Aviation safety investigations & reports

Elevator balance tab failure, Boeing Company 737-229, VH-OZX, Port Moresby, PNG, 31 December 2007

Investigation number:
AO-2008-001
Status: Completed
Investigation completed

Summary

Download Final Report
[Download  PDF: 382KB]
 

After departing Port Moresby, Papua New Guinea, at 0406 Universal time, coordinated on 31 December 2007, the flight crew of a Boeing 737-229 aircraft, registered VH-OZX, operating a scheduled flight from Port Moresby to Brisbane, experienced severe vibration through the aircraft's airframe, resulting in the crew declaring a MAYDAY and returning to Port Moresby.

A subsequent examination found a section of the right elevator balance tab had detached and was missing. Examination of the remaining sections of the balance tab revealed that two attachment screws from one of the elevator balance tab hinge blocks had unwound, which led to the tab failure.

The investigation found that airframe vibration had been reported by the flight crew the day prior to the accident. On that occasion, a level I - General Inspection of the aircraft was conducted by a licensed aircraft maintenance engineer after the aircraft landed, with no defects found.

The aircraft manufacturer was aware that other operators had experienced in-flight vibration as a result of excessive wear in the elevator balance tab hinge and control linkages, and had issued a number of service bulletins (SBs) to address the issues. These SBs included SB737-55A1070, which directed operators to carry out detailed inspection of the elevator balance tabs, including checks for free-play, control rod wear and loose hinge screws.

As a result of this accident, the aircraft operator implemented a 'fleet campaign directive' requiring the immediate accomplishment of SB 737-55A1070 on all of its aircraft.

Download Final Report
[Download  PDF: 382KB]
 
 
 

Preliminary

Download Preliminary Report
[Download  PDF: 164KB]
 

Preliminary report released 27 February 2008

After departing Port Moresby, Papua New Guinea, at 0430 Coordinated Universal Time on 31 December 2007, the flight crew of a Boeing 737-229 aircraft, registered VH-OZX, being operated on a scheduled flight from Port Moresby to Brisbane, reported severe vibration through the airframe, resulting in a Mayday broadcast and return to Port Moresby.

A subsequent examination on the ground, found a section of the right elevator balance tab had detached and was missing. Preliminary examination of the tab indicated that a failure of one of the elevator tab hinge blocks had occurred.

Download Preliminary Report
[Download  PDF: 164KB]
 
 
 
General details
Date: 31 December 2007   Investigation status: Completed  
Time: 0430 UTC   Investigation level: Complex - click for an explanation of investigation levels  
Location   (show map): Port Moresby    
State: International   Occurrence type: Objects falling from aircraft  
Release date: 23 June 2009   Occurrence class: Technical  
Report status: Final   Occurrence category: Accident  
  Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 737  
Aircraft registration VH-OZX  
Serial number 21177  
Type of operation Air Transport High Capacity  
Damage to aircraft Substantial  
Departure point Port Moresby, PNG  
Departure time 0430 UTC  
Destination Brisbane, QLD  
Last update 14 November 2018