Report on serious incident during descent to Sørkjosen Airport, Norway on 21 February 2006 with Bombardier DHC-8-103, LN-WIE operated by Widerøes Flyveselskap AS

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Description

Serious incident on Widerøe's flight WIF922. Heavy turbulence was encountered early during descent to Sørkjosen. The Power Levers was pulled back to reduce the airspeed, but they got unintentionally into reverse aft of the Flight Idle gate. As a result the propellers reached uncontrollably high rotational speeds and the right engine had to be shut down. The aircraft rolled right, put the nose down and lost about 1,000 ft altitude. The crew decided to return to Tromsø where a single engine landing was performed without additional problems. The engine/propeller was found to be severely damaged and it was mere by chance that the left engine avoided similar damage.

Widerøe has implemented several measures to avoid a reoccurrence, amongst them modified the Power Lever protection system. The Accident Investigation Board Norway recommends that the type certificate holder (Bombardier) must introduce measures to prevent propeller overspeed during unintended management of Power Levers.

Safety recommendation

Safety recommendation No. 2012/04T

This serious aircraft incident has shown that on the aircraft type DHC-8 it is possible to inadvertently pull the Power Levers back past Flight Idle while airborne. The consequences of this may include propeller overspeed, possible engine failure and loss of aircraft control.

The Accident Investigation Board Norway recommends that Transport Canada and EASA require the type certificate holder (Bombardier) to introduce measures to prevent propeller overspeed during unintended management of Power Levers.

Location
Sørkjosen Airport
Occurrence date
21.02.2006
ICAO Location indicator
ENSR
Aircraft
DeHavilland DHC-8
Registration
LN-WIE
Meteorological conditions
IMC
County
Troms
Type of occurrence
Serious incident
Type of operation
Scheduled air transport
Category of operation
Heavy, aeroplane (> 10 000kg)
Aircraft category
Landplane, Multi-engine, Turboprop/turboshaft
FIR/AOR
ENBD (Bodø ATCC)
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