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NTSB AVIATION ACCIDENT/INCIDENT DATABASE REPORT


General Information

Data Source:                          NTSB AVIATION ACCIDENT/INCIDENT DATABASE
   Report Number:                        CHI94LA277 
   Local Date:                           08/19/1994
   Local Time:                           12:50 CDT
   State:                                WI    
   City:                                 JANESVILLE                         
   Airport Name:                                                  
   Airport Id:                                 
   Event Type:                           ACCIDENT
   Injury Severity:                      NONE   
   Report Status:                        FINAL      
   Mid Air Collision:                    NO 

Operations Information

Category of Operation:                GENERAL AVIATION       
   Aircraft Type:                        AIRPLANE       
   Aircraft Damage:                      SUBSTANTIAL      
   Phase of Flight:                      540 CRUISE                                            
   Aircraft Make/Model:                  BEECH BE-90-C90A                
   Operator Doing Business As:           UNIVERSITY OF NORTH DAKOTA    
   Operator Name:                        UNIVERSITY OF NORTH DAKOTA    
   Operator Code:                            
   Operator:                                                                       
   Owner Name:                           FIRST SECURITY BANK OF UTAH   

Narrative

WHILE IN CRUISE FLIGHT AT 20,000 FEET MEAN SEA LEVEL, AND MA NEUVERING 
   AROUND BUILD-UPS THE FLIGHT ENTERED IMC.  SHORTLY AFTER ENTERING THE 
   CLOUDS THE AIRPLANE ENCOUNTERED SEVERE TU RBULENCE AND SOME OF THE 
   FLIGHT INSTRUMENTS BECAME UNRELIABLE (TUMBLED).  POSITIVE CONTROL OF 
   THE AIRPLANE WAS REGAINED BETWEEN 16,800 AND 17,000 MSL.  SUBSEQUENT 
   EXAMINATION FOUND SUBSTANTIAL DAMAGE TO THE AIRFRAME.

Sequence of Events

Occurrence #: 1  110 ALTITUDE DEVIATION, UNCONTROLLED
   Phase of Operation: 540 CRUISE

           Findings
           Subject - Modifier - Personnel Cause/Factor

   1a.   20000(S) - 2226(M)  Factor
         WEATHER CONDITION - TURBULENCE IN CLOUDS
   1b.   24023(S) - 3102(M) - 4000(P)  Factor
         FLIGHT INTO KNOWN ADVERSE WEATHER - CONTINUED - PILOT IN COMMAND
   2a.   10101(S) - 1104(M)
         WING, SPAR - BENT
   2b.   24538(S) - 3107(M) - 4000(P)  Cause
         DESIGN STRESS LIMITS OF AIRCRAFT - EXCEEDED - PILOT IN COMMAND

Probable Cause

THE PILOT-IN-COMMAND'S EXCEEDING THE DESIGN STRUCTURAL LIMITS OF THE 
   AIRPLANE.  FACTORS WERE TURBULENCE IN CLOUDS AND THE PILOT- 
   IN-COMMAND;S CONTINUED FLIGHT INTO KNOWN ADVERSE WEATHER.

Aircraft Information

Number of Seats:                      8  
   Aircraft Use:                         INSTRUCTIONAL      
   Type of Operation:                    14 CFR 91 
   Domestic/International:                            
   Passenger/Cargo:                                        
   Registration Number:                  1553N 
   Air Carrier Operating Certificates:   
   Aircraft Fire:                        NONE

                  Injuries
          Fatal  Serious  Minor  None
   Crew      0       0       0      3
   Pass      0       0       0      0
   Other     0       0       0      0
   Invlvd    0       0       0      3

   Landing Gear:                         TRICYCLE-RETRACTABLE
   Certificated Maximum Gross Weight:    10160
   Engine Make:                          P & W        
   Engine Model:                         PT6A-21      
   Number of Engines:                    2 
   Engine Type:                          TURBO PROP                  

Environment/Operations Information

Basic Weather Conditions:             VISUAL METEOROLOGICAL CONDITIONS (VMC)  
   Wind Direction (deg):                 220
   Wind Speed (knots):                   5
   Visibility (sm):                      5
   Visibility RVR (ft):                  0
   Visibility RVV (sm):                  0
   Cloud Height Above Ground Level (ft): 9000
   Visibility Restrictions:              HAZE (H)
   Precipitation Type:                   NONE
   Light Condition:                      DAYLIGHT
   Departure Airport Id:                 DET 
   Departure City:                       DETROIT
   Departure State:                      MI
   Destination Airport Id:               GFK 
   Destination City:                     GRAND FORKS
   Destination State:                    ND
   Flight Plan Filed:                    INSTRUMENT FLIGHT RULES (IFR)
   ATC Clearance:                        IFR
   VFR Approach/Landing:                 
   Event Location:                       OFF AIRPORT/AIRSTRIP

Pilot-in-Command

Certificates:                         COMMERCIAL
   Ratings:
     Plane:                              SINGLE ENGINE LAND, MULTIENGINE LAND
     Non-Plane:                          NONE
     Instrument:                         AIRPLANE
   Had Current BFR:                      YES
   Months Since Last BFR:                5  
   Medical Certificate:                  CLASS 1
   Medical Certificate Validity:         VALID MEDICAL-NO WAIVERS/LIMITATIONS

              Flight Time (Hours)
   Total       :    642  Last 24 Hrs :    7
   Make/Model  :     70  Last 30 Days:   20
   Instrument  :     94  Last 90 Days:  157
   Multi-Engine:    402  Rotorcraft  :    0

NTSB Identification: CHI94LA277. The docket is stored in the (offline) NTSB Imaging System.

 

Accident occurred AUG-19-94 at JANESVILLE, WI
Aircraft: BEECH C90A, registration: N1553N
Injuries: 3 Uninjured.

WHILE IN CRUISE FLIGHT AT 20,000 FEET MEAN SEA LEVEL, AND MANEUVERING AROUND BUILD-UPS THE FLIGHT ENTERED IMC. SHORTLY AFTER ENTERING THE CLOUDS THE AIRPLANE ENCOUNTERED SEVERE TURBULENCE AND SOME OF THE FLIGHT INSTRUMENTS BECAME UNRELIABLE (TUMBLED). POSITIVE CONTROL OF THE AIRPLANE WAS REGAINED BETWEEN 16,800 AND 17,000 MSL. SUBSEQUENT EXAMINATION FOUND SUBSTANTIAL DAMAGE TO THE AIRFRAME.
Probable Cause
the pilot-in-command's exceeding the design structural limits of the airplane. Factors were turbulence in clouds and the pilot- in-command's continued flight into known adverse weather.

Full Narrative:

On August 19, 1994, at approximately 1250 central daylight time, a Beech C90A, N1553N, operated by the University of North Dakota, and piloted by commercial pilots, encountered severe turbulence while deviating around weather at 20,000 feet mean sea level, in the vicinity of Janesville, Wisconsin. The airplane experienced an uncontrolled altitude deviation, descending 3,000 feet before recovery by the pilots. During the recovery the airframe sustained substantial damage. The two pilot crew and one non- flying instructor reported no injuries. The CFR 14 Part 91 instructional flight was on an instrument flight plan. Thunderstorms were reported in the area. The flight departed Detroit, Michigan, at 1230. After the event the flight continued to the intended destination of Grand Forks, North Dakota.

The instructor pilot in a detailed statement indicated that in the vicinity of Janesville, Wisconsin, while cruising at 20,000 feet mean sea level, and maneuvering around build-ups the flight entered instrument meteorological conditions. Shortly after entering the clouds the airplane encountered severe turbulence and some of the flight instruments became unreliable (tumbled). She said that the power was reduced and the vertical speed indicator was observed to indicate a 3,000 feet per minute altitude loss and the airspeed indicator was at the "barber pole." Positive control of the airplane was regained between 16,800 and 17,000 feet. The flight then continued to the destination airport without further incident.

The instructor stated that weather was checked prior to departure from Detroit, Michigan, and the possibility of thunderstorm activity along the proposed route of flight was forecast.

The instructor pilot stated that an examination of the airframe after the event revealed that the airframe had sustained substantial damage as a result of the weather encounter; however, she stated that she does "not feel that the control inputs during the recovery were in such a manner to over-stress the aircraft."

Source: National Transportation Safety Board