DEN99LA139

Approximately 20 miles from the destination airport, while nearing completion of an IFR cross-country flight, the pilot had descended from his cruising altitude of 10,000 feet to 8,000 feet as assigned by approach control. Shortly after stabilizing at the lower altitude, the engine lost all power. After unsuccessfully attempting to restart the engine, the pilot made an emergency landing on broken prairie terrain 10 miles from the airport. The aircraft struck a dirt bank during the landing. No evidence was found of malfunction or preimpact damage to the engine.

On August 6, 1999, at 1130 mountain daylight time, a Beech V35B, N3059W, conducted a forced landing when the engine lost all power approximately 5 miles northeast of Elizabeth, Colorado. The private pilot and his three passengers received serious injuries and the aircraft sustained substantial damage. Visual meteorological conditions prevailed and an instrument flight rules (IFR) flight plan was filed for this cross-country flight operating under Title 14 CFR Part 91. The flight originated from Tulsa, Oklahoma, at 0915 central daylight time, with a filed destination of Centennial Airport, Englewood, Colorado.

According to the pilot, the aircraft had 32 gallons of fuel in each of the two internal wing fuel tanks at the time he departed Tulsa.

The pilot said he initiated the flight on the left fuel tank and it took 15 minutes for the climb out to his assigned cruising altitude of 10,000 feet above mean sea level (msl). During the climb, the pilot noted a "small" stream of fuel leaking around the fuel filler gasket on top of the right wing fuel tank. He said the gasket leak had happened before and always stopped when fuel usage lowered the level of fuel in the tank. He switched to the right tank and said the leak stopped in 20 to 30 minutes. He did not know the quantity of fuel that leaked from the tank and said that on previous occurrences the leakage had no measurable effect on fuel quantity.

In the account the pilot provided, he said that he set the power to use 14 gallons of fuel per hour based on fuel flow. He flew for 1 hour on the right tank, then switched to the left tank and flew between 1+15 and 1+30 hours. He then switched back to the right tank.

According to the pilot's statement, about the time he switched back to burning fuel from the right tank the flight was cleared to descend to 9,000 feet followed by a clearance to 8,000 feet with several turns for traffic sequencing.

About 20 miles from the airport, the engine began losing power and the pilot said he notified Denver approach control. They gave him priority handling and a vector direct to the airport. Shortly thereafter, the engine lost all power and approach control gave the pilot information that there was a highway south of his location that might be usable for a forced landing. During the emergency descent for landing, the pilot said he tried unsuccessfully to restart the engine as he turned the aircraft in that direction but could not extend the glide to get to the highway. He made the decision to land and touched down on broken prairie terrain approximately 10 miles southeast of Centennial Airport. During the landing roll, the aircraft collided with a dirt bank in a dry creek bed. The aircraft sustained damage to the fuselage and both wings during the landing.

Calculations based on the pilot's account and the performance section of the aircraft flight manual were conducted and are as follows:

There was 32 gallons of fuel in each tank at the beginning of the flight. Start, taxi, and takeoff was conducted on the left tank at a fuel usage of approximately 3 gallons. Climb to 10,000 feet was on the left tank at a total fuel usage of 6.3 gallons, and between 1+15 and 1+30 hours of cruise was conducted on the left tank at an approximate fuel usage of 19 gallons.

The right tank calculated fuel usage, according to the pilot's account, was 21 gallons which would leave approximately 11 gallons in the tank at the time the engine lost power. There are two unknowns in the fuel calculations regarding the right tank. One is the amount of fuel that leaked from the right tank due to the filler cap seal leak, and the other is the amount of fuel burned between the start of the descent and the loss of engine power.

Thus, when the pilot switched to the right fuel tank for the descent/approach phase of the flight, it is calculated, that he had approximately 3.7 gallons of usable fuel remaining in the left tank, and 11 gallons usable fuel, minus the leaked fuel, in the right tank when the descent was started. When the engine lost power, the right tank fuel quantity would have been reduced by the amount lost because of the leak and fuel used during the descent.

The fuel system in this aircraft consisted of a 40-gallon (37-gallon usable) rubber fuel cell in each wing leading edge with a flush type filler cap for each cell. A visual measuring tab is attached to the filler neck of each cell. The bottom of the tab indicates 27 gallons of usable fuel and the detent on the tab indicates 32 gallons of usable fuel in the cell provided the wings are level during fueling. According to the airplane flight manual, 3 gallons of fuel in each tank is unusable.

According to the aircraft flight manual, under certain (non-defined) conditions, impact ice can form in the engine air induction system. The manual explains that if the air intake or filter becomes clogged with ice, a spring-loaded door in the air intake duct will open automatically and the induction system will operate on alternate air. If the alternate air source door becomes frozen in the closed position, a pull-and-release T-handle is provided to force the door open.

In an interview, the pilot said that "When we were at 9,000 feet we were in and out of a scattered broken layer {clouds} and at 8,000 we were just in the base of them."

Using the reported temperature/dew point (75/55) at Centennial Airport and applying standard lapse rate temperature reduction, the temperature/dew point at 8,000 feet msl was calculated to be 68/48. According to charts from research done by the Aviation Safety Bureau, Transport, Canada, at the above calculated temperature/dew point, when flying in the clouds, serious induction system icing can occur at glide power and moderate induction system icing can occur at cruise power.

The procedures to be followed for engine failure, other than during takeoff, and engine restart procedures are reproduced from the airplane flight manual as follows:

Engine failure after liftoff and in flight

1. Fuel Selector Valve - SELECT OTHER TANK (Check to feel detent). 2. Auxiliary Fuel Pump - ON 3. Mixture - FULL RICH, then LEAN as required. 4. Magnetos - CHECK LEFT and RIGHT, then BOTH. 5. Alternate Air T-handle - PULL AND RELEASE.

Air start procedure

A. Fuel Selector Valve - SELECT TANK MORE NEARLY FULL (check to feel detent). B. Throttle - RETARD. C. Mixture - FULL RICH. D. Auxiliary Fuel Pump - ON until power is regained then OFF. (Leave on if Engine driven fuel pump is inoperative.) E. Throttle - ADVANCE to desired power. F. Mixture - LEAN as required.

An examination of the engine and airframe fuel system was conducted at the facilities of Beegles Aircraft Services, Greeley, Colorado, on August 11, 1999. Persons present during the examination were representatives from the FAA, Beech Aircraft, and Continental Engines. The examination provided no evidence of preimpact component failure or malfunction. Details of the examination are as follows:

The engine was separated from the airframe engine mounts and remained attached by hoses and cables. The propeller remained attached to the engine and all three blades were broken loose in the hub. Blade 'A' exhibited a rearward 180-degree curl approximately 13 inches outboard from the hub and chordwise scuffing. Blade 'B' was curled to the rear about 45 degrees just outboard of the hub, twisted toward low pitch, and bore leading edge gouges. Blade 'C' was deformed rearward about 25 degrees from the hub and the tip was curled to the rear.

The propeller governor was spring loaded to full increase.

All cylinders remained attached and continuity through the engine was intact. The engine was rotated by hand and all cylinders produced "thumb" compression.

The engine driven fuel pump was removed and examined. It could be rotated approximately 90 degrees by hand in either direction, the coupler w