Root SHERPA N1415B

Summary

On 18 September 2007 at about 00:45 local time, a Root SHERPA registered N1415B was involved in an accident near Scappoose, Oregon, United States. 2 people were on board and one was seriously injured, one 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

18 September 2007 at 00:45

Classification

Accident

Location

Scappoose, Oregon, United States

Nearest airport

Scappoose Industrial Airpark (SPB)

Coordinates

Not recorded

Aircraft

Root SHERPA

Registration

N1415B

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Scappoose → Scappoose

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX07LA280

1 person was seriously injured.

A loss of aircraft pitch control due to the fatigue failure of the fuselage tube structure at the flight control stick gimbal mechanism due to an incomplete weld penetration at the root of the weld.

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

Read the full NTSB narrative

The pilot was a potential buyer of the airplane and was flying it on short final approach. He said that he attempted to correct for a sink rate, which included pulling back full aft on the control stick to arrest the descent. The airplane's nose then abruptly pitched down about 45 degrees and the airplane struck the runway. A visual examination of the airplane's flight control system by Federal Aviation Administration (FAA) inspectors revealed that the flight control stick gimbal mechanism had fractured and the control stick was separated from the mechanism. The flight control stick gimbal mechanism and a portion of the fuselage structure were shipped to the Safety Board's Materials Laboratory for a metallurgical examination. According to the metallurgical examination, the fatigue cracking of the fuselage tube structure in the area of the control stick gimbal mechanism emanated from the root of a weld in an area between tube joints. The Safety Board's senior metallurgist reported that the fatigue had propagated through approximately 30 percent of the wall thickness. The fatigue crack was located near an area of the fuselage tube that contained a 0.7-inch-long region of incomplete weld penetration at the root of the weld.

Quoted verbatim from the NTSB record.