Mooney Aircraft Corp. M20K N262MK accident near Hillsborough Township, New Jersey

Probable cause

The partial loss of engine power due to maintenance personnel’s failure to ensure that the ignition harnesses were properly secured and the pilot’s inappropriate pitch control inputs, which resulted in the airplane exceeding its critical angle of attack and subsequently entering an aerodynamic stall.

NTSB analysis

The pilot reported that the first leg of the cross-country flight was uneventful and that the accident occurred during takeoff following an en route stop to add fuel. He reported the takeoff roll was normal; however, during the initial climb the engine began to lose power. Video of the accident showed that the pilot attempted to continue the initial climb in three separate pitch-up attempts. Subsequently, the airplane descended, rolled to the left, and impacted terrain, which resulted in substantial damage to the fuselage and wings. It is likely that the pilot’s repeated attempts to increase the pitch of the airplane following the reported reduction in engine power likely resulted in the airplane likely exceeding its critical angle of attack and a subsequent aerodynamic stall.

Postaccident examination of engine found that the Nos. 1 and 5 cylinder top spark plug ignition harnesses were loose to their respective sparkplugs. The No. 3 top spark plug ignition harness was found completely unscrewed, detached, and lying next to the spark plug on top of the cylinder shroud. There were no other anomalies discovered with the engine. Based on this information, it is likely that the reduction in engine power the pilot reported during the takeoff was due to this ignition system anomaly.

The airplane had undergone maintenance and had been flown for 1.5 hours since the last inspection. The mechanic who performed that maintenance could not recall servicing any spark plugs, nor did he recall removing any ignition harnesses. Although the mechanic may not have loosened or removed the ignition harness, it is likely that he, or other maintenance personnel performing maintenance tasks at some other point, did not ensure the ignition harnesses were properly tightened before returning the airplane to service.

Text from the NTSB. Open the NTSB docket for ERA23LA225 for the full record.