N6861T accident descriptionGo to the Utah map...
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|Accident date||April 17, 2003|
|Aircraft type||Cessna 310D|
Near 40.241666 N, -111.717778 W
HISTORY OF FLIGHT
On April 17, 2003, at 1739 mountain daylight time, a Cessna 310D, N6861T, registered to Smith & Barlow Enterprises, Inc., and operated by Advantage Aviation, Inc., both of Provo, Utah, impacted terrain 1.07 miles north of the Provo Municipal Airport, Provo, Utah. Three commercially certificated flight instructors were fatally injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the instructional flight being conducted under Title 14 CFR Part 91. The flight originated at Provo approximately 1600.
According to the operator, 19.0 gallons of 100-LL fuel were used to fill the airplane's main fuel tanks to capacity (50 gallons each tank, 100 gallons total useable) at the end of the day before the accident. The auxiliary fuel tanks had been inoperative for some time, and the fuel gauges and fuel filler caps had been placarded accordingly. The next day, the airplane flew once before the accident flight. The instructor on that flight said he visually "checked the main tanks and confirmed that the airplane was topped off with fuel." He did not check the auxiliary fuel tanks. The flight departed shortly after 1400. According to the flight instructor, he and his student and an observer (the observer was also the observer on the accident flight) flew for 1.6 hours, and performed a simulated right engine failure and subsequent rejected takeoff, several other simulated engine failures, and a complete right engine shutdown. They also made three takeoffs and landings. The instructor said that at the conclusion of the flight, he verified the fuel quantity. The tanks were half-full. The airplane was released to the accident pilot approximately 1630.
According to the operator, the accident flight departed Provo approximately 1600 and was aloft for approximately 1.7 hours. It, too, was an instructional flight. The pilot-in-command, identified as being in the right front seat, was giving multiengine instructor training to the pilot-in-training, identified as being in the left front seat. The other flight instructor, seated on a rear bench seat, was observing. The operator (which is also the fixed base operator at Provo Municipal Airport), routinely tape-recorded the airport's Common Traffic Advisory Frequency (CTAF). The recorder was voice-activated and had no time channel. According to the tape recording and transcript, approximately 1730 the pilot reported they were "descending south of the airport. We'll be entering [a] left downwind [for] runway one eight, flying single engine pattern. Correction, right downwind." In the next transmission, he reported they were "on a right downwind one eight behind three eight hotel. We're going to be breaking off to the west, Provo." Shortly thereafter, the pilot called "three hotel this is six (unintelligible) yo we're inside of you. Can we get priority to the runway? We've got a difficulty." The pilot of N5338H agreed to yield and extended his downwind leg. The pilot on N6861T thanked him. This was the last transmission from the airplane.
Twenty-seven written witness statements were collected by the Provo Police Department, Utah County Sheriff's Office, and the Utah State Patrol. Although there were variances, the consensus was that the airplane made a steep right turn from base leg to final approach, and then it descended vertically to the ground, exploded on impact, and burned. The captain of Executive Jet flight 93, who was waiting for N6861T to land so that he could take off on (the opposite) runway 36, said the airplane "appeared to do a snap roll to the right." Witnesses said that they thought the airplane was doing "trick maneuvers" (2). The airplane was at low altitude (4) and flying slow (1), when it made a sharp (4), steep (1), or severe (1) bank to the right (3) or left (4) and descended vertically (13) to the ground. The airplane was spinning (4), "twisting" (1), "swaying back and forth" (1), or spiraling (1). Some witnesses said it sounded as if the airplane was having engine trouble (1), because the engine were "sputtering" (3), and "cutting out" (2), like they "ran out of gas" (1), then the engines stopped (2), or the engine noise decreased in volume (1). The first 9-1-1 call was received by the Utah County Sheriff's Office at 1739.
The accident occurred during day visual meteorological conditions at a location of 40 degrees, 14.494 minutes north latitude, and 111 degrees, 43.072 minutes west longitude, or 1.07 miles from the threshold of runway 18. Bearing from the runway was 006 degrees magnetic.
The pilot-in-command, age 47, held a commercial pilot certificate, dated April 30, 2002, with airplane single/multiengine land and instrument ratings. He also held a flight instructor certificate, dated March 4, 2002, with airplane single/multiengine and instrument ratings. His first class airman medical certificate, dated March 12, 2003, contained the limitation, "Must wear corrective lenses."
Two logbooks belonging to the pilot-in-command were recovered from the wreckage and examined. The first logbook contained entries from December 23, 1999, to April 3, 2003. The second logbook contained entries from April 3, 2003, to April 12, 2003. According to these logbooks, he had accumulated the following flight time (in hours):
Total time: 863.8 Pilot-in-command: 731.4 Airplane single-engine land: 622.9 Airplane multiengine land: 241.9 Cessna 310: 142.7 Instruction given: 354.2 Instruction received: 279.2 Cross-country: 309.4 Night: 97.5 Actual instruments: 32.6 Simulated instruments: 91.2
According to the logbooks, the pilot-in-command first flew a Cessna 310 on January 24, 2002, and first flew N6861T on November 20, 2002. His last recorded flight in a Cessna 310 (and in N6861T) was on July 9, 2002.
The pilot-in-training, age 32, held a commercial pilot certificate, dated July 9, 2002, with airplane single/multiengine land and instrument ratings. He also held a flight instructor certificate, dated October 2, 2002, with airplane single-engine and instrument ratings. At the time of the accident, he was working on the multiengine instructor rating. His second class airman medical certificate, dated March 18, 2002, contained no limitations or restrictions. According to his application for this medical certificate, he estimated he had logged 300 hours total flight time, 70 hours of which were accrued within the previous 6 months.
The pilot-observer, age 42, held a commercial pilot certificate, dated May 4, 2002, with airplane single/multiengine land and instrument ratings. He also held a flight instructor certificate, dated June 12, 2002, with airplane single-engine and instrument ratings. At the time of the accident, he was working on the multiengine instructor rating, and was observing to gain additional insight. His second class airman medical certificate, dated January 15, 2003, contained the restriction, "Must wear corrective lenses." According to his application for this medical certificate, he estimated he had logged 580 hours total flight time, 200 hours of which were accrued within the previous 6 months.
N6861T (s/n 39161), a model 310D, was manufactured by the Cessna Aircraft Company in 1960. It was powered by two Continental IO-470-D engines (s/n CS105533-R, left; 79764-1-D, right), each rated at 260 horsepower, driving two Hartzell 3-blade, all-metal, constant speed, full-feathering propellers (m/n HC-A2VF-2B).
According to the aircraft's maintenance records, the airplane received an annual inspection on December 20, 1994, at a Hobbs meter reading of 4,230.0 hours. The next logbook entry was 5 years later, on December 10, 1999, when the airplane was certified as airworthy to be ferried from Richfield, Utah, to Provo. The Hobbs meter reading was 4,232.5 hours. The next annual inspection was fifteen months later, on March 15, 2001, at a tachometer reading of 4,256.2 hours. During that period, considerable work was done to the airplane, including changing the MINIMUM SPEED placard from 84 knots to 83 knots, and installing a TAKE OFF AND LAND WITH AUX PUMP ON placard on the instrument panel. The last annual inspection recorded in the maintenance records was on November 6, 2002, at a Hobbs meter reading of 4,256.2 hours.
On December 1, 1999, the left engine was removed from the airplane for a major overhaul, and was reinstalled on April 13, 2000, at a tachometer reading of 4,236.4 hours. On October 15, 2000, the left engine, which had been "damaged" due to "oil contamination," was removed for repair that included installing a serviceable crankcase, crankshaft, 6 connecting rods, and 2 chrome cylinder stud assemblies. The engine was reinstalled on the airplane on December 20, 2000. Total time and time-since-overhaul were not given. The engine was given 100-hour inspections on March 15, 2001, April 6, 2002, and November 6, 2002, the latter at a tachometer reading of 4,256.2 hours.
On April 15, 2000, the right engine was removed from the airplane for a major overhaul, and was reinstalled on April 24, 2000, at a tachometer reading of 4,240.8 hours. The last 100-hour inspection was on November 6, 2002, the latter at a tachometer reading of 4,256.2 hours.
The propeller maintenance log contained entries for work done on both propellers, but did not differentiate which propeller. On November 6, 2002, both propellers received 100-hour inspections.
The following was the PVU METAR (routine aviation meteorological report) that was observed at 1735: Wind, 220 degrees at 6 knots; visibility, 10 statute miles (or greater); sky condition, clear; temperature, 16 degrees C.; dew point, -1 degree C.; altimeter, 29.65 inches of mercury.
Provo Municipal Airport, elevation 4,497 feet msl, is located 2 miles southwest of the city of Provo. It is equipped with 2 runways: 13-31 and 18-36. At the time of the accident, runway 18 (6,937 ft. x 150 ft., asphalt) was the active runway.
WRECKAGE AND IMPACT INFORMATION
The accident site was examined in April 18, 2003. Ground signatures indicated the airplane impacted a soft, muddy pasture in a steep nose down, left wing slightly low attitude. No horizontal energy path was observed. Both engines were buried in mud at angles between 50 and 80 degrees. Both propeller assemblies, which remained attached to their respective crankshaft flanges, were each missing a propeller blade. The right propeller blades exhibited slight S-bending, leading edge polishing, and some chordwise scoring. The left propeller blades were bent aft 45 degrees at midspan, and bore some leading edge polishing. The spinner was uniformly crushed around the hub dome, and bore no discernible rotational scoring.
The airplane rested flat on the ground. The nose and tail sections were aligned on magnetic headings of 181 and 192 degrees, respectively. The cockpit and cabin areas, including most of the instrument panel, were destroyed by post-impact fire. The left and right engine tachometers, however, registered 2,600 and 1,400 rpm, respectively. Both throttles, mixture controls, and propeller levers were in the full forward position. The clock was stopped at 7:34. A watch found in the wreckage was stopped at 5:37.
The left wing exhibited more structural damage than the right wing. The outboard portion of the left wing was buckled upward at a 30-degree angle and twisted aft. The outboard portion of the right wing was destroyed by fire. Both main (tip) tanks were separated from the wings. There were burn areas around each tank. Half of the left main tank was in a crater. Most of the right main tank was located about 75 feet from the wreckage, and was not fire damaged. Both auxiliary fuel tanks were empty and had not been breached, but the cross feed fuel lines underneath the cabin had been compromised. Both engine fuel selector valves were positioned on their respective main fuel tanks.
The empennage was intact. The horizontal and vertical stabilizers, elevators, and rudder exhibited some deformation and skin wrinkling. All observed flight control cables were intact and connected to their respective bellcranks, and all observed turnbuckles were intact and safety wired. However, only partial control continuity could be established because of the fire damage.
The left front seat and rear bench seat remained in the wreckage and were destroyed by fire. The right front seat separated from the seat attachments and was located outside, and next to, the wreckage. Two clasped safety belt buckles were found in the front cockpit area. The webbing had been burned away. The airplane was not equipped with shoulder harnesses.
The airplane was examined again on April 19, 2003, at the Spanish Fork, Utah, Airport. The landing gear was retracted. Measurement of the chain links on the flap motor sprocket indicated the flaps were extended 5 degrees. Measurement of the right aileron trim tab actuator indicated the tab was deflected full down (aileron up, wing down). It was noted that when the rudder was aligned with the vertical stabilizer, the rudder trim tab was fully deflected to the right. Measurement of the rudder actuator confirmed this observation (left rudder). Measurement of the elevator trim tab actuator indicated the tab was 15 degrees down (elevator up). According to the Cessna Aircraft Company, this is about half of the total deflection range.
MEDICAL AND PATHOLOGICAL INFORMATION
Autopsies were performed on all three occupants by the Utah State Medical Examiner's Office in Salt Lake City (#R200300562, -563, and -561). The medical examiner's office also performed toxicological screens on the flight instructor and pilot receiving instruction. According to their reports, both pilots tested negative for drugs. Due to a mistake in identifying the pilot-in-command, FAA's Civil Aeromedical Institute (CAMI) performed a toxicological screen only on the pilot receiving instruction. CAMI's report, likewise, was negative for drugs. Additionally, no carbon monoxide, cyanide, or ethanol was detected.
TESTS AND RESEARCH
On August 4 and 5, 2003, the engines were disassembled and inspected at the Teledyne-Continental Motors (TCM) factory in Mobile, Alabama. No anomalies were noted. Both fuel pumps and manifold valves were bench tested and found to operate satisfactorily within service limits. The left engine was equipped with an AirMelt crankshaft. According to TCM, the crankshaft should have been replace with a TCM VASR crankshaft during overhaul.
On August 8, 2003, the propellers were disassembled and inspected at Hartzell Propellers factory in Piqua, Ohio. According to Hartzell's report, neither propeller was feathered. The left propeller was at the low pitch stop, and the right propeller was just past this position. According to Hartzell, both propellers were at a low power setting at impact.
According to the Cessna 310D Owner's Manual, each main tank holds 51 gallons of fuel (102 gallons total), of which 50 gallons (100 gallons total) are useable. According to the Climb Data and Cruise Performance Charts (p. 7-3 thru 7-5), each engine will consume between 14.9 and 26.6 gallons per hour (gph) at 7,500 feet msl and under standard atmospheric conditions, depending on the power setting (manifold pressure and rpm). During climb between 5,000 and 7,500 feet msl, each engine will consume between 6.2 and 7.5 gph, depending on power setting.
On July 25, 1969, FAA issued A.D. 69-15-09. Entitled "To Prevent Fuel Starvation During High Angle Descent, the airworthiness directive mandated compliance with Cessna Service Letter ME69-19 entitled, "Minimum Fuel and Power Setting Placards." The service letter stated (in part), "Operation with less than five gallons of fuel in each main tank is prohibited. Useable fuel in each tank is 45 gallons. Maintain power within the green arc during descent."
The wreckage was released to the insurance company's representative on January 29, 2004.
In addition to the Federal Aviation Administration, parties to the investigation included the Cessna Aircraft Company and Teledyne Continental Motors, Inc.