Pilot Debrief

CESSNA 210 near Arbuckle, CA — 2010-05-19

Final reportWPR10LA248
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Date
2010-05-19
Location
Arbuckle, CA, USA
Airport
O08
Aircraft
CESSNA 210
Registration
N580TP
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Cruise

Probable cause

Insufficient clamping force to the connecting rod bolt, which resulted in looseness in the connecting rod bearing area that led to the fatigue fracture of the connecting rod and a subsequent loss of engine power.

NTSB narrative

During cruise flight, the pilot heard a loud “bang” and immediately observed oil coming from the engine cowling. The pilot subsequently initiated a forced landing and struck trees. A postaccident examination of the engine revealed two holes in the top of the crankcase between the Nos. 1 and 2 cylinders. The No. 2 connecting rod was visibly bent and no longer attached to the crankshaft. The end cap and a section of the yoke were separated and found outside of the engine case. The No. 2 cylinder piston, pin, connecting rod, and separated sections were sent to the National Transportation Safety Board’s materials laboratory for examination. A materials specialist determined that the damage to the connecting rod was a result of a high-cycle fatigue fracture. The fatigue in the location of the connecting rod would likely occur due to looseness in the connecting rod bearing area due to wear or damage to the bearing, small journal diameter, or insufficient clamping force from the connecting rod bolts. The bearing pieces did not show signs of significant wear and the journal diameter was not known. However, fretting was observed on the clamping surface of the connecting rod cap, which likely indicates that the connecting rod bolt had insufficient clamping force.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have conducted a precautionary landing after hearing the loud bang.

NTSB coding

Evidence available

  • Photos
  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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