Wingtip To Wingtip PANZL S-330 N330JK

Summary

On 3 July 2011 at about 00:40 local time, a Wingtip To Wingtip PANZL S-330 registered N330JK, operated by John Klatt Airshows, Inc., was involved in an accident near Battle Creek, Michigan, 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

3 July 2011 at 00:40

Classification

Accident

Location

Battle Creek, Michigan, United States

Nearest airport

W K Kellogg Airport (BTL)

Coordinates

42.3064, -85.2500

Aircraft

Wingtip To Wingtip PANZL S-330

Registration

N330JK

Category

Airplane

Engines

1

Operator

John Klatt Airshows, Inc.

Operating rule

Part 91: General Aviation

Purpose of flight

Air Race/Show

Phase of flight

Not recorded

Route

Battle Creek → Battle Creek

Aircraft damage

Substantial

Weather

VMC

Light

Dusk

NTSB number

CEN11LA459

Nobody was injured.

The inadequate aileron hinge design, which resulted in the in-flight separation of the left aileron following a fatigue failure of the center hinge rod-end.

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

Read the full NTSB narrative

The entire left aileron separated from the airplane as the pilot was performing an aerobatic aileron-roll maneuver during an airshow aerobatic demonstration flight. The pilot was able to recover into level flight and make an uneventful landing. The pilot stated that his preflight inspection before the accident flight did not reveal any mechanical issues with the airplane, including loose jam nuts or any other aileron anomalies. However, the pilot reported that his aviation mechanic had to retighten the jam nut for the center aileron hinge rod-end after it had been found loose on several occasions before the accident flight. A postaccident examination revealed that the center aileron hinge had failed in the shank region of the rod end due to reverse bending fatigue. No material issues were identified with the center aileron rod end, which met the part specifications. A design analysis confirmed that the aileron rod ends were adequate for the limit loads on the structure but were inadequate for fatigue tolerance. The stress levels in the rod end shank were at or above the endurance limit for the specified rod end material, regardless of a loose or tight jam nut. However, a loose jam nut further increased the stress in the rod end about 28 percent and would have reduced the cycles to a fatigue failure. Following the accident, the airplane manufacturer redesigned the aileron bracket assemblies by increasing the diameter of the rod end shank and reducing the moment arm between the bearing and the aileron bracket. The redesign yielded a total stress reduction of about 83 percent in the rod end, which was significantly below the endurance limit for the specified material.  

Quoted verbatim from the NTSB record.