CEN22LA040

The flight instructor completed about a 1-hour instructional flight with a student pilot, then was able to add only 4.19 gallons of fuel due to an issue with the airport’s fuel pump. The flight instructor then completed another 1-hour flight with a second student pilot. During this flight they used both fuel tanks, switching between tanks about every 30 minutes, and the flight instructor thought there would have been about 11 gallons remaining in the left tank and about 3 gallons in the right tank. They had completed one touch-and-go landing, then after takeoff, about 500 ft above ground level, the engine sustained a loss of power. The flight instructor took control of the airplane and requested that the student pilot complete the emergency checklist for a loss of engine power. They were unable to restart the engine and made an emergency landing to an area of mesquite trees. The airplane sustained substantial damage to the wings, fuselage, and empennage. The initial postaccident examination revealed that the wing fuel tanks were breached during the impact with trees and there was no sign or smell of residual fuel at the accident site. A detailed examination of the engine and fuel system did not reveal any residual fuel in the fuel system or engine components, and there were no anomalies found that would have precluded normal operation. The airplane manufacturer issued service instructions in 1974 that increased the amount of total unusable fuel from 1 gallon to 7.6 gallons (3.8 gallons per tank). The instructions had not been complied with since there were no updated placards to indicate 26 gallons of usable fuel for each tank. A postaccident fuel consumption estimation was completed based on the available evidence, which concluded that there could have been up to 7.79 gallons of usable fuel available. Since there was no recorded engine data, fuel quantity data, fuel at the accident site, or fuel remaining the airplane, the investigation was unable to determine the exact amount of usable fuel available, if any, when the loss of engine power occurred. It is likely that the flight instructor’s misunderstanding of the usable fuel quantity, and his inadequate management of the available fuel, resulted in fuel starvation and a loss of engine power.

On November 15, 2021, about 1150 central standard time, a Beech 23 airplane, N8701M, was substantially damaged when it was involved in an accident near Abilene Regional Airport (ABI), Abilene, Texas. The flight instructor received serious injuries and the student pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor stated that on the morning of the accident, 4.19 gallons of fuel were added to the right fuel tank; no additional fuel was added due to an issue with the self-service fuel pump. After fueling, the instructor estimated that the airplane contained about 15 gallons in each the left and right tanks. The first instructional flight was 1 hour, and the airplane consumed an average of 8 gallons per hour in cruise flight. He estimated that after the first flight there would have been about 15 gallons remaining in the left tank and 7 gallons in the right tank. The second instructional flight was about 1.1 hours, during which they completed maneuvers in the local area then returned to ABI for practice landings. During this flight they used both fuel tanks equally, switching between tanks about every 30 minutes, and there would have been about 11 gallons remaining in the left tank and about 3 gallons in the right tank. They had completed one touch-and-go landing at ABI, then after takeoff, about 500 ft above ground level (agl), the engine sustained a loss of power. The flight instructor took control of the airplane and requested that the student pilot complete the emergency checklist for a loss of engine power. They were unable to restart the engine and made an emergency landing to an area of mesquite trees. The student pilot stated that, after the initial loss of engine power, he followed the checklist and switched the fuel selector from the left to the right fuel tank. He stated the engine started but sputtered like it was not getting fuel. The airplane owner stated that he had leased the airplane to two pilots who intended to use it for their flight instruction business. He estimated that on the morning of the accident there would have been about 32 gallons of fuel in the airplane. The responding Federal Aviation Administration Inspector reported that the fuel tanks were breached and there was no sign or smell of residual fuel at the accident site. The fuel line from the fuel pump to the carburetor was void of fuel. The carburetor bowl was intact, but the position of the wreckage prevented an examination of the contents of the bowl at the accident site. The airplane sustained substantial damage to the wings, fuselage, and empennage. Postaccident examination of the airplane revealed that the fuel selector handle was positioned to OFF, and when actuated, it moved through LEFT, RIGHT, and OFF positions without issue. Air was blown through the fuel selector in the LEFT and RIGHT positions with no obstructions noted. The fuel strainer was intact andattached to the airplane, and it did not contain any fuel or contaminants. The engine-driven fuel pump was intact and attached to the engine. The fuel pump actuated with no anomalies noted. The carburetor was found partially fractured near the butterfly valve area. There was no fuel in the carburetor bowl and no anomalies noted with the unit. The fuel tank filler ports were not placarded with any information. The fuel selector valve displayed placards that indicated 29 gallons of (usable) fuel for each tank. In 1974, Beechcraft Service Instructions No. 0624-281, Fuel System – Replacarding to indicate minimum fuel for takeoff and increase amount of unusable fuel, was issued for the accident airplane. The pilot’s operating handbook revealed that the total unusable fuel increased from 1 gallon to 7.6 gallons (3.8 gallons per tank). The instructions had not been complied with since there were no updated placards to indicate 26 gallons of usable fuel for each tank. A fuel consumption estimation was completed based on the available evidence, which used only information recalled by the owner and pilots and could not be validated with any recorded data or other evidence. The estimation concluded that there could have been up to 7.79 gallons of usable fuel available. The flight instructor later stated that he thought the airplane was equipped with a 59.8-gallon system and was not aware that the usable fuel was only 52.2 gallons. He added that accident was possibly a result of fuel exhaustion.