American Champion 8KCAB N60GK

Summary

On 26 July 2012 at about 21:30 local time, a American Champion 8KCAB registered N60GK was involved in an incident near Oshkosh, Wisconsin, United States. One person was on board and nobody was injured. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

26 July 2012 at 21:30

Classification

Incident

Location

Oshkosh, Wisconsin, United States

Nearest airport

Wittman Regional Airport (OSH)

Coordinates

43.9844, -88.5569

Aircraft

American Champion 8KCAB

Registration

N60GK

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Air Race/Show

Phase of flight

Not recorded

Route

Oshkosh → Oshkosh

Aircraft damage

Not recorded

Weather

VMC

Light

Day

NTSB number

CEN12IA498

Nobody was injured.

The failure of the pilot’s seat bottom frame due to the manufacturer’s improper production, installation, and inspection of that seat bottom, which resulted in a temporary loss of control during an air show performance.

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

Read the full NTSB narrative

The pilot was performing at an air show and entered the aerobatic box with a 45 degree descending roll. At an airspeed of 150 mph, the pilot pulled up into a loop and then initiated a “snap-on-top-of-a-loop” maneuver. The pilot’s seat then broke, and the pilot and seatback fell backward onto the rear seat and rear control column, temporarily jamming the flight controls. The pilot was then able to recover the airplane to a “right-side-up” position with wings level. He flew away from the crowd to assess the situation and subsequently landed without further incident. An examination revealed that the airplane’s seat bottom frame was not equipped with a required reinforcement truss stiffener. The manufacturer reviewed its production work orders and discovered that a batch of 10 seats were produced that were not constructed with the truss stiffener and, therefore, did not conform with the airplane’s production type certificate. As a result of this investigation, the manufacturer added steps to the seat production and inspection procedures to ensure proper seat assembly. Additionally, the manufacturer added to the seat welding fixture a locator (a visual cue) for the truss stiffener parts. Further, Service Letter 437 was published indicating that owners should perform a one-time inspection to ensure that the seat bottom frame contains the required reinforcement truss stiffener.

Quoted verbatim from the NTSB record.