NTSB Identification: FTW91FA043.
The docket is stored on NTSB microfiche number 44805.
Accident occurred Friday, February 22, 1991 in TULSA, OK
Probable Cause Approval Date: 01/28/1993
Aircraft: MITSUBISHI MU-2B-60, registration: N274MA
Injuries: 3 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

AIRPLANE WAS DEPARTING ON A REQUIRED MAINTENANCE TEST FLIGHT FOLLOWING REPLACEMENT OF BOTH ENGINES. WITNESSES STATED THAT THE TAKEOFF ROLL AND INITIAL CLIMB APPEARED NORMAL, BUT THAT AT ABOUT 500 FT AGL, THE AIRPLANE ENTERED A RIGHT BANK WHICH CONTINUED UNTIL THE WINGS WERE VERTICAL AND THE NOSE FELL THROUGH. AIRPLANE IMPACTED IN AN INVERTED STEEP NOSE DOWN ATTITUDE. EXAMINATION OF WRECKAGE REVEALED THAT THE RIGHT ENGINE HAD BEEN SECURED AND FEATHERED. SUBSEQUENT INVESTIGATION DID NOT REVEAL ANY EVIDENCE OF PRE-IMPACT FAILURE OR MALFUNCTION OF EITHER ENGINE OR ANY OF THE AIRFRAME SYSTEMS. ENGINE MOUNTING/RIGGING CONTINUITY COULD NOT BE ESTABLISHED DUE TO IMPACT DAMAGE. THE PILOT WAS A PRINCIPAL IN THE OPERATOR'S ORGANIZATION AND NOT ONE OF THE REGULAR LINE PILOTS. EVIDENCE INDICATED THAT THE GEAR WAS UP AND THAT THE LEFT SPOILER WAS DEPLOYED AT IMPACT. EMERG PROCEDURE TAUGHT IN TRANSITION TRAINING IS TO USE RUDDER TRIM AS SOON AS POSSIBLE AFTER ENG FAILURE TO PRECLUDE DEPLOYMENT OF SPOILERS. RUDDER TRIM FOUND IN NEUTRAL POSITION.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

THE SHUTDOWN OF ONE ENGINE FOR UNDETERMINED REASONS, AND THE PILOT'S FAILURE TO MAINTAIN VMCA DURING A CRITICAL PHASE OF FLIGHT. A FACTOR IN THE ACCIDENT WAS THE PILOT'S IMPROPER EMERGENCY PROCEDURE.

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