Swissdrones Operating SDO 50 V2 N780PA

Summary

On 18 January 2024 at about 16:23 local time, a Swissdrones Operating SDO 50 V2 registered N780PA, operated by Phoenix Air Unmanned LLC, was involved in an accident near Antioch, Georgia, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

18 January 2024 at 16:23

Classification

Accident

Location

Antioch, Georgia, United States

Coordinates

33.9406, -85.1561

Aircraft

Swissdrones Operating SDO 50 V2

Registration

N780PA

Category

Helicopter

Year built

2018

Engines

1

Operator

Phoenix Air Unmanned LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Antioch → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA24LA099

Nobody was injured.

A partial loss of engine power due to a reduction of fuel flow for undetermined reasons. Contributing to the accident was the UAS manufacturer’s lack of instructions for a partial loss of engine power landing.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

During an instructional flight of an intermeshing rotor-equipped unmanned aircraft system (UAS), the remote pilot-in-command (RPIC) received warnings of high fuel pump voltage, followed by warnings of max fuel pump voltage. Recorded data revealed that during these high and max fuel pump voltage spikes, the turbine engine lost power and the collective limiter would engage automatically. While attempting to have the UAS return for landing, the UAS had another partial loss of engine power, and the collective limiter was engaged again and remained engaged for the rest of the flight. The UAS touched down on the ground and then became airborne again; subsequently, the RPIC commanded an engine shutdown. After the engine shutdown, the UAS descended and contacted the ground hard on the skids; subsequently, the rotors contacted two of the vertical stabilizers, which resulted in substantial damage to the vertical stabilizers. According to the airframe manufacturer, it is possible that during a partial loss of engine power, the UAS may become airborne again after contacting the ground, as the autopilot will increase collective when the rotor rpm recovers after contacting the ground. This information was not provided to operators in the Unmanned Flight Manual at the time of the accident, so the RPIC was not aware of the need to engage the auto-land function. A postaccident examination of the airframe and the engine’s fuel system revealed no anomalies that would have precluded normal operation. Fuel samples taken just after the accident revealed no visible signs of fuel contamination or debris. An engine test run was performed using the turboshaft engine, electrically driven fuel pump, and the engine control unit (ECU). The engine operated normally at all tested RPMs and there were no anomalies that would have precluded normal operation. During the test run, a loss of fuel flow was simulated by slowly removing the fuel pickup tube from the fuel tank; the fuel pump voltage would increase to its maximum allowable voltage and the engine would lose power. Given that the main fuel tank was still full at the time of the accident, it is unlikely that the fuel pickup would have become unported during the accident flight. The fuel pump was bench-tested and then inspected. There were no anomalies observed that would have precluded normal operation. Similar cases of high/max fuel pump voltage spikes with accompanying reduction in fuel flow of similar make and model UAS aircraft were reported to the manufacturer and were found to have debris in the fuel system, which degraded the fuel pump’s performance. However, there was no debris found in the accident UAS’s fuel system during the examinations. Based on the available evidence, the partial loss of engine power was likely a result of a reduction of fuel flow to the engine. The reason for the reduction in fuel flow could not be determined.

Quoted verbatim from the NTSB record.