ANC97FA099

The pilot boarded the 4 passengers and cargo (unsecured) for a chartered flight to a fishing lodge. The floatplane departed uneventfully. About 45 min. later, while cruising about 1,700 ft. above rugged terrain and a river, the engine began to lose power and the floatplane descended. The pilot attempted a forced landing in a small lake that was 1,200 ft. in length and located about 1 mile west of the river. During the approach to landing, the airplane stalled and impacted swampy terrain at the lake's edge in a steep nose down attitude. An examination of the wreckage revealed that the no.1 engine exhaust pushrod had failed in fatigue just below the top (valve) ball end. Examination of the pushrod revealed that material had been pushed away from the rod during installation of the ball end. The fatigue crack may have initiated from a score mark produced by the installation. Pushrod life is reduced due to surface scratches. The life of the failed pushrod could not be determined. Insufficient information exists in the overhaul manual regarding pushrod life/inspection.

History of flight

On July 5, 1997, about 0930 Alaska daylight time, N5164G, a de Havilland DHC-2 floatplane, operated by Alaska Bush Carrier, Inc., collided with terrain and was substantially damaged during a forced landing attempt near Skwentna, Alaska. The forced landing was precipitated by a loss of engine power during cruise flight. The commercial rated pilot and three passengers were killed. A fourth passenger was seriously injured. Visual meteorological conditions prevailed and a company flight plan had been filed. The on-demand air taxi flight departed from Lake Hood, Alaska, at 0840 and was destined for Chelatna Lake, Alaska. The flight was conducted under Title 14 Code of Federal Regulations Part 135.

According to the sole survivor of the accident (interview synopsis and written statements attached), he and the three other passengers arrived at the dock of Alaska Bush Carriers (ABC) sometime between 0700 and 0800 on the morning of the accident for a chartered flight to a fishing lodge. The group was greeted by an ABC employee (interview synopses attached) who asked the passengers how much they weighed. The survivor stated that the accident pilot fueled the airplane and then began loading the baggage. He further stated that he helped load the airplane, and that "light" items were loaded first, followed by a large raft and numerous large bags. The survivor stated that the height of the cargo load did not exceed the height of the rear bench seat back. He said that he was "certain" that the baggage was not secured after it had been loaded; no one had strapped the bags down and he did not see any cargo netting. The survivor further stated that "all of the gear did not fit" in the airplane, and the rest was left behind on the dock.

After all the passengers had boarded, the pilot started the engine. According to the survivor, the airplane then departed on a "normal takeoff." The survivor stated that the airplane flew about 2,000 feet over a "small river" after the takeoff and climbout. He remembered that he noticed the altitude displayed on the airplane's altimeter, and that he compared the readings from the airplane's Global Positioning System (GPS) display with the display of his hand-held GPS.

The survivor stated that there were some "sporadic" and "light" clouds around, but it was still "sunny." He said that he could "always see the ground" during the flight, and that the airplane stayed at 2,000 feet, without any low passes over the ground during the flight.

About "a half an hour to 45 minutes" into the flight, the survivor noticed that the engine suddenly "cut out" for less than a second, then came back in again and sounded "normal." He described the "cut out" as a "cough" that lasted for a "split second." When this occurred, the "pilot immediately started to react" and "banked left." The survivor stated that the pilot "seemed mostly intent on finding a place to land." He stated that he and the other passengers "did not panic" when the engine cut out, because it sounded like the engine came back to "normal" again.

The survivor stated that the initial left turn "was not severe," and it seemed that the pilot leveled the wings again after the left turn. The survivor remembered that the airplane was "slowly going down" and that the pilot continued to fly and look out the windows for a period of time that was probably "greater than 60 seconds and less than five minutes." During this time, the engine periodically cut out and coughed for brief moments, and then came back to sound "normal" again. He remembered that this occurred more than two times, but less than ten times. The survivor stated that the momentary cough would occur about every 10 to 15 seconds, but he was not sure of the time, and that the period of time between each cough was random. He also stated that he never heard any loud noise coming from the engine (relative to what the engine sounded like to him in a "normal" mode), nor did he hear any loud mechanical banging noise. He stated that the engine did not vibrate severely, and he did not recall a decrease in the engine noise, as if the pilot had turned the engine off.

The survivor stated that the pilot appeared to be talking on the radio and looking out of the airplane during this time. Then, the pilot said something like "we're going down." The survivor stated that he then began to worry. Shortly thereafter, one of the other passengers asked: "Where are we going to land?" According to the survivor, the pilot indicated that he was going to land on a lake directly beneath the airplane. The survivor remembered that the airplane "turned left real hard" and began to descend steeply. He said the turn was "drastic" and he felt like he was "dropping." The survivor stated that it was "obvious" that the airplane was "too high" to land at the lake.

The survivor then remembered feeling that the airplane "lost control." He said he must have "blacked out" at that time, because the next event he remembered was when he was on the ground in the wreckage and partially submerged in water.

According to the Director of Flight Operations for ABC, he arrived at Lake Hood after the accident flight had departed. He told his son, an ABC pilot, to fly the remaining baggage left over from the accident airplane to Lake Chelatna. His son flew to Lake Chelatna later that morning, noticed that the accident airplane had not arrived, and began to search for it along its intended route over the Lake Creek river. The airplane was spotted at the edge of a small lake by the pilot about 3 hours after the accident. It was found about 70 nautical miles northwest of its departure point, and about 40 nautical miles from its destination, along nearly direct routing.

The accident occurred during daylight conditions at the following coordinates: North 62 degrees, 00.57 minutes; West 150 degrees, 57.96 minutes. PERSONNEL INFORMATION

The pilot, male, age 27, possessed a commercial pilot certificate containing ratings for single-engine land, single-engine sea, multiengine land, and instrument airplanes. According to FAA records, the pilot was issued an FAA Second Class Medical Certificate on February 8, 1997, with no restrictions.

An examination of FAA records, ABC's pilot training records, and daily flight logs (excerpts attached) indicate that the pilot had accumulated a total of about 3,350 hours of flight time, including 2,200 hours in type. The records further indicate that the pilot had flown 3.9 hours in the accident airplane the day before the accident, and 3.2 hours in the accident airplane two days before the accident.

Three days before the accident, on July 2, 1997, the pilot satisfactorily completed an FAA Part 135 Airmen Competency/Proficiency Check (FAA Form 8410-3 attached) in a de Havilland DHC-2. The check ride, conducted by an FAA aviation safety inspector from Anchorage, was 0.8 hours in duration and included "Powerplant Failure," "Approaches to Stalls," and "Emergency Procedures."

Ten months prior to the accident, on September 3, 1996, the pilot was involved in another ABC accident that occurred after takeoff in Port Alsworth, Alaska. According to Safety Board records, the accident involved a Cessna 206 floatplane. The Safety Board determined that the probable cause was "the pilot's inadequate compensation for the wind conditions. A factor associated with the accident was the unfavorable wind." According to ABC pilot training records, the director of flight operations provided additional training to the pilot two days after the accident and reassigned the pilot to full flight status. He also notified the Anchorage FAA Flight Standards District Office of the action. There was no record of any FAA enforcement actions against the pilot.

According to the survivor, the pilot appeared to be in a "normal" mood immediately prior to the accident flight; the