777 Wiggly Amps Major Glitch

[barkingmad]

http://avherald.com/h?article=4c1cc3f6&opt=0

Any triple (ex) drivers on this forum seen and understood this one?

Implications that QRH mishandling or misunderstanding played a part but things have gone quiet.

Boeings design offices night-time electricity bill may be showing a spike or few over this winter, not due to a cold snap??!!

[Slasher]

Have sent the link to a 777 Texan capt mate of mine who's with my old mob in the Gulf Mr Mad. He knows the bloody aeroplane inside out and sideways. I'll let you know the contents his reply.

[barkingmad]

Thank you Slasher for that, as usual sharing knowledge might help out someone else unlucky enough to meet such a defect even if there might have been a HF contribution.

Somewhat surprised at the lack of response to this one both here and elsewhere.

[barkingmad]

Of course most if not all 777s are ETOPS capable and employed as such.

Would that be the reason for the deafening silence on the topic of electrical system integrity?

[ian16th]

Of course most if not all 777s are ETOPS capable and employed as such.

Would that be the reason for the deafening silence on the topic of electrical system integrity?

Are not some fitted with RR Trent's subject to a limitation at the moment?

[Fox3WheresMyBanana]

Thanks barkingmad, very interesting. I would guess the silence is because this is a complicated one to work out. I suspect they reset the CBs after the incident, did checks, and everything worked. Presumably so since the airframe is back in service.
Power surges in a particular component can sometimes cause cascade failures like this, although the system is supposed to be designed to avoid same. Sometimes odd environment conditions and/or CB manufacturing tolerances can contribute that normally aren't a factor. It may take quite a while to work out what, and there's no guarantee Boeing will, or that it will ever happen again. Boeing would ideally like the whole airframe to run diagnostics on, but there's no chance that'll happen.

[Slasher]

Sorry Barking - to date there's been no reply from the Texan skipper. Scuttlebutt says he's on vacation and I know he turns off all social media associated with work when he does. His Whatsapp shows one tick only. I could email him but I don't think it's serious enough to warrant that.

I posted on the 320 Whatsapp expat group the same question if they could pass it to the 777 group, which one of 'em did. I also posted same to the Boeing guys who haul in my 'shine to BKK. Again no reply as yet from anyone. Maybe they're as stumped as we are. The 777 instructors here haven't heard of the incident but say they might look into it.

I'll post something here if I get a reply from somebody qualified.

[barkingmad]

Thanks for your efforts Slasher. I have to wonder why the lack of info on this one and my paranoia says someone somewhere is trying to hush it up.

Plenty of material in T O P though.

[Slasher]

Ok the Texan replied to the question. You have to refer to the EICAS system display below.

IMG_1976.JPG (88.83 KiB) Viewed 283 times

There was an existing short somewhere between the R backup gen and L R XFR buses. This caused the bus C/B tripoffs of which caused the R Gen Ctl to be not accepted on the busses. The APU in this case should've taken over all busses but the short prevented this.

After landing all gens give way to APU priority and powered all busses after the Bus C/Bs were set. The fault was a short in the distribution somewhere between the R Backup gen to L XFR and R XFR busses.

It might be the PIC didn't request feedback on the cause and the incident was left at that. The Texan said he had similar once in the 777 to Cairo but the APU gen was ok carrying the L busses in his case.

[Slasher]

Forgot to add he mentioned no such system-wide failure has occurred on any other 787. In his case he noticed that both batteries were showing a discharge which meant the batts were supplying the Essential AC bus via a static inverter. Everything else was ok. The 'smoke' the pax smelt was probly coming from the MEC as the racks inside got a bit hot prior to the buses tripping. Not smoke but an electric smell.

[barkingmad]

Sorry to be pedantic Slasher.

(My brain was seriously modified by RAF CFS back in '79!)

Didya mean "any other 787"?

[Slasher]

Sorry...I meant to say 'any other 777'.