Engine Failure Leads to Emergency Landing in Denmark

Casualties unknown • Serious incident to OY-AHY 3 nm south of the city of Assens on 11-8-2022, DK

A Reims F 172 H experienced a sudden engine failure due to internal mechanical breakage, forcing an emergency landing in a field near Assens.

What happened

On August 11, 2022, a private flight carrying three skydivers was en route from Kolding/Vamdrup to a landing site near Bjørnø. While flying at 5,000 feet, the pilot noticed an unusual engine sound accompanied by a significant rise in oil temperature, though oil pressure remained stable. After attempting to reduce engine RPM without success, the pilot decided to return to the departure airfield.

While flying over Lillebælt near Fyn, the engine stopped abruptly. The pilot declared a MAYDAY, and the skydivers exited the aircraft as it approached land. The pilot successfully executed an emergency landing in a harvested rye field south of Assens. The aircraft sustained no damage during the landing, and the pilot was able to signal to a nearby military aircraft that they were unharmed.

The investigation

Investigators examined the engine and the wreckage at the scene. They discovered oil leakage from the cylinder intakes and found cracks and a hole in the upper engine block at cylinder number 2. Upon dismantling the engine, technicians found significant metal debris in the oil pan, which had blocked the oil pump suction filter.

Detailed inspection revealed that a connecting rod bolt in cylinder number 2 had failed due to fatigue. This failure caused the remaining bolt to bear excessive load, leading to the disintegration of the connecting rod assembly. The loose components subsequently struck the engine block, causing extensive internal damage and the eventual engine seizure. The investigation also noted that the engine had operated 2,832 hours beyond its recommended Time Between Overhaul (TBO) and had not undergone a shockloading inspection in over 2,600 hours.

Findings

  • The failure of a connecting rod bolt in cylinder number 2 increased the load on the remaining hardware and generated metal particles.
  • These metal particles clogged the oil pump suction filter, reducing oil flow and causing the observed rise in oil temperature.
  • The subsequent failure of the second bolt and the rod itself caused severe internal engine damage and a total engine failure.
  • The engine was operating significantly beyond its recommended TBO and overhaul intervals.

Probable cause

The engine failure was caused by the fatigue failure of a connecting rod bolt in cylinder number 2, which led to a catastrophic mechanical breakdown and engine seizure. The engine's operation well beyond its recommended overhaul period and the long interval since the last shockloading inspection were significant contributing factors.

Frequently asked questions

What happened in the 2022-08-11 aircraft accident near Serious incident to OY-AHY 3 nm south of the city of Assens on 11-8-2022, DK?

A Reims F 172 H experienced a sudden engine failure due to internal mechanical breakage, forcing an emergency landing in a field near Assens.

What aircraft was involved and where did it happen?

The accident on 2022-08-11 involved a aircraft, registration OY-AHY, at Serious incident to OY-AHY 3 nm south of the city of Assens on 11-8-2022, DK.

What was the probable cause of the accident?

The engine failure was caused by the fatigue failure of a connecting rod bolt in cylinder number 2, which led to a catastrophic mechanical breakdown and engine seizure. The engine's operation well beyond its recommended overhaul period and the long interval since the last shockloading inspection were significant…

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