NTSB Factual Report

On July 16, 2015, about 1851 eastern daylight time, an experimental amateur built Young SeaRey, N236JY, was substantially damaged during landing on Laurel Lake, near Corbin, Kentucky. The student pilot/owner, the sole occupant was not injured. The amphibious airplane was substantially damaged. The airplane was registered to a private individual and operated under the provisions of 14 Code of Federal Regulations (CFR) Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The local flight originated about 30 minutes earlier from London-Corbin Airport – Magee Field (LOZ), London, Kentucky.

The pilot stated that in preparation of the intended flight to Lake Cumberland where he intended to perform water landings and takeoffs, he performed a preflight inspection of the airplane. Part of the inspection included siphoning all the fluid from the coolant overflow bottle and adding it into the coolant expansion tank. He indicated that because of this procedure, he permanently installed the siphon hose into the aircraft. He also indicated that in the 6 weeks of owning the airplane he needed to add 1 pint of coolant.

The pilot further stated that after takeoff while wearing a Telex Echelon 20 noise cancelling headset and flying around the Laurel Lake area (located within the Daniel Boone National Forest), he "thought he heard sputter or something." He later indicated he was not sure if he heard it or perceived it. At that point while flying about 2,700 feet mean sea level (msl), he looked down and later reported to either the Federal Aviation Administration (FAA) or National Transportation Safety Board (NTSB) noticing a higher than normal indication (235 degrees Fahrenheit (F)) for water/coolant or oil temperature, respectively. He informed the FAA inspector that the typical water/coolant temperature during level flight is 180 degrees F, and the maximum water/coolant temperature is 248 degrees F. He immediately reduced power from between 5,000 and 5,200 rpm to 4,000 rpm in an attempt to cool the engine, and trimmed the airplane. Rather than fly from the airplane's present location to LOZ, between which is no suitable forced landing site, he opted for a precautionary landing on Laurel Lake.

The pilot reported the landing on the lake was, "beautiful/perfect", but about 100 feet after touchdown felt like he "hit a brick" or something underwater with the hull which slightly penetrated the front hull causing the airplane to take on water at a greater rate than the bilge pump could keep up with. The incoming water caused the airplane to sink up to the wings before he could water taxi to a nearby boat ramp. He further indicated it was obvious from the postcrash damage that he had hit something, but indicated to the FAA inspector-in-charge (FAA-IIC) that he did not see the reported object (log) that he hit.

One witness reported to the FAA-IIC that while on a boat, she observed the airplane approach over the overflow at Laurel Lake and flew past the boat she was on. The airplane was observed in a hard left turn, going around a point of land. Although the witness was unable to determine the aircraft's height or see the water due to rising terrain, she did report observing a large plume of water that engulfed the airplane. The witness further reported the landing was not normal for a seaplane and that it, "splashed down in a wall of water" rather than gliding. They then drove the boat around the point and observed the airplane while attempting to water taxi at a high power setting. They assisted the pilot with towing the airplane to the nearby boat ramp and did not notice any object in the water that may have been contacted by the airplane. Additionally, no further damage was done to the airplane that was not already present. The same witness used her mobile phone to record audio and video of the airplane while water taxiing, and subsequently provided the video clip to the FAA-IIC. A copy of the witness interview summary is contained in the NTSB public docket.

The video segment taken by witness's phone was subsequently provided to the NTSB for review. The provided video segment contained 52 seconds of video and audio with commentary heard from several occupants of the boat (male and female voices). Closer review of the video segment revealed it began with a view of the airplane on the water attempting to be taxied at a high power setting. Beginning at 19 seconds elapsed time into the video segment, a female indicated, "I know it crashed, he was coming in, that was a hard hit." The audio and video continued to record the engine being operated while continuing to attempt to water taxi while the audio recorded voices from individuals on the boat. At 49 seconds elapsed time, the same female who reported the hard hit indicated, "… well when we come around and I see that big of a hit…."

Immediately following the accident, a special agent with the U.S. Forest Service responded to the boat ramp to where the airplane had been towed to and obtained information from the pilot-in-command. After the exchange of information, the pilot inadvertently left behind in the agent's car a Go-Pro camera; the camera was secured. The camera was subsequently sent to the NTSB Vehicle Recorder Division for read-out, but it did not contain a "SD" memory card, and the camera does not have internal memory; therefore, video footage of the accident sequence was not available. The camera was returned to the owner.

The previous owner of the airplane who holds a certified flight instructor (CFI) certificate with airplane single engine rating and operated the airplane for about 180 hours reported to the FAA that the typical CHT indication is 235 degrees F, which is unmarked or between the marks of 210 and 250. He also indicated that during the first winter of owning the airplane with his father flying it, his father noticed an elevated cylinder head temperature (CHT) reading that caused him to divert to an airport which has a facility that specializes in Rotax engines. Inspection of the engine revealed damage consistent with operation of the engine with no coolant that was caused by a hole in the hose to the overflow bottle. The engine was repaired and returned to service. The previous owner also reported another cooling system issue while ferrying the airplane to the new owner the month before the accident. About 20 minutes after takeoff while flying near the Ohio River in Ohio, he noted a cylinder head temperature (CHT) reading of 270 degrees, which was above the typical reading. As a result, he performed a precautionary landing on the Ohio River. After landing he began trouble shooting and noted the coolant level in the expansion tank was very low. He added clean river water to the expansion tank and located a FAA certified repair station (FAA-CRS) about 6 to 7 miles away. He departed from the river and flew about 3 minutes to the nearby airport. While there at the FAA-CRS, the coolant system was drained and new coolant was purchased and added. Following the maintenance, he continued the ferry flight adding that he flew about 5 hours before delivering the airplane; no discrepancies were noted with the CHT reading or engine after cooling maintenance was performed. After delivering the airplane to the new owner, he reported giving him 2.0 hours of instruction which did not include water operations nor gear operation. The previous owner/CFI indicated he provided the pilot a 1.5 page long endorsement for the new owner's pilot logbook to fly with the gear down to an airport for instruction purposes; he did not make a copy of the endorsement. The previous owner also reported that after delivering the airplane to the new owner, he was asked several times to fly with him and land in the same area as the accident location, but refused citing that it was a federally protected area. A copy of the FAA and NTSB interview summaries and also the engine repair records are contained in the NTSB public docket.

Following recovery of the airplane, inspection of the aircraft was performed by the FAA-IIC. Inspection of the airplane, serial number (S/N) 1DK085, revealed cracks in the hull above both main landing gears. Additionally, further inspection of the hull revealed numerous stress fractures and outer fiberglass separations with no evidence of punctures or solid impact signatures. The cockpit glare shield and windshield were noted to be shifted to the right of aircraft centerline, and the tailboom fairing and empennage skin overlap exhibited damage. The airplane was equipped in part with oil temperature and cylinder head temperature (CHT) gauges. They were marked in increments of 120, 180, 210, 250, and 300, with a green arc noted between 210 and 250 on the oil temperature gauge. The airplane was not equipped with a coolant temperature probe or gauge. The hour meter indicated 193.55. Inspection of the flight controls revealed continuity for roll, pitch, and yaw. The right outboard wing float was displaced outboard about 45 degrees and the forward vertical oriented tubular member exhibited a compression wrinkle on the inboard portion. Inspection of the Rotax 912UL engine, S/N 4401703 revealed the oil level was serviceable and the oil cooler was secure and in a serviceable condition. Inspection of the coolant system components revealed the level of coolant in the expansion tank and overflow bottle were at serviceable levels. There were no reported leaks or discrepancies noted in the cooling system components. The CHT probe was installed in the No. 2 cylinder position, which according to the engine manufacturer representative is the hottest cylinder in the pusher configuration. There was no reported preimpact failure or malfunction of the engine or its systems. A copy of the report from the FAA-IIC is contained in the NTSB public docket.

According to a representative of the airplane designer, his review of pictures depicting the damage to the airplane revealed it was consistent with two scenarios, either impact with the water while in an excessively nose-down condition or landing with the landing gear extended. The representative also indicated that the reported CHT reading would be considered slightly elevated, but would not be considered unusually high. He also indicated if the CHT would indicate 240 degrees, that would be the borderline temperature for a pilot to decide whether to land at that time or continue to a safe landing site. At 240 degrees, he would expect a pilot to reduce power in an effort to cool down the engine. If the temperature stabilizes he would expect a pilot would be safe to proceed to a destination airport, but if the temperature increases then a precautionary landing would be prudent.

Review of the engine Operator's Manual (OM) revealed the normal operating oil temperature is between 190 and 230 degrees F, and the maximum specified oil temperature is 285 degrees F. When using either waterless or conventional coolant, the maximum cylinder head temperature is specified to be 300 degrees F. Section 4.4 of the OM indicates that if the maximum oil temperature reading of 285 degrees F is exceeded, the engine power is to be reduced to the minimum necessary to maintain flight and carry out precautionary landing. Excerpts from the engine OM are contained in the NTSB public docket.

According to a representative of the engine manufacturer, the Rotax 912UL engine is not equipped at manufacture with a coolant temperature probe installed, rather; it is equipped with a cylinder head temperature probe that measures the temperature of the material at the cylinder head and not the coolant temperature. The representative also indicated that it is expected that the CHT reading would be higher than the coolant temperature if a coolant temperature probe and gauge were installed.

According to the Unites States Department of Agriculture Forest Service "Occupancy and Use", landing of aircraft on waters of the Daniel Boone National Forest is prohibited without a permit; the pilot did not have a permit issued to him. A copy of the document is contained in the NTSB public docket.

NTSB Probable Cause

The pilot’s improper conduct of a precautionary landing, which resulted in abnormal water contact that damaged the hull.