LOPEZ, WA, USA
N77190
CESSNA 140
AFTER CHANGING THE AIRCRAFT'S OIL AND CHECKING THE OIL SCREEN, THE PILOT REINSTALLED THE OIL SCREEN AND OIL TEMPERATURE SENSING BULB. DUE TO BEING DISTRACTED BY HIS INCORRECT SAFETY WIRING OF THE OIL SCREEN NUT, THE PILOT FAILED TO FULLY TIGHTEN THE OIL TEMPERATURE SENSING BULB NUT. ON THE FIRST FLIGHT AFTER THE OIL CHANGE, AN ENGINE FAILURE OCCURRED WHEN THE OIL TEMPERATURE SENSING BULB NUT BACKED OUT OF ITS ATTACH POINT, AND ALL OF THE ENGINE OIL WAS LOST FROM THE ENGINE. AFTER THE ENGINE FAILURE, THE AIRCRAFT WAS DITCHED IN THE WATERS OFF LOPEZ ISLAND.
HISTORY OF FLIGHT On January 18, 1994, at 1245 Pacific standard time (PST), a Cessna 140, N77190, ditched in the waters off of Lopez Island, Washington. The private pilot, who was the sole occupant of the aircraft, received fatal injuries, and the aircraft sustained substantial damage. The personal pleasure flight, which was en route from Diamond Point Airstrip, Gardiner, Washington to Anacortes Airport, Anacortes, Washington, was being operated in visual meteorological conditions at the time of the accident. No flight plan had been filed, and there was no report of an ELT activation. According to friends of the owner/pilot, he had been at Diamond Point Airstrip in order to have a new muffler system installed on the aircraft. On the morning of the accident, while the work on the muffler system was being completed by a certified mechanic, the owner had changed the aircraft's oil and removed the oil screen for inspection. According to the mechanic who was working on the muffler, the owner was doing this work as owner maintenance, and the mechanic was not supervising the activity. The mechanic said that the owner inspected the screen, screwed it back into the accessory case, and safety wired the screen to the accessory case himself. Almost immediately after he had applied the safety wire, the owner saw that he had applied the wire to the screen nut incorrectly, and he brought his mistake to the attention of the mechanic for confirmation. The mechanic said that he confirmed the owner's error, told him to go ahead and rewire it correctly, and then reached down and felt the oil temperature probe, which appeared to be screwed into the rear of the oil screen. He said that he only felt the probe nut with his fingers, and did not use a wrench to check whether it had been tightened into the screen nut. According to the mechanic, he and the owner then continued their individual tasks independently of each other, and upon completing the muffler installation, the mechanic recorded his work in the aircraft log book. The engine was then run on the ground in order to test its operation, and to check on the proper function of the new mufflers and carburetor heat system. After the engine checks had been completed, the pilot called an FBO at the Anacortes Airport for an update on the weather, and then departed for Anacortes at about 1230 PST. The aircraft's route prior to the accident site could not be determined as the pilot was not communicating with air traffic facilities and no transponder signature was being received from the aircraft. About two minutes before the ditching, the pilot contacted Whidbey Island Approach Control and advised them that his engine had quit, and that he was attempting to glide to the shore of Lopez Island. Witnesses on the island, who had heard the aircraft's engine run rough and then stop, watched the aircraft glide toward the shore, but ultimately ditch in the water about one-half mile off shore. The witnesses said that the aircraft dropped the last few feet toward the water, and that it seemed to hit quite hard, splashing a considerable amount of water into the air. The aircraft floated for about two minutes, and then sank with no sign of the pilot exiting the aircraft. WRECKAGE AND IMPACT INFORMATION According to the divers who reached the aircraft, it was sitting upright on the bottom, and the pilot was still strapped in his seat by his lap belt and shoulder harness. The aircraft was recovered from the water on January 26, 1994, and inspected on the dock at Anacortes Harbor. All main structural portions of the aircraft were present. The bottom of the engine cowl and the lower part of the nose bowl were crushed back into the engine and the firewall by hydraulic impact. The fuselage was wrinkled in a number of places and fully buckled on the belly just aft of the main gear box structure. The center of the front wind screen was shattered, and the last ten inches of one prop blade was bent aft about ten degrees. Inspection of the engine revealed portions of the accessory case eaten through by the salt water, and a large hole in the upper end of the crankcase. This hole was displaced outward, and it could be seen that the large end of number one and number two connecting rods had failed. The crankshaft was intact and could be rotated approximately 340 degrees. Number one and number two connecting rod journals were heavily scored and blackened. Both of these journals showed impact damage from the respective connecting rods. Discoloration was also present adjacent to the number four connecting rod journal, and its bearing was found in the process of being extruded from between the journal and the rod end. Further inspection revealed that the safety wire securing the oil screen housing to the accessory case was still connected backwards, and that the oil temperature sensing bulb had backed completely out of the oil screen housing. The mechanic who confirmed the incorrect safety wire installation to the owner at Diamond Point said that it appeared to him that the owner had never reworked the original safety wire installation. Although the safety wire was installed incorrectly, the oil screen was still tightly secured in the accessory case. But with the oil temperature probe being backed out of the oil screen nut, there was a clear path around the edges of the probe for the engine oil to escape from the accessory case. According to the representative of Teledyne Continental Motors who assisted in the partial teardown and inspection of the engine, the failure of the engine "...was consistent with an oil starvation event which was caused by an improperly secured oil temperature bulb nut." According to this representative, when the bulb nut backed out of the bushing at the back of the oil screen housing, the engine oil was pumped out of the engine through the oil probe orifice. ADDITIONAL DATA AND INFORMATION The body of the pilot was recovered from the wreckage two days after the accident, and an autopsy was performed by the San Juan County Coroner. Death was attributed to salt water drowning secondary to aircraft accident. No pre-accident evidence of incapacitation was noted. A toxicology examination was completed by the FAA Toxicology and Accident Research Laboratory, and no carboxyhemoglobin, cyanide or drugs were detected. The same examination detected no ethanol in the blood, but measured the presence of both methanol and ethanol in the urine and vitreous fluids. The aircraft was released to Toplis and Harding Insurance Adjusters, a representative of the owner, on January 17, 1994, at Anacortes, Washington.
THE PILOT/OWNER'S IMPROPER INSTALLATION OF THE OIL TEMPERATURE SENSING BULB, THE TOTAL LOSS OF ALL ENGINE OIL, AND THE SHEARING OF A CONNECTING ROD CAP.
Source: NTSB Aviation Accident Database
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