NTSB Identification: WPR11LA290
14 CFR Part 91: General Aviation
Accident occurred Sunday, June 26, 2011 in Alkali Lake, OR
Probable Cause Approval Date: 11/03/2011
Aircraft: CHRISTEN INDUSTRIES INC PITTS S-1T, registration: N77MN
Injuries: 1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot reported that, during cruise flight, a large amount of oil suddenly covered the windscreen, causing her to initiate a precautionary off-airport landing as the oil pressure dropped to zero. Because of the uneven terrain in area in which she was flying, suitable landing sites were minimal. During the landing, the pilot attempted to pitch the tail-wheel airplane upward in order to drag the tail along the ground to slow the airspeed. The pilot stated that she had no response from the elevator or ailerons. The airplane impacted the uneven terrain in a nose-low attitude and cartwheeled, resulting in structural damage to all four wings and the fuselage. Examination of the recovered engine revealed that the front bearing oil seal was partially extruded from the crankcase nose seal bore. No additional mechanical anomalies were noted during the examination of the engine or airframe. The reason for the front bearing oil seal becoming extruded from the crankcase bore area was undetermined.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The loss of engine oil during cruise flight due to the failure of the front bearing oil seal.

Full narrative available

Index for Jun2011 | Index of months