NTSB Identification: LAX91FA001.
The docket is stored on NTSB microfiche number 44603.
Accident occurred Wednesday, October 03, 1990 in FLAGSTAFF, AZ
Probable Cause Approval Date: 08/06/1993
Aircraft: MOONEY M20K, registration: N231AX
Injuries: 1 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.

THE PILOT HAD RETURNED FROM AN EARLIER DEPARTURE BECAUSE HE HAD SMOKE INSIDE THE AIRPLANE, AND REQUESTED THE ASSISTANCE OF A MECHANIC. UNABLE TO OBTAIN THIS ASSISTANCE, HE BORROWED A PAIR OF PLIERS FROM THE FBO. AFTER INSPECTING THE AIRPLANE HIMSELF, HE RETURNED THE PLIERS AND COMMENTED SOMETHING ABOUT THE EGT PROBE TO THE LINE PERSON ON DUTY. SOON AFTER THE SECOND DEPARTURE, THE AIRPLANE WAS SEEN RETURNING TOWARDS THE AIRPORT TRAILING SMOKE AND POSSIBLY FIRE. THE AIRPLANE ROLLED INVERTED AND DESCENDED INTO TREES. THE AIRPORT MANAGER RESPONDING TO THE ACCIDENT SCENE LOCATED THE EXHAUST TAILPIPE. THE FRACTURED TURBO CLAMP WAS LOCATED AT THE WRECKAGE. METALLURGICAL ANALYSIS REVEALED THAT CRACKING OCCURRED AS A RESULT OF INTERGRANULAR CORROSION. ON 9/26/90 THE TURBOCHARGER WAS REMOVED, REPAIRED AND REINSTALLED.

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

THE PILOT'S DECISION TO OPERATE THE AIRCRAFT WITH A KNOWN DISCREPANCY; INADEQUATE MAINTENANCE PROCEDURES; AND THE PILOT'S INFLIGHT LOSS OF CONTROL DUE TO SMOKE AND FUMES IN THE COCKPIT.

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