NTSB Factual Report

HISTORY OF FLIGHT

On July 5, 2011, about 1219 Pacific daylight time, a Stinson 108-2, N9351K, was substantially damaged when it impacted trees and terrain just after takeoff from Columbia Airport (O22) Columbia, California. The pilot and his passenger received minor injuries. The pilot had been contracted by the new owner of the airplane to deliver the airplane from southern California to the owner in Alaska. The flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the flight.

According to the pilot, about 3 months before the accident, the airplane was flown to Compton Woodley Airport (CPM), Compton, California, topped off with fuel, and then remained dormant until the delivery flight. In the days just prior to the accident flight, the pilot examined the airplane; the only anomalies he noted were that the fuel tanks were no longer full, and that there was water in the fuel tanks. He stated that it took him about 12 separate fuel samples over a 5 hour period to obtain a fuel sample that did not contain any water.

The first leg of the trip, from CPM to O22, was uneventful. The airplane was refueled at O22. The pilot observed other airplanes departing on runway 17, but based on the airport's Automated Weather Observation System (AWOS) broadcast and his observation of the windsock, the pilot decided to use runway 35 for his departure. The pilot stated that the AWOS indicated winds of 2 to 3 knots "from the north" and that the windsock presented a similar indication. The engine runup was normal, and the pilot used one notch of flaps for the takeoff. The takeoff seemed normal until the airplane reached the end of the runway, where the climb performance deteriorated. The airplane was unable to clear the obstacles, impacted trees and terrain, and came to rest about 1,600 feet beyond the end of the runway. A fire erupted immediately, but the pilot and passenger were able to exit the airplane. The fire consumed much of the airframe, and all of the baggage, which included some airplane records.

PERSONNEL INFORMATION

According to Federal Aviation Administration (FAA) information, the pilot held a commercial pilot certificate with single-engine land and sea ratings. The pilot reported a total flight experience of 3,215 hours, which included 31.5 hours in the accident airplane make and model. His most recent FAA second-class medical certificate was issued in June 2011, and his most recent flight review was completed in February 2011.

AIRCRAFT INFORMATION

According to FAA information, the airplane was manufactured in 1947, and was first registered to the new owner in June 2011. It was equipped with a Franklin 165 hp 6-cylinder, normally aspirated engine. The airplane was equipped with four seats.

According to the owner, some of the airplane maintenance records were onboard. No records were recovered from the wreckage. Partial maintenance records were available as follows:

Airframe – Subsequent to June 15, 1990

Engine - Subsequent to February 2, 2000

Propeller - Subsequent to August 22, 2006

Examination of the available records indicated that the airplane was in compliance with applicable FAA inspection requirements.

According to the maintenance records, the engine and carburetor were overhauled and installed in the airplane in July 1994, when the airplane had accumulated a total time in service (TT) of 2,033 hours. At that same time, the wings, ailerons and flaps were "re-rigged." In July 2000, when the airplane had a TT of about 2,180 hours, the horizontal stabilizers were repaired for unspecified reasons. In September 2008 new spark plugs were installed, when the engine had accumulated a TT since major overhaul (TSMOH) of 221 hours; no airplane TT was documented for that entry. In October 2009 the two-blade, fixed-pitch metal propeller was overhauled and re-installed on the airplane. At that time, the airplane had accumulated a TT of 2,298 hours. In November 2010, the number 3 cylinder was overhauled and reinstalled, and the most recent annual inspection was completed. The records indicated that at that time, the airplane had accumulated a TT of 2,374.4 hours, and the engine had accumulated a TSMOH of 339.8 hours.

METEOROLOGICAL INFORMATION

The automated weather observations for O22 reported the following conditions surrounding the accident period:

METAR KO22 051855Z AUTO 23004KT 10SM CLR 35/11 A2998 RMK AO1=

METAR KO22 051915Z AUTO 23003KT 10SM CLR 34/12 A2998 RMK AO1=

METAR KO22 051935Z AUTO 23007KT 10SM CLR 35/13 A2998 RMK AO1=

The density altitude was calculated to be 4,863 feet. Temperature and dew point values for the approximate time and location of the accident indicated that the relative humidity was approximately 30 percent. According to a carburetor icing probability chart, the intersection of the two temperature values was located in the region designated as "Icing at Glide and Cruise Power."

AIRPORT INFORMATION

According to FAA Airport/Facilities Directory (A/FD) information, O22 was equipped with a single paved runway, designated 17/35, which measured 4,670 feet long by 75 feet wide. The threshold was displaced 597 feet for runway 17, and 384 feet for runway 35. The pilot did not report where he began his takeoff roll. Airport elevation was 2,118 feet above mean sea level (msl). The airport was not equipped with an air traffic control tower.

Examination of airport and terrain data from Google Earth indicated that the overall paved runway length was about 4,815 feet. The runway 17 approach end elevation was 2,125 feet, and the runway 35 approach end elevation was 2,071 feet, which yielded an average slope of 1.1 percent for the overall pavement length. The wind tee located approximately mid-field on the west side of the runway, was about 2,100 feet from the approach end of runway 35 pavement, and about 2,700 feet from the departure end of that pavement.

The A/FD "Airport Remarks" section for O22 contained the following statement: "Varying wind direction and velocity may be encountered at mid point of Rwy 17–35 due to terrain features and wind flow patterns."

WRECKAGE AND IMPACT INFORMATION

No representatives of the NTSB or the FAA traveled to the accident scene.

The airplane impacted trees and other vegetation, and a post-accident fire occurred. The fire involved the surrounding trees and vegetation. The airplane came to rest about 1,800 feet north of the runway 17 threshold. The site elevation was approximately 2,140 feet.

The wreckage was recovered and transported to a recovery facility, where it was examined by representatives of the NTSB and the FAA. Most of the airplane was consumed or severely damaged by fire, and the structure also exhibited crush, twist, and fracture damage consistent with impact. When examined by investigators, the wreckage was comprised of 8 major segments, which were a result of impact and recovery effects. The only airplane skin that remained was that of the vertical, rudder, and horizontal stabilizers and their elevators. The inboard section of the left wing was not observed, and evidence was consistent with its consumption in the fire.

Flight control system continuity and routing could not be determined due to damage levels. Some flight control surfaces remained attached to their respective aero-surfaces, but no useful information regarding range of travel or freedom of motion was able to be obtained.

The two blade, metal, fixed-pitch propeller remained attached to the engine. Both blades were bent aft about 90 degrees near their mid-span locations. The engine remained attached to the engine mount, which was partially separated from the firewall and fuselage structure. The carburetor, magnetos, alternator, starter, oil cooler and exhaust mufflers remained attached to the engine. The intake and exhaust tubing remained attached to the engine, but exhibited impact and fire damage, which precluded any integrity determinations.

The engine was identified as a 6-cylinder Franklin model 6A4-165-B3. All cylinders remained attached, but exhibited some impact and fire damage. Overall, the engine exhibited damage and signatures consistent with exposure to the post-impact fire. The engine was removed from the airframe, and the accessories were removed from the engine. The crankshaft was able to be rotated by hand. Thumb compressions were obtained for all cylinders, with the exception of the number 2 cylinder. All rocker box covers were removed, and all rocker arms were observed to actuate with engine rotation. A cold compression check was made on the cylinders using 80 psi shop air. The results were as follows:

• Cylinder 1 – 0 psi

• Cylinder 2 – 0 psi

• Cylinder 3 – 25 psi

• Cylinder 4 – 25 psi

• Cylinder 5 – 25 psi

• Cylinder 6 – unable due to damage

Cylinders 1 and 2 were removed for additional examination. Both exhibited deposits on the piston heads and cylinder domes. The cylinder walls were in good condition, with loose contamination but no obvious permanent damage. All piston rings were present and undamaged. When solvent was poured into each inverted cylinder, it was observed to run out through the intake and exhaust valve openings on both cylinders, which indicated that the valves no longer seated or sealed properly. The valves were removed, and all four valves and valve seats exhibited varying degrees of contamination on their faying surfaces, which was consistent with the observed fluid leakage past the valve seats. It could not be determined whether the contamination was present before the accident, or was an artifact of the post accident fire.

The carburetor was fire-damaged. Both the throttle and mixture control cables remained attached to their respective arms on the carburetor. The throttle valve was observed to move throughout approximately full travel. The mixture control/apparatus was damaged and inoperative due to fire. The bowl drain fitting was observed to be installed securely and safetied. One float had separated from its arm, and the other float had separated into its component halves.

Fire damage to the magnetos precluded operational testing or determination of their pre-accident functionality. All spark plugs were present and installed. All electrodes were heavily contaminated with oil, carbon, rust and other unidentified debris. Some electrodes exhibited readily visible erosion, which increased the effective spark gaps.

The fuel selector valve internal passages indicated that it was set to the left tank. The fuel strainer remained attached to the firewall, but fuel lines and the strainer were severely fire damaged.

Refer to the NTSB public docket for this accident for detailed information.

ADDITIONAL INFORMATION

Airplane Weight and Balance

The airplane had a certificated maximum takeoff weight of 2,230 pounds. The pilot reported that there was about 110 pounds of baggage on board, that the combined occupant weight was about 345 pounds, and that the fuel tanks had a total capacity of 40 gallons. Although the pilot and passenger provided lists of their on-board possessions, the lists did not contain any weight information, and the lists could not be independently verified for accuracy. In his written report to the NTSB, the pilot reported that the accident flight takeoff weight was 2,085 pounds. In an interview with FAA personnel, the pilot stated that he "really did not know" what the empty weight of the airplane was, and that he "considered the airplane to be below the [maximum allowable] gross weight" for the takeoff from O22. Due to the consumption of the baggage and parts of the airplane by the fire, a substantiated determination of the actual weight and balance could not be accomplished.

Airframe and Propeller Information

In the pilot's written and verbal recounts of the flight and accident, he reported that during cruise flight of the first leg, and during the attempted climbout during the accident leg, the pitch attitude seemed higher than it should have been. He did not report any other operational or handling irregularities or problems. Review of the available maintenance documentation indicated that the airplane had been re-rigged about 17 years and 340 flight hours prior to the accident flight. Accident damage precluded determination of the rigging status, or of the accuracy of the tachometer or airspeed indicator.

According to the Airplane Flight Manual (AFM) and FAA Type Certificate Data Sheet, the accident propeller was approved for installation on the airplane, provided it was within specified diameter dimensions, and that specified static rpm values could be achieved. The condition of the propeller and the lack of maintenance records precluded those determinations by the investigation.

Takeoff Performance

Due to the original certification date of the airplane, only limited operational procedure information and performance data for takeoff and climb was produced by the manufacturer. Operational guidance and some performance data was provided in the Owner's Manual (OM), while performance data specific to the installed propeller was provided in the AFM. AFM takeoff and climb data was predicated on a takeoff weight of 2,230 lbs, full throttle, flaps up/retracted, 80 mph climb speed, zero wind, and zero slope runway. The OM stated that "The quickest take-off is obtained when the flap control is placed in the first notch," but neither the OM nor the AFM defined or elaborated on the meaning of "quickest take-off." The OM stated that in using the takeoff and climb performance data, "allowance must be made for actual conditions." However, neither the OM nor the AFM provided any guidance regarding the specific methods or values that were to be used to determine those allowances.

The AFM-derived values for takeoff distance to 50 feet and rate of climb were determined to be about 3,250 feet and 545 feet per minute, respectively. The actual runway slope was about 1.1 percent up, the pilot used "one notch" of flaps, and he attempted to climb out at 70 mph. No allowances for any effects of weight, wind, runway slope, flap setting, or climb speed variations from the AFM baseline conditions were able to be made by the investigation.

The pilot did not report any engine roughness or rpm loss during the attempted takeoff and climb from O22.

Refer to the NTSB public docket for this accident for detailed information.

NTSB Probable Cause

The airplane’s failure to climb at a sufficient rate to clear trees and terrain beyond the end of the runway for reasons that could not be determined because postaccident examination did not reveal any mechanical malfunctions or failures that would have precluded normal operation.