Black Boxes Failed Minutes Before Jeju Air Crash

The B-737-800 pre 2010 build had both the CVR and FDR wired to the L &R AC electrical buses………not the Battery or Emergency Battery bus which was incorporated on later 2010 and subsequent models. So if the bird strike caused the right engine to compressor stall and flame out or only produce partial power AND in the overshoot, it’s possible the crew shut down the wrong engine. This would assume the right engine wasn’t producing any electrical output ( a wild possibility if the engine was still running even at idle) then all AC power would have been stopped. The crew did not start the APU and the aircraft from what I gather was not equipped with a RAT. So a double engine failure requiring an immediate return to land (quicker on the opposite end) and failure to manually drop the gear. Slats/flaps may have been inop due to complete engine/electrical failures or not attempted due to glide distance required to make the runway. IMO, just thinking out loud on a Saturday.

No, the black boxes didn’t fail. The black boxes lost all sources of electric power, and as a result, stopped recording. As further explained by highflyer.

I don't understand how the APU didn't just start automatically start without crew involvement....

Far back in the early 90s, (My Rockwell Intl days) I was involved in a study of the B737 electrical distribution system (my task was count the wires and weigh them from the 1600-page microfilm record Boeing gave us from a build of 4 -300s i think to a European Airline in the 1990s.) My car-pool mate's job with others was to reverse-engineer how it worked using wiring diagrams of the power relay contactor and aux-contactors on the power busses.

2 busses:
Left non-essential loads buss, driven off Left essential load buss, driven off left generator
ditto right.

if an engine generator failed, 1) BOTH non-essential load busses were dropped; 2) a transfer contactor between the essential load busses tied the essential busses together; and 3) the combination of aux contactors told the APU to WAKE UP and spin up its generator, (so that it could be auto-tied into whichever essential buss generator had failed.) (then the system re-energized the non-essential busses.)
if ANOTHER GENERATOR (or APU) let go, the surviving generator picked up ONLY the essential loads and the VCRs, seat phones, etc (this was the 90s) went dark with 1/2 the lights probably.
(and if ANOTHER ANOTHER generator failed, the battery had an inverter on it for about 1/2 hour of flight instruments for the Pilot, with 1 hydraulic motor and 1 radio. I think that was the "critical" buss.)

THIS WAS ALL DONE with 3 phase Contactors, aux contactors and wire. NO computers, no SW. think KISS... (Keep It Simple & Stupid). there was so much redundancy because other than light bulbs, the generator/drive trains for them were the most failure-prone system on the aircraft.

SO I ask again: Unless the system has been "improved" since the '90s into non-operation or something failed or was set to disable it, why no APU?????

Blancolirio has made the case for Boeing not changing the backup power supply arrangement for the flight data and voice recorders the possibility that it might have required a change in the aircraft type certification.

This is why RIPS (Recorder independent power supply) should be mandatory by all regulatory authorities and not constantly be extended by regulatory authorities… if both engines and power were lost means no hydraulic pressure to systems. How were the thrust reverser deployed as shown on the video?? The gear emergency extension is purely mechanical and will free fall, why wasn’t the gear extended to slow the A/C down? Something smells fishy here.. why is there no information posted on who these pilots were and time on A/C type? No (CRM) Crew Resource Management is a big problem in these regions including Russia, Africa, Central Asia being a witness sitting jump seat in the cockpit… High power-distance has been known in many A/C accidents as the root cause. Someone is hiding something, Too much redundancy and safety measures in aviation for unanswered questions in todays aviation world.

I can't see why the crew didn't drop the landing gear. They were landing on the airport runway, not in a field or on water. At least with gear down wouldn't they have brakes?

Were there communications with the tower in the last 4 minutes? Why no mention of this?

Dan Gryder, on YT, has an interesting opinion. He believes the puff wasn't a compressor stall but a release of the Halon bomb, possibly on the wrong engine, or both. Which would kill all electrical power on the given engine(s).

I'm an aviation fan, not a pilot... I'm amazed with the importance of the black boxes, they don't have their own batteries? Yes, batteries = potential fire? but if the engines stop / lots is going wrong, the black boxes are bricks? Or just in older models?

My best thoughts are the crew got saturated and screwed up the checklist killing electric. Things compounded scaring the crew into landing at all cost. Or, an electrical issue like smoke in the cockpit from a battery issue expanding into toxic fumes. Cascading events induced by pilots #1 cause of accidents.

I guess it's too hard to have a separate network attached storage receiviing data from a flight recorder. NAS has only been around for 20 years or more. Of course ICAO would object to the cost. So splat the only device and splat the data. Better still, have automatic data over radio to ground stations via satellite, you know, just like hikers have.

The CVR and FDR were DEI acquisitions. What did you expect?

Suspicious... Breakers Pulled... For both to fail is not likely!