page_title: LOT Polish Airlines Flight 5055
section_title: Cause
hierarchical_section_title: LOT Polish Airlines Flight 5055 / Cause
caption_attribution_description: Zylinderrollenlager, Innenring mit beidseitigen Borden, Aussenring ohne Borde, Blechkaefig aus Stahl, zerlegbar, Explosionsdarstellung, Hinweis: Innenaufbau des Lagers (insbesondere des Kaefigs) variiert je nach Hersteller und Baugroesse rolling contact bearings
context_page_description: LOT Polish Airlines Flight 5055 was an Ilyushin Il-62M of LOT Polish Airlines that crashed in the late morning hours of Saturday, May 9, 1987. The event happened in the Kabaty Woods nature reserve on the outskirts of Warsaw, Poland. The flight prepared to leave from Warsaw to New York City's John F. Kennedy International airport when it encountered multiple catastrophic events with the numbers 1 and 2 engines as well as the elevator shortly after departure. All 183 passengers and crew on board perished in the crash, making it the deadliest accident involving an Ilyushin Il-62, the most fatal crash in the history of LOT, and the deadliest aviation disaster in Polish history. It was determined to have been caused by the disintegration of an engine shaft due to faulty bearings.
context_section_description: After the crash of the Il-62 operating as LOT Polish Airlines Flight 007, the airline had started replacing its Ilyushin Il-62s with the more modernized Ilyushin Il-62M version. These had newer engines (Soloviev D-30 instead of Kuznetsov NK-8), but both of these turbofan engines shared the same critical point — low pressure turbine and engine shaft design and construction.
  According to the Polish investigatory commission, the cause of the crash was the disintegration of an engine shaft due to faulty bearings inside the number 2 engine which seized, causing extensive heat. This in turn caused the consequent damage to engine number 1 (and its fire), rapid decompression of the hull, a fire in the cargo hold (which was not detected due to a damaged fire alarm system sensor), as well as the loss of elevator controls and progressive electrical failure.
  The bearings concerned were roller bearings; each was designed to have 26 rollers inside, but because the supply of the rollers to the factory was delayed — while the bearings had to be finished on time due to expiring contracts — each bearing had only 13 rollers.
caption: A roller bearing. The circular ring is the 'race' that the rollers run in.
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