Beechcraft C23 N793Y

Summary

On 11 May 2021 at about 20:00 local time, a Beechcraft C23 registered N793Y was involved in an accident near Merrill, Wisconsin, United States. 2 people were on board and 2 had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 May 2021 at 20:00

Classification

Accident

Location

Merrill, Wisconsin, United States

Nearest airport

Merrill Municipal Airport (RRL)

Coordinates

45.2420, -89.6133

Aircraft

Beechcraft C23

Registration

N793Y

Category

Airplane

Year built

1979

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN21LA213

2 people had minor injuries.

The loss of engine power due to tappet failure.

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

Read the full NTSB narrative

The pilot reported that he was returning to the airport after a 1-hour flight when the engine started to run rough and gradually lost power. The pilot switched fuel tanks and cycled the magnetos, with no change in the power loss. He executed an off airport forced landing. The landing gear collapsed during the landing and the airplane slid to a stop coming to rest upright. The airplane sustained substantial damage to both wings and fuselage. Examination of the engine found that the oil filter contained metallic particles that were determined to be consistent with tappet material. Further examination revealed 7 of the 8 tappets were destroyed. A metallurgical examination of the tappets revealed that the tappets fractured from overstress. The fracture started along the heads facing their corresponding camshaft lobes, which proceeded towards the back surface. While there were no indications of pre-existing cracks, such as from fatigue, there was evidence of pitting and surface wear on many of the tappet head faces that contact the camshaft. Of note was the No.2 exhaust tappet, the only tappet that underwent wear on the tappet face significant enough to change its geometry. The engine was overhauled 19 years before the accident and had accumulated 838 hours since the overhaul. The engine manufacturer recommends overhaul of the engine at 2,000 hours, or 12 years in service, whichever comes first. No record of tappet replacement was found in the maintenance records.

Quoted verbatim from the NTSB record.