Accident Overview
On June 19, 2009, at approximately 1100 eastern daylight time, a Cessna 170B, registration N8339A, collided with a hill during an emergency landing in Mahwah, New Jersey. The private pilot sustained serious injuries, and the airplane was substantially damaged by impact forces. The flight was operated as a personal flight under 14 CFR Part 91 with a visual flight rules flight plan filed. Visual meteorological conditions prevailed for the planned flight to Greenwood Lake Airport (4N1) in West Milford, New Jersey. The flight originated from Barnes Municipal Airport (BAF) in Westfield, Massachusetts.
Pilot Statement
The pilot reported that during the cross-country flight, the engine began to vibrate heavily. She attempted to continue to the destination but lost total engine power. She then attempted an emergency landing in a field but collided with a hill during the landing roll.
Previous Vibration Incident
The pilot recalled experiencing a vague vibration during a previous cross-country flight. After landing, she informed her mechanic, and an inspection was performed. The mechanic was unable to identify the source of the vibration, and it was assumed that carburetor ice may have developed.
Post-Accident Examination
An examination by a Federal Aviation Administration (FAA) inspector revealed that the airplane overshot a field during the landing roll and collided with a hill. The airframe and flight control system components showed no evidence of preimpact mechanical malfunction. Engine examination revealed that the No. 1 cylinder was separated from the engine case. Six of the eight cylinder attachment thru bolts were separated at the cylinder attachment flange, and the bolt nuts were not found. The other thru bolts remained attached to the case but were loosely held by the nuts. One of the thru bolts exhibited corrosion and discoloration on its threads.
Maintenance History
Review of logbooks showed the last annual inspection was conducted on March 6, 2009, at 3,258.6 hours total engine time. A log entry on June 10, 2009, at 3,263.1 engine total time, documented an inspection for a "possible rough running engine." After various component checks, a "no defects noted" statement was entered, and the airplane was returned to service. The engine had a top overhaul on March 1, 2001, at a tachometer time of 116.5 hours.