For nearly two years, Nippon Otis Elevator Co. knowingly left frayed and rusted cables unfixed at the Roppongi Hills Mori Tower in Tokyo, likely leading to the fire in the high-rise last month, company officials said.
In January 2005, the company, which was in charge of maintaining its 11 elevators at the complex, decided to service the elevators after finding rust on cables, the officials said Tuesday.
Even so, the elevator system where the fire started was not serviced until November, and even then the rust was not completely removed. The firm reported no trouble with the elevator during routine maintenance in March even though it could not inspect the cables thoroughly due to the remaining rust.
According to the company, although rust does not compromise a cable’s strength, it can make it difficult to detect frayed wires.
“There were problems with our company’s organization, as we failed to thoroughly control the people on the ground,” Eiji Esaki, president of the Japanese unit of U.S. elevator manufacturer Otis Elevator Co., told a news conference at the transport ministry.
The company said the decision to service the elevators was not immediately conveyed to its workers, and the servicing began only last September — 20 months after the rust was first found. It took another two months for the elevator with the frayed cable to undergo servicing.
After the November overhaul, the company serviced the elevator in question three times — in December and in early and late March — but each servicing lasted only two hours and the rust was only partly removed, the company officials said.
The frayed cable is believed to have caused sparks by scraping surrounding components of the lift system, according to the company.