CEN19LA159

The pilot departed on a maintenance test flight in the airplane to break in an engine cylinder, which had just been replaced. During the flight, the pilot noticed an oil pressure warning light illuminate, followed by a low oil temperature indication. The pilot attempted to divert to a nearby airport; however, the engine experienced a total loss of power, and he conducted a forced landing, during which the wings sustained substantial damage. Examination of the airplane revealed a hole in the engine case above the No. 4 cylinder. Further examination revealed that the engine oil pressure switch had separated into two pieces . A detailed examination of the switch found that it had failed at a manufacturing swaged joint between its threaded section and cap piece. Therefore, it is likely that the swaging process was insufficient during manufacture. The broken switch allowed engine oil to escape the system, resulting in oil starvation and failure of the No. 4 cylinder.

On May 30, 2019, about 1100 central daylight time, a Lancair LC41 airplane, N2514F, conducted a forced landing near the Cleburne Regional Airport (CPT), Cleburne, Texas. The pilot was not injured, and the airplane sustained substantial damage. The airplane was registered to and operated by Van Bortel Aircraft, Inc under the provisions of Title 14 Code of Federal Regulations Part 91 as a maintenance test flight. Visual meteorological conditions prevailed for the local flight at the time of the accident. The flight was conducted to break-in the engine's No. 5 cylinder, which had just been replaced. During the flight, the pilot noticed the oil pressure warning light illuminate, followed by a low oil temperature indication. The pilot attempted to divert to CPT; however, the engine experienced a loss of power and he conducted a forced landing. During the landing, the airplane collided with trees and came to rest upright and partly submerged in a small pond about one mile from CPT. Inspection of the airplane revealed substantial damage to the wings, and water submersion damage to the airplane. The airplane's Hobbs meter read 1,090.1 hours. The airplane was recovered to a secure facility for further examination. The examination was conducted by the NTSB Investigator-in-Charge, a representative from Van Bortel Aircraft, and technical representatives from the engine and airframe manufacturers. The examination noted the engine case had a hole above the No. 4 cylinder, and when the propeller was rotated by hand, the engine had limited rotation and internal binding was noted. A light, oil film was noted on the bottom of the airplane. The exam also found an oil pressure switch separated in two pieces. The threaded section remained to its mating joint; the other section rested on an exhaust tube and attached by its wire connector as seen in Figure 1. Figure 1: Oil Pressure Switch Photo Continental A visual inspection of the switch noted that the switch had separated at a manufacturing joint between the body and threaded section. The switch was removed and sent to Textron Aviation, Inc, Materials Laboratory for a detailed examination of the switch. Textron's examination noted the switch failed at the swaged joint between the threaded section and the base cap section of the switch. The examination was not able to determine how the joint failed, since there were no physical indications as to how the swaged joint failed.