Accident Overview
On December 1, 2024, at 1821 central standard time, a Piper PA-28R-200 airplane, registration N41997, sustained substantial damage during an accident near Boscobel, Wisconsin. The aircraft was operated as a 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor and the pilot receiving instruction were not injured.
Flight and Emergency
According to the flight instructor, the aircraft was established in cruise flight at 9,000 ft msl on the return leg of a night cross-country instructional flight when an odor was noticed in the cockpit. The instructor noted no additional issues and adjusted the cabin heat control, after which the odor diminished. Shortly after, the windscreen became opaque, and the instructor initially suspected icing conditions. The instructor contacted ATC and requested a lower altitude. Using a flashlight to illuminate the windscreen, a “brown river” was observed completely obscuring forward visibility. The cockpit engine oil pressure gauge indicated little to no oil pressure.
The instructor declared an emergency with ATC and took over control from the pilot receiving instruction. The nearest airport was located for a forced landing. Due to the restricted visibility caused by the oil-covered windscreen, the airplane landed hard adjacent to the runway, bounced, and then came to rest upright on the ground. The airplane sustained substantial damage to the right horizontal stabilator, and engine oil was found on the top engine cowling, windscreen, and empennage.
Postaccident Examination
During recovery, the engine oil breather tube and alternate air outlet were obstructed by ice that had accumulated during the flight. Subsequent examination of the engine revealed that the solid-ring crankshaft oil seal was extruded from the crankcase.
According to the airplane manufacturer, Piper Aircraft, Inc., the engine oil breather tube should contain two secondary alternate air outlets located within the engine cowling area, and the breather tube primary outlet should not extend beyond 0.5 inches outside the engine cowling. The accident airplane’s engine oil breather tube, which was not a Piper part, contained one alternate air outlet fabricated about 1.5 inches from the end of the tube. The end of the breather tube extended about 3 inches outside the engine cowling.
Maintenance History
A review of the maintenance records revealed that the engine oil breather tube was replaced on December 18, 2006, with an unknown part number. No subsequent maintenance entries were noted that referenced any maintenance of the breather tube.