Incident Overview
On December 9, 2009, at approximately 1400 mountain standard time, a Beech 35-33, registration N316Z, experienced a loss of engine power and subsequently performed a forced landing near Lehi, Utah. The aircraft, registered to Omni-Air LLC of Washington, Utah, was operated by the pilot under Title 14 Code of Federal Regulations Part 91. The private pilot, the sole occupant, sustained serious injuries. Visual meteorological conditions prevailed at the time, and no flight plan had been filed for the cross-country flight. The flight had departed from St. George Municipal Airport, St. George, Utah, around 1230, with an intended destination of South Valley Regional Airport (U42) in Salt Lake City, Utah.
Witness Accounts
Witnesses at a Fixed Base Operator (FBO) at U42 reported overhearing a mayday radio transmission on the Common Traffic Advisory Frequency (122.7 MHz). The transmission stated, "Mayday mayday, I am at the point of the mountain, 5,100 feet, my engine just quit." A certificated flight instructor (CFI) responded, instructing the pilot to verify that the fuel selector was on the fullest tank, the fuel was on, the mixture was full rich, and the magnetos were on both. The CFI then asked for the airplane’s registration number and whether the pilot had copied the instructions. No further radio transmissions were received from the pilot. A helicopter pilot who heard the mayday call proceeded toward the location and observed the downed airplane just south of the mountain.
According to local law enforcement, witnesses near the accident site reported seeing the airplane on a westerly heading near Interstate 15, then suddenly banking to the right to a northerly heading before descending into terrain.
Examination Findings
Post-accident interviews with family members indicated that the pilot did not remember the accident flight or the sequence of events.
An examination by a Federal Aviation Administration (FAA) inspector revealed that the airplane came to rest upright in a grassy, snow-covered area between Interstate 15 and a southbound highway off-ramp, at an elevation of approximately 4,625 feet mean sea level. The left wing was bent upward about 45 degrees approximately mid-span, and the fuselage was buckled aft of the cabin area. The fuel selector valve was found in the "right main" position. Fuel was observed in both the left and right main fuel tanks.
During wreckage recovery, approximately 36 gallons of aviation fuel was removed from the left and right main wing tanks (about 18 gallons per side), and a minimal amount of fuel was recovered from the auxiliary fuel tanks on the left and right wings.
The recovered engine and airframe were examined by representatives from Teledyne Continental Motors (TCM) and the FAA under the supervision of the Safety Board investigator-in-charge.
Examination of the airframe showed that the left and right wings had been removed for transport. The left and right fuel main and auxiliary tanks were filled with water to verify integrity; no leaks were observed. During removal of the fuel selector valve, a liquid consistent with fuel was noted in the left auxiliary fuel tank inlet line and in the fuel lines from the fuel selector to the engine pump supply and auxiliary fuel boost pump lines. The fuel selector valve was removed and examined. Fuel drained from the airframe fuel sump was free of debris, and a sample tested negative for water using water-finding paste. The airframe fuel filter housing and the left and right main fuel tank screens were free of debris. Air pressure applied to all fuel lines revealed no blockages.
The auxiliary fuel pump switch was found in the "OFF" position. The auxiliary fuel pump appeared intact; when placed in water with battery power applied, water flowed through the pump normally.
Engine Testing
The engine was removed and shipped to TCM facilities in Mobile, Alabama. Due to impact damage, the fuel control unit, oil sump, starter adapter, and parts of the induction system had to be replaced. The engine was installed on a test cell and successfully started. It was run at various RPM settings for approximately 25 to 30 minutes, with the throttle advanced from idle to full throttle six times; no anomalies were noted. A leak was observed from the fuel pump adjustable orifice assembly, but it did not affect the engine’s ability to produce rated power. A second engine run with the original fuel control unit was performed at various RPM settings with no anomalies. The engine-driven fuel pump did not exhibit any fuel leaks during the second run.
The engine-driven fuel pump was subsequently removed and tested on a bench, functioning properly throughout its full range of operation with no leaks observed.