NTSB Factual Report

HISTORY OF FLIGHT

On March 10, 2008, at 2150 Pacific daylight time, a Cessna 402C, N594DM, made a forced gear up landing at Desert Rock Airport (DRA), Mercury, Nevada. Distribution Management Corporation, Inc., (DMC) operated the flight under the provisions of Title 14 Code of Federal Regulations Part 135 as a cargo flight (check hauler). The pilot, the sole occupant, was not injured. The airplane landed gear up and sustained structural damage to both wings and the undercarriage. A company visual flight rules (VFR) flight plan had been filed for the cross-country flight that departed the Reno/Tahoe International Airport (RNO), Reno, Nevada, at 2030, with a planned destination of North Las Vegas Airport (VGT), Las Vegas, Nevada.

In a written statement, the pilot reported that he departed RNO with 1,000 pounds (about 166 gallons) of fuel onboard, combined in both main tanks. About 1 hour into the flight, at 15,000 feet, the pilot noted a fuel imbalance; the right engine fuel gage showed a depletion while the left engine fuel gage remained constant. The airplane was also beginning to display a tendency to roll to the left. He consulted his checklist for a fuel system emergency, and attempted to cross feed fuel from the left fuel tank to the right fuel tank, and set the auxiliary pumps on LOW. The pilot reported that there was no indication on the fuel gauge that the left fuel tank was decreasing in fuel quantity.

The pilot reported that he was receiving vectors to VGT, when the right engine lost power. He immediately feathered the right engine propeller, and did not attempt to restart the engine. He concluded that since his previous attempts to cross feed fuel to the right engine had been unsuccessful; attempting to restart the engine would also be unsuccessful. The pilot was notifying air traffic control (ATC) of the right engine failure when the left engine lost power. He set the auxiliary fuel pumps to the HIGH position, and informed ATC that he had experienced a dual engine failure. The left engine momentarily regained power before it shut down and remained shut down. The controller provided vectors to the nearest airport; Desert Rock Airport.

The pilot noted that when he neared the airport, he could not activate the runway lights through the Common Traffic Advisory Frequency (CTAF). The ATC controller vectored him to the runway, and as the airplane neared the ground, he was able to see the runway, and input aft back pressure on the yoke just prior to contact with the runway. The airplane slid off the west side of runway into a grass/dirt area, sustaining structural damage to the wing spars and fuselage.

The operator provided a fuel receipt dated March 10, 2008, indicating that the airplane had been fueled with 127.8 gallons of 100LL Av-gas at the Elko Regional Airport (EKO), Elko, Nevada. EKO is located about 199 nautical miles (nm) northeast of RNO.

In a statement to a Federal Aviation Administration (FAA) inspector, the pilot also noted that the right fuel quantity indicator continued to display a decrease in fuel. The pilot then set the fuel selectors to the main tanks (right fuel selector back to the right main tank position), and advised air traffic control (ATC) from Nellis Air Force base of his potential problem. A few minutes later, ATC informed the pilot that they were going to declare an emergency for him due to the nature of the problem and the upcoming Las Vegas airspace.

The pilot of the previous flight of the accident airplane submitted a statement to the FAA inspector. He indicated that when the airplane was parked on the ground for any length of time, fuel tended to drain from the left main tank to the right main tank. He believed that this was due to the uneven positions of the main gear struts; he estimated that when the airplane was parked on level ground, the left wing tip was 12 inches higher than the right wing tip. The pilot stated that his regular practice was to turn off both fuel selectors and close the emergency shut off cross feed valve when he parked the airplane.

The accident pilot submitted the handwritten note that had been addressed to him from the pilot who had last flown the airplane to the FAA. It stated, "I turned the fuel off and shut the cross feed because this plane leans really badly. If this plane sits for any length of time all the fuel goes from the left engine over to the right."

WRECKAGE AND IMPACT

FAA inspectors responded to the accident site and examined the airplane. They were able to establish flight control continuity from the cockpit to all flight control surfaces. They drained about 12 ounces of fuel from the right main fuel tank sump. The liquid resembled 100LL Av-gas and appeared to be free of contaminants. No fuel was drained from the left wing. The inspectors reported that the left main fuel tank had ruptured, and there was evidence of fuel staining on the ground underneath the left wing. First responders to the accident reported that they estimated about 45 gallons of fuel had spilled out from the left wing.

TESTS AND RESEARCH

A National Transportation Safety Board investigator examined the airplane's fuel system. The left and right fuel valves were functionally tested, with a leak found at the flexible rubber fuel hose/clamp at the fuel valve fitting on the right wing. He reported that the left and right fuel valves were cable operated and each valve had a main inlet, cross feed inlet, cross feed outlet, and off positions. Both valves were placed in the OFF position and high pressure air was placed in the cross feed IN and cross feed OUT positions for both fuel valves. On the right side fuel valve, air was heard escaping from the engine fitting at the firewall into the wing. Examination of the flexible rubber hose revealed a leak at the hose clamp at the fuel valve fitting. The high pressure air was placed on the left wing fuel valve in the cross feed IN and cross feed OUT positions; no leak was identified.

The airplane's fuel system is described in the Cessna 402C Pilot Operating Handbook section 7. The main fuel tanks are in integral portion of the sealed wet wing and supply their respective engine in normal operations. An auxiliary fuel pump, located outside the tank in line between the tank and the fuel selector valve, provides 5.5 psi fuel pressure for priming during engine start and to purge fuel vapor from the lines when necessary. In the event of an engine driven fuel pump failure, the auxiliary pumps can provide adequate fuel for engine operation. The engine driven fuel pumps are the main pumps for the system and draw fuel by suction from the tanks through the fuel valves. Two fuel selector handles in the cockpit are mechanically linked to the fuel valves in the wings and allow for the selection of main fuel tanks, cross feed, and off. During normal flight operations, the left selector valve is positioned to the left tank and feeds the left engine, while the right selector valve is positioned to the right tank and feeds the right engine. Fuel may be cross fed from the left main tank to the right engine or from the right main tank to the left engine by positioning both selector valves to the desired fuel tank. As an example, placing both fuel valves to the left main tank position will feed both engines from the left tank. An "OFF" position on each valve can be selected by pushing a center button on the selector, which would stop fuel to the corresponding engine driven fuel pump.

ADDITIONAL INFORMATION

According to United States Department of Energy (DOE) personnel, the FAA Airport Master Record (OMB 2120-0015 at http://www.gcr1.com/5010WEB/REPORTS/AFD02142008DRA.pdf shows no operational control tower (item 85), the airfield is unattended (item 17), no schedule for airfield lighting (item 81), and no airport beacon (item 80). Prior permission to land is required from DOE. The airport/runway lights may require manual operation, which requires a minimum of 15-30 minutes coordination prior to use.

NTSB Probable Cause

A loss of power to both engines resulting from a fitting failure and leak at the right fuel selector valve that allowed fuel from the right tank to be lost overboard, and that then introduced air into the left engine's fuel lines during an attempted cross-feed operation.