Aviation safety investigations & reports

Skyfox HEDARO CA25N, VH-KKM, 1 July 2000

Investigation number:
200002727
Status: Completed
Investigation completed

Summary

The instructor and student pilot were conducting circuit training. The instructor reported the aircraft was on late downwind when there was a sudden loud bang and the aircraft began to roll to the left. He immediately took control of the aircraft and requested a priority landing. As the aircraft was descending he noticed that all engine indications were normal, however the aircraft required excessive right aileron and right rudder control. A visual inspection revealed the entire right aileron had separated from the aircraft. The descent was continued at a higher than normal speed and the aircraft landed safely.

The separated section of aileron was not recovered. Examination of the remaining aileron to wing attachment (wooden strut) fittings, shows all failures were because of overload. There was no evidence of wood rot or previous damage to any of the fittings.

The ailerons are actuated by a steel control tube from the cockpit, which fits into an aluminium tube (spar) aileron fitting. There is a small shim spacer collar between the inner and outer tubes. The tubes are secured by aluminium pop rivets with steel mandrels.

On the incident aircraft, the inner section of the steel tube shows extensive areas of corrosion (rust), particularly around the securing rivets. There does not appear to be any corrosion proof material present between the tubes or spacer surfaces.

A small broken piece of the aileron (aluminium tube) fitting was still attached to the steel control tube from the cockpit. Part of the broken surface indicates a dark area similar to a pre-existing stress crack, which emanates from a rivet hole. There is also evidence of exfoliation corrosion on this section. The evidence indicates the aileron failure set up at this point. It is probable the aileron then deflected and the air loads tore it from the wing attachments. The initial investigation was able to examine 3 other similar aircraft. Of these, 2 were found to have a significant degree of rust on the inner steel control tube and extensive exfoliation corrosion around the rivet section of the outer aluminium tube.

Safety Action

Because of the possible safety implications for the aircraft type, all the preliminary evidence was passed to the Civil Aviation Safety Authority (CASA) and the Australian Ultralight Federation.

General details
Date: 01 July 2000   Investigation status: Completed  
Time: 0930 hours EST    
Location   (show map): Maroochydore/Sunshine Coast, Aero.    
State: Queensland    
Release date: 03 August 2000    
Report status: Final   Occurrence category: Incident  
  Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Skyfox Aviation Ltd  
Aircraft model CA25  
Aircraft registration VH-KKM  
Serial number CA25N049  
Type of operation Flying Training  
Damage to aircraft Minor  
Departure point Maroochydore, QLD  
Departure time 0925 hours EST  
Destination Maroochydore, QLD  
Crew details
Role Class of licence Hours on type Hours total
Pilot-in-Command 175.0 435
Last update 13 May 2014