Partnair Flight 394
Encyclopedia
Partnair Flight 394 was a chartered flight which crashed on 8 September 1989 off the coast of Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 18 km north of Hirtshals
Hirtshals
Hirtshals is a town in Hjørring municipality in Region Nordjylland on the north coast of the island of Vendsyssel-Thy at the top of the Jutland peninsula in northern Denmark, Europe.-The town of Hirtshals:...

. All 50 passengers and 5 crew members on board the aircraft perished, making it the deadliest civilian aviation accident involving an all-Norwegian airline company. It was also the highest death toll of any aviation accident involving a Convair 580. It was caused by fraudulent aircraft parts
Unapproved aircraft part
Unapproved aircraft parts are aircraft parts not approved by civil aviation authorities for installation on type certified aircraft.The Federal Aviation Administration defines a "standard part" as a part produced in accordance with government regulations, and it defines an "approved part" as a...

.

Aircraft

The aircraft, registered LN-PAA, was a 36-year-old Convair 580 operated by the charter airline Partnair
Partnair
Partnair was a Norwegian charter airline company owned by Terje and Rolf Thoresen. The company was formed by a merger including Nor-Fly Charter in 1985. The company operated mainly in the ad hoc marked with oil companies as their primary customer...

. The plane had switched owners several times and had various modifications. The aircraft had multiple previous registrations, N73128, N5120, N51207, HR-SAX, N9012J, N770PR and C-GKFT, and had been in an accident before and been rebuilt. The most significant modification was a change from piston engines to turboprop engines in 1960; this added more horsepower to the aircraft. A Canadian company that specialized in servicing Convairs was the owner of the aircraft before Partnair acquired it. LN-PAA was one of the most recently acquired aircraft in the Partnair fleet.

Background

At the time of the accident Partnair was not doing well financially. The airline owed so much money that, on the day of the accident flight, the Norwegian aviation authorities sent a notice to airports telling Norwegian airports to not let any Partnair aircraft take off since Partnair had not paid several charges and fees.

Flight

The Convair 340-580 aircraft was en-route from Oslo
Oslo
Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

 Fornebu
Fornebu
Fornebu is a peninsular area in the suburban municipality of Bærum in Norway, bordering western parts of Oslo.Oslo Airport, Fornebu served as the main airport for Oslo and the country since before WWII and until the evening of October 7, 1998, when it was closed down...

, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 to Hamburg
Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

, West Germany
West Germany
West Germany is the common English, but not official, name for the Federal Republic of Germany or FRG in the period between its creation in May 1949 to German reunification on 3 October 1990....

. The passengers were employees of the shipping company Wilhelmsen Lines
Wilhelmsen Lines
Wilh. Wilhelmsen Holding ASA is a global maritime industry group, headquartered in Lysaker, Norway. The group employs approximately 16,000 people and has operations in 73 nations....

 who were flying to Hamburg for the launching ceremony of a new ship. Half of the employees of the company's head office were on board. Leif Terje Løddesøl
Leif Terje Løddesøl
Leif Terje Løddesøl is a Norwegian businessperson.He was born in Oslo as a son of Aasulv Løddesøl and Liv Marie Bjørlykke . He has been married twice. He graduated from the University of Oslo with the cand.jur. degree in 1960, and studied further, among others at the Hague Academy of...

, an executive of Wilhelmsen, said that the atmosphere in the company was "very very good" prior to the accident flight. He said that some of the employees "maybe" had been to prior naming ceremonies, which he described as "quite exciting." A regular employee on the flight, one of the top-performing employees in the company, had been asked to give the speech during the launching ceremony. Løddesøl said that it was not often that a "normal person" in the company was chosen to read the speech in the naming ceremony.

The flight crew consisted of Captain Knut Tveiten and First Officer Finn Petter Berg. Before the flight the crew found that one of the two main power generators did not work, and the mechanic who inspected the aircraft was unable to fix it. In the Norwegian jurisdiction an aircraft is only allowed to take off if it has two operable sources of power. The first officer decided that he would run the auxiliary power unit
Auxiliary power unit
An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...

 (APU) throughout the flight so that the flight would have two sources of power and therefore be allowed to leave. The pilots did not know that one of the three APU mounts was broken, and the resulting vibration would be a factor in the accident flight. The airport refused to let the flight go until the catering bill was paid. Before the aircraft took off, the first officer left the cockpit to pay the catering company.

As the Partnair aircraft passed over the water, a Norwegian-piloted F-16 jet passed by it. The fighter pilot was startled by the sudden appearance of the aircraft and contacted Oslo air traffic control. He believed that the radar data were false and that the aircraft was closer to his jet than his on-board computer had indicated.

As the aircraft neared the Danish coastline, 22,000 feet over the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

, the tail section of the aircraft started to rattle. The broken APU mount vibrated due to counterfeit bolts in the tail of the aircraft, which were weaker than the authentic parts. The investigators concluded that the vibrations reached the same frequency and went into synchronization, a phenomenon known as resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

, causing a coupled harmonics force similar to the one that caused the Tacoma Narrows Bridge
Tacoma Narrows Bridge (1940)
The 1940 Tacoma Narrows Bridge was the first incarnation of the Tacoma Narrows Bridge, a suspension bridge in the U.S. state of Washington that spanned the Tacoma Narrows strait of Puget Sound between Tacoma and the Kitsap Peninsula. It opened to traffic on July 1, 1940, and dramatically collapsed...

 collapse in 1940; the force of each vibration wave would add to that of another vibration, increasing in amplitude until the structure failed.

The rudder jammed to the left, and the aircraft was forced into an abrupt left turn that caused the aircraft to roll over. The crew recovered for a brief moment. The rudder jammed to the left again and the shroud doors, which provide mechanics access to weights in the aircraft's tail that control the movement of the rudder, broke off. The aircraft went into a second roll, and the tail section of the aircraft disintegrated. The rest of the aircraft disintegrated on the way down to the sea.

Investigation

Accident Investigation Board Norway (AIBN) investigated the disaster. Fifty of the 55 bodies were recovered. The recovered bodies were given autopsies in Denmark. Investigators used side-scan sonar to plot positions of wreckage. The pieces settled over an area 2 kilometres (1.2 mi) wide. This told the investigators that the aircraft disintegrated in the air. The investigators re-constructed 90% of the aircraft.

Some initial speculation in Norwegian press stated that a bomb brought down Partnair. In December 1988 a bomb downed Pan Am Flight 103
Pan Am Flight 103
Pan Am Flight 103 was Pan American World Airways' third daily scheduled transatlantic flight from London Heathrow Airport to New York's John F. Kennedy International Airport...

. In addition the Prime Minister of Norway
Prime Minister of Norway
The Prime Minister of Norway is the political leader of Norway and the Head of His Majesty's Government. The Prime Minister and Cabinet are collectively accountable for their policies and actions to the Sovereign, to Stortinget , to their political party, and ultimately the...

 Gro Harlem Brundtland
Gro Harlem Brundtland
Gro Harlem Brundtland is a Norwegian Social democratic politician, diplomat, and physician, and an international leader in sustainable development and public health. She served three terms as Prime Minister of Norway , and has served as the Director General of the World Health Organization...

 had used that particular Partnair aircraft on her campaign trips. The Norwegian press believed that the crash was a failed assassination attempt. Witnesses of the crash said that they heard a loud noise as they saw the aircraft fall. The fact that the aircraft had disintegrated in the air gave credibility to the bomb theory.

The cockpit voice recorder
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...

 (CVR) usually records the final minutes of an accident flight. In the Partnair crash it recorded the start of the flight and stopped shortly before the aircraft took off. From the maintenance records investigators found that, 10 years prior to the accident flight, the cockpit voice recorder was modified so that the CVR would use the aircraft's generator instead of the aircraft's battery if full power was applied for takeoff. Since the generator was inoperative on this flight, this meant that power to the CVR ended as the aircraft took off. An unpaid catering bill and the failed CVR led Norwegian investigators to scrutinize Partnair and the aircraft.

The flight data recorder
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...

 (FDR), an antiquated analog model, used a rotating metal foil strip and marking pins which scratched the strip. The FDR did not record many of the parameters that it was supposed to record. The needle recorded some lines twice, initially confusing the investigators. The team sent the FDR to the American company which manufactured it.

When the aircraft was re-assembled, investigators found small traces of high-powered military explosives. Members of the public believed that the traces could have been from a bomb or from the NATO war exercise "Operation Sharp Spear," which took place on the day of the accident flight near the flight path. Investigators found that the residue was not from a bomb, nor was it from a warhead, as there was not enough of it present. Finn Heimdal, an AIBN investigator, said in an interview that the residue appeared to be more like a contamination than any other possibility. The sea had old munitions as many battles had been fought off the coast of Denmark. Investigators concluded that the aircraft pieces acquired residue from the bottom of the sea.

Metallurgist Terry Heaslip of the Canadian Company Accident Investigation and Research Inc. examined the aircraft skin from the tail and found signs of overheating, specifically that the skin had been flexed, through a phenomenon known as flutter. This caused investigators to further scrutinize the tail of the aircraft. The investigation team found that the APU, which was in the tail, had melted plastic parts from the cabin present inside the turbine. This indicated that the APU was operating; normally the APU would not be operating when the aircraft was in flight. The mechanic who had inspected the aircraft on the day of the accident flight told the investigators that one of the aircraft's two main generators had failed and that he was not able to repair the faulty generator. The investigators discovered that the APU had been operated to replace one of the main generators, and that one of the three APU mounts was broken. The mount was broken before the accident flight, and people on previous flights had said that they experienced vibration. One passenger of a previous flight said that the accident Convair had vibrated more than the company's other Convairs. Other passengers of previous flights did not mention any vibration.

The two shroud doors on the aircraft tail were not present in the tail. The doors, constructed with an aluminium honeycomb liner, had reflective properties also found in aluminium foil. Heimdal, who had served in the military, knew that the doors would appear on radar. The unidentified objects found at a high altitude by Swedish radar were likely the shroud doors, which had separated from the aircraft tail. The investigators found that the tail failed at 22,000 feet. If the rudder moved in a violent manner, the weights would as well and hit the shroud doors. Therefore the rudder had made a violent movement as the accident unfolded.

Partnair said that an F-16 fighter jet was flying at a faster velocity and closer to the Convair than reported in the media. Therefore the jet, which would have broken the supersonic barrier at that point, would have had flown too close and at supersonic speed near the Partnair plane. The pressure wave, resulting from the breaking of the supersonic barrier, would have caused the Convair to disintegrate in midair. Flygtekniska Försöksanstalten, a Swedish aviation technology research facility said that there was a 60% chance of this being the cause. The Norwegian F-16 pilot testified that his aircraft was more than 1,000 feet above the Convair. The investigators concluded that the F-16 would have had to have been within a few metres of the Convair to have affected the passenger aircraft; the investigators had no evidence that the two aircraft were that close together. One aspect that had not been written in the final report is that the investigation had doubted radar information that it received and believed that the jet was traveling closer to the Partnair aircraft than the radar information stated; the pilot of the F-16 stated that he believed the radar data was false. After the investigation concluded, the Thoresen brothers filed a lawsuit, but a ruling in the Norwegian lagmannsrett (intermediate court) dismissed this theory in 2004.

The manufacturer of the defective flight data recorder asked an ex-employee, the highest expert regarding the company's flight data recorders, to leave retirement to examine the FDR. The expert concluded that the needle supposed to have been recording the altitude had been shaking so much that it left another mark on the foil. The particular FDR was able to record for hundreds of hours; the expert unspooled the foil and found that the needle had been shaking for months. This told investigators that another component of the aircraft had been vibrating. The investigators charted the vibrations and found that two months before the crash, the vibrations stopped for two weeks. Afterward, the vibrations increased up to the accident flight. Investigators found that during the two week period in July 1989 the aircraft received a major overhaul in Canada by the airline's previous owner. When the Canadian company made test flights and during the aircraft's first several passenger flights for Partnair, the FDR recorded almost no abnormal vibrations. When the investigators reviewed the maintenance records, they found that, during the overhaul, mechanics discovered wear on one of the four bolts/pins that connected the vertical fin to the fuselage. During the overhaul the mechanic replaced one of the bolts/pins. The vibrations stopped after the bolt/pin was replaced. Investigators found the four bolts/pins that held the tail on to the fuselage. Heaslip found that the three bolts/pins that were not replaced were not authentic parts
Unapproved aircraft part
Unapproved aircraft parts are aircraft parts not approved by civil aviation authorities for installation on type certified aircraft.The Federal Aviation Administration defines a "standard part" as a part produced in accordance with government regulations, and it defines an "approved part" as a...

 and were incorrectly heat-treated during manufacture. Therefore, each bolt had 60% of its intended strength. The three unreplaced bolts/pins were too weak for regular usage on the aircraft. After the period without vibration, the tail vibrated for 16 completed flights and the accident flight. The investigation team concluded that the usage of the APU (which had a broken mount) when combined with the vibrating tail (due to the wear and deformation of the substandard bolts/pins and associated sleeves) caused an aeroelastic oscillation that caused the aircraft's primary control surfaces to fail during the accident flight.

The disaster investigation team concluded that three of the bolts/pins used to secure the tail section were counterfeit and inferior to the parts that should have been used. The metal in the bolts was not strong enough and failed when resonant vibration occurred in the auxiliary power unit.

Aftermath

As a result of the accident, safeguarding against forged aircraft parts
Unapproved aircraft part
Unapproved aircraft parts are aircraft parts not approved by civil aviation authorities for installation on type certified aircraft.The Federal Aviation Administration defines a "standard part" as a part produced in accordance with government regulations, and it defines an "approved part" as a...

 increased. Peter Friedman, an expert on forged parts, stated in an episode of the television programme Mayday (Air Crash Investigation, Air Emergency) that the Partnair accident was the "seminal event" that caused people around the world to recognize the proliferation of forged aircraft parts in parts inventories. The spare aircraft parts industry had little regulation in many places in the world at the time of the Partnair accident. The United States Department of Transportation
United States Department of Transportation
The United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966, and began operation on April 1, 1967...

 (USDOT), which oversees the Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...

 (FAA), examined the scope of the spare parts in the United States. The USDOT audited the FAA's inventory and found that 39% of the parts in the bins were forged. The fraudulent parts came from a parts broker that was prominent in the parts broker industry; 95% of the parts in that broker's inventory were forged. Mary Schiavo
Mary Schiavo
Mary Fackler Schiavo, JD, is the outspoken former Inspector General of the United States Department of Transportation , where for six years she withstood pressure from within DOT and the Federal Aviation Administration as she sought to expose and correct problems at the agencies...

, the former inspector general of the USDOT, said that American parts brokers had "no regulation whatsoever." Schiavo said that an individual with a telephone and a fax machine could become a parts broker and could get his or her parts from a variety of sources, including junkyards, scrap facilities, older aircraft, aircraft involved in accidents and incidents
Aviation accidents and incidents
An aviation accident is defined in the Convention on International Civil Aviation Annex 13 as an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, in which a...

, and illegal parts manufacturers. Forged parts were often less expensive than authentic parts. Friedman said that "bottom line-driven" airlines, including those on the verge of bankruptcy, wanted to cut costs, driving them to acquire false parts.

The FAA investigated false parts and captured illegal parts dealers in sting operation
Sting operation
In law enforcement, a sting operation is a deceptive operation designed to catch a person committing a crime. A typical sting will have a law-enforcement officer or cooperative member of the public play a role as criminal partner or potential victim and go along with a suspect's actions to gather...

s. The FAA found that there was an industry for making thousands of worn and inferior parts to look like newly-manufactured parts. At the time of the Partnair accident, aircraft parts were required to have documentation with signatures indicating that the parts were authentic. The FAA found that illegal business forged FAA tags to make the parts appear authentic. Schiavo said that many of the operators signed the tags with forged signatures of real inspectors. Friedman said that the tags had more monetary value than the actual illegal parts. The Americans initially believed that the proliferation of false parts mainly affected only smaller airlines; Schiavo said that smaller airlines and repair stations were usually the businesses that were the most likely to accept false parts. The FAA later found forged parts in larger operations; in particular Air Force One
Air Force One
Air Force One is the official air traffic control call sign of any United States Air Force aircraft carrying the President of the United States. In common parlance the term refers to those Air Force aircraft whose primary mission is to transport the president; however, any U.S. Air Force aircraft...

, the aircraft used by the President of the United States
President of the United States
The President of the United States of America is the head of state and head of government of the United States. The president leads the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces....

, had fraudulent parts. As a result illegal parts dealers faced arrests and convictions. Schiavo said that the most important action taken by the United States government regarding the proliferation of forged parts was to cause the convictions of the parts dealers. The FAA created a more rigorous documenting system to prevent the proliferation of fake aircraft parts. Airlines would receive criminal charges if they knowingly accept defective aircraft parts. In the 2000s Schiavo said that forged parts are not proliferated as often because there is more regulation in that time period than in the 1980s and the 1990s.

Dramatization

The Partnair crash is dramatized in the episode "Deadly Prize" ("Silent Killer," "Blown Apart") of the Canadian television documentary series Mayday
Mayday (TV series)
Mayday, also known as Air Crash Investigation in the United Kingdom, Australia and Asia and Air Emergency and Air Disasters in the United States, is a Canadian documentary television programme produced by Cineflix investigating air crashes, near-crashes and other disasters...

(Air Crash Investigation, Air Emergency).

External links


Airline production list of Convair props (zip file, Excel spreadsheet)

Letter in the Norwegian parliament to the Minister of Communications (in Norwegian)
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