A B757 encountered severe mountain wave activity over the front range at FL370 which resulted in a 5...

Attributes
ACN	999255
Time
Date	201203
Local Time Of Day	0001-0600
Place
Locale Reference	ZLC.ARTCC
State Reference	UT
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 200 Flight Crew Total 18000 Flight Crew Type 11000
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence

Narrative:

Crossing the front range eastbound at FL370; we encountered severe mountain wave with occasionally light wave. Our mach went from .82 to .857; about 5 KT overspeed with the overspeed warning horn on and the throttles closed. There were no hurt crewmembers or guests. The over speed lasted for about 5 seconds; later in the flight my pfd; nd and FMC screens went completely dark and got the warning beeper along with an uncommanded roll to the left of about 10 degrees. I called and discussed all with dispatch and maintenance. All agreed ok to continue. No further issues. I understand that there was an issue with the left AC bus.

Original NASA ASRS Text

Title: A B757 encountered severe mountain wave activity over the Front Range at FL370 which resulted in a 5 second; 5 KT overspeed and later the Captain's PFD; ND and FMC blanked along with an uncommanded 10 degree roll. The Left AC Bus may have had a problem.

Narrative: Crossing the Front Range eastbound at FL370; we encountered severe mountain wave with occasionally light wave. Our mach went from .82 to .857; about 5 KT overspeed with the overspeed warning horn on and the throttles closed. There were no hurt crewmembers or guests. The over speed lasted for about 5 seconds; later in the flight my PFD; ND and FMC screens went completely dark and got the warning beeper along with an uncommanded roll to the left of about 10 degrees. I called and discussed all with Dispatch and Maintenance. All agreed ok to continue. No further issues. I understand that there was an issue with the left AC bus.

Data retrieved from NASA's ASRS site as of July 2013 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.

A B757 encountered severe mountain wave activity over the front range at FL370 which resulted in a 5 second; 5 KT overspeed and later the captain's pfd; nd and FMC blanked along with an uncommanded 10 degree roll. The left AC bus may have had a problem.