Aviation safety investigations & reports

Gates Learjet Corporation 45, VH-SQR, Brisbane, Qld, 13 March 2003

Investigation number:
Status: Completed
Investigation completed


The Australian Transport Safety Bureau did not conduct an on-scene investigation of this occurrence. The report presented below was prepared principally from information supplied to the Bureau.


On 13 March 2003, while on final approach during a training flight, the crew of a Lear 45 aircraft, registered VH-SQR, reported feeling a severe vibration through their respective control columns, followed by a rapid 10 to15 degree nose-down pitch change. Attempts to manually trim the nose of the aircraft up failed, with both crew members required to pull back on the control columns in order to regain control of the aircraft.

A subsequent inspection of the aircraft by the operator's engineers revealed that the aircraft's horizontal stabiliser could be moved by hand, vertically, approximately four inches at the leading edge. On examination, the horizontal stabiliser actuator appeared normal, with all attachments in place. However, the actuator was found to have free movement of its shaft in and out of the actuator body. Further detailed examination indicated that the actuator's primary `Acme screw' had failed. With this screw failed, the horizontal stabiliser load should have been retained through a secondary rod, however, the threaded retaining nut had unscrewed from the rod.

The United States National Transportation Safety Board (NTSB) advised the Australian Transport Safety Bureau (ATSB) that they were conducting an investigation into the failure of the horizontal stabiliser actuator, and the ATSB appointed an Accredited Representative to that investigation.

As a result of the incident, the US Federal Aviation Administration (FAA) issued emergency Airworthiness Directive (AD) 2003-06-51, on 20 March 2003, requiring operators to conduct an immediate inspection of Lear 45 aircraft horizontal stabiliser actuators and to remove from service any actuators that were the same part number as the failed one.

The Australian Civil Aviation Safety Authority issued Airworthiness Directive 5/2003, on 21 March 2003, requiring all Australian Lear 45 operators to comply with the requirements of the FAA AD. Additionally, the actuator manufacturer completed a new actuator design and has since had the new actuator certified for fitment to all affected Lear 45 aircraft.

The US NTSB is yet to publish its final investigation report (number ENG03WA011).

General details
Date: 13 March 2003   Investigation status: Completed  
Time: 1615 hours EST    
Location   (show map): Brisbane, Aero.    
State: Queensland   Occurrence type: Flight control systems  
Release date: 06 May 2005   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Gates Learjet Corp  
Aircraft model 45  
Aircraft registration VH-SQR  
Type of operation Flying Training  
Damage to aircraft Nil  
Departure point Brisbane, QLD  
Departure time 1530 hours EST  
Destination Brisbane, QLD  
Last update 13 May 2014