Engine failure forces emergency landing in Co. Cork

Casualties unknown • IE

A training flight in a Robinson R44 Raven II ended in an emergency autorotation after a catastrophic engine failure near Ringaskiddy.

What happened

On 18 August 2014, a Robinson R44 Raven II, registration EI-DDA, was conducting a local training flight from Cork Airport. While en route near Ringaskiddy, Co. Cork, the pilot experienced significant vibrations and observed low rotor RPM warnings, accompanied by the illumination of the clutch light.

In response to the engine failure, the pilot declared a "Mayday" and initiated an autorotation. During the descent, the pilot had to perform two maneuvers to avoid obstacles: first, a flare to clear overhead cables, and second, an adjustment to avoid a hedge and trees. The helicopter landed heavily on a downward slope in an agricultural field, sliding several meters before coming to a stop. There were no injuries to the two crew members on board, though the engine sustained substantial damage.

The investigation

The AAIU investigation involved a detailed strip inspection of the Lycoming engine at an approved overhaul facility. Investigators found the engine was seized and unable to rotate. Upon opening the oil sump, significant metallic debris was discovered, including fragments of steel, aluminum alloy, and phosphor bronze.

Detailed examination revealed that the Number 3 connecting rod had fractured. This failure caused extensive secondary damage, including the destruction of the Number 3 and 4 cylinder skirts and damage to the crankcase. Metallurgical analysis confirmed that metal particles found in the oil filter matched the material of the Number 3 small end bushing. Maintenance records indicated the engine was within its recommended time between overhaul (TBO) at the time of the incident.

Findings

  • The engine suffered a catastrophic in-flight failure.
  • The deterioration of the Number 3 small end bushing over an unknown period led to excessive clearance between the bushing and the piston pin.
  • This excessive clearance caused the connecting rod to become overloaded and eventually fracture.
  • The subsequent movement of the broken rod parts caused widespread damage to the engine's internal components, including the crankcase and cylinders.
  • The engine was operating within the manufacturer's recommended TBO of 2,200 hours.

Probable cause

The primary cause of the engine failure was the gradual deterioration of the Number 3 small end bushing, which created excessive clearance and led to the catastrophic fracture of the connecting rod.

Frequently asked questions

What happened in the null aircraft accident near IE?

A training flight in a Robinson R44 Raven II ended in an emergency autorotation after a catastrophic engine failure near Ringaskiddy.

What aircraft was involved and where did it happen?

The accident on null involved a aircraft, registration EI-DDA, at IE.

What was the probable cause of the accident?

The primary cause of the engine failure was the gradual deterioration of the Number 3 small end bushing, which created excessive clearance and led to the catastrophic fracture of the connecting rod.

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