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| QA1
June 22, 2025, 17:01:00 GMT permalink Post: 11908688 |
From a presentation I was given when the 787 came into service, it states that the RIPS only supplies the CVR section of the fwd EAFRs. IIRC this was stated in an earlier response. If both fwd and aft EAFRs have lost power with the RAT in operation, am I correct in thinking there is no flight data to record \x96 hence only the CVR is powered?
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| Kraftstoffvondesibel
June 22, 2025, 17:50:00 GMT permalink Post: 11908714 |
SLF here. Mods - please delete summarily if this does not contribute to the discussion, I have no wish to waste anyones time. No 'AI' was used in the preparation of this post.
My understanding is that, as you say, the CAM has a preamp. That preamp can be powered by the RIPS that accompanies the forward EAFR. In addition, I believe there is a single analogue connection from the CAM+preamp to the aft EAFR in addition to the analogue connection from the CAM+preamp to the forward EAFR. I believe, but am not sure,that the other flight-deck audio (headsets) is carried digitally over the fibre-optic network to the aft EAFR. The network may or may not be in operation in the event of an electrical failure: I simply don't know. The publicly available information I can find is not stunningly clear about this. AEROSAFETY WORLD, January 2008 - https://flightsafety.org/asw/jan08/a...47-48.pdf?dl=1 GE Aviation: Consolidate and increase recording power with the 3254F EAFR. - https://www.geaerospace.com/sites/de...rder-3254F.pdf As for power, this NTSB document describes the power set-up for the EAFRs https://data.ntsb.gov/Docket/Documen...ort-Master.PDF So the forward EAFR is powered from the left 28V DC bus with the possibility of being powered by the RIPS, and the aft EAFR is powered from the right 28 V DC bus. What I have been unable to determine is whether the right and/or left 28 V DC buses are powered from the main battery in case of failure of the AC power supply. To my untrained eye, it looks like the Captain's flight displays are powered from the main battery in extremis (28 V DC - C1), but that there are various circuit breakers, that could be automated, that may or may not allow or prevent other loads (such as the F/O's flight displays (28 V DC - C2), or the aft EAFR, being supplied by the main battery, (See link to diagram). There could well be very drastic automated load shedding. https://kb.skyhightex.com/wp-content...l-1024x640.png If the right 28 V DC bus was unpowered for any period, it follows that the aft EAFR was not recording for that period. This would make the forward EAFR important in case of a power failure that prevented the right 28 V DC bus from providing power. All the information that is unclear to me will be transparently clear to the crash investigators. But it seems to me that the aft EAFR will not hold data for any period that the right 28 V DC bus is not operating. Whether that applies to this incident is an open question. Having two combined recorders is already more backup than what had previously been the norm, in addition theres the independently powered area mic going analog to the front recorder. The common models I have checked the sheets for also provides a digital output (which is probably sent to the aft recorder via normal busses. Having a seperate analog line going to the aft recorder would be several Kg of extra weight, and probably a substantial amount of loom design and paperwork for what is then a backup to an already redundant system. Hence, imho why this signal only goes to the forward recorder. It is already a \xabbonus\xbb. The power for microphone and preamp is in the >1watt range range, completely insignificant. I am still interested in reliable information as to what is expected to be on the recorder of an aircraft which has lost the generators, what about the battery powered prinary instruments? Does some systems and the aft recorder come online with the RAT or would everything be down to the one cockpit mic? Surely not? |
| Senior Pilot
June 26, 2025, 16:01:00 GMT permalink Post: 11911339 |
https://www.pib.gov.in/PressReleseDe...x?PRID=2139785
Status Report on recovery and examination of data from Black Boxes – Air India Flight AI-171
On the evening of 24 June 2025, the team led by DG AAIB with technical members from AAIB and NTSB began the data extraction process. The Crash Protection Module (CPM) from the front black box was safely retrieved, and on 25 June, 2025, the memory module was successfully accessed and its data downloaded at the AAIB Lab.The analysis of CVR and FDR data is underway. These efforts aim to reconstruct the sequence of events leading to the accident and identify contributing factors to enhance aviation safety and prevent future occurrences.
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| D Bru
June 26, 2025, 21:39:00 GMT permalink Post: 11911519 |
https://www.pib.gov.in/PressReleseDe...x?PRID=2139785
Status Report on recovery and examination of data from Black Boxes \x96 Air India Flight AI-171 Note the front EAFR is the one with RIPS battery backup. 1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss; 2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake. Regards, D Bru |
| grumpyoldgeek
June 26, 2025, 21:58:00 GMT permalink Post: 11911531 |
Thx, this indicates at least two issues:
1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss; 2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake. Regards, D Bru |
| D Bru
June 26, 2025, 22:05:00 GMT permalink Post: 11911534 |
Really, Grumpy? If aft EAFR (not RIPS supported) would have had any data/voice after elec failure following T/O, I think the AAIB would have been more than happy to extract everything from that one since it was found earlier and most likely more intact than the front one. Regards
Last edited by D Bru; 26th June 2025 at 22:17 . Reason: Sorry but I didn't want to sound too "grumpy" ;) |
| EDLB
June 28, 2025, 08:26:00 GMT permalink Post: 11912392 |
If someone is interested how much detail in the EFARs is stored the 2013 B787 Japan Airline battery incident is a good example.
https://data.ntsb.gov/Docket/Documen...man-Master.PDF
Given the wealth of data and the 10 minutes RIPS supply for the forward EFAR the investigation body should by now have a good idea how the events unfold. |
| D Bru
June 28, 2025, 17:04:00 GMT permalink Post: 11912578 |
I am not certain on that. Remember the 737 didn't have them on the standby bus (Jeju). The NTSB doc states they're powered from the L/R 28VDC buses on the 787.
This shows the centre TRUs can only power the instrument buses not the L/R DC buses, the RAT can't really power the right TRU without powering both R1/R2 buses, and powering the left TRU would require powering the left 235/115 ATU which would probably be a lot of magnetising current even if not much actual load. The contactor naming supports that. My money is on the L/R DC buses being unpowered in RAT operation; only the CA/FO instrument buses and the 235VAC backup bus. Last edited by D Bru; 28th June 2025 at 17:06 . Reason: deleting a repeat image of the elec system |
| AAKEE
June 28, 2025, 18:19:00 GMT permalink Post: 11912613 |
Not useless
much netter than\x85nothing. Thats most certainly the background to the new regulations to battery backup. |
| EXDAC
June 28, 2025, 18:53:00 GMT permalink Post: 11912625 |
FAA requirements and the discussion/changes that resulted from the initial NPRM here - https://www.federalregister.gov/docu...er-regulations |
| DaveReidUK
June 28, 2025, 19:10:00 GMT permalink Post: 11912632 |
However you are correct in that the requirements only specify that the CVR functions and the CAM must continue to operate. |
| PJ2
June 28, 2025, 19:12:00 GMT permalink Post: 11912634 |
That's exactly why I would really recommend reading through the NTSB FDR report on the 2013 JA829J Boston incident helpfully posted by
EDLB
. There's potentially a wealth of data concerning a to me at least surprisingly number of 2000 of parameters written on a 787 EAFR, that is that at least if there's elec power. Even the 10 min RIPS is useless if there's no data sent from electrically shut off systems.
Auxiliary Power Unit Battery Fire Japan Airlines Boeing 787-8, JA829J Boston, Massachusetts January 7, 2013 |
| D Bru
June 28, 2025, 19:17:00 GMT permalink Post: 11912637 |
The requirements I have seen indicate that RIPS is applicable only to CVR or the CVR function of an EAFD. If you are aware of any requirement for RIPS to support flight data recording would you please provide a reference.
FAA requirements and the discussion/changes that resulted from the initial NPRM here - https://www.federalregister.gov/docu...er-regulations Yes, possible electric failure on the eafr is of course a totally different story concerning voice recording |
| EXDAC
June 28, 2025, 19:40:00 GMT permalink Post: 11912643 |
"The front panel contains one connector, J1, and a grounding stud. • J1 provides the main EAFR power supply, Aircraft Data Network, Ethernet Channels A and B, analog audio input, input and output discretes, and other miscellaneous signals." If RIPS is external and the GE EAFD only has a "main power supply" pin then I agree it seems likely that the flight data function is powered by RIPS. For RIPS to power only the CVR function I would have expected to see separate main power and RIPS power input pins. I could not find any data except the two page marketing brochure which is not definitive. |
| paulross
June 29, 2025, 14:23:00 GMT permalink Post: 11913058 |
AI171 Thread by Subject
I have rebuilt the site that organises this thread by subject here:
https://paulross.github.io/pprune-th...171/index.html
Main changes:
Raise issues here https://github.com/paulross/pprune-threads/issues or PM me. |
| nnc0
June 29, 2025, 15:01:00 GMT permalink Post: 11913074 |
By the time you're down to EMER GEN you usually know what the problem is and most systems with parameters that could be recorded on the FDR are unpowered so what's the point of trying. The CVR with a RIPS at least helps us to try understand how or why the events to regain control after that failed.
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