Mooney M20J N4474H

Summary

On 15 July 2021 at about 18:54 local time, a Mooney M20J registered N4474H was involved in an accident near Dinsmore, California, United States. 4 people were on board and 4 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

15 July 2021 at 18:54

Classification

Accident

Location

Dinsmore, California, United States

Nearest airport

Dinsmore (D63)

Coordinates

40.4920, -123.5982

Aircraft

Mooney M20J

Registration

N4474H

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

WPR21FA272

4 people died.

The airplane’s degraded engine performance due to wear to the intake cam lobes, which diminished the airplane’s takeoff and climb performance, resulting in a subsequent collision with trees.

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

Read the full NTSB narrative

A witness who was near the departure airport reported observing the airplane circle the area, land on the runway, and stop at the midpoint of the runway. At that time, three people disembarked from the airplane, one of whom walked around the airplane. All three people then boarded the airplane, and the airplane taxied toward the approach end of the runway. The witness observed the airplane take off and stated that the airplane appeared to have rotated just short of the displaced runway threshold. The witness stated that the airplane “barely cleared the fence” and that the rotation was not smooth. Subsequently, the airplane impacted trees just beyond the departure end of the runway, where a postimpact fire ensued. Postaccident examination of the engine revealed that the intake camlobes were worn and exhibited a rounded (instead of an elliptical) shape. The corresponding tappets for the intake cam lobes were galled. The alteration of the camlobe profile will in turn alter the amount and duration of the intake valves opening, thus negatively affecting power output. As a result, takeoff and climb performance would be directly affected. Although the extent of the degradation to the accident engine's power output could not be determined from the available evidence, the degradation was likely sufficient to cause a partial loss of engine power.

Quoted verbatim from the NTSB record.