Engine Failure Leads to Forced Landing of Thrush S2R-H80 in Brazil

Casualties unknown • PERDIZES, MG, BR

A turboprop agricultural aircraft suffered a catastrophic engine failure during pesticide application, resulting in a forced landing in a plantation in Minas Gerais.

What happened

On September 6, 2017, a Thrush S2R-H80, registration PR-RSP, was performing agricultural pesticide application duties near Perdizes, Minas Gerais. Approximately 15 minutes after takeoff from the Aerodrome of Fazenda Água Santa, the aircraft's engine lost power. The pilot was forced to perform an emergency landing in a nearby plantation. The aircraft struck the ground at a low angle with a slight left bank, traveling 60 meters before coming to a stop. The aircraft sustained substantial damage, but the pilot escaped without injuries.

The investigation

CENIPA investigators examined the wreckage and analyzed data from the aircraft's MVP-50T digital engine monitoring system. The investigation revealed that the engine had suffered a catastrophic internal failure. Evidence of oil leakage was found on the engine cowling, and a hole was observed in the cowling where internal debris had exited the compartment.

Upon disassembly of the engine, investigators found severe damage to the power turbine rotor, which had lost all its blades, and a bent quill-shaft. A fracture was identified in the Reduction Gear Box (RGB) Oil Tube. Furthermore, the investigation noted that the pilot had continued the second flight of the day despite having lost the torque indication on the previous flight. The investigation also looked into the manufacturing quality of the RGB Oil Tube, noting non-conformities in the TIG welding process.

Findings

  • The primary cause of the engine failure was operating the engine beyond its specified design limits, specifically regarding torque.
  • The pilot's transition from conventional piston engines to turboprop operations may have led to a reliance on the digital instrument color arcs (green, yellow, red) without consulting the required torque limit diagrams for specific temperatures and altitudes.
  • Manufacturing non-conformities in the TIG weld of the RGB Oil Tube, including lack of penetration and overlapping layers, contributed to the tube's fracture.
  • The pilot's decision to continue flight operations after the loss of torque indication on an earlier flight contributed to the accident sequence.
  • The failure to use aircraft manual diagrams to determine usable torque limits compromised flight preparation.

Probable cause

The catastrophic engine failure was caused by operating the engine beyond its certified power limits, exacerbated by a manufacturing defect in the Reduction Gear Box Oil Tube and the pilot's failure to adjust power settings based on altitude and temperature charts.

Frequently asked questions

What happened in the 2017-09-06 aircraft accident near PERDIZES, MG, BR?

A turboprop agricultural aircraft suffered a catastrophic engine failure during pesticide application, resulting in a forced landing in a plantation in Minas Gerais.

What aircraft was involved and where did it happen?

The accident on 2017-09-06 involved a aircraft, registration PRRSP, at PERDIZES, MG, BR.

What was the probable cause of the accident?

The catastrophic engine failure was caused by operating the engine beyond its certified power limits, exacerbated by a manufacturing defect in the Reduction Gear Box Oil Tube and the pilot's failure to adjust power settings based on altitude and temperature charts.

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