A cpr light transport was unable to hold altitude in turbulence.

Attributes
ACN	276257
Time
Date	199407
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sbm
State Reference	WI
Altitude	msl bound lower : 5400 msl bound upper : 7000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Learjet 25
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 70 flight time total : 7300 flight time type : 178
ASRS Report	276257
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance other anomaly
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : exited adverse environment
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

On jul/tue/94 at approximately XA40 am, I was PIC of a lear jet model 25B en route from sbm to grb on a maintenance ferry flight. During preflight briefing, we were informed about the thunderstorms that had moved through our area of flight. The thunderstorms at the time of departure were all east of our intended flight path. At a cruise altitude of 6000 ft MSL, we were in IMC, fog, very light rain. Our radar screen set on 40 mi scale showed us no echoes, no returns, other than very light rain. Without warning, we were caught in severe up- and downdrafts with heavy turbulence and wind shear. Altitude control became impossible, altitude control was maintained until it passed, and we returned to 6000 ft MSL as assigned. The amount of deviation was 1000 ft up and 600 ft down. An immediate attempt to contact center was made, however there was a lot of static interference and other aircraft talking on the same frequency and we received no response from center during or after the deviation. The total deviation time lasted approximately 1 min. I believe that center never heard us.

Original NASA ASRS Text

Title: A CPR LTT WAS UNABLE TO HOLD ALT IN TURB.

Narrative: ON JUL/TUE/94 AT APPROX XA40 AM, I WAS PIC OF A LEAR JET MODEL 25B ENRTE FROM SBM TO GRB ON A MAINT FERRY FLT. DURING PREFLT BRIEFING, WE WERE INFORMED ABOUT THE TSTMS THAT HAD MOVED THROUGH OUR AREA OF FLT. THE TSTMS AT THE TIME OF DEP WERE ALL E OF OUR INTENDED FLT PATH. AT A CRUISE ALT OF 6000 FT MSL, WE WERE IN IMC, FOG, VERY LIGHT RAIN. OUR RADAR SCREEN SET ON 40 MI SCALE SHOWED US NO ECHOES, NO RETURNS, OTHER THAN VERY LIGHT RAIN. WITHOUT WARNING, WE WERE CAUGHT IN SEVERE UP- AND DOWNDRAFTS WITH HVY TURB AND WIND SHEAR. ALT CTL BECAME IMPOSSIBLE, ALT CTL WAS MAINTAINED UNTIL IT PASSED, AND WE RETURNED TO 6000 FT MSL AS ASSIGNED. THE AMOUNT OF DEV WAS 1000 FT UP AND 600 FT DOWN. AN IMMEDIATE ATTEMPT TO CONTACT CTR WAS MADE, HOWEVER THERE WAS A LOT OF STATIC INTERFERENCE AND OTHER ACFT TALKING ON THE SAME FREQ AND WE RECEIVED NO RESPONSE FROM CTR DURING OR AFTER THE DEV. THE TOTAL DEV TIME LASTED APPROX 1 MIN. I BELIEVE THAT CTR NEVER HEARD US.

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.