posted on Aug, 22 2013 @ 09:19 AM
In what proves that engine icing is still a less than understood phenomenon, an AirBridge 747-8F (VQ-BGZ) flying between Moscow and Hong Kong suffered
damage to three engines, and a power loss in two during an icing event.
The report says that the aircraft was cruising at 41,000 feet near Chengdu, about 1.5 hours before landing, when there was a temperature rise shown on
systems in the cockpit. The temperature went from -54C to -34C. The crew had changed course to avoid a thunderstorm, and flew through a cloud that
didn't show up on weather radar.
They put the engine ice protection into manual, instead of automatic and flew that way for almost ten minutes before going back to automatic. Around
20 minutes later, the number two engine (inboard left), suffered a surge and an automatic restart. Two minutes later, the outboard left engine (#1)
went to 70% power, while #2 remained at idle.
After landing, and inspecting the engines, it was found that three of the four engines (#1, #2, and #4) showed first stage high pressure compressor
blade damage from ice. The aircraft suffered a crystal icing event, which is not well understood, and extremely difficult to detect, on the unheated
portions of the high-pressure compressor.
Icing has always been a problem for aircraft that fly high enough. American Eagle 4184 crashed, killing everyone on board after flying into icing
conditions where the rain hit the wing, and rolled back behind the deicing boots before freezing. British Airways 38 was also caused by ice building
in the fuel system. I've also seen four B-1s grounded for maintenance after ice went through their engines. It's a constant battle to figure out new
ways to detect and prevent ice.
Russian authorities are investigating an serious icing incident in cruise during which three engines on a Boeing 747-8 freighter sustained damage
and two suffered a loss of thrust.
Federal air transport authority Rosaviatsia identifies the aircraft involved as an AirBridge Cargo 747-8F, registered VQ-BGZ. The 747-8F is powered by
four General Electric GEnx-2B engines.
It had been operating between Moscow Sheremetyevo and Hong Kong on 31 July, and was cruising at 41,000ft at the time.
The incident occurred at night in the vicinity of Chengdu, about 1.5h before landing, as the aircraft deviated to the right of its intended flightpath
in order to avoid a thunderstorm.