NTSB Identification: LAX00LA237.
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Accident occurred Wednesday, June 21, 2000 in EL MONTE, CA
Probable Cause Approval Date: 08/21/2001
Aircraft: Cessna 150M, registration: N704QJ
Injuries: 2 Uninjured.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

During cruise, the engine lost power then nosed over during a forced landing in an open, dirt field. No mechanical anomalies were experienced with the engine sound or gages prior to the loss of engine power. About 10 minutes into the flight the engine began to run roughly. The CFI performed the emergency checklist and picked one of two open fields to make a forced landing. During the approach to the second field, a construction vehicle drove into their flight path. The CFI shortened the approach and landed in the first field. On the landing roll the nose wheel dug into the dirt and the airplane nosed over. The external examination of the engine revealed that the left muffler end cap had separated in an outward direction from the muffler about 350 degrees in circumference in a 45-degree angle. This allowed heat to be directed at the firewall. The P-leads located within the electrical harness were melted, which allowed the conductors to short within the wires.

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

The inadequate maintenance inspection by other maintenance personnel of the exhaust system that resulted in an eroded muffler that allowed hot gases to impinge on magneto wiring and resulted in loss of engine power. A factor was the soft terrain at the forced landing site.

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