Investigation into Structural Failure of Tecnam P92 Echo

Casualties unknown • Farm Rietfontein in the Orange Farm area, ZA

A metallurgical investigation into the structural failure of a Tecnam P92 Echo, registration ZU-DMT, has determined that the wing separation was caused by excessive lift forces during flight.

What happened

A Tecnam P9 and 2 Echo light aircraft, registration ZU-DMT, experienced a significant structural failure during flight. The aircraft, which had completed 134 flight hours following a previous rebuild, suffered the separation of its right-hand wing from the main fuselage. This separation triggered a chain of structural failures, including the subsequent detachment of the rudder and horizontal stabilizer assembly, as well as the separation of the left-hand wing and center section from the cabin truss.

The investigation

SACAA AIID investigators conducted a detailed metallurgical examination of the wreckage using Scanning Electron Microscopy (SEM) and X-ray Energy Dispersive Analytical System (EDS) analysis. The investigation focused on determining the fracture modes of the failed components and assessing whether the aircraft's previous reconstruction contributed to the failure.

Microscopic analysis of the wing struts, L-shaped structural beams, and the cabin truss revealed that the fractures were consistent with ductile material failure under overload conditions. The investigation also included hardness testing and spectroscopy to verify that the aluminum alloys used in the wing ribs and spars matched the Original Equipment Manufacturer (OEM) specifications for 6061-T6 and 2024-T3 aluminum. No evidence of pre-impact fatigue, cracks, or structural weaknesses was found in the metal surfaces.

Findings

  • The primary cause of the right-hand wing separation was excessive lift forces acting on the wing during operation.
  • These aerodynamic forces created intense bending moments and compression forces between the strut and fuselage attachment points, leading to visible buckling of the wing structure.\n- The separation of the right-hand wing subsequently induced forces that caused the rudder and horizontal stabilizer to fail.
  • The structural integrity of the materials was found to be in compliance with OEM standards.
  • The previous rebuilding of the aircraft had no impact on the structural failure.

Safety action

  • Operators must strictly adhere to the operating envelope limitations established by the OEM and aviation authorities to prevent excessive aerodynamic loading.

Probable cause

The right-hand wing separated from the fuselage due to extreme aerodynamic loads and excessive lift forces that induced structural buckling and subsequent overload failure.

Frequently asked questions

What happened in the 2008-10-24 Tecnam P92-S Echo accident near Farm Rietfontein in the Orange Farm area, ZA?

A metallurgical investigation into the structural failure of a Tecnam P92 Echo, registration ZU-DMT, has determined that the wing separation was caused by excessive lift forces during flight.

What aircraft was involved and where did it happen?

The accident on 2008-10-24 involved a Tecnam P92-S Echo, registration ZU-DMT, at Farm Rietfontein in the Orange Farm area, ZA.

What was the probable cause of the accident?

The right-hand wing separated from the fuselage due to extreme aerodynamic loads and excessive lift forces that induced structural buckling and subsequent overload failure.

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