Piper PA-28R-200 N41997

Summary

On 2 December 2024 at about 00:21 local time, a Piper PA-28R-200 registered N41997 was involved in an accident near Boscobel, Wisconsin, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

2 December 2024 at 00:21

Classification

Accident

Location

Boscobel, Wisconsin, United States

Nearest airport

Boscobel (OVS)

Coordinates

43.1595, -90.6782

Aircraft

Piper PA-28R-200

Registration

N41997

Category

Airplane

Year built

1974

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Fairmont → Lake in the Hills

Aircraft damage

Substantial

Weather

VMC

Light

Night/Dark

NTSB number

CEN25LA053

Nobody was injured.

The ice obstruction of the engine oil breather tube and alternate air outlet, which resulted in a failure of the crankcase oil seal and loss of engine oil. Contributing to the accident was the incorrect engine oil breather tube installed in the airplane by maintenance personnel.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

During cruise on the return leg of a night cross-country instructional flight at 9,000 ft mean sea level (msl), the flight instructor and student pilot noticed an odor in the cockpit. The flight instructor then noticed an opaque windscreen and immediately thought they had encountered icing conditions. The flight instructor contacted air traffic control (ATC) and requested a lower altitude. Using a flashlight, the flight instructor illuminated the windscreen and noticed a “brown river” completely obscuring their forward visibility. The cockpit engine oil pressure gauge indicated little to no oil pressure. The flight instructor declared an emergency with ATC and assumed control of the airplane from the pilot receiving instruction. The flight instructor located the nearest airport to attempt a forced landing. However, due to restricted visibility due to 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 the airframe contained engine oil on the top engine cowling, windscreen, and empennage. During recovery of the airplane, recovery personnel noted that ice obstructed the engine oil breather tube and the alternate air outlet. The obstructed breather tube created increased crankcase pressure and caused the extrusion of the solid-ring crankshaft oil seal from the crankcase and subsequent loss of engine oil. Airplane records showed that the oil engine breather tube was replaced about 18 years before the accident. The design, fabrication, and installation of the accident airplane’s oil breather tube did not comply with the airplane manufacturer’s original design criteria. Specifically, the oil breather tube protruded about 3” outside the engine cowling when it should only extend 0.5”. The additional length of oil breather tube outside of the engine cowling would be more susceptible to ice accretion during flight. Additionally, the replaced oil breather tube was not fabricated with alternate air outlets that were positioned within the engine compartment, which would have provided an unobstructed vent after the primary outlet became contaminated with ice during the flight.

Quoted verbatim from the NTSB record.