CE750 encounters severe turbulence at FL490. Unable to maintain altitude or aircraft control.

Attributes
ACN	618270
Time
Date	200405
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zmp.artcc
State Reference	MN
Altitude	msl single value : 45000
Environment
Flight Conditions	IMC
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp.artcc
Operator	general aviation : corporate
Make Model Name	Citation X
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	climbout : vacating altitude climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 6000 flight time type : 1500
ASRS Report	618270
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	altitude deviation : undershoot altitude deviation : excursion from assigned altitude inflight encounter : turbulence other anomaly
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment flight crew : regained aircraft control other
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Aircraft Environmental Factor Flight Crew Human Performance
Primary Problem	Environmental Factor
Air Traffic Incident	Pilot Deviation

Narrative:

While climbing to FL490 in IMC, we encountered severe turbulence. The aircraft rolled 90 degrees left and descended to FL450. Roll control became very difficult. Altitude control was impossible. We requested block altitude FL430-FL450. We were unable to maintain this block altitude. ATC offered us block altitude FL410-FL450. This condition continued from 5-10 mins until we entered VMC. We reported severe turbulence and being unable to hold altitude at this time. Radar did not depict any returns.

Original NASA ASRS Text

Title: CE750 ENCOUNTERS SEVERE TURB AT FL490. UNABLE TO MAINTAIN ALT OR ACFT CTL.

Narrative: WHILE CLBING TO FL490 IN IMC, WE ENCOUNTERED SEVERE TURB. THE ACFT ROLLED 90 DEGS L AND DSNDED TO FL450. ROLL CTL BECAME VERY DIFFICULT. ALT CTL WAS IMPOSSIBLE. WE REQUESTED BLOCK ALT FL430-FL450. WE WERE UNABLE TO MAINTAIN THIS BLOCK ALT. ATC OFFERED US BLOCK ALT FL410-FL450. THIS CONDITION CONTINUED FROM 5-10 MINS UNTIL WE ENTERED VMC. WE RPTED SEVERE TURB AND BEING UNABLE TO HOLD ALT AT THIS TIME. RADAR DID NOT DEPICT ANY RETURNS.

Data retrieved from NASA's ASRS site as of July 2007 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.