What happened
On 26 July 2001, a student pilot was conducting a solo cross-country navigation training flight in a Robin HR200/120B, registration G-VECA, traveling from Wellesbourne Mountford toward Tatenhill. While cruising at 2,400 feet, the pilot noticed unusual engine vibrations and declared a PAN call to Wolverhampton Air Traffic Control, expressing the intent to return to the airfield.
Shortly after, the aircraft experienced loud bangs and increasingly severe vibrations. As the engine RPM dropped and oil pressure vanished, the pilot realized the engine was failing and began searching for a suitable field for a forced landing. Although radar vectors were provided for RAF Cosford, the pilot opted for Runway 06 instead of the active Runway 24 to ensure a safer approach path away from nearby buildings, given the declining engine performance.
The aircraft landed safely at the airfield, though the pilot encountered difficulty exiting the cockpit because the engine cowling had bulged outward during the failure, jamming the sliding canopy. There were no injuries to the crew.
The investigation
Upon inspecting the engine, investigators found that the number 4 cylinder had detached from the engine near the attachment flange. The failure also caused the connecting rod and piston to break, resulting in significant oil leakage throughout the engine bay and fuselage underside.
A metallurgical examination of the failed cylinder revealed that a primary crack had developed on the front of the barrel, eventually leading to a full 360-degree separation. The investigation identified that the crack originated from a deep corrosion pit located between the attachment flange and the first cooling fin. While the material dimensions were within specification, severe corrosion was also noted on the other three cylinders of the engine.
Findings
- The engine failure was caused by fatigue cracking initiated by a corrosion pit on the cylinder barrel.
- The engine had only accumulated approximately 299 hours of flight time since new.
- Although Textron Lycomm issued a Service Instruction earlier in 2001 regarding similar cylinder failures in France, the engine in G-VECA was manufactured and shipped prior to the implementation of improved corrosion-resistant assemblies.