Accident Description
On 6 October 2020, at 21:30 UTC, a Piper PA-25-235, registration LV-LXM, took off from a private aerodrome in Los Toldos, Buenos Aires, for a local training flight. Immediately after takeoff from runway 09, the engine lost power. The pilot performed an emergency landing, and the aircraft impacted terrain adjacent to Provincial Route 65. The accident occurred during daylight with good visibility.
The initial impact marks on the road suggested contact with the tailwheel. The aircraft continued, and the left main landing gear struck the ground, causing the aircraft to rotate approximately 180 degrees counterclockwise. It came to rest heading 295 degrees without debris dispersion.
Investigation
Visual inspection of the engine revealed no obstructions in the air intake system and kinematic continuity of components. However, the carburetor bowl contained no fuel. The propeller was deformed and showed no rotation marks, indicating the engine was stopped at impact.
An oil sample from the sump drain was tested and found unsuitable due to high viscosity. The main fuel tanks in both wings were disconnected from the fuel system; only the supplemental tank in the nose was used. Inspection of the fuel system valve connecting the supplemental tank found polymeric material remains. The carburetor was analyzed, and an obstruction in the fuel nozzle was identified, caused by a fibrous polymeric material. Similar polymeric material was found in the oil filter.
Fuel was stored in a 205-liter metal barrel at the operations base, labeled as lubricating oil. A sample from this barrel was tested and found suitable for use.
The pilot reported that after takeoff, the engine experienced power loss but did not stop, prompting the emergency landing. The pilot's medical certificate was expired. The aircraft logbooks had not been updated since the last annual inspection in October 2019. The aircraft was assigned to an aerial work company whose Certificate of Aerial Work Operator (CETA) had expired on 20 March 2020, and the last Annex I registration expired on 14 February 2018.
Analysis
The investigation determined that the damage was consistent with ground impact. The presence of polymeric material in the fuel system valve and carburetor nozzle, combined with the empty carburetor bowl, indicated that the engine failure resulted from obstructions that prevented fuel flow. The source of the polymeric material could not be definitively established.
Probable Cause
The engine failure occurred as a consequence of obstructions in the fuel system that prevented fuel flow.