Posts about: "CVR" [Posts: 96 Pages: 5]

That picture of the mostly intact tail section should indicate that the FDR and CVR should be eminently recoverable, most likely not even damaged, right?

Assuming we're not facing a repeat of the Boeing 737‑800 crash at Muan International Airport when loss of loss of both engines apparently also cut power to Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR)

787 gear and flaps/slats are both on the centre system, powered by 2x big electric pumps and no EDPs, so retraction should be minimally impacted by engine failure assuming electric power was still available and reconfiguration worked. Note the 787 has two generators per engine so generator failure is also unlikely to contribute, unless both engines failed taking out all four generators (and presumably no APU running).

From that thread, I believe it was discussed that on most/all other large transports, deploying the RAT re-powers the CVR/FDR. The 737 didn't have that happen because no RAT. You may still get a few second gap while the RAT deploys.

The 787 has 2x Enhanced Airborne Flight Recorders (EAFR), which each record both cockpit voice and flight data. I expect they are also fitted with the dedicated batteries that the Jeju was a year or two too early to require. Per the NTSB , the forward recorder has a 10-minute backup battery.

Hopefully flight data is not going to be an issue for this investigation.

The suggestion is that the buzzsaw/propeller sound is the RAT; it does sound a bit like an interference pattern, but you don't get the engine roar with it.

It's also maybe visible in a few stills (e.g. post 64).

True. We won\x92t know until the CVR and Flight Data recordings have been analysed. I think these will give a clear indication of what happened. The airport has reopened so I assume there\x92s no fuel contamination risk.

Very sad day, let’s hope that the investigation is thorough and lacking any “political” or “cultural” interference, the aircraft sounded very quiet to me on the video…but it’s just a video, the DFDR and CVR should reveal all.

From the airport CCTV video it looks to me like a normal takeoff and start of climb, until suddenly there's a loss of climb performance with no obvious upset at that point. From the picture of the wing post crash it looks like the flaps were still deployed (N.B. based on pre-accident photos that's the right wing so closest to the camera is aileron and flaps are further away, damage had me confused first time), so I'm going with loss of thrust rather than flap retraction.

From the videos from bystanders it looks like RAT deployment (both sound and zoomed in pictures) rather than thrust lever retard, and that would also explain failure to retract gear - if you are dealing with both engines out at that altitude then gear isn't your first thought. From the airport CCTV video I don't see anything that looks like bird strikes at that point in the climb i.e. no obvious flocks of birds, no smoke out of the engines, no slewing one way as one engine fails and then the other is cut by accident - plus you wouldn't cut the engine at that point, you'd climb on one engine and then sort it out.

Even fuel contamination or water build up in both tanks is likely to result in one engine failing a few seconds before the other. So I can't come up with anything other than both fuel cutoff switches that would result in loss of thrust and RAT deployment. Looking at a picture of the cutoff switches https://www.nycaviation.com/2013/08/...is-fired/30179 I don't see how they get hit by accident.

I'm confused, hope we get an FDR / CVR readout soon.

The Dreamliner as two identical “Enhanced Airborne Flight Recorders”, one in the tail section and one beneath the flight deck. Each one contains the CVR + FDR in one module, both have 10 minutes of battery power backup. I see reports that the one in the tail section has been recovered. All to easy to surmise the contents will be tampered with at the request of politicians/investors

It's fine that the \x93Enhanced Airborne Flight Recorders\x94 have 10 minutes battery backup. If the bits of equipment/sensors sending data to be recorded don't have power, you will be recording 10 minutes of silence/blank data.

The concept of powering 'critical (sensor) equipment' has been floated - the problem being that it must be possible to power down malfunctioning equipment in case of fire - real or suspected. Having independent power supplies and battery back-ups all around the airframe, each with an ability to lose their magic smoke, is a poor idea.

Commercial passenger jet aircraft already have robust power supplies with multiple generators and emergency battery support. However, if one malfunctions, rather than fails completely, it can be difficult to decide which one to disable, as it can cause problems in all systems.

Especially when the video is clearly taken on the ground, when you could easily expect source switching due to shutting down an engine for single-engine taxi, then switch to APU, then ground power.

IIRC the CVR battery (in this case EAFR battery) is required to power at least the cockpit area microphone, if not the pilots' mics.

Once the RAT deployed at least some data should have come back.

This has been discussed upthread and has happened before (on a 777 IIRC) but did not result in a crash.

It does not explain the RAT and generally you would expect crews to shove the thrust levers fully forward.

It looks like you recall correctly. This skybrary PDF document "Fade Free Memory" describes the EAFR

https://skybrary.aero/sites/default/...shelf/2955.pdf

I quote from it:
That seems to indicate that as long as the forward EAFR is powered, the datastream from the cockpit area microphone will be available to both EAFRs (assuming the network to the aft EAFR is available and working).

The whole document is worth reading to glean more details.

Having experience of many crash sites over a long career, taking off without flaps with the config horn/ warning blaring (or not if u/s) is a possibility Also selecting flaps up, instead of gear up at the positive rate of climb call, is also not unheard of and has happened. Both engines failing/ losing power at rotation/ initial climb out would be extremely rare, but not impossible. With the descent and lack of climb clear, unless a mistake of retracting flaps instead of gear, why wasn't the gear selected up as dragging that around is only going to end one way.
he sound from the well documented video would suggest the engines were running, but were certainly not selected to TOGA/ full power which you might expect when faced with high buildings growing larger in the windshield.
Due to the tail section being relatively intact, the CVR/ DFDR will be downloaded very soon, if not already, so we will all know shortly....

I can't tell you off the top of my head. I was an engineer at final assembly (mostly final body join and functional testing) and then did support for airlines post delivery (working with their engineering teams on maintenance and operation) so I wasn't intimately involved in anything data wise on the FDR. My personal belief is that it should end up being glaringly obvious why the engines stopped working with the data they have, just to many coincidences happening at literally the exact same time for it to be some minuscule problem never envisioned before. Pretty sure FDR and CVR will tell all.

Bit surprising that we don't have confirmation of the 2nd FDR recovery by now, especially with the seemgly realtively intact tail section. The
DFDR was reportedly recovered from this rooftop:




The CVR can't far away and muss be a rather high priority search item.

Interdentally I have read some reports mentioning a DVR (Digital VIDEO recorder). Is AI fitting such devices in their aircrafts ?

Are the FDR and CVR not combined in the 787? (One in the front and one in the tail, but recording the same info??)

Or he may have heard the RAT spooling up. Valuable as a witness account may be, we’ll have to wait for FDR and CVR data and/or wreckage analysis before drawing conclusions.

A preliminary report is supposed to be published within 30 days.

But I would fully expect some findings from the FDR and CVR analyses within the next few days, given the high profile of the accident and the fact that operators of 1000-odd 787s are waiting anxiously in case there turns out to be some previously undiscovered failure mode that could affect their fleets (though that's highly unlikely IMHO);

One has to assume the second blackbox will now just be used as a confirmation of data from the first one? In the 787 they're combined units (EAFRs to be precise, combining FDR and CVR) and effectively duplicated, with one at the front and one at the back.

Yes, the media (not only in the quoted article) are still having trouble with the concept that the 787 doesn't have a separate CVR and FDR.

Hi tumtiddle,
yes, I do read all the posts in any thread from the start and noted that it is basically just a dupe in this case, but many posters do not seem to do so and even just a little upthread (and also in lots on news media even currently) it has again been mentioned that only one was reported found, as if that would be a disavantage. Just wanted to add it to the thread clearly, for those of us who read all posts!

Good point. In the survivor's narrative, the sequence is: 5-10s after takeoff -> plane seemed stuck in the air -> green & white light came on -> they "gave race for more takeoff" (revved up) -> entered straight into (hostel).