N928RK

HISTORY OF FLIGHT On September 15, 2015, about 0606 Alaska daylight time, a single-engine, turbine-powered, float-equipped de Havilland DHC-3T (Otter) airplane, N928RK, impacted tundra-covered terrain just after takeoff from East Wind Lake, about 1 mile east of the Iliamna Airport, Iliamna, Alaska. Of the 10 people on board, three passengers died at the scene, the airline transport pilot and four passengers sustained serious injuries, and two passengers sustained minor injuries. The airplane sustained substantial damage. The airplane was registered to and operated by Rainbow King Lodge, Inc., Lemoore, California, as a visual flight rules other work use flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Dark night, visual meteorological conditions existed at the departure point at the time of the accident, and no flight plan was filed for the flight. At the time of the accident, the airplane was en route to a remote fishing site on the Swishak River, about 75 miles northwest of Kodiak, Alaska.

The manager of Rainbow King Lodge reported that the accident airplane was being used to transport sport-fishing clients and guides to a remote area for a day of salmon fishing. The manager noted that, on the morning of the accident, a lodge employee transported the guests to East Wind Lake in a lodge-owned van for the early morning departure.

The pilot reported that, on the morning of the accident, he woke at 0430 to check the weather and prepare for the flight. He stated that he had been sleeping normally and was feeling well except for pain in his right knee. He left the lodge at 0515 to conduct a preflight of the airplane. He stated that, for an easterly departure, the light on the building near the departure point is left on so the pilot can use it as a visual reference, but for a westerly departure, there are no lights to use as a reference. The pilot typically used a ridgeline about 7 miles west of Iliamna as a horizon, but the dark night conditions made it difficult to see the ridgeline. He stated that a very small percent of flights departed in the dark.

The lodge employee that drove the guests to the lake stated that they left the lodge at 0545. The airplane had been loaded the day before with fishing equipment. He said that, after all of the passengers boarded the airplane and the pilot had started the engine, he then untied the airplane's floats so the pilot could taxi away from the shoreline. The lodge employee reported it was dark but that he was still able to watch the airplane as it started its westerly takeoff run. He said that, after liftoff, the airplane began to climb and then descended, and the floats subsequently struck the water's surface. The airplane then became airborne again and veered right, but he lost sight of it behind an area of rising terrain.

The pilot stated that, during takeoff, he looks outside the airplane and does not focus on his instruments. The pilot stated that, after the airplane lifted off the water at what seemed like a normal pitch, he heard a noise from the left side of the airplane that distracted him. He looked outside for visual cues but was unable to see due to the dark night conditions. According to the automatic dependent surveillance-broadcast (ADS-B) data, the airplane then began a gradual right turn before reaching a maximum altitude of 175 ft above the water. The airplane then descended toward the water's surface, flew low over the water and terrain, and then climbed briefly again before it impacted terrain. The pilot stated that he did not know that the airplane touched the water's surface after the initial liftoff or that it then turned right.

A search and rescue team was assembled consisting of Iliamna residents, lodge employees, and Alaska State Troopers. Dark night conditions delayed the search and the discovery of the wreckage by about 30 minutes. PERSONNEL INFORMATIONThe pilot, age 54, held an airline transport pilot certificate with an airplane multiengine land rating and commercial pilot privileges with an airplane single-engine land rating. He also held a type rating for Beech 1900 and Beech 300 airplanes and a flight instructor certificate with an airplane single-engine land rating.

According to the Federal Aviation Administration (FAA) medical certification file, the pilot was first medically certificated in 1981. His most recent FAA second-class medical certificate was issued May 12, 2015, with the limitation that he must have available glasses for near vision. At that time, he measured 71 inches tall and weighed 249 lbs. He reported no medications, and the examining physician did not identify any abnormal findings.

According to the pilot's logbooks, he had about 11,280 total flight hours, about 450 hours of which were in the accident airplane make and model. In the 90 and 30 days before the accident, the pilot logged 200 and 70 flight hours, respectively. His most recent flight review was on February 9, 2014, in a Schweizer S269C helicopter.

The pilot had flown for Rainbow King Lodge during the 2012 to 2015 fishing seasons. The first two seasons were before the Otter was converted to a turbine-powered airplane (see the next section for more information about the conversion). The pilot stated that he had not received any training in the airplane since the turbine conversion. AIRCRAFT INFORMATIONThe accident airplane was a high-wing, float-equipped, single-pilot, de Havilland DHC-3T, N928RK, serial number 61, manufactured in 1954. It was powered by a Honeywell TPE 331-12JR-702TT turboprop engine per a Texas Turbine Conversions, Inc., supplemental type certificate (STC). It was equipped with a Hartzell model HC-B4TN-5NL four-bladed propeller.

In April 2014, the airplane was sent to Recon Air Corporation in Geraldton, Ontario, Canada, for a major overhaul and the turbine conversion. The airplane's US registry was changed to N928RK. The airplane was also modified with a Baron STOL kit and an upgross kit per an STC to improve its performance. The upgross kit increased the maximum gross weight of the airplane from 8,000 lbs to 8,367 lbs. The airplane was configured to carry one pilot and 10 passengers and cargo.

On May 24, 2014, after the overhaul, a new weight and balance calculation was performed, which showed that the airplane's basic empty weight on wheels was 4,345 lbs.

On May 30, 2014, an 800-hour inspection of the airplane and special inspection items was completed. The records indicated that all applicable airworthiness directives were complied with at this time. According to maintenance records, the airplane's last inspection was a 100-hour inspection on July 25, 2015, at which time, the airframe had accumulated 15,436 total hours, and the engine had accumulated 384 total hours.

On June 11, 2014, another weight and balance calculation was performed, which indicated that the airplane's empty weight on floats was 4926.8 lbs with a useful load of 3,073.2 lbs and that its center of gravity (CG) was 131.79 inches. A maximum gross weight of 8,000 lbs was used for the computation, not the adjusted weight of 8,367 lbs. The installation of the upgross kit was noted in the equipment list, but the increase of the maximum gross weight was not reflected in the final weight and balance paperwork.

On August 30, 2015, a 150-hour engine inspection was conducted with no defects or leaks noted. At the time of inspection, the engine had a total of 430.3 hours.

Weight and Balance Study

The accident airplane was configured to carry 62 gallons of fuel in the forward tank, 102 gallons of fuel in the center tank, and 51 gallons of fuel in the aft tank. The Texas Turbine Conversions, Inc., Airplane Flight Manual (AFM) supplement instructs the operator to burn fuel from the forward tank during takeoff and, after takeoff, from the aft tank forward to leave as much fuel in the forward tank as possible for landing. The minimum amount of fuel for takeoff is 20 gallons in each of the three tanks to prevent introduction of air into the fuel system. The pilot stated the center and forward tanks were full, and there was "residual" fuel in the aft tank.

Rainbow King Lodge had no procedures in place or equipment available for calculating preflight weight and balance. Pilots should calculate the airplane's actual weight and balance using the procedures contained in the original DHC-3 Otter AFM, published by de Havilland Canada, along with the information in the various flight manual supplements for the STCs installed on the airplane. The entire flight manual and all of its supplements were carried in the airplane during the accident flight. When asked how he calculated the weight and balance for the accident airplane before departure, the pilot said he "guesstimated" it.

As noted, the airplane was carrying the pilot and nine passengers. The seating location of each passenger was determined based on passenger statements. In accordance with passenger statements, 10 lbs was added to each person's weight to account for gear and clothing, including chest waders and boots.

All of the cargo, which included fishing gear, coolers, firewood, and passenger bags, was loaded in the baggage compartment located behind the last row of passenger seating. After the accident, these items were removed and weighed. See table 1 for a summary of the weight and balance calculations.

Table 1. Summary of weight and balance calculations.

Using this data, the airplane's weight before takeoff was calculated to be 8,875.6 lbs, which was 508.6 lbs over the maximum gross weight. The CG range for the airplane at 8,367 lbs was between 140.3 and 148.3 inches. The airplane's pretakeoff CG was calculated to be 152.38 inches, 4.08 inches aft of the aft CG limit. METEOROLOGICAL INFORMATIONThe closest weather reporting weather station was Iliamna, about 1 mile south of the accident site. At 0553, a METAR reported, in part, wind 270° at 7 knots; visibility 10 statute miles; ...