VolaBologna Forum

Venerdì scorso un 77W di SQ in volo sulla CDG-SIN ha effettuato un atterraggio di emergenza a DEL: http://airlinersindia.s4.bizhat.com/...ic.php?p=39938

Ennendoci stati 14 episodi del genere in 10 mesi, di cui 9 per In-Flight Shut Down (IFSD), su A.net si è aperta una discussione in proposito, ovviamente non sulla sicurezza della macchina ma su eventuali penalizzazioni nella certificazione ETOPS. I forumisti più esperti hanno concluso che, per per avere problemi di quel tipo, sarebbe servito circa il doppio di episodi nello stesso periodo.

OldAeroGuy dice che:
There have been 136 773ER's and 19 772LR's delivered. These are the sole users of the GE90-11XB.

Of these 155 airplanes, 82 were delivered over a year ago and 73 were delivered from April '07 thru Mar. '08 (12 months). The delivery rate was about 6 per month.

Good utilization is 4000 hours per year.

Flight hours for the past 12 months would be:

(4000/12)*12*(82+6) = 35200
(4000/12)*11*(6) = 22000
(4000/12)*10*(6) = 20000
(4000/12)*9*(6) = 18000
(4000/12)*8*(6) = 16000
(4000/12)*7*(6) = 14000
(4000/12)*6*(6) = 12000
(4000/12)*5*(6) = 10000
(4000/12)*4*(6) = 8000
(4000/12)*3*(6) = 6000
(4000/12)*2*(6) = 4000
(4000/12)*1*(6) = 2000

From May '07 through the end of April '08, the 773ER/772LR has 484000 flight hours.

This means the GE90-11xB has 968000 operating hours.

For 207 min ETOPS, the minimum IFSD requirement is .02 per 1000 engine hours or 2*10-5.

For 968000 engine hours, the number of allowable IFSD's are:

9.68*10+5 * 2*10-5 = 19.4 or 19 IFSD's in a 12 month period.

The GE90-11xB could have twice as many IFSD's as those reported above and still maintain 207 min. ETOPS.

Iceman2 conferma:
The 777-300ER/-200LR (GE90-115B powered) fleet has had 14 diversion or air turnback events over the last 10 months by my records. Of these 9 were IFSDs. That makes the IFSD rate for the GE90-115B fleet about 0.01, based on ~ 1 million engine hours over the last year.
That rate is short of the ETOPS guideline of 0.02, however some individual operators may be getting near that level.
Industry average IFSD levels for long range aircraft generally run at below the 0.05 level, so the -115B is having a bad run based on that level.
By all accounts the problems the -115B engine is having are fundamental mechanical failures, several different issues.

The engine went a while in service without any events, so this run is quite a contrast.

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ElevenInShadowsTDODT by fabio braghini, su Flickr

Sarà un sabotaggio per far tornare in auge i quadrigetti...

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"Ma che dici? ,allora perchè non vietare i ciclisti i motociclisti gli automobbilisti gli ecsursionisti i camioni e più ne più ne metta , col quelli l'ambulanza viene pure e la paghi pure"

giran voci che la AVIO che produce dei pezzi e nei casini...

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ElevenInShadowsTDODT by fabio braghini, su Flickr

Ahia!