CEN12LA437

The pilot reported that the engine experienced a loss of oil pressure and power during aerial-application flight maneuvers. The airplane impacted a hay bale and roadside ditch during the subsequent forced landing. A postaccident examination revealed that one of the oil lines associated with the oil-cooler had ruptured. The oil line’s reinforcing steel braiding was corroded, and a majority of the individual steel strands were fractured in the immediate area surrounding the rupture. A review of available records indicated that there were no unresolved maintenance items and that there was no history of engine oil leaks since the last engine overhaul. The installation date and total time in-service of the ruptured engine oil line could not be determined from the available maintenance information.

On July 12, 2012, at 0700 mountain daylight time, a Piper model PA-25-235 airplane, N8801L, was substantially damaged during a forced landing following a loss of engine power near Mott, North Dakota. The commercial pilot was not injured. The airplane was registered to and operated by the pilot, under the provisions of 14 Code of Federal Regulations Part 137 without a flight plan. Day visual meteorological conditions prevailed for the local aerial-application flight that originated from Mott Municipal Airport (3P3), Mott, North Dakota, about 0615. The pilot reported that the engine experienced a loss of oil pressure and power during aerial-application flight maneuvers. The airplane impacted a hay bale while the pilot attempted to maneuver the airplane to a nearby road during the forced landing. The airplane subsequently impacted a roadside ditch. The airplane sustained substantial damage to the fuselage and left wing during the accident. A postaccident examination of the airframe revealed engine oil covering the lower fuselage, left fuselage sidewall, left horizontal stabilizer, and the left elevator. An external examination of the engine did not reveal any crankcase damage. The engine oil dip-stick indicated that there was little to no available oil within the engine. The oil lines associated with the oil-cooler were removed for examination. One of the oil lines had ruptured about 13-inches from the oil-cooler. The oil line reinforcing steel braiding was corroded and a majority of the individual steel strands were fractured in the immediate area surrounding the rupture. The engine, a Lycoming O-540-B2C5, serial number L-14001-40, had accumulated 1,618 hours since the last overhaul, which was completed on April 1, 1987. A review of available records indicated that there were no unresolved maintenance items and that there was no history of engine oil leaks since the last engine overhaul. No engine related issues were identified during the last annual inspection that was completed on August 2, 2011. The airplane had accumulated 46 hours since that annual inspection. The installation date and total time in-service of the ruptured engine oil line could not be determined from the available maintenance information. The closest weather observing station was at Hettinger Municipal Airport (KHEI), located about 25 miles southwest of the accident site. At 0653, the KHEI automated surface observing system reported the following weather conditions: wind 240 degrees at 5 knots, visibility 10 miles, sky clear, temperature 18 degrees Celsius, dew point 14 degrees Celsius, altimeter setting 29.99 inches of mercury.