Substandard fasteners triggered the structural breakup of Partnair Flight 394, plunging the aircraft into the Skagerrak sea and killing all 55 people on board on September 8, 1989.
The charter flight operated by Partnair A/S left Oslo/Fornebu Airport in Norway headed for Hamburg, Germany, according to an investigation report by The Aircraft Accident Investigation Board Norway. Five crew members and 50 passengers boarded the Convair CV-340/580, registered as LN-PAA. Takeoff happened at 15:59 local time after delays caused by administrative snags and technical trouble with the AC generator.
Investigators found that the aircraft climbed to a cruising altitude of 22,000 feet before radio contact and radar signals vanished abruptly over Copenhagen controlled airspace. No emergency call came from the cockpit before the structure failed mid-air.
Tail Section Structural Failure
Severe, un dampened vibrations on the tail control surfaces caused the pilots to lose control. The investigation revealed abnormal clearances in the joints connecting the vertical stabilizer.
Bolts and sleeves securing the vertical tail fin failed to meet manufacturer specifications for hardness and tensile strength. Maintenance crews also used incorrect procedures during installation.
An Auxiliary Power Unit front mount added to the disaster. Poor local design and shoddy welding caused the APU mount to vibrate and break during the flight, worsening the tail section failure.
Questions about the Partnair Flight 394 crash
What caused the Partnair Flight 394 crash?
Investigators traced the disaster to counterfeit bolts and sleeves on the vertical stabilizer that failed to meet hardness and tensile strength standards.
When did the Partnair disaster happen?
The crash occurred on September 8, 1989, at approximately 16:38 local time in the Skagerrak sea north of Hirtshals, Denmark.
How many people died in the accident?
All 55 people on board perished, consisting of five crew members and 50 passengers.