CEN18FA030 · Temco GC 1B

The airline transport pilot departed on a cross-country flight to relocate his newly-purchased airplane to his home state. A fixed-based operator employee at the airport reported that the pilot overflew the airport and requested verification that his landing gear were extended. The employee confirmed that they were down. After overflying the runway the airplane descended and impacted trees and terrain.

Another witness reported that after the low pass, the airplane started to climb and then turned right at an altitude of 250 to 300 ft above ground level. He added that as the airplane turned, its tail "wobbled," which he attributed to a loss of engine power. Then the nose pitched down before it descended below the tree line. The airplane separated into several pieces, and the forward fuselage and engine came to rest inverted behind the empennage.

The signatures on the propeller were consistent with little or no power at the time of the accident. A postaccident examination of the engine, airframe, and flight controls revealed no preimpact anomalies that would have precluded normal operations. Investigators were not able to ascertain why the pilot asked for verification of the landing gear position. The landing gear were found retracted in the airplane wreckage.

The airplane had been equipped with an aftermarket auxiliary fuel tank system; however, the system installed did not match the specifications of the supplemental type certificate (STC) identified in the maintenance logbooks or any other STC approved for the make and model of the airplane. The system had been installed about 9 years before the accident and before the pilot had purchased the airplane. The airplane had only flown about 4.5 hours since the fuel tanks were installed.

The auxiliary fuel tanks were not vented properly which could have resulted in a vacuum preventing fuel flow through the lines and to the engine. In addition, neither auxiliary fuel tank was equipped with a fuel pickup line inside of the tank. During a turn into the selected fuel tank it is possible that the fuel could unport resulting in fuel starvation and a loss of engine power.

The fuel selector valve was selected to the main tank which was empty; however, it is unknown what position change the pilot may have made following the loss of engine power. Evidence of fuel was found in the fuel lines and fuel pump following the accident. Although the amount of fuel onboard the airplane could not be determined, this evidence indicates there was likely sufficient fuel and that fuel exhaustion did not occur.

Given the configuration of the auxiliary fuel tanks, the engine likely lost power due to fuel starvation. This resulted from the unporting of the fuel due to the auxiliary fuel tank's improper configuration and occurred during the right turn the airplane entered after the low pass over the airport.

Verbatim NTSB analysis and probable cause from the NTSB dataset