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. The airplane was operated by Rainbow King Lodge, Inc., under 14 CFR Part 91 as a visual flight rules other work use flight. Dark night visual meteorological conditions existed; no flight plan was filed. The flight was en route to a remote fishing site on the Swishak River.
The lodge manager reported the airplane transported sport-fishing clients and guides for salmon fishing. On the morning of the accident, a lodge employee drove guests to East Wind Lake.
The pilot stated he woke at 0430, checked weather, and felt well except for right knee pain. He left the lodge at 0515 to preflight. The pilot noted that for an easterly departure a building light was left on as a visual reference, but for a westerly departure there were no lights. He typically used a ridgeline about 7 miles west of Iliamna as a horizon, but dark night conditions made it difficult to see. He stated very few flights departed in the dark.
The lodge employee reported they left the lodge at 0545. The airplane had been loaded the day before with fishing equipment. After passengers boarded and the pilot started the engine, the employee untied the floats. He reported it was dark but he watched the westerly takeoff run. After liftoff, the airplane climbed then descended, and the floats struck the water's surface. The airplane became airborne again, veered right, and disappeared behind rising terrain.
The pilot stated he looks outside during takeoff and does not focus on instruments. After liftoff at a normal pitch, he heard a noise from the left side and looked outside but could not see due to dark night conditions. ADS-B data showed a gradual right turn after reaching 175 ft above the water, then descent, low flight over water and terrain, a brief climb, and then impact. The pilot did not know the airplane touched the water or turned right.
A search and rescue team assembled, but dark night conditions delayed wreckage discovery by about 30 minutes.
Personnel Information
The pilot, age 54, held an airline transport pilot certificate with airplane multiengine land rating and commercial privileges with single-engine land rating. He held type ratings for Beech 1900 and Beech 300 and a flight instructor certificate. His most recent FAA second-class medical certificate was issued May 12, 2015, with a limitation requiring glasses for near vision. He reported no medications, and the examining physician found no abnormal findings.
According to logbooks, the pilot had about 11,280 total flight hours, about 450 in the accident make and model. In the 90 and 30 days before the accident, he logged 200 and 70 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 2012–2015 fishing seasons. The first two seasons were before the Otter was converted to a turbine-powered airplane. He stated he had not received training in the airplane since the turbine conversion.
Aircraft Information
The accident airplane was a de Havilland DHC-3T, serial number 61, manufactured in 1954. It was powered by a Honeywell TPE 331-12JR-702TT turboprop engine per a Texas Turbine Conversions STC, with a Hartzell four-bladed propeller. In April 2014, the airplane underwent major overhaul and turbine conversion by Recon Air Corporation. It was modified with a Baron STOL kit and an upgross kit that increased maximum gross weight from 8,000 lbs to 8,367 lbs. The airplane was configured to carry one pilot and 10 passengers and cargo.
A weight and balance calculation on May 24, 2014, showed basic empty weight on wheels as 4,345 lbs. On June 11, 2014, another calculation indicated empty weight on floats as 4,926.8 lbs with a useful load of 3,073.2 lbs and CG at 131.79 inches; the maximum gross weight used was 8,000 lbs, not the adjusted 8,367 lbs. The upgross kit was noted in the equipment list but the increased weight was not reflected in the final paperwork.
The airplane's last inspection was a 100-hour inspection on July 25, 2015, with airframe total hours 15,436 and engine total hours 384. A 150-hour engine inspection on August 30, 2015, found no defects.
The airplane carried 62 gallons in the forward tank, 102 in the center, and 51 in the aft. The AFM supplement instructs burning fuel from the forward tank during takeoff and then from the aft tank forward. Minimum fuel for takeoff is 20 gallons in each tank. 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 or equipment for calculating preflight weight and balance. The pilot said he "guesstimated" it. Post-accident calculations using passenger statements and weighed cargo showed the airplane's weight before takeoff was 8,875.6 lbs, 508.6 lbs over maximum gross weight. The CG was 152.38 inches, 4.08 inches aft of the aft CG limit (CG range at 8,367 lbs: 140.3 to 148.3 inches).
Meteorological Information
The closest weather station at Iliamna reported at 0553: wind 270° at 7 knots; visibility 10 statute miles; scattered clouds at 700 ft, overcast at 4,400 ft; temperature 48°F; dew point 47°F; altimeter 29.61 inches of mercury. Civil twilight began at 0706, sunrise at 0748.
Wreckage and Impact Information
The main wreckage was found about 510 ft from the shore of East Wind Lake at N59.777778 W154.917778, on a magnetic heading of 020°, about 0.5 miles from the departure point. The airplane impacted soft, tundra-covered terrain. There was no evidence of impact between the lake and the wreckage. A ground scar about 20 ft long and 10 inches deep was aft and in line with the right wing; another scar aft of the right float was about half its length.
The left wing remained attached; the right wing separated at the wing root. The right flap and right lift strut separated. The last 10 ft of the right wing had extensive aft accordion-style crushing. The tail was displaced about 30° left. The stabilator remained attached and relatively undamaged. The elevator trim indicator and manual control wheel were in a nose-up position; rudder trim slightly right; flaps in the "takeoff" position.
Navigation, beacon, cockpit, and instrument lights were on; dome, strobe, and landing lights off. The propeller was attached; three blades had leading edge gouging and torsional twisting; one blade tip separated, one rotated 180°, one buried in terrain. The power lever was slightly above flight idle; condition lever midrange; fuel shut-off not off; fuel selector on center tank; ignition set to continuous. All fuel caps on and secure.
Medical and Pathological Information
Hospital records revealed the pilot had a 1-week history of right leg swelling before the accident. In addition to crash-induced injuries, he was diagnosed with right leg deep vein thrombosis and bilateral pulmonary emboli. Two days after admission, he suffered a syncopal episode attributed to another pulmonary embolus.
Toxicology testing of the pilot's urine collected on admission was negative for ethanol and drugs of abuse but detected ibuprofen, ketamine, and its metabolite norketamine. Ketamine was administered during postaccident transport; ibuprofen is a nonsedating pain medicine.
The pilot and nine passengers were aboard. Three passengers died at the scene; the pilot and four passengers sustained serious injuries; two passengers sustained minor injuries. The airplane sustained substantial damage.
Probable Cause
No probable cause was stated in the source.