline, same color as text).
I quote from the link:
fishing-for-handoff theory:
«… the oddly timed altitude report was made to encourage a handoff to HCM. That’s a little early to attempt that (MH370 was more than 50 miles from the ATC boundary at that point), but it is a very real possibility. For those unfamiliar with the concept, sometimes air traffic controllers simply forget about you. When you’ve passed a point where you’d expect a handoff, it’s normal to say something to call attention back on yourself. I found a nifty trick is to hit a button on the transponder (the “Ident” button) which brightens up your data on their screen. It calls attention to you. Works nearly every time—hit that button, get a handoff. Z’s unsolicited altitude report 50 miles from boundary with HCM might have been just that. A way to get attention to MH30, and encourage an early handoff. Seems like a plausible thing. »
pilot-is-rattled theory:
« My guess is that the oddly placed altitude report[…] was about the time Fariq was ordered out of the cockpit. He had to have been ordered out of the cockpit at some point. Perhaps Z was a bit rattled by his own actions, and for some reason reaffirmed his altitude unnecessarily. »
« Another reason to make the extra radio is to effectively report “back on” when the pilot has been distracted. As much as I try to always keep radio vigilance, occasionally I have doubts about whether I heard every call, so I’ll throw in an extra radio call just in case. Could the MH370 flight crew have been temporarily distracted with and then made the radio call? »
The second FL350 report could be associated with confirming if the comms jamming was operating appropriately at the time. Seems perhaps it wasn’t yet
@TBill
I think it’s best to have as little assumptions as possible for the proposed route. Navigation from waypoint to waypoint obviously has a big advantage to other routes. But I also want to keep the changes in speed as few as possible, especially for the proposed route from arc 2 to 6. One change in speed is inevitable, but in particular I’m looking for constant mach speed (no manual change in speed) from BEBIM onwards. If strong winds set in only after 20S (after arc 6) and groundspeed is therefore higher (although no manual change), then distances between arc 4 and 5, and arc 5 and 6, won’t work out completely.
If however, you are sure, that the higher winds after arc 6 result into a groundspeed higher by 10 kts (or an arrival five minutes too early), then the path from BEBIM to NOBEY would be a better match.
The Richard Godfrey spreadsheet, however, says that groundspeed was only 7.5 kts more, but perhaps this is temporary? Would you say a ground speed of +10 kts is a good estimate (just caused by the wind)?
@ MH
“The second FL350 report could be associated with confirming if the comms jamming was operating appropriately at the time. Seems perhaps it wasn’t yet”
I haven’t read this line of reasoning before, it makes a lot of sense actually. Pilot making that unnecessary call after ordering copilot out and being ‘rattled’? Possible, but instinctively doesn’t feel ‘right’ to me. Second call in order to prompt early handoff? Bit early isn’t it… A very experienced pilot doing that…? Why? The explanation above however, comms jamming, now makes sense to me.
@Havelock H – I might suggest it may have been the hi-jacker speaking as its being suggested the voice was neither Shah or the co-pilot.
@MH:
“comms jamming”?
@Johan,
all forms of communications, VHF, RF, sat-comms,
so a jammer is needed to blanket block all transmissions from MH370…
@MH:
I think I get it, I must have missed that discussion, or parts of it.
Is the idea that the culprit has a device with him which can be turned off and on, and that he is testing it when making the call? It should jamm all communications, perhaps even among passengers?, but it doesn’t work for the radio at that point yet?
I do remember the discussion about the plane leaving no text messages from the time of boarding.
What does this disappearance not include?
What would it take to come by such a device and how would you get it onboard?
@Johan, my thinking it was a military intercept at around IGARI. MH370 was escorted by them to a military airbase probably in western Sarawak which is almost near the 7th arc. BTW: I heard speculation that Freescale was developing the hardware such a device…..
@MH:
It seems to me you are leaving one or two questions unanswered there….
Still, the radio calls probably are a key, if we find the right keyhole.
Keeping it a bit closer to home, but in the same district: wouldn’t it be possible for the pilot to switch off the cockpit speakers for the comm. radio, or turn down the volume to nill? I saw an image of a radio front that suggested that. Anyone?
@Nederland
I think you should go by Richard’s speed deltas for now. I don’t think the wind effect is perfectly known, so that is one reason why predicted BTO may not exactly match actual BTO. The wind is really strong down there below 20S and sometimes I wonder if folks are under-estimating the wind impact because it’s so strong and makes hitting Arc6 BTO difficult.
@Johan
Jamming device would have to be rather powerful, large and complex in order to block all devices which operate at different frequencies. Also, signal of active jammer could be easily detected by the military facilities whoch monitor all sorts of radio communications. However, is it possible that someone was probing to switch off and on or short different electrical circuits and wanted to make sure that the one for radio communication was still on? Can that explain SDU log on request as well, especially if the circuit powers some other vital device? I am sorry if that was discussed before and I am asking again.
@Johan
Re: No text messages from passengers on MH370
Allegedly Mohamad Sofuan Ibrahim 33yo tweeted this selfie from within MH370 prior to departure from KL on 8th March 2014;
https://mobile.twitter.com/OOTDM/status/442483578350211073/photo/1
Going back to Debris with observation and recommendations aiming a progressing our mutual understanding.
I had another neutral look on the photos in this independent report regarding the debris (https://drive.google.com/file/d/0B461FEILFXxacDJwVTZxVVFIZHM/view) and I hope the following will help progress the case. I confirm below some of my earlier observations. I also welcome Structural Engineers and Mechanical Engineers and others to further comment.
My approach is to analyse the photos stipping off all the assumptions and conclusions from that report and just focussing on the key observations.
For those less technical, we need to distinguish load bearing components (primary structure) and secondary structure (with minimum load bearing components) – same as the primary walls in a house and the secondary walls.
For the flaperon (imagine it is water flowing down – same analogy), the lift/drag load is normally passed on the honeycomb panel over the exposed surface area then the primary stucture of the component (the aluminum frame of the flareron) then the hinges then the primary aluminum stucture of the wing.
In a nut shell, those panels are not designed to sustain any in-plane loads either compressive or tensile. They are just designed to resist bending due to uniform lift load on the surface (top FRP layer in tension and bottom FRP layer in compression, the honeycomb is basically maintaining the distance between the layers without much strength).Those panels can arguably take a little bit of shear load due to drag forces on the top skin (top and bottom forces in opposite direction) but not much due to limits in the honeycomb strength.
The second thing to consider are the GRP properties. The GRP is very tough in tensile mode much stronger than Steel. In compression mode, it buckles easily and only the honeycomb is preventing this. This is from far the weakest failure mode. If it fails, you will see fibres pulled out link strings on a rope failing under tension. For the skin under compression, you will see sign of compression on the honeycomb but the fibres will have to be pulled out as well. Also, a perfect manufacturing does not exist, there are always delamination (small bonding defects) between the honeycomb and the GRP skin to weaken further the compressive strength.
The hinges are usually much stronger as all the load is passing through them (analogy door hinges).
So you could imagine, if there is a large impact the hinges are expected to fail last. The part of the skin that will buckle is expected to fail first. This report is good to point this out p29 onwards. Failure of the hinges in a high speed impact is odd given it is a strong component. Take a wooden door hinge for instance and imagine you burst through the door, the most likely failure would be on the plywood or screw wood interface but not the hinge itself which is stronger. The way both hinges have failed due to lateral (not vertical) movement in p9 is not expected and merrit a closer examination. Secondly, i would tend to agree that the hinges have been subject to cyclic fatigue. It is hard to confirm cyclic force on p9 but on p7, the hinges appear to have been suject to cyclic lateral forces which are not expected in any accidental circumstances (take door hinges for intance and imagine the hinge fail after 50 times someone is trying to burst through – you can try at home but it is very unlikely to happen). This of course requires a closer look by experts to double confirm. I cannot think myself of any possible lateral force on this part in the first place but a lateral force that will fail the hinges and not the skin which is weaker is very hard to explain. Try with a wooden door and tell me if you manage.
All to say more forensic study is required.
The other issues are:
* the scratches and apparent tampering traces on most photos that for sure did not come from a crash at sea. The source is unknown and most likely occurred before the flaperon was found and after the plane disapeared or perhaps during the investigation.
* the missing rear/ trailing edge of the flaperon. This is also very hard to explain. This part is not expected to be subject to any signigicant forces in any accidental scenario (even if detached mid-air). Even if you assume intentional act onboard, this part will unlikely be subject to any subtantial force.
* the missing plate ID (outside my competence)
* the holes are also not expected. Seawater does not corrode such materials. May need to check with MAS maintenance if they had experience of such holes
Regarding the other debris, i am surprised by the very small size for these particular components. Taking the analogy of stress flowing like water flowing, you would not expect such debris to fail on all the edges in any circumstances even high speed impact. Maybe only penetration impact could do that but unlikely (try to break a sugar cube on all the edges). The shape of the failure edges and the cross sectional failure of the honeycomb (45 deg in some case) is not typical due to the orientation of the honeycomb. Perhaps a specialist in this type of components could provide some light.
I suggest the investigation to discuss the holes issue with specialists in maintenance and re-examine how the hinges and the flaperon trailing edge have possibly failed. Also review the scratches and traces of tampering if anything can be deduced from that taking into account the journey of these debris. An expert in honeycomb composites could also further review the failure patterns.
@HB
Thanks for attempting to simplify a complex problem. You raise some valid points. But respectfully, by focusing on the flaperon, you seem to be missing the big picture.
To extend your analogy :
The problem is NOT “why did the hinge break while someone was trying to open the door”.
The forces weren’t concentrating solely on the flaperon, but acted on the whole structure.
A better analogy would be :
“You find the rubble of a house. In the rubble there’s a door and half of the hinge is still attached, the door itself is mostly intact. What caused the house to break?”
If it were an earthquake, you’d expect the door to be crushed, with the hinges still attached or possibly pulled at the attachment points (the screws). So the cause isn’t the earthquake.
Maybe it’s not a wooden door after all. But a steel door, with soldered hinges, and a steel frame. If it was a tornado ripping through the house, the wind could have broken the windows blown the unlocked door open and shut past maximum free rotation angle of the hinge and it broke.
In the case of MH370 one has to remember that the whole structure disintegrated on impact. How is the flaperon affected when the whole wing breaks?
Or if it separated in the air, is it not possible that the hinge would fatigue before the GRP/honeycomb in case of flutter?
I don’t have answers to these questions. It’s all very perplexing to me. And with only a dozen “bricks” of the house found… difficult to be certain of anything.
@Marijan:
Thanks. Sounds like something Z would have trouble getting into the cockpit without anyone seeing.
Whatever is not communicated on acars messages as long as that was working. Trying if radio was working still after switching off a certain circuit breaker or similar maneuvre is plausible indeed, if in conformity with available data. There could be a couple more options I think.
I am not the master of the relogon; whenever I bring it up Jeff or someone else jumps in and gently directs my thoughts. I have troubles making it stick in my head. But I believe it was said you can’t do that with a switch in the cockpit. The PCB was invented when my brain was in a formative age, and I still grapple with understanding electricity; much (such much) from recent years tends to “pass right through” even when I am fully convinced I was smart enough to understand it.
@Steve Barratt:
Many thanks for that one. Its a first time for me. Remains to see if it is genuine. No discussions around about this single exception to the social media and comm darkness after boarding? Any chance some people are afraid there loved ones become staple illustrations in works of poor journalism for all time to come?
Touching though and a little scary if it is genuine.
@sinux thanks for your feed back
It is a either or situation. For the case of
(1) fluttering: wing beat ng much stronger is not expecte to desintegrate. If hydraulic power is on, fluttering is unlikely to cause any desintegration. If off, Fluttering forces are up and down and the hinges are free to move. Lateral forces i think would be small in comparison with the vertical forces and not be strong enough to cause fatigue on the hinges. That is the main reason i commented above. I would agree it may be worth performing some tests or modelling to further assess the failure mechanism.
(2) desintegration on impact: by definition it is not fatigue. Fatigue failures are visually recognisable. Let us assume the hinges have failed under a single displacement force, the photo implies lateral forces, which ever part of airplane hit first you would not expect the two hinges to fail in this direction. It eould be unlikely.
For the earthquake analogy, i still would not expect the hinges to fail:
There has been some interesting release of Inmarsat communication log files. It seems MH370 did actually make connections to Inmarsat’s Pacific satellite (POR) as well as Indian Ocean Region satellite (IOR). So it would seem it might be interesting to confirm the BFO for the POR satellite as MH370 may have flown towards the POR satellite.
@HB
I tend to agree with you. But I wouldn’t limit myself to two options.
1. Fluttering. Unlikely as you say. The flaperon is free to rotate, so no moment can be created at the hinge base. Flutter could explain the failure of the flaperon edge, but not the hinge, imho.
2. ground/water impact. Also unlikely to me. How does the hinge break without more damage to the rest of the flaperon? Is it possible that the failure line follows a welding line? Could be a weaker spot. Looking at the pictures, it seems to me that the break starts at the front of the hinge then propagates to the back with slight rotation of the flaperon downward.
3. in flight wing failure. This is to me the most likely scenario. High speed dive at the end of the flight leads to overloading of the wing. The wing breaks just after the engine pylon, where the bending moment to wing strength ratio is the highest. One hinge is connected to the “plane body”, the other to the “failed wing”. The hinges then fail in a mix of tension and torsion. Leaving what’s left of the flaperon mainly intact.
4. I’m sure there are other failure modes. I just can’t think of a good one right now 😉
@Sinux, HB. I had a look at the flaperon sequence a couple of months ago, just a part of this.
The ATSB has shown it is likely that the flaperon and the retrieved outer flap part both separated from the wing when retracted.
From my estimation the flaperon would have separated immediately if its trailing edge had departed in flight. This separation could not have been from the retracted position.
That would be from its centre of lift shifting forward and drag increasing. Hence the composite aerodynamic loading line of action would move forward of the flaperon hinge enough for the consequent tensile force on the one active flaperon actuator to extend it, increasing aerodynamic loading. The loading would increase as the flaperon rotated rearwards and it would break away.
IF both hypotheses are right, the trailing edge could not have separated in flight ie in flutter.
https://www.dropbox.com/s/i4bygiic796opn6/Right%20flaperon%20separation.docx?dl=0
@Johan said:
“Is the idea that the culprit has a device with him which can be turned off and on, and that he is testing it when making the call? It should jamm all communications, perhaps even among passengers?, but it doesn’t work for the radio at that point yet? ”
Why try to jam aircraft comms with a blocker when you can simply turn them all off from the cockpit? Simples, and you absolutely know nothing’s getting through that way. Not to mention the problems you’d have with the Faraday effect and the VHF/HF aerials being on the plane’s underside, roof and tail with no direct line of sight through a window.
Blocking the passengers’ cell phones *inside* the aircraft is different: cell phone blockers have a limited range depending on size/power/battery size, one small enough to pass through security as a normal handheld or table ‘radio’ (or as a ‘broadband router’, more likely, given the multiple aerials) would likely be limited to 50 metres or less and so need to be placed centrally in the plane to cover all 79m of it. In fact, the overhead lockers above where the Ukranians were sitting are about halfway and would probably do fine. Those seats are also very handy for the door to the crew rest area in the hold.
Here’s an example of what they look like – click the ’30-40m’ or ’50-80m’ effective radius filter on the top of the page:
http://www.jammerfromchina.com/categories/Mobile_Phone_Jammers/?o=40
@SteveBarratt said:
“Allegedly Mohamad Sofuan Ibrahim 33yo tweeted this selfie from within MH370 prior to departure from KL on 8th March 2014;”
In this scenario, the passengers’ cell phones would work onboard until the person(s) with the cell blocker boarded, or until it was turned on. If placed in luggage in the overhead locker, the last opportunity to turn it on might have been push back (seat belt lights go on); the next opportunity just after top of climb (seat belt lights go off). If in someone’s shirt pocket, then on boarding or at any time after, but the units are a fair size for a 40m-50m radius range – not likely to fit in a pocket. The blocker might have been in the hold (composite floor structure might allow penetration) but might not have been as effective – bit of a chance to take unless you can test it first. Some blockers come with a remote control. Next: out of (up to) 239 cell phones on the aircraft, explain why the FO’s cell phone was allegedly the only one detected at Penang.
@HB said:
“In a nut shell, those panels are not designed to sustain any in-plane loads either compressive or tensile. They are just designed to resist bending due to uniform lift load on the surface (top FRP layer in tension and bottom FRP layer in compression”
Surely if it’s a bending moment around the hinge mounting points (ie bending upwards) the bottom panel will be in tension and the top in compression? The flaperon panel is only fixed at one end. As an example, think of placing a load acting downwards at the end of a cantilever: the top surface of the cantilever would be in tension, the lower surface in compression. The effect you describe would be seen if both ends were fixed, as in a bridge structure, or on the main body of the wing (where both ends of the lower wing panel are fixed).
“It is a either or situation. For the case of
(1) fluttering: wing beat ng much stronger is not expecte to desintegrate. If hydraulic power is on, fluttering is unlikely to cause any desintegration. If off, Fluttering forces are up and down and the hinges are free to move.”
If fluttering without hydraulic power, the flaperon might well hit the hinge stops top & bottom. Repeated, and with force, that might be enough to detach the hinges or fracture the metal they’re mounted to. Bend a piece of metal repeatedly and it will break.
Not that I think it did come off in a dive.
I need time to digest all of these.
@PS9, you are right the top layer should be in compression i did not pay attention to the actuator pin location.
I agree there could be more scenarios but i not sure if wing desintegration is likely without some other induced failure. The ATSB argument for retracted position is based on the guiderail failure mode. Worth having another look at this. I doubt any of these will lead to cyclic failure though in the horizontal direction
@HB
Cyclic failure in horizontal (and vertical) direction could imo also happen when control surfaces like a flaperon hit the water surface under low angle of attack hitting wave after wave under great speed.
A kind of ‘flutter’ could occure due to the cyclic stresses from hitting and releasing those wave-forces while plowing through the water surface.
@David
Very interesting paper. I also think fatigue of the FRP due to fluttering of high speed descent is unlikely. FRP is very resistent to fatigue damage. I really cant associate an accidental scenario with that trailing edge damage..
The other ther issue is whether the hinges experienced fatigue or yield.
@David
Nice job on the flaperon hypothesis. Give me the bottom line if you are correct, are you saying like Ge Rijn maybe the flaperon came off on hitting water or pull up out of a dive? I am having trouble with the high altitude descent theory as far as flight path and end location.
@Ge Rijn
In case of wave impact, if at all this piece fails, my expectation would be to have the FRP composite failure not the hinges. Also here it wont be fatigue. You would expect over 20 cylcles at least to get fatigue. In fatigue failure a crack would form and propagate reducing the strength like for brittle materials as opposed with a yield failure. If you bend a fork 5 to 10 times it will fail and this failure is yield failure. Yield failure is visually recognisable. In a shallow angle hit scenario you describe, yield failure is possible but fatigue is very unlikely. If hinges fail in a first place it should be a yield failure but i think the FRP will fail first.
Aluminium is a ductile material and can sustain a lot of plastic deformation before failure ie it is highly resistent to impact. A fatigue failure should be easily recognisable on that basis.
Composite materials have very specific properties: they have a very weak resistence to impact and their strength is only along the fibres.
I personnaly think the hinges failure are not compatible with this scenario however the trailing edge damage may be. maybe this could be one possible explanation for trailing edge damage but this raises a few questions regarding the hinges.