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What happened

On 30 December 2011, a Bombardier DHC-8-102 aircraft, registered VH-QQA, was being operated on a scheduled passenger service to Cairns, Queensland. During the landing, the crew perceived that the aircraft decelerated much quicker than they expected given that reverse thrust and landing gear brakes had not been selected. A subsequent inspection of the aircraft found nothing to explain the perceived problem, and a review of the flight recorder data indicated that there was no abnormal operation of the engines or propellers, and that reverse thrust had not been used.

What the ATSB found

Although unrelated to the reported occurrence, subsequent inspection of the aircraft identified a design problem within the aircraft’s power lever control quadrant. The problem related to the friction device within the power levers and its interaction with the flight idle gate, which was designed to prevent the power levers from going into the ground range in flight. When the friction knob was wound to the full out (friction off) position, the flight idle gate was lifted by contact between the friction device and the flight idle gate. That action rendered the flight idle gate inoperative.

The design problem only applied to the first 39 DHC-8-100 aircraft that were manufactured; subsequent aircraft were manufactured with a modified design. The aircraft manufacturer introduced a service bulletin requirement in 1986 to retrospectively modify these 39 aircraft, but the service bulletin omitted a requirement to modify or replace a specific part, which resulted in the bulletin being ineffective.

What has been done to fix it

Once informed of the design problem, the aircraft manufacturer took prompt action to address the issue. It issued a service bulletin to modify the relevant part, and this action was subsequently mandated by Transport Canada and the Civil Aviation Safety Authority of Australia.

Safety message

This investigation highlights the importance of crews reporting occurrences and other perceived problems. Although in this case the actual event reported by the crew was not serious, and no problems relating to the aircraft or crew performance leading to the perceived event were identified, the subsequent investigation did identify a safety issue in the design of the aircraft.

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Safety issue

AO-2012-005-SI-01 -  

Dash 8-100 Power lever design issue

The first 39 manufactured DHC-8-100 aircraft had a design problem such that, if the friction control was wound to the full out (friction off) position, the flight idle gate was ineffective in reducing the likelihood of pilots inadvertently moving the power levers below flight idle in flight.

Safety issue details
Issue number:AO-2012-005-SI-01
Who it affects:Operators of Dash 8 100 series aircraft with serial numbers from 001 to 039.
Status:Adequately addressed

General details
Date: 30 December 2011 Investigation status: Completed 
Time: 0800 EST  
Location   (show map):Cairns Airport Investigation type: Occurrence Investigation 
State: Queensland Occurrence type: Powerplant/propulsion - Other 
Release date: 12 February 2013 Occurrence class: Technical 
Report status: Final Occurrence category: Incident 
 Highest injury level: None 
Aircraft details
Aircraft manufacturer: de Havilland Canada 
Aircraft model: DHC-8 
Aircraft registration: VH-QQA 
Serial number: 5 
Type of operation: Air Transport Low Capacity 
Damage to aircraft: Nil 
Departure point:Normanton, QLD
Destination:Cairns, QLD
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Last update 18 April 2018