Aviation occurrence briefs

Flap failure involving Cessna U206, Dimbulah, Qld, on 6 March 2018

Number:
AB-2018-032
Status: Completed
Investigation completed

Brief

Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation.

What happened

On 6 March 2018, a Cessna 206 was being operated on a training flight from Mareeba, Queensland (Qld) to Dimbulah, Qld (Figure 1) with a student and instructor on board.

Figure 1: Map showing locality
ariel view of terrain with labels
Source Google Earth, annotated by ATSB

At about 1045 Eastern Standard Time, as the aircraft was on approach to Dimbulah, with flaps selected to 20 degrees and at 80 knots, the flight crew heard a loud clunk. The flight crew thought that they may have struck a bird and discontinued the approach. They commenced climbing and found that they required significant right aileron to remain tracking straight. Once at a safe altitude, the crew raised the flaps in stages.

The crew diverted the aircraft to Mareeba to conduct a flapless straight-in approach. As the aircraft slowed during the landing roll, the flaps extended towards 20 degrees.

The operator inspected the aircraft and found several issues, including:

  • failure of the synchronising rod at the rod-end
  • disconnection of the transmission worm drive between the actuating tube and the collar
  • damage to the preselect cable clamp
  • damage to the right flap track
  • failure of the right centre aft roller. 

Figure 2: Diagram showing position of synchronizing rod assembly on aircraft
Black and white illustration of an aircraft with two labels
Source Cessna Illustrated Parts Catalog

The operator replaced the damaged parts. The operator then carried out a return to service flight. The flaps system cable tension was found to be low. Maintenance subsequently readjusted the cable tension.

Safety message

This incident highlights the importance of conducting a go-around if something unexpected occurs during an approach to land. The flight crew immediately conducted a go-around, which allowed them time to consider the implications of the technical failure and the opportunity to conduct a diversion to an airport where appropriate emergency response facilities were available if required.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

 

General details
Date: 06 March 2018   Investigation status: Completed  
Time: 10:45 EST    
Location   (show map): Dimbulah    
State: Queensland    
Release Date: 06 July 2018   Occurrence category: Incident  
Report status: Final    

Aircraft details

Aircraft details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model U206  
Type of operation Flying Training  
Sector Piston  
Damage to aircraft Minor  
Last update 11 July 2018