Cirrus Design Corp SR22T N773GB accident near Davenport, Iowa

Probable cause

The fatigue failure of the No. 5 cylinder head, which resulted in a total loss of engine power. Contributing to the accident was the maintenance which did not fully blend to the depth necessary to preclude the failure.

NTSB analysis

The pilot reported that, as he descended toward the airport to land, smoke came from the engine cowling and oil splattered over the windscreen. The engine lost all power and the pilot executed a forced landing to a corn field. During the forced landing the airplane’s landing gear collapsed and both wings sustained substantial damage.

Postaccident examination of the engine revealed that the No. 5 cylinder fractured, which resulted in the engine’s lubricating oil being pumped outside of the cylinder. Examination of the fracture surface of the accident cylinder showed fracture features consistent with high-cycle fatigue. The cylinder was subject to FAA Airworthiness Directive (AD) 2020-16-11, which required compliance with the manufacturer’s Mandatory Service Bulletin (MSB)18-08. The MSB required blending of the cylinder casting in the area where the fracture originated. The cylinder had evidence of work consistent with compliance with the MSB.

The blending on the cylinder from the accident aircraft spanned the entire outboard edge but did not extend the full 0.25 inches indicated in the MSB. The loss of engine power was likely due to the fatigue fracture of the exhaust rocker arm support area of the No. 5 cylinder head, which allowed the engine’s lubricating oil to be pumped outside the cylinder. The loss of lubrication resulted in catastrophic failure of other engine components.

Text from the NTSB. Open the NTSB docket for CEN24LA079 for the full record.