NTSB Factual Report

On September 11, 2010, about 0930 mountain standard time, an experimental Extra Flugzeugbau GMBH EA-300, N102EX, experienced a loss of engine power while maneuvering near Sierra Vista, Arizona. During the landing rollout the left wing collided with a moving vehicle on highway 90. The pilot/owner operated the airplane under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. The pilot, the sole occupant, was not injured; the driver of the vehicle, the sole occupant, was not injured. The airplane sustained substantial damage to the left wing. Visual meteorological conditions prevailed for the local area flight that departed the Sierra Vista Airport about 0850. No flight plan had been filed.

According to the pilot, he had spent the past 6 months overhauling the engine, which included the addition of an inverted oil system. Prior to the accident, he had flown the airplane about 6 hours. On the accident flight, he had performed a couple of touch-and-go takeoffs and landings, and then went to an aerobatic area. He completed left and right slow aileron rolls; he noted that the oil pressure was 65 – 70 psi initially, went to about 40 psi, and then back to 70 psi while inverted. He then did left and right 90-degree inverted turns.

As the pilot completed a steep turn, he noticed that the oil pressure was at 0 psi. Before he could take any action, the engine seized and stopped. He was about 7,000 feet mean sea level (msl), and thought about bailing out of the airplane. He looked for possible landing zones, and decided to stay in the airplane due to the city suburbs on his left side. Due to several automobiles on the road, he had to stay higher than he wanted to, but landed successfully on the road. On the landing rollout he had to negotiate around a 45-degree left bend in the road. As the airplane rounded the curve in the road, a vehicle traveling in the opposite direction collided with the left wing.

After securing the airplane, he exited the airplane and removed the inspection panel on the cowling. He observed a connecting rod near the back of the engine had gone through the crankcase.

Inspectors from the Federal Aviation Administration (FAA) examined the airplane at the owner’s hangar, and pertinent parts of their report follow. Detailed inspection notes are in the public docket.

The engine had a catastrophic failure near cylinders number 5 and 6. The engine case had a large hole on the number 6 cylinder side between the two push rod tubes. Looking down through the hole, the FAA inspectors observed that the connecting rod for cylinder number 6 was broken, and the cam shaft had several impact marks. The engine’s accessory housing also had a large hole in it.

The inspectors had the owner remove the oil filter, and observed no significant debris in it. They checked the oil level, and it was at a normal level for the engine type.

While interviewing the owner, the inspectors learned that the previously installed engine had failed, and this engine (the accident engine) was its replacement. After further questioning, it was learned the owner did not send the propeller, propeller governor, oil lines and hoses, air oil separator, and the shuttle assembly for the inverted oils systems out for overhaul or cleaning prior to reuse. He did send the oil coolers to repair station to have them flushed.

Inspectors asked the owner to remove the hoses going to the shuttle valve, which controlled oil flow while the airplane was in inverted flight. They observed no contamination in the lines. When inspectors looked at the shuttle valve, one end of the shuttle's end caps had impact marks. They determined that the impact marks were caused by the owner of the airplane when he removed the cap to flush the shuttle valve out after the last engine failure. The shuttle also did not sound as though the steel balls inside were moving freely. One inspector removed the snap ring, end cap, ball, and spring from the side with the impact marks. The inside of the shuttle on that side had been polished with some type of abrasive. The owner confirmed he used a scotch brite type pad to clean the inside of the shuttle. The inspector noticed several small indentations on the inside wall of the shuttle with raised metal. After sticking his finger all the way in the shuttle valve, the inspector found a triangular shaped shard of metal wedged under the remaining steel ball. This kept the ball from moving its full travel to the shut off position.

NTSB Probable Cause

A loss of engine power due to metal debris contamination of the inverted oil system shuttle valve, which resulted in a disruption of oil flow and subsequent oil starvation.