Hub Defect Cover-up Background

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Defective Hubs and Wheels Falling Off Mitsubishi Fuso Trucks

Some 50 accidents in Japan involving Mitsubishi Fuso were classified by the company as result of improper maintenance by users. One of these accidents in 2002 killed a woman, Shiho Okamoto, and injured her two children in Yokohama. Mainichi reported that the hub that fixed the wheel to the front axle was found broken and it was subsequently learned that since 1992, there have been about 50 reported cases where hubs produced by MMC were broken and caused tires to fall off the axles. Okamoto's family has filed a civil damages lawsuit against Mitsubishi Motors and Mitsubishi Fuso in Yokohama District Court.

Mitsubishi Motors Japan started voluntarily replacing the wheel hubs for free after that. However, in case of that accident resulting in a death, it blamed improper tightening of bolts by the consumer.

Japanese police raided Mitsubishi Fuso in October 2003 and January 2004, according to Mainichi newspaper. Reuters quoted the top Japanese government spokesperson as stating ,"They should have found out the cause of the accident promptly and taken measures. The company's morals may come into question as well as whether the Transport Ministry had given proper instructions."

According to Asahi newspaper, a company engineer in charge of testing critial truck parts' endurance, in March 2003, during a metting presented a 40-page report and said that cracks in the hub were not caused by abrasion resulting from poor maintenance. Asahi Shinbun further reports that Kanagawa prefectural police, who are investigating possible criminal charges of professional negligence resulting in bodily injury and death in relation to the 2002 accident, has obtained a copy of the engineer's report and are looking into how it was handled by the company, according to sources. Transport ministry officials also are aware of the report who are doing their own investigation. Deja Vu for Mitsubishi Motors!

According to Kyodo News on 23rd March, a dealer had warned Mitsubishi Motors' head office after an accident in October 2000. In that accident in the town of Aira in Kagoshima Prefecture, a Mitsubishi truck, while coming to a halt at a traffic light, lost its front-right wheel that hit a bicycle parked on the other side. Mitsubishi Motors, blamed the truck's owner for not tightening the nuts sufficiently. Moreover Kyodo reports that the first accident related to this defect defective hubs connecting wheels and axles occurred in 1992, making it 12 years since then for a formal recall.

Mainichi reports that finally on 24th March 2004, Mitsubishi Motors admitted to the Ministry of Land, Infrastructure and Transport that "the metal hubs were defective because they had been not sufficiently melted (in the manufacturing process)," in its report.

Daily Yomiuri reported that Mitsubishi switched from model C to model D in March of 1993 as a result of the 1992 accident. It coined a word - wagiri (cutting slices) to describe a condition where the brim of the hub falls off. In June 1994 another accident took place and, Yomiuri writes that, "senior officials of MMC's bus and truck development head office had had a meeting on its wheels, hubs, bolts and nuts in November 1994 to discuss the design of its vehicles' main structural parts and measures to be taken."

March 25. Asahi reports that in May 2002 a working group was formed in the company. It tested 500 trucks and 30% of them had cracks. Significanty, there was no "difference in the ratio of cracks between hubs with abrasions from loosened bolts that attached the hub to the shaft and hubs showing no abrasions." In July, the working group, under a vice president, prepared a report stating that the cracks to the hub were caused by abrasions from faulty maintenance. Mitsubishi subsequently submitted a report to the transport ministry, blaming poor maintenance and not mentioning the sample tests. "Filing false reports to the ministry would constitute a violation of the Road Transport Vehicle Law," Asahi writes.

Wire services reported on 25th March that in January 2002, Mitsubishi Motors inspected Fuso trucks and offered free replacements following the fatal accident but excluded buses, telling the Tranport Ministry that since buses don't run at high speed, that was not enough burden to cause abrasions. However buses were showing signs of abrasion too and their hubs were replaced by agents selling those.

Nikkei (Nihon Keizai Shinbun) reported on March 29 that Mitsubishi Fuso Truck and Bus will recall more vehicles after it discovered about 40 cases of defective rear-wheel hubs on its products.

Kyodo reports that Mitsubishi could have altered data it gave to the transport ministry. It allegedly increased the amount of wear on the wheel hub so that its responsibility will be reduced. The truck operator was told of a small amount of wear. This too could be a breach of law.


A few links in reverse chronological order.

MMC and Mitsubishi Fuso Apologies
Arrest of Fuso executives
Criticism of MMC by Governement, victims, lawyers
Fuso Trucks in Danger of Losing ISO 9001 Certification
First reaction to MMMC's Fuso Hub Defect Cover-up Scandal