Beechcraft B36TC N7220B

Summary

On 9 October 2021 at about 02:04 local time, a Beechcraft B36TC registered N7220B was involved in an accident near Los Banos, California, United States. One person was 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

9 October 2021 at 02:04

Classification

Accident

Location

Los Banos, California, United States

Nearest airport

Los Banos Muni (LSN)

Coordinates

37.0423, -120.8618

Aircraft

Beechcraft B36TC

Registration

N7220B

Category

Airplane

Year built

1984

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Paso Robles → Novato

Aircraft damage

Substantial

Weather

VMC

Light

Dusk

NTSB number

WPR22LA005

Nobody was injured.

The total loss of engine power due to the improper installation of the No. 4 connecting rod bolt nut during a recent overhaul.

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 on the return leg of a cross country flight, about 10,000 ft mean sea level, when the engine lost oil pressure and the manifold pressure dropped. He immediately diverted to the nearest airport. While in the descent to his divert location, the engine was initially producing partial power, but then exhibited serious vibrations and subsequently lost all power. During this time, the cockpit filled with smoke, and fire and sparks were observed exiting from the engine cowling. Due to the fire, the pilot elected to make a forced landing on a road near the approach end of runway. The airplane struck an object during the landing roll which resulted in substantial damage to the wings. A postaccident examination of the engine revealed that the No. 4 connecting rod bolt nut was missing. Prominent thermal distress was observed in the area where the No. 4 connecting rod connected to the crankshaft and was consistent with oil starvation. In June of 2020, the engine was disassembled for a propeller strike inspection. The inspection was about 27.3 hours before the accident. As part of the inspection, the connecting rods were overhauled and then reinstalled on the crankshaft using new bearings, rod bolts, and nuts. Given the recency of the work, it is likely that insufficient torque was applied during installation of the No. 4 connecting rod bolt nut, which subsequently became loose and separated.

Quoted verbatim from the NTSB record.