NTSB Factual Report

On February 27, 2016, about 1125 eastern standard time, a Beech model V35 single-engine airplane, N2714T, was substantially damaged during a forced landing on Interstate I65, near Seymour, Indiana. The private pilot and his two passengers were not injured. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91. Day visual meteorological conditions prevailed for the personal flight that departed Indianapolis Metropolitan Airport (UMP), Indianapolis, Indiana, about 1045, with the intended destination of Bowman Field Airport (LOU), Louisville, Kentucky.

The pilot estimated that the airplane had departed with about 40 gallons of fuel for the planned 46 minute flight. He further estimated that, before departure, the right and left main fuel tanks contained about 30 gallons and 10 gallons, respectively. Both outboard tip tanks only contained residual fuel. After departure, the flight continued toward the planned destination and received visual flight rules (VFR) flight following from air traffic control (ATC). The pilot reported that he switched from the right main fuel tank to the left main fuel tank after reaching the final cruise altitude of 5,500 feet mean sea level (msl). After drawing fuel from the left main fuel tank for about 10 minutes, he switched back to the right main fuel tank as he prepared for his initial descent to the destination airport.

The pilot reported that the engine began to run roughly after operating on the right main fuel tank for about 3 minutes. He switched back to the left main fuel tank, increased the mixture control to full rich, and turned on the high-boost auxiliary fuel pump. The engine continued to run roughly with occasional power surges. Additionally, the pilot reported that the engine would occasionally backfire, which was followed by a corresponding surge in engine power. The pilot then selected the low-boost auxiliary fuel pump and changed back to the right main fuel tank, which contained significantly more fuel than the left main fuel tank. He reported that engine operation briefly improved, over a 15-20 second period, before it resumed producing partial power with occasional power surges. The pilot reported that he continued to select different fuel tanks, including the right wingtip tank that only had residual fuel available. Ultimately, the pilot selected the right main fuel tank and the engine continued to operate at partial power for the remainder of the flight.

Air traffic control initially provided radar vectors toward Freeman Municipal Airport (SER), located near Seymour, Indiana; however, the pilot subsequently determined that the airplane did not have enough altitude to reach the airport and made a forced landing to the southbound lanes of Interstate Highway I65, near mile marker 42. He reported that the airplane touched-down at about 80 knots indicated airspeed with the flaps fully extended. Shortly after touchdown, the pilot had to maneuver the airplane to avoid another vehicle and it subsequently entered the grass median separating the northbound and southbound lanes. The pilot reported that the airplane's left wing impacted a grass embankment after the airplane traversed into the median. The pilot reported that, following the accident, he moved the mixture control to the idle-cutoff position before he evacuated the airplane.

The airplane was subsequently recovered from the interstate median to a hangar located at SER. A postaccident inspection, completed by a Federal Aviation Administration (FAA) Airworthiness Inspector, revealed substantial damage to the airplane's left wing aft spar. Further inspection established that there was ample fuel remaining within each main wing fuel tank. According to the airplane's fuel quantity indicators, the right main tank was about 3/4 full (about 30 gallons) and the left main tank was about 1/4 full. The pilot, under the supervision of the FAA inspector, drained 9 gallons of fuel from the left main fuel tank. A majority of the collected fuel was returned to the left main fuel tank. The left and right wingtip tanks contained about 1 gallon of fuel each and was considered residual fuel. Both auxiliary fuel pumps functioned normally when electrical power was applied.

An operational engine test run was completed by the pilot under the direct supervision of the FAA Airworthiness Inspector. The engine was run on the airplane without any modifications to the airframe fuel system and using the remaining fuel in the main tanks (no fuel was added). The FAA inspector reported that the engine experienced a normal start and warm-up. The pilot noted that the engine idle speed decreased 100-200 rpm during the engine warm-up and that the engine ran rough for the first few minutes as the engine warmed-up; however, at no point did the engine run stop running. The FAA inspector reported there were no engine anomalies during a pretakeoff engine run-up, which included a magneto functional check and cycling of the propeller.

The pilot indicated that the engine performed within its normal operating parameters throughout the engine test run. The only anomaly the pilot noted was a slight engine hesitation as he increased engine speed toward maximum static rpm; however, the engine subsequently demonstrated the ability to produce maximum static rpm. Additionally, while at a cruise engine power setting, there was no interruption to engine operation while the pilot alternated between the right and left main fuel tanks. To simulate an inadvertent fuel selector position during cruise flight, the fuel selector handle was placed between the right and left main fuel tank positions with the engine operating at a typical cruise power setting. Normal engine operation continued for about 30 seconds before there was a noticeable loss of engine power and an associated engine backfire from fuel starvation. The fuel selector was immediately repositioned to the right main fuel tank and normal engine operation was reestablished without any manipulation of the engine controls and/or activation of an auxiliary fuel boost pump. Ultimately, the operational test run did not reveal any anomalies that would have precluded normal operation of the Continental model TSIO-520-DB7B engine.

According to the airplane manufacturer, a turbo-charged engine, a separate low-boost auxiliary fuel pump, and wingtip fuel tanks were installed, in conformance with supplemental type certificates, at the factory during the original manufacture of the airplane. When equipped with a turbo-charged engine, the airplane is often referred as a Beech model V35TC. The original auxiliary fuel pump was designated as the "high-boost" when the low-boost auxiliary fuel pump was installed. The accident airplane was placarded against takeoffs with less than 13 gallons of fuel in each main tank; however, according to the airframe manufacturer, there is no prohibition against using all useable fuel from a main tank during the other phases of flight. The placarded fuel requirement for takeoff is to prevent a fuel tank outlet from unporting due to excessive fuel migration and sloshing that can be experienced during the takeoff phase.

The Beech model V35TC Owner's Manual states that when there is a loss of engine power, the auxiliary fuel pump should be used momentarily until engine power is regained. However, if engine operation does not improve within a few moments, the auxiliary fuel pump should be turned off. The airplane flight manual supplement associated with the turbo-charged engine installation stipulates that if a fuel tank becomes fully depleted, the low-boost auxiliary fuel pump should be turned on while changing fuel tanks; however, the auxiliary fuel pump should be turned off once engine restarts. Additionally, the flight manual supplement cautions that operating with the high-boost auxiliary fuel pump turned on, with a functioning engine-driven fuel pump, can produce an over-rich fuel mixture and a partial or total loss of engine power.

NTSB Probable Cause

The pilot's improper placement of the fuel selector handle between two tank positions, which resulted in a restricted fuel flow to the engine and the initial loss of engine power, and his improper decision to use the high-boost auxiliary fuel pump for an extended period, which resulted in an over-rich fuel mixture condition that prevented the engine from resuming normal operation.