B757 experiences multiple unexplained anomalies apparently associated with airframe and engine icing...

Attributes
ACN	801181
Time
Date	200808
Place
Locale Reference	airport : zzzz.airport
State Reference	FO
Altitude	msl single value : 36000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzzz.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : flight engineer pilot : multi engine pilot : instrument
Experience	flight time last 90 days : 100 flight time total : 6000 flight time type : 1500
ASRS Report	801181
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather inflight encounter other
Independent Detector	aircraft equipment other aircraft equipment : eicas wngs
Resolutory Action	aircraft : equipment problem dissipated flight crew : overcame equipment problem
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft Weather
Primary Problem	Aircraft

Narrative:

We were in level cruise and in and out of clouds. The rudder limit and mach speed lights came on. At this time the aircraft started to drift off of altitude (500 FPM up). I disconnected the autoplt and started to hand fly while the captain worked the problem. He turned on the wing and engine anti-ice. Shortly thereafter; the right engine bleed EICAS message came on. I also could not hold airspeed and the throttles were retarding toward idle. I started hand flying the throttles. I still could not make airspeed and xrefed to the captain's airspeed indicator. Mine was 30 KTS slower than the captain's in a slow decay. It bottomed out at 120 KIAS. As I continued to fly the aircraft; the captain worked the problems. When the wing anti-ice was turned off; the right bleed system was restored. 5 mins later; the first officer's airspeed indicator returned to normal. We think it might have been icing on the aircraft. We do not know what caused the rudder failure. Also; we had the problem that the wing anti-ice was causing the bleed system failure.

Original NASA ASRS Text

Title: B757 EXPERIENCES MULTIPLE UNEXPLAINED ANOMALIES APPARENTLY ASSOCIATED WITH AIRFRAME AND ENGINE ICING.

Narrative: WE WERE IN LEVEL CRUISE AND IN AND OUT OF CLOUDS. THE RUDDER LIMIT AND MACH SPD LIGHTS CAME ON. AT THIS TIME THE ACFT STARTED TO DRIFT OFF OF ALT (500 FPM UP). I DISCONNECTED THE AUTOPLT AND STARTED TO HAND FLY WHILE THE CAPT WORKED THE PROB. HE TURNED ON THE WING AND ENG ANTI-ICE. SHORTLY THEREAFTER; THE R ENG BLEED EICAS MESSAGE CAME ON. I ALSO COULD NOT HOLD AIRSPD AND THE THROTTLES WERE RETARDING TOWARD IDLE. I STARTED HAND FLYING THE THROTTLES. I STILL COULD NOT MAKE AIRSPD AND XREFED TO THE CAPT'S AIRSPD INDICATOR. MINE WAS 30 KTS SLOWER THAN THE CAPT'S IN A SLOW DECAY. IT BOTTOMED OUT AT 120 KIAS. AS I CONTINUED TO FLY THE ACFT; THE CAPT WORKED THE PROBS. WHEN THE WING ANTI-ICE WAS TURNED OFF; THE R BLEED SYS WAS RESTORED. 5 MINS LATER; THE FO'S AIRSPD INDICATOR RETURNED TO NORMAL. WE THINK IT MIGHT HAVE BEEN ICING ON THE ACFT. WE DO NOT KNOW WHAT CAUSED THE RUDDER FAILURE. ALSO; WE HAD THE PROB THAT THE WING ANTI-ICE WAS CAUSING THE BLEED SYS FAILURE.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.