Colorado Aviation Accidents & Incidents

On May 22, 2000, at 1700 mountain daylight time, a Piper PA-32R-300, N424TP, sustained minor damage when the engine failed catastrophically during climb to cruise. The two private pilots were not injured. The flight was operating on an instrument flight rules flight plan, in visual conditions, under the provisions of Title 14 CFR Part 91. The landing site was about 10 miles north of Erie Tri-County Airport, Lafayette, Colorado, and the takeoff occurred from Jefferson County Airport, Broomfield, Colorado, about 20 miles south of the landing site.

As the flight was climbing through about 8,000 feet above mean sea level (msl), [3,000 feet above ground level] the engine lost all power and oil was observed by the pilot on the cowl and wind screen. The pilot made an emergency landing in a field. No damage was incurred as a result of the landing.

Initial examination of the engine revealed that the number 2 cylinder separated from the case and all the cylinder hold-down studs had sheared. The connecting rod contacted the skirt of the piston and fractured the skirt and jammed. The piston and connecting rod rotated nearly 180 degrees and the piston lodged in the case. The case revealed some piston impact damage. One connecting rod bolt and both connecting rod nuts with the bolt ends were recovered along with the connecting rod cap and both halves of the main rod bearings. One inner cylinder base nut with the stud end attached was also recovered. All fragments were found inside the engine cowling.

Visual examination of the portions of the connecting rod bolts and the cylinder hold down studs provided evidence of "necking" at the fracture points. The bearing surfaces of the connecting rod, the rod and cap had no signatures of oil starvation or heat distress. The sequence of events, as provided by the witness marks, provided evidence that the connecting rod bolt failure was secondary in nature and resulted from cylinder separation.

The cylinder was visually inspected and no paint or foreign material on the crankcase mounting surface or cylinder base surface was found. The other five cylinders had torque putty on all the cylinder hold down nuts.

Examination of the engine at an engine overhaul facility provided evidence that none of the hold down nuts on the remaining five cylinders had sufficient torque. Improper installation of cylinders by unknown maintenance personnel who failed to torque the cylinder stud nuts sufficiently.