TOMEI S12 XL — Pleasant Grove, CA, 2011

TOMEI S12 XL — Pleasant Grove, CA

1 fatal Low-time pilotIMC

Date	April 3, 2011
Location	Pleasant Grove, CA
Aircraft	TOMEI S12 XL
Purpose of flight	Personal
Conditions	Day · Instrument Meteorological Cond
Phase / occurrence	Takeoff Loss of engine power (total)
Pilot age	53
Pilot total time	165 hrs · Low time
Time in type	165 hrs
Fatalities	1

Probable cause

The pilot’s failure to allow the airplane’s engine to properly warm up before applying takeoff power, which resulted in the forward cylinder's piston seizing and a subsequent loss of engine power. Also causal was the pilot's failure to maintain an adequate airspeed after the loss of engine power, which resulted in a stall-spin.

NTSB findings

Aircraft-Aircraft power plant-Engine (reciprocating)-Recip eng cyl section-Malfunction - C
Personnel issues-Action/decision-Action-Incomplete action-Pilot - C
Personnel issues-Task performance-Planning/preparation-(general)-Pilot - C
Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Airspeed-Not attained/maintained - C
Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C

What happened

A pilot-rated witness said that the airplane was airborne within “a couple of minutes” after the engine was started and that, when the airplane reached an altitude of 200 to 300 feet above the ground during climb out, it appeared to slow. The witness said that the airplane then banked left and descended in a spiral until it impacted the ground. Postaccident examination of the engine revealed evidence of abnormal piston wear and cylinder damage, including mechanical scoring and vertical grooves along the forward cylinder walls and piston skirt. A representative of the engine manufacturer reported that the observed cylinder and piston damage was consistent with an in-flight cold seizure of the piston (a condition where the piston seizes within the cylinder). About 17 years before the accident, the engine manufacturer issued a Service Information Letter (SIL) that addressed the potential for such a piston seizure. The SIL stated in part “...Putting a cold engine to hard work without uniform and correct warm up will cause the piston to expand quicker than the cylinder, minimizing clearance and creating piston scuffing and seizure.” It is likely that the pilot did not allow enough time for the engine to warm up before taking off.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.