N17YSSchweizer 269C · 1992

On August 18, 2015, about 0900 mountain daylight time, a Schweizer 269C helicopter, N17YS, experienced a complete loss of engine power and subsequent hard landing about 10 miles northwest of the North Las Vegas Airport (VGT), Las Vegas, Nevada. The certified flight instructor was not injured, and the pilot undergoing instruction sustained minor injuries. The helicopter sustained substantial damage to the tailboom. The helicopter was privately owned and operated by Airworks Aviation Academy under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed and no flight plan was filed for the local flight. The flight originated from VGT at 0845.

The flight instructor reported that after the student leveled the helicopter off at 4,500 ft mean sea level, he was going to demonstrate, with the student following along on the controls, entry procedures for an autorotation maneuver. The flight instructor smoothly lowered the collective, input right pedal, and pulled back on the cyclic to enter the autorotation. Immediately after entering the maneuver, he heard a change in engine noise and he observed that the engine RPM gauge was zero. The flight instructor attempted several times to restart the engine by pressing the start button, however every time the start button was pressed, there was no indication that the starter engaged. The flight instructor continued the descent to the ground. The helicopter landed hard; subsequently, the main rotor blades severed the tailboom.

A postaccident engine examination conducted by a Federal Aviation Administration Inspector revealed that the positive lead was found separated from the battery terminal, and that the lead exhibited corrosion. The positive lead was attached to the battery, and the engine started and operated normally.

On April 22, 2009, about 1400 Pacific daylight time, a Schweizer 269C helicopter, N17YS, landed hard following a loss of engine power near Las Vegas, Nevada. Airwork LLC was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot with a certified flight instructor (CFI) certificate and the student pilot undergoing instruction (PUI) were not injured; the helicopter sustained substantial damage when it rolled over. The local instructional flight departed the North Las Vegas airport about 1330. Visual meteorological conditions prevailed, and no flight plan had been filed.

The CFI reported that while making an approach to land on a pinnacle, the helicopter engine lost power when they were about 15 feet above the ground. The helicopter hit the ground hard and then rolled down the hill and came to rest on its right side.

The helicopter was examined on site by Federal Aviation Administration (FAA) inspectors and recovered for further examination.

The FAA inspectors attempted to start the engine, but the engine appeared to be “locked up.”

On May 13, 2009, investigators examined the engine at the owner’s hangar facilities at the North Las Vegas airport.

During the engine examination, the top spark plugs were removed and noted that they were free of mechanical malfunction at the electrodes. The engine cooling fan was rotated by hand in the direction of normal rotation, at which time copious amounts of engine oil was forced out of the spark plug holes of the number 2 and 4 cylinders.

Mechanical continuity was established throughout the engine during the thumb compression check. The magnetos remained secure on their respective mounting flanges. The spark plugs and exhaust system components exhibited a light gray-brown coloration and remained free of oil residue. The oil suction screen remained free of visible contaminates.

The engine was transported to the facilities of Nevada Aircraft Engines, Henderson, Nevada, to be run on a dynamometer test stand under the supervision of the investigation team. The engine started on the first attempt, and after a warm-up and magneto check, the engine produced 185 hp at 3,065 rpm. According to the data plate affixed to the engine, the subject engine is rated at 190 hp at 3,200 rpm. The engine ran smooth and exhibited no abnormal indications or sounds.

Investigators concluded that engine oil migration into the number 2 and 4 cylinders occurred during the time the helicopter lay resting on its right side. This contributed to a hydraulic lock event that was present when the Federal Aviation Administration inspectors attempted to start the engine. Once the oil was drained from the cylinders during the thumb compression check, the condition was mitigated, which allowed unimpeded full rotation of the crankshaft.