Rolls Royce Trent engine surge vs severe damage
 

The Trent powered 777/787s have an engine surge EICAS message as an aid to diagnosis. There are severe damage conditions whch could also be expected to caused surge conditions. My question is would the surge EICAS be inhibited in this scenario? Very limited 787 FCOM guidance on severe dmage symptoms. Thanks in advance.

No RR guys able to comment?

belongs to the aircraft guys, what instruments mean and how to respond

Not on the ones I fly (777 Trent 895); there may be on the 787? RR engines often have automatic relight/surge control.

Both the Eng Lim/Surge/Stall and Eng Svr Damage/Sep checklists on the 777 are unannunciated, which means you have to do the diagnosis and selection yourself.

In terms of severe damage, with most engines I’d be looking for things like no rotation in any of the spools, bad vibration, missing engine parameters, etc. Loud noises, flames and the like can be indicative of surge/stall but to get to that point the engine has often suffered a fair amount of damage. The Lim/Surge/Stall checklist will lead to shutting it down if the conditions persist and if in doubt you can always call for the Svr Damage/Sep checks...

I don't know for sure about the Rolls Trent, but on the GEnx, the EICAS engine surge indication means that a continuous or multiple stall condition exists (three or more surge/stall events within 30 seconds) - it would not be displayed for a single surge/recovery.
I'd be mildly surprised if the Trent 1000 logic is meaningfully different.

In that case, the FADEC logic in theory would set a fixed bleed schedule to partially recover the engine albeit with increased EGT (needing to be monitored).

In actuality it's a fail safe condition limited by the capability of the turbine to sustain the increase in temperature over time

I have no idea if this is the subject of the OP nor if this applies to any specific engine mentioned in this thread above.

Lomopaseo, the FADEC does have surge recovery logic, that's why there is no message for a single surge - no crew action is required. The idea is that if the surge/stall doesn't clear or keeps repeating, there is something more seriously wrong with the engine so you tell the pilot they need to do something.

tdtracer

I agree with what you said, I was expanding this a tad to include that after multi surges in a period of time the FADEC could employ a different logic which latches bleed(s) open permanently to prevent the engine from repeating the same old acel-line surge condition for an assumed failure condition (like bird damage).

I expanded this a bit just in case that might be part of an answer to the OP

RMC - How about this...

Surge EICAS - Follow memory items (end with thrust lever idle)

If it hasn't calmed down continue with the eng severe damage/sep cx...