WPR12LA437

The student pilot reported that, shortly after takeoff for his practical test for a sport pilot certificate, when the airplane was about 100 ft above ground level, the engine lost power. He then began an emergency descent to a nearby field. During the landing, the airplane collided with a dirt berm and subsequently nosed over. Postaccident examination of the engine revealed damage to both the forward and aft cylinder assemblies. The aft cylinder assembly's top piston ring was missing, and damage was noted to the associated ring land groove and piston. The lower piston ring was in place; however, the piston ring was distorted and jammed in its corresponding ring land groove. Mechanical-type damage was noted on the internal cylinder domes and piston faces of both the forward and aft cylinder assemblies, and the damage was consistent with pieces of the broken piston ring contacting the cylinder domes. The reason for the piston ring failure could not be determined. Postaccident review of the airplane's maintenance records revealed multiple entries outlining repairs to both the forward and aft cylinder assemblies; most of the repairs were associated with piston ring anomalies. One maintenance log entry indicated that the both the forward and aft cylinder assemblies' piston rings were replaced and that the cylinders were resurfaced due to "overheat damage."

On September 25, 2012, about 0915 Pacific daylight time, an experimental McCleery-Rans S6ES airplane, N623LB sustained substantial damage following a loss of engine power and subsequent forced landing near Elverta, California. The student pilot and Designated Pilot Examiner (DPE) conducting the check ride were not injured. The airplane was registered to the pilot, and operated as a visual flight rules (VFR) practical test exam flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local flight that originated from Elverta shortly before the accident.The accident occurred during the student pilot's practical test for a Sport Pilot certificate. The student pilot reported that he demonstrated a soft-field takeoff with 2 notches of flaps; as the airplane accelerated in ground effect to approximately 55 mph he transitioned to a climb. As the airplane climbed, about 100 feet above ground level (agl), the engine lost power and the pilot began an emergency descent to a nearby open field. He reported that the airplane touched down on the main wheels with the nose wheel off the ground; however, during the rollout in the open field the airplane collided with a dirt berm and subsequently nosed over. The airplane sustained substantial damage to the wing lift struts and fuselage. The experimental two-place high wing airplane was equipped with a Rotax 582 two-stroke, two-cylinder reciprocating engine rated at 65 horsepower. Postaccident airframe and engine examination by representatives from the Federal Aviation Administration and Rotax revealed the following findings: Aft (MAG) Piston and Cylinder Assembly The MAG piston was in place in the cylinder and remained attached to its associated connecting rod. The top MAG piston ring was missing and damage was noted to the associated ring land groove and piston. The lower piston ring was in place; however, the piston ring was distorted and jammed in its corresponding ring land groove. Mechanical type damage was noted to the internal cylinder dome of the cylinder head. The damage was consistent with pieces of the broken piston ring contacting the cylinder dome. Forward (PTO) Piston and Cylinder Assembly The PTO piston was in place in the cylinder and remained attached to its associated connecting rod. Both the upper and lower piston rings were in place and seated in their respective ring land grooves. Mechanical type damage was noted to the internal cylinder dome and piston face. The damage was consistent with pieces of the broken piston ring contacting the cylinder dome and piston face. Postaccident review of the airplane's maintenance records showed multiple entries that outlined repairs to both the MAG and PTO cylinder assemblies. In 2010 (specific date not legible) at 401 hours total time since new (TTSN) the MAG piston and ring assembly were replaced due to a cracked ring. An entry dated September 4, 2011 (at530 hours TTSN) indicated that the "top end" was reconditioned and new "rings" were installed. An entry dated November 05, 2011 (542 hours TTSN) indicted that the PTO and MAG rings were replaced and the cylinders were resurfaced due to "overheat damage."