WILLCOX, AZ, USA
N50105
MOONEY M20J
THE PROPELLER RPM SURGED AND AS THE PILOT ATTEMPTED TO REDUCE POWER, THE ENGINE VIBRATED VIOLENTLY AND STOPPED WHEN THE THROTTLE WAS CLOSED. A FORCED LANDING WAS MADE TO A MESQUITE AND SAGE BRUSH COVERED DESERT. DURING ROLLOUT THE AIRCRAFT IMPACTED SEVERAL LARGE CLUSTERS OF MESQUITE AND A FENCE RESULTING IN SUBSTANTIAL DAMAGE TO BOTH WINGS AND HORIZONTAL STABILIZERS. EXAMINATION OF THE 580 HOUR ENGINE REVEALED THAT TWO CONNECTING RODS HAD FAILED DUE TO LACK OF LUBRICATION. A BEARING WAS FOUND TO HAVE SPUN, BLOCKING THE ENGINE OIL FLOW. THE AIRPLANE HAD BEEN INVOLVED IN AN INCIDENT 108 HOURS PRIOR TO THE ACCIDENT IN WHICH THE ENGINE WAS OPERATED WITH LOW OIL QUANTITY AND LOW OIL PRESSURE.
On May 25, 1994, at 1800 Pacific daylight time, a Mooney M20J, N50105, was substantially damaged during a forced landing near Willcox, Arizona. The instrument rated private pilot was not injured. Visual meteorological conditions prevailed for the business flight. An IFR flight plan was filed for a flight from Fort Stockton, Texas, to Scottsdale, Arizona. The pilot reported that he was in cruise flight at an assigned altitude of 10,000 feet, when "he noticed a change in engine and propeller sound, accompanied by the propeller RPM increasing beyond the red line." Propeller control could not be regained by moving the propeller control lever, and "when the power was reduced, the engine began to shake violently." When the pilot closed the throttle, the engine stopped. After declaring an emergency, and establishing a glide to the Cochise County Airport, near Willcox, Arizona, the pilot attempted to restart the engine with the starter without success. The pilot further stated that the airport was beyond the gliding distance of the airplane, and a forced landing was attempted on the rough and uneven desert, "pretty well covered by mesquite and brush." The right main landing gear was torn from the wing during the landing roll. Both wings and horizontal stabilizers sustained substantial damage due to a collision with mesquite trees and a fence. A detailed examination of the 580 hour engine revealed that the 3 and 4 connecting rods had failed due to lack of lubrication. A bearing was found to have spun, blocking the oil flow. According to the aircraft and engine records, an incident involving the operation of the engine with low oil occurred approximately 108 hours prior to the accident. The details of the incident are enclosed in the pilot/operator report.
THE FAILURE OF THE CONNECTING ROD DUE TO LACK OF LUBRICATION. FACTORS WERE THE PREVIOUS DAMAGE TO THE ENGINE, AND THE UNSUITABLE TERRAIN AT THE PILOT'S DISPOSAL FOR THE FORCED LANDING.
Source: NTSB Aviation Accident Database
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