LAX96FA097

The engine suddenly quit during cruise flight and, unable to reach land, the pilot ditched in the ocean. After recovery, oil streaks were observed inside the engine cowling that proceeded back along the underside of the aircraft to the empennage. Also noted was a separation of the magneto housing from the accessory case and an oil residue. Examination of the housing revealed the presence of wear on the contact surfaces of the hold down lugs that suggests both lugs were loose prior to the accident. The looseness of the lugs would allow the magneto to vibrate, resulting in fatigue cracking through the mounting flange. The magneto was recently installed on the aircraft at the last inspection and the mechanic who performed the work did not have an inspection authorization.

History of flight

On January 19, 1996, at 1720 hours Pacific standard time, the pilot of a Piper PA-28-236, N2476Y, experienced a loss of engine power during a cruise flight near Seal Beach, California. Visual meteorological conditions existed at the time. The aircraft sustained substantial damage. The pilot was not injured and his two passengers received minor injuries. The aircraft departed John Wayne Airport in Santa Ana, California, at 1700 for a local pleasure flight.

The pilot stated that he was cruising at 2,000 feet above the water at an indicated airspeed of 125 knots when the engine suddenly stopped with no warning. The engine gauges were indicating normal prior to the power loss. The pilot attempted to restart the engine twice with no success. When he realized he wasn't going to make landfall, he ditched the aircraft in the water about 200 yards offshore at Seal Beach. The occupants got out of the aircraft and swam to the shore after it sank.

Aircraft information

The aircraft was operated and maintained by a local flying club at the John Wayne Airport. The last inspection was completed in June, 1996. During this time, the magneto was overhauled and reinstalled on the aircraft by a local mechanic. According to the FAA, the mechanic did not have an inspection authorization certificate.

Wreckage

The aircraft sank in 27 feet of water as measured by a pneumofathometer. The aircraft was found intact lying on the bottom in an inverted position and was partially submerged in the ocean silt. The aircraft was recovered intact on January 22, 1996, washed with fresh water, and brought to shore at San Pedro, CA. An examination of the aircraft revealed an oil stain on the inside of the engine cowling that proceeded back along the underside of the aircraft to the empennage. Afterwards, the aircraft was taken to a facility in Compton, California, for a more detailed examination.

Examination of the engine revealed that the magneto housing had separated from the accessory case at the mounting flange with oil residue present in the area. The magneto and the mounting flange were sent to the Board's metallurgical laboratory in Washington, D.C., for examination.

Tests and research

The separated pieces of the magneto housing were cleaned ultrasonically in acetone and examined with a scanning electron microscope (SEM). According to the metallurgist, the SEM examination disclosed no discernible fracture features on the upper surface. However, the SEM examination of the lower piece revealed fatigue striations in fracture areas with lesser amounts of corrosion. Due to extensive corrosion, the exact extent of the fatigue cracking was not determined. Examination of the lower lug with the aid of a low power binocular microscope revealed evidence of wear on the contact surface. The amount of wear on the contact surface of the upper lug was significantly less.

Additional data

The aircraft was verbally released 1/23/96 to Mr. Daniel Heersema of Associated Aviation Underwriters of Universal City, California. The magneto was returned to Mr. Heersema on September 30, 1996.