Aviation safety investigations & reports

Stall warning device event, Alice Springs, NT, 2 August 2006, VH-NXE, Boeing Company 717-200

Investigation number:
200604439
Status: Completed
Investigation completed

Summary

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At 0938 Central Standard Time on 2 August 2006, a Boeing Company 717-200 aircraft, registered VH-NXE, took off from Alice Springs Airport, NT, on a scheduled flight to Perth, WA.

The applicable aircraft take-off settings and techniques were applied by the flight crew for the takeoff. The recorded data showed that, 4 seconds after lift off, when about 31 ft above the runway, the aircraft's stall warning system activated for 4 seconds, and that the aircraft did not approach an aerodynamic stall condition at any time during the stick shaker activation. In response to the activation of the stick shaker, the flight crew increased engine thrust and reduced the aircraft's pitch attitude.

It is almost certain that an incorrect left wing slat sensor signal was received by the proximity sensing electronics unit (PSEU) from one of the two left wing slats proximity sensors. Consequently, the different slat position signals from the two sensors in the left wing resulted in the PSEU defaulting to the slats not-extended indication for the left wing. As a result of the different slat position signals sent by the proximity sensing electronics unit for the left wing (slats not-extended) and right wing (slats extended), the aircraft's flight control computers used the flaps-extended/slats-retracted stick shaker angle of attack schedule, leading to stick shaker activation and other stall indications.

Although no explanation could be found for the incorrect signal received by the PSEU from one of the two left wing slats proximity sensors, the aircraft manufacturer concluded that there did not appear to be a systemic problem in the worldwide 717 fleet.

Download Final Report
[Download  PDF: 504KB]
 
 
 
General details
Date: 02 August 2006   Investigation status: Completed  
Time: 0938 CST    
Location   (show map): Alice Springs Airport    
State: Northern Territory   Occurrence type: Avionics/flight instruments  
Release date: 30 January 2008   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 717  
Aircraft registration VH-NXE  
Serial number 55063  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Alice Springs, NT  
Departure time 0938  
Destination Perth, WA  
Last update 18 April 2018