LAX96LA347

The pilot reported that during the departure climb about 2,500 feet msl, there was a loud bang, followed by severe airframe vibration. The pilot closed the throttle and pulled the mixture control into idle cutoff. The pilot established a glide and made an uneventful off-airport landing. Postaccident examination revealed that about 20 inches of one propeller blade was missing. The remaining propeller blade and hub was sent the Safety Board's Materials Testing Laboratory for analysis. The analysis report documented a crack progression starting at the blade's trailing edge and migrating forward through about 50 percent of the chord. At that point the blade failed from overload. The report indicated that a mechanical type damage had occurred at the trailing edge crack initiation point. According to the records, at the time of this accident the engine and the propeller had accumulated 307.24 hours since overhaul.

History of flight

On July 12, 1996, about 1810 hours Pacific daylight time, a Piper PA-28-180, N5388L, operated by Sun Air Aviation, Inc., of Camarillo, California, was substantially damaged near Palm Springs, California. Visual meteorological conditions prevailed for the personal cross-country flight and no flight plan was filed. Neither the pilot nor the pilot rated passenger were injured. The flight originated at Bermuda Dunes, California, at 1805 as a return flight to Camarillo.

The pilot stated that during the departure climb, about 2,500 feel msl, there was a loud "bang" followed by severe airframe vibration. The pilot closed the throttle and pulled the mixture control into idle cutoff and established a glide. Palm Springs Approach Control was advised of the emergency landing prior to touchdown in a dirt field.

Postaccident examination of the airplane revealed that part of the propeller blade separated about 20 inches from the blade tip. Further examination revealed that structural damage occurred to the airframe from the imbalance.

Aircraft history

As a result of a prior off-airport landing, the aircraft had received major repairs to the forward section of the airframe. The engine was overhauled and the propeller was replaced with a used overhauled propeller. The aircraft was returned to service with an annual inspection on December 18, 1995, at a tachometer reading of 4186.05. The engine and the propeller were listed as zero time since overhaul. According to the records, the engine had accumulated 307.24 hours since overhaul at the time of the accident.

Propeller history

The propeller had been purchased by Aircraftsman, the aircraft repair shop that performed the major repairs to the airframe. Aircraftsman purchased it from Global Aircraft, who had purchased it from a salvage dealer in Canada. The propeller was overhauled by Southern California Propeller Service for Aircraftsman on December 8, 1995, and installed on the accident aircraft. At the time of this accident, the propeller had accumulated 307.24 hours since overhaul.

Testing and research

The damaged propeller, less the missing tip section, was sent to the Safety Board's Materials Testing Laboratory in Washington D. C., for metallurgical analysis. According to the report, "An optical examination of the fracture face revealed fatigue progression from the trailing edge forward through about 50 percent of the chord." The report indicated that the crack initiation point was a result of a mechanical type damage or impact to the trailing edge area.