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On June 21, 1996, about 0905 mountain daylight time, N1236Y, a Cessna 150B, operated by the owner/pilot, collided with rising terrain while maneuvering and was destroyed near Hailey, Idaho. The private pilot and his passenger were fatally injured. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight was conducted under 14 CFR 91. The flight departed from Hailey at 0852 and was destined for Manila, Utah.
According to witnesses (interviews attached), the pilot and his brother-in-law arrived at the Friedman Memorial Airport in Hailey about 1600, one day prior to the accident, after flying in from Kelso, Washington. The pilot had 12 gallons of fuel placed in his airplane, and he spent the night at a friend's home in Hailey. According to the friend, the pilot intended on flying to Manila the next day to fly fish. The pilot told his friend that the airplane "flew great," and that he (the pilot) "felt fine." The pilot ate dinner with the friend about 1800 on the evening prior to the accident, and the pilot subsequently went to sleep about 2130.
The next morning, on the day of the accident, the pilot awoke about 0600. The pilot, passenger, and the pilot's friend then went to the airport. The pilot had the airplane "topped off" with about one gallon of fuel, because he wanted to ensure the airplane had the maximum amount of fuel it could carry for endurance purposes. An examination of the airport's fuel receipts and quality control checks (attached) revealed no evidence of fuel contamination. The pilot also performed a preflight; no anomalies with the airplane were reported to the pilot's friend or airport personnel.
According to personnel at the air traffic control tower in Hailey, and tower transcripts (attached), the accident airplane departed from runway 31 and was advised to "make a left downwind departure." The pilot acknowledged. About two minutes later, the pilot was then advised to "make a slight right turn and proceed on the east side of the valley until you get the altitude for your left turn." Again, the pilot acknowledged, but never initiated the left downwind turn. About three minutes later, the controller asked the pilot for his position. This occurred after the airplane had turned right and disappeared from the controller's view behind a hill to the north of the airport known as Red Devil Hill (area map attached). The pilot responded: "I'm heading up the valley, heading east of the airport out of Hailey." After another query by the controller, the pilot responded: "I'm just about to come out of the valley at the east end." This was the pilot's last recorded transmission. No distress calls from the pilot were received.
The airplane impacted rising mountainous terrain about 6 nautical miles northeast of Hailey at an elevation of about 6,700 feet above mean sea level (msl). The Idaho State Division of Aeronautics stated that an emergency locator transmitter signal was received by the U.S. Air Force about 1236 on the day of the accident. The wreckage was later spotted about 1700.
The accident occurred during the hours of daylight at the following coordinates: 42 degrees, 33.77 minutes North; 114 degrees, 10.68 minutes West.
The accident airplane, a 1962 Cessna model 150B, had been owned and operated by the pilot since May 4, 1995. The two-seat aircraft was powered by a single 100-horsepower Continental engine. An examination of the airplane's maintenance records did not reveal any unresolved discrepancies. The airplane underwent an annual inspection on August 4, 1995, and had flown about 46 hours from the time of the inspection to the time of the accident
According to aircraft delivery documents from the Cessna Aircraft Company, the empty weight of the airplane was 1,002 pounds. The Safety Board computed the weight and balance of the airplane for the accident flight with weight data collected for the aircraft occupants, fueling, and baggage. The computations (attached) revealed that the airplane was over its published gross weight by about 50 pounds, and it was also beyond its published aft center of gravity at the time of the accident.
According to 1962 Cessna 150B Owner's Manual, the aerodynamic stall speed at gross weight and with flaps up is 54 miles per hour. The maximum rate of climb at maximum published gross weight, 5,000 feet above mean sea level (msl), and 41 degrees F is 550 feet per minute. This rate of climb figure does not take updrafts and downdrafts into account.
According to FAA records, the pilot, age 43, was issued an FAA private pilot certificate with ratings for single engine land airplanes in 1977. He was also issued an FAA Third Class Medical Certificate on May 29, 1996, with the limitation that he "must wear corrective lenses." A review of the pilot's personal flight log book revealed that he had logged a total of 220 hours of flight time, including 14 hours in type during the 30 days preceding the accident. According to witnesses, the pilot was not familiar with the Friedman Memorial Airport in Hailey, nor the surrounding area and departure procedures.
According to a meteorological surface observation taken at the Friedman Memorial Airport in Hailey about the time of the accident, the following conditions prevailed: scattered clouds at 5,000 feet above the ground level (agl), broken cloud ceiling 8,000 feet (agl), temperature 48 degrees F, visibility 30 statute miles, wind speed at 12 knots from 360 degrees magnetic, altimeter pressure setting of 29.92 inches of mercury.
Safety Board computations revealed that the density altitude at the airport at the time of this observation was 5,840 feet. The airport sits at a standard sea level elevation of 5,315 feet msl. The standard sea level elevation of the accident site is about 6,700 feet.
WRECKAGE AND IMPACT INFORMATION
The airplane wreckage was examined at the accident site one day after the accident on June 22, 1996, and again on June 23, 1996. The airplane came to rest in the crevice of a steep ravine below a saddle in mountainous terrain. The wreckage was distributed along a magnetic bearing of 210 degrees along downsloping terrain. The wreckage path was measured to be about 50 feet in length.
No evidence of fire, explosion, or in-flight structural failure was found. All primary and secondary flight control surfaces were accounted for at the accident site. The wing flaps were found in the retracted position. The tailcone was completely separated from the cabin area. Both wings were resting, leading edge down, on opposite slopes of the ravine; their leading edges displayed evidence of "accordion" crush damage. The nose of the airplane was imbedded into the ground in a near vertical attitude.
Flight control cable continuity was verified for all flight controls, except the right rudder cable. While applying vigorous manual tension on the cable from the separated cabin area, the cable became loose and was pulled out of the cabin floor. An examination of the separated end cable revealed that it was corroded. The corroded area of the cable occurred at a location where the cable passes underneath the forward portion of the cabin near the forward door post. Pulleys for the rudder cable are mounted in the front doorpost bulkhead assembly. An examination of the area did not reveal any evidence of corrosion or mechanical deficiency. A section of both ends of the cable were extracted and sent to the Safety Board's metallurgical laboratory for further analysis.
An examination of the cockpit revealed that the fuel mixture control was in the full forward position. The throttle control was pulled aft about two inches and jammed. The oil temperature gage was pointing to the bottom of the green arc. The elevator trim wheel was pointing on the third index mark from the most forward "nose down" range. The tachometer time read 1130.50 hours. The recorded tachometer time just prior to the accident flight, as per the pilot's flight planning documents (attached), was 1130.32 hours.
An examination of the engine did not reveal any evidence of catastrophic failure. The B-nut fitting on the no. 1 cylinder bottom spark plug cap was partially separated from the spark plug at the accident. No evidence of impact damage was found in the B-nut threads.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy was performed on the pilot on June 24, 1996, at Mountain West Laboratories, Inc., in Burley, Idaho, by Dr. Kerry B. Patterson, M.D. A toxicological analysis (report attached) was performed on specimens taken from the pilot by the FAA Civil Aeromedical Institute in Oklahoma City, Oklahoma.
TESTS AND RESEARCH
An examination of the failed rudder cable was performed by the Safety Board's Materials Laboratory Division. According to the metallurgist's factual report (attached):
The mating ends of the cable sections appeared to be corroded severely.... Examining the separate wires in the cable revealed heavy corrosion approximately an inch adjacent to the separation.....Measuring the diameters of the separate wires revealed that most wires had reduced sections from 30% to 70% of the original diameter.
The report also stated that an energy dispersive spectroscopy (EDS) of an uncleaned cable revealed "high peaks of oxygen and iron, and low peaks of zinc and silicon, indicating oxidation on the examined section....The low peaks of zinc of the broken end indicated that most of the zinc protection layer was corroded away adjacent to the fracture."
The aircraft wreckage, except for the engine and rudder cable section, was released to Mr. Dan Dolan, Hailey, Idaho, on June 23, 1996. The engine and rudder cable section were subsequently released to Mr. Harry Malett, HLM Air Services, Inc., Independence, Oregon, on October 4, 1996.