ERA23FA249 · Cessna 182 D

The pilot departed on the third skydiving flight of the day with four skydivers on board and climbed to about 11,000 ft mean sea level (msl) when the jumpers departed the airplane. The pilot flew back to the airport and reported over the common traffic advisory frequency (CTAF) that he was descending through 6,000 ft msl. The operator reported hearing the pilot make another radio call on the CTAF but the “…call did not sound like a normal one and I could not identify what he said. I thought by the sound of his voice something was off.” A witness heard the engine sputtering followed by the engine losing power and then heard the impact. The airplane impacted trees and terrain about 1 nautical mile from the center of the intended airport, coming to rest in a nose-low, tail-high attitude with the left wing separated at the wing root. Postaccident examination of the flight controls revealed flight control continuity, and all fractures were consistent with overload. The examination of the engine revealed crankshaft, camshaft, and valvetrain continuity. The air induction, exhaust, lubrication systems, magnetos, and spark plugs revealed no evidence of preimpact failure or malfunction. The carburetor heat was found in the off position.

Postaccident examination of the airframe revealed that the right-wing fuel bladder was intact and contained about 25 ounces of fuel. The left-wing fuel bladder was breached; there was no evidence of significant fuel leakage from the ruptured left-fuel tank evidenced by minimal fuel blight of the vegetation in the immediate area. There was no evidence of fuel siphoning aft of either wing-tank fuel filler cap. The fuel selector was found in the left-tank detent. No fuel was found in the left- or right-inlet fuel lines or the outlet line of the fuel selector valve. No fuel stains were noted on the interior panel below the fuel selector valve. About 5 ounces of fuel were drained from the airframe fuel strainer and about 4 ounces were found in the carburetor bowl.

The pilot fueled the airplane the day before by adding 30.3 gallons of 100 low lead fuel. The amount of fuel in the airplane before he added the fuel is unknown. He then flew two uneventful skydiving flights that day. The operator reported that on the next day the pilot flew another skydiving flight in the morning, and when the pilot returned from the flight, he checked the fuel level with a dipstick and stated that he had 40 gallons of fuel on board. The operator reported that the pilot had enough time to refuel the airplane but chose not to. The pilot flew another skydiving flight before the accident flight, which was the fifth flight since he fueled the airplane the day before. The operator reported the airplane burned 7 to 9 gallons of fuel per skydiving flight. The pilot used a fuel dipstick to assist in determining the fuel level in the tanks. However, the fuel dipstick used was not made for the make and model of the accident airplane. Therefore, a fuel conversion chart was created to indicate how much fuel was actually in the tank when the dipstick was used. If the airplane had 40 gallons of fuel on board as the pilot stated, there should have been enough fuel for the intended flight. However, had the pilot misinterpreted the fuel dipstick reading, he may have believed he had about 43 gallons of fuel on board, as indicated by the dipstick, when instead there were about 24 gallons, as indicated by the conversion chart. In that case, during the next three flights, the airplane could have sustained fuel exhaustion as a result of the fuel burn and the unusable fuel in each tank. The nearest weather station, located about 29 miles from the accident site, indicated the temperature and dew point spread was 27°C and 8°C, respectively, which was conducive for carburetor icing at glide or cruise power. About 1443, ADS-B data indicated that the airplane began its descent from about 11,000 ft msl and 3 minutes later it descended through 6,000 ft msl, about a 1,666 ft-per-minute rate of descent. The last ADS-B radar point was about 1450, and the airplane was about 1,500 ft msl. While the pilot had a history of diabetes being treated with a medication and a documented history of retinopathy, it is unlikely that the pilot had symptoms of severe high or low blood glucose at the time of the accident. Minor symptoms of diabetes, such as fatigue or blurry vision, could not be entirely excluded. Due to his heart disease, the pilot was at significantly increased risk of a sudden impairing or incapacitating cardiac event, including angina, arrhythmia, or heart attack. There is no autopsy evidence that such an event occurred; however, such an event does not leave reliable autopsy evidence if it occurs immediately before death. It is possible that the pilot’s report of the fuel level using the dipstick did not account for the fuel conversion chart that would have indicated that the airplane had about 24 gallons of fuel on board, and not the reported 40 gallons. In this scenario, the pilot would have departed on the flight with substantially less fuel than anticipated, and the engine lost power due to fuel exhaustion. However, the evidence supports another possible scenario: the airplane was descending from about 11,000 ft msl and at a high rate of descent in atmospheric conditions that were conducive to carburetor icing in cruise and glide power. The carburetor heat was found in the off position after the accident. Had the pilot not used carburetor heat during the descent, it is also possible that the engine sustained a complete loss of engine power due to carburetor icing. Accordingly, the definitive cause of the total loss of engine power could not be determined.

Verbatim NTSB analysis and probable cause from the NTSB dataset