What happened
The flight was interrupted when the aircraft engine experienced a complete failure. This mechanical stoppage occurred immediately following a total loss of engine oil pressure. The root cause of the fluid loss was traced to an assembly issue between the oil cooler and the engine block. Specifically, the bolts securing this connection had not been tightened to the required specification. This undertorquing allowed pressurized oil to bypass the internal seals rather than circulating through the cooling system.
At the time of the incident, the engine had accumulated 162 hours of operation since its last major overhaul. It had also undergone an annual inspection just three hours prior to the flight, indicating that the defect was likely introduced during or immediately after that maintenance event.
Upon detecting the failure, the pilot initiated a forced landing procedure. The aircraft was directed toward an area of rough terrain suitable for an emergency stop. The impact with the uneven ground resulted in substantial structural damage. The main landing gear sheared off under the stress of the touchdown. Simultaneously, the nose gear collapsed, causing the front of the airframe to pitch forward and rest on its nose.
The investigation
Investigators examined the engine components to determine the sequence of events leading to the failure. Analysis of the oil cooler assembly confirmed that the fasteners were not properly secured. This physical evidence supported the conclusion that mechanical looseness permitted the oil to escape the system entirely, leading to lubrication starvation and subsequent engine seizure.
Findings
The primary factor contributing to the accident was the loss of engine oil caused by the improperly torqued assembly. The maintenance history showed the engine was relatively fresh on time, but the specific installation error negated the benefits of the recent annual inspection. The resulting forced landing on rough terrain exacerbated the damage, leading to the collapse of the landing gear and the nose-over attitude of the aircraft.