Amateur-built RV-10 N569JC accident near Lancaster, Texas

Probable cause

A partial loss of engine power due to a faulty magneto/ignition system, which resulting in a forced landing.

NTSB analysis

Just after takeoff following a touch-and-go landing, the engine backfired and lost partial power. The pilot decided that he could not land on the remaining runway, so he continued to climb the airplane, raised the flaps, and increased airspeed. The manifold pressure continued to decrease despite the pilot’s application of full throttle, and the pilot attempted to return to the airport, but had insufficient altitude, and conducted a forced landing to a field. The nose landing gear sheared off, and the main landing gear collapsed. Both wings sustained substantial damage.

Examination of the engine and accessories revealed that the left magneto fired on only 3 of its 6 terminals. The airplane was equipped an electronic ignition system that was coupled to the magnetos. The system created multiple sparks over a longer duration and synchronized timing between the two magnetos. This synchronization was accomplished by using the left magneto as a trigger for the complete system. When the electronic ignition was operating, it relied solely on the left magneto points to fire both magnetos with an enhanced multi-spark. If the left magneto failed or deteriorated, then the complete ignition cycle would be compromised. The degraded functionality of the left magneto was likely the cause of the partial engine power loss.

Text from the NTSB. Open the NTSB docket for CEN19LA326 for the full record.