Grave inconveniente a B747-8F Airbridge Cargo

[albert]

Grave inconveniente ad un B747-8F Airbridge Cargo in volo tra Mosca e Hong Kong, che per ingestione di ghiaccio in alta quota ha subito danni ai motori #1, #2 (entrambi hanno subito uno stallo), e #4.
Rosaviatsia ha aperto una inchiesta.

http://avherald.com/h?article=46679ba1&opt=0
"Incident: Airbridge Cargo B748 near Hong Kong on Jul 31st 2013, both left hand engines surged at same time, one right hand engine damaged too
By Simon Hradecky, created Tuesday, Aug 6th 2013 17:24Z, last updated Wednesday, Aug 21st 2013 16:54Z


An Airbridge Cargo Boeing 747-800, registration VQ-BGZ performing freight flight RU-349 from Moscow Sheremetyevo (Russia) to Hong Kong (China), was enroute at FL410 about 80 minutes prior to estimated landing when both left hand engines (GEnx) surged simultaneously, engine #2 (inboard) temporarily shut down and auto-started again. The aircraft continued to Hong Kong for a safe landing on all 4 engines about 80 minutes later.

Rosaviatsia reported on Aug 6th 2013 that the aircraft entered a zone of dramatic temperature fluctuations, the temperature changing between -53 and -33 degrees C, when the engines surged, #2 spontaneously shut down and auto-started again without crew intervention. Both engines received damage to high pressure compressor blades.

In a safety message to operators released on Aug 20th 2013 Rosaviatsia rated the occurrence a "very serious incident" reporting that engines 1,2 and 4 were affected. Ice accumulated on unheated parts of the high pressure compressor in unpredictable and poorly understood meteorological conditions leading to the disruption of air flow inside the engine causing surges of the left hand engines. The flight was continued to destination, a post flight examination showed "unacceptable damage" to the high pressure compressor blades of engines 1,2 and 4 (both left and outboard right hand engine). Rosaviatsia is investigating the occurrence together with Boeing and General Electric, the FAA and EASA have been notified about this very serious incident."

[JT8D]

Un incidente molto interessante da analizzare. Dalle prime analisi e in base a ciò che si dice, sembrerebbe un caso di Ice Crystal Icing:

http://www.skybrary.aero/index.php/High ... on_Engines

Secondo questo articolo, si stanno già studiando modifiche al software di gestione dei propulsori:

http://www.aviationweek.com/Article.asp ... 609559.xml

Paolo

[JT8D]

Da AvHerald: On Nov 25th 2013 Boeing confirmed that a Multi-Operator-Message (MOM) has been sent to B747-8 and B787-800 customers, "who operate some GE-powered engines after instances of ice crystal icing that resulted in temporary diminished engine performance. To reduce chances of ice crystal conditions, Boeing also updated its Airplane Flight Manual (AFM) to prohibit flight within 50 nautical miles of large convective weather systems that may contain ice crystals. Boeing is working with its customers and GE to address the icing issue. Only a small number of GEnx engines have experienced the ice crystal icing issue in flight. GE will introduce the improvements necessary to return the engine to expected performance levels. Boeing is disappointed in any impact this situation may have on our customers, as is the GE team. We, like our customers, expect the delivered product to meet all expectations and will work closely with GE to address the subject condition. We regret the business disruption this will cause for our customer and remain ready to provide whatever assistance we can to Japan Airlines."

(http://avherald.com/h?article=46679ba1&opt=0)

Sembra quindi confermato il caso di Ice Crystal Icing, e la problematica che interessa i GEnx.

Paolo

[JT8D]

FAA ha rilasciato oggi una AD relativa a questo problema.

Da AvHerald:"On Nov 27th 2013 the FAA released Airworthiness Directive AD-2013-24-01 requiring operators of Boeing 747-8, Boeing 747-8F and Boeing 787-8 aircraft powered by GEnx engines to "revising the airplane flight manual to advise the flight crew of potential ice crystal icing (ICI) conditions at high altitudes, and to prohibit operation in moderate and severe ICI conditions. This AD also requires inspecting the engine after any ICI event is detected by the flight crew." The FAA argues that there had been reports of engine damage and loss of thrust in Ice Crystal Icing (ICI) conditions while flying at high altitudes. This type of icing does not appear on weather radar and thus often remains undetected by flight crew. Flying in these conditions leads to accumulation of ice crystals in the core gas flow of the engine. In events leading to prior airworthiness directives the ice had shed during throttle transients and in the descent phase of flight causing temporary loss of thrust, now newer events have occurred at cruise altitudes at or above FL330 while flying through a mesoscale convective system (continuous cloud larger than 100km/62 nm across). The AD reports that nine events have occurred leading to this AD, in two events two engines on Boeing 747-8 freighters experienced thrust losses, in one event both engines recovered, in the other event one engine remained at idle thrust for the remainder of the flight. In both events the two engines experienced thrust loss showed damage as well as a third engine that did not suffer a loss of thrust. On 4 events uncommanded engine decelerations occurred for about 20 seconds, in three other events on 787-8 aircraft at least one engine showed increased vibration levels until exiting the weather system."
(http://avherald.com/h?article=46679ba1&opt=0)

Qui potete trovare l'Airworthiness Directive FAA:

http://rgl.faa.gov/Regulatory_and_Guida ... -24-01.pdf

Paolo

[Ospite]

Concordo con l'FAA. Mi chiedo quanto tempo impiegherà la GE a risolvere il problema.