History of Flight
On January 18, 2013, about 1300 mountain standard time, a Piper PA-28-235, registration N49DS, collided with a fence during a forced landing in Rock Springs, Wyoming. The private pilot, operating under 14 CFR Part 91, was not injured. The airplane sustained substantial damage. The cross-country flight departed Gillette-Campbell County Airport, Gillette, Wyoming, about 1110, with a planned destination of Rock Springs-Sweetwater County Airport, Rock Springs. Visual meteorological conditions prevailed, and no flight plan was filed.
The pilot reported that after initiating a descent from 12,500 feet, he approached the right base for runway 27. During the approach, he switched the fuel selector valve to the left tip tank, and turned on both carburetor heat and the auxiliary fuel pump. During the turn from right base to final, the airplane descended too low, and he applied full engine power. The engine did not respond, and a few seconds later lost all power. He subsequently elected to land the airplane in rough terrain ahead. During the landing sequence, the airplane struck a fence and berm, sustaining substantial damage to both wings.
The pilot expressed concern that he may have inadvertently starved the engine of fuel during the approach by turning the fuel selector valve beyond its left tip tank travel limit to the OFF position. He stated that after the engine lost power, he performed a cursory check of emergency items but did not reach down to check the fuel selector valve for fear of becoming disoriented and stalling the airplane. He could not recall the valve position after the accident but confirmed he switched it to OFF while securing the airplane on the ground. A fuel receipt from Flightline Incorporated of Gillette indicated he purchased 27.3 gallons of fuel the day prior, resulting in a total of 64 gallons onboard.
Additional Information
The FAA-approved airplane flight manual and pilot's operating manual did not prohibit the use of tip tanks during landing, stating that their total capacity is useable, and that for approach and landing the selector valve should be set to the "Proper Tank."
Tests and Research
Fuel Selector Valve: The airplane was equipped with a combination fuel selector valve/fuel drain located under the cabin floor, just behind the forward right seat. The valve was connected to a selection lever in the center console. During examination, the valve moved through its entire travel range with appropriate friction within the detents at each tank position. The selection lever had an override button (interlock) between the left tip and OFF positions to prevent inadvertent movement to OFF. Testing showed the lever could be moved midway between the OFF and left tip detents before the button prevented further movement.
Engine and Airframe Examination: The left tip tank was ruptured during the accident sequence, preventing an accurate fuel quantity assessment. The engine sustained minimal damage, primarily crushing of the lower cowling and induction airbox. All fuel lines forward of the firewall were intact and contained residual fuel droplets. About 1/2 ounce of blue-colored fuel was present within the combination fuel selector valve/fuel drain, and about 3 tablespoons of fuel was drained from the carburetor bowl plug. The fuel line from the left tip tank through to the selector valve was examined and free of obstruction. No anomalies were noted that would have precluded normal operation.
Engine Test Run: The airplane was connected to a fuel source via the left tip tank inlet at the selector valve. The engine was started and operated at varying speeds for about 5 minutes, running smoothly throughout its speed range with a nominal speed drop observed during a magneto check.
Engine Monitor: The airplane was equipped with a JP Instruments EDM 730 engine data monitoring system recording exhaust gas temperature (EGT), cylinder head temperature (CHT), fuel flow, fuel used, and battery voltage at 6-second intervals. Data from the accident flight was downloaded and examined. For most of the flight, EGT and CHT remained relatively constant with fuel flow between 12 and 15 gph. About 5 minutes before the recording ended, fuel flow dropped to 9 gph with corresponding decreases in EGT from 1,400 to 1,250 °F and CHT from 325 to 285 °F, consistent with descent power reduction. About 45 seconds before the recording ended, fuel flow increased to 15 gph, and EGT spiked about 100 °F. Shortly after, fuel pressure dropped to zero, and CHT fell to 500 °F.