Failure Knowledge Database / 100 Selected Cases

Conceal knowledge of recalls at Mitsubishi Motors
Jan. 10th, 2002, Yokohama, Kanagawa
KOBAYASHI, Hideo (Tokyo Institute of Technology)(Summary)
The cover up of recalls by Mitsubishi Motors Corp. started from the failure a ccident involving a trailer
truck's tire-hub. On January 10th, 2002, a tire of a heavy-duty truck came off the truck and hit a pedestrianhousewife. She was killed, and her two sons were slightly injured.
The ca use of the a ccident was the fail ure of the t ire-hub. There w ere 57 c ases of tire-hu b fail ures ofheavy vehicles manufactured by Mitsubishi Motors Corp. since 1992, and a tire actually came off in 51 of
the cases. Mitsubishi Motors Corp. claimed that these accidents happened because of poor maintenance by
the owners of the vehicles. However, Mitsubishi Fuso Truck & B us Corp., who took over the commercial
truck and bus branch, accepted its responsibility for the failures as manufacturer and reported a recall of allof its heavy-duty vehicles to the Ministry of Infrastructure and Transport in March 2004. In May 2004, fiveformer executives of Mitsubishi Fuso Truck & Bus Corp. were arrested on suspicion of violating the Road
Trucking Vehicle Law (fal se report), and t wo former executives of M itsubishi Motors Corp. were arrested
on s uspicion of ca using deaths and b odily inj ury thr ough prof essional negligence.

The c ompany i tself

was also prosecuted criminally for suspicion of violating the Road Trucking Vehicle Law (false report). The
responsibility of the company was directly called into question.
1. Component
Tire-hub of heavy-duty truck.

Fig. 1 shows a typical super-great tractor.

2. Event
A tire cam e of f of a he avy-duty tr uck an d h it a h ousewife, Shi ho O kamoto (K amiwada Yamato-city,
Kanagawa pr efecture). She di ed s oon af ter, a nd her four-year-old and one-year-old so ns wer e sli ghtly
injured.
Police in the Seya Station said the tire that had come off was th e front left tire of the 26 tires on thetruck. The tire came off with its w heel and fell down a slop e for 50 m before it h it Ms. O kamoto on her
back. She was walking on the left side of the street. The tire was 1m in diameter, 28 cm wide, and the total
weight with its wheel was 140 kg. The hub is a c omponent located between the tire and the axle that turns
around the axle. The Kanagawa Prefectural Police found that the hub was broken and that the tire had come
off with the brake drum.
This trailer truck was purchased in 1994, and it mostly carried heavy machinery like power shovels. The
trailer truck passed an automobile inspection in January 2001. However, because the hubs lie inside the tire,
it is difficult to see t hem from the o utside. An i nspector said that he checks hubs by tapping around themwith a hammer. Mitsubishi Motors Corp. said that they had started to sell this type of trailer truck in 1986
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Failure Knowledge Database / 100 Selected Cases

and that there are abo ut 750 trailer trucks in use n ow. Mitsubishi Motors Corp. also said t hat none of thetires had come off yet and that it has never recalled a trailer truck due to defects related to tires.
Figure 2 shows the positions of th e hub and the tire, and Fig.3 shows the cross-sectional configurationof a hub. A hub is a cylinder with a disc-shaped head (flange). A flange is attached to the wheels with bolts.
An axle is placed inside of the cyli ndrical part of the hub. A hub acts as a joint between an axle

and awheel. The Kanagawa Prefectural Police investigated the tire that came off of the truck and found that thehub (22 kg, m ade by spec ial cast iron) w as torn between t he cy linder part a nd the dis k p art. I nside a ndoutside of the hub's disk part, there were corners to fit the wheel and the brake drum to the hub. This is thecritical poi nt where trailer truc k's weight a nd app lied load whil e t he vehicle is m oving reach t heir
maximum. The crack propagated in a straight line connecting the inside and outside corners. There wereeight bolts remaining on the wheel.
3. Course
It was later re vealed that there had been many cases of tires that had come off because of broken hubs
before the a ccident of the Mitsubishi M otors trailer tr uck in t he Se ya-ward of Y okohama. Th e resp onse
(free collection / repair) of Mitsubishi Motors for t he recall was poor, and they repeatedly covered-up andmisrepresented incidents. Finally, Mitsubishi accepted their responsibilities for this accident and reported afull recall. Five former executives of Mitsubishi Motors were arres ted on suspicion of violating the Road
Trucking Vehicle L aw (false report) a nd two form er executives of Mitsu bishi Motors were arrested on
suspicion of hom icide by professio nal neg ligence. The com pany itself was prosecuted crim inally forsuspicion of violating the Road Trucking Vehicle Law (false report). The responsibility of the company was
directly called into question.
Mitsubishi Motors had lost public confidences before. In July 2000, information from complaints about
more than ten types of cars was concealed in Mitsubishi Motors, so that those cars were not recalled.
The fol lowing incidents s how the development of e vents from th e a ccident t o t he pros ecution of
Mitsubishi Motors and recall of the vehicles.
- 21/June/1992
The left-front tire o f a refrigerated van came off in Tokyo (confirmed by Mitsubishi Motors to be th e
first hub breaking case).
- June/1999
The right-front tire of a bus came off on the highway in Hiroshima.
- July-Aug/1999
A meeting a bout the bus i ncident w as held. It w as decided t o re port t o the f ormer Min istry ofTransport that the hub failure had occurred due to bad maintenance.
- 10/Jan./2002
The l eft-front tire of a h eavy-duty trai ler truck c ame off in Sey a-ward, Yokohama. The tire killed amother and injured her two sons.
Mitsubishi Motors began providing free maintenance for the hubs of heavy-duty trailer trucks. They

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Failure Knowledge Database / 100 Selected Cases

concluded that the Yokohama case was due to bad maintenance, and they did not recall the vehicles.
- 17/Jan./2002
The c ountermeasures h eadquarters was s et u p i n Mi tsubishi Motors to d iscuss how to ke ep si milar
accidents from happening.
- 1/Feb./2002
The

countermeasure headquarters c oncluded that the cause of t he hub fai lures wa s fricti onal wear.
They set out the basis of exchange in which the hub had to be exchanged when the wear was morethan 0.8mm, and they reported this value the Ministry of Infrastructure and Transport.

- Feb./2002
A w orking group of evaluation of fro nt hub's stren gth w as s tarted in M itsubishi M otors. Theyevaluated the strength of the hubs.
- Mar./2002
The w orking group o btained resu lts from a sam pling inspection th at in dicated t hat crac king occurs
with less than 0.8mm of wear.
- June/2002
The m easure council f or re calls i n the Ministry of I nfrastructure and T ransport au dited t he headdepartment of development at Mitsubishi Motors (Kawasaki).
- July/2002
The w orking grou p of ev aluation of front hu b's strength concluded tha t frictional wear due to bad
maintenance l ed t o hub fai lure. H owever, it w as believed t hat t his c onclusion w as made in order toavoid a recall.
- Jan./2003
Mitsubishi Fuso Truck & Bus Corp. was founded as the truck and bus branch of Mitsubishi Motors.
Mr. Vilfried Port, the former president of Daimler Chrysler, became the president and CEO.
- 19/Mar./2003
A y oung engineer a t M itsubishi M otors reported in an i ntra-office conference t hat t he re lationshipbetween hu b failure an d frictional wear due to ba d m aintenance w as weak. He emphasized theimportance of evaluating the fatigue lifetimes of the main components.
- 24/Oct./2003
The Kana gawa Prefectura l Polic e searched th e he adquarters of Mi tsubishi M otors on susp icion of
homicide by professional negligence. The police inspected the headquarters again in January 2004.
- 11/Mar./2004
Mitsubishi Fuso Truck & Bus Corp. admitted its responsibility as the manufacturer of the hubs, and it
reported a full recall to the Ministry of Infrastructure and Transport.
- 6/May/2004
Because of the fatal accident in Yokohama, five former executives of Mitsubishi Motros were arrested
on suspicion of violating the Road Trucking Vehicle Law (false repor t) and two former executives ofMitsubishi Motors were arrested on suspicion of homicide by professional negligence.

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Failure Knowledge Database / 100 Selected Cases

4. Cause
The reasons for the illegal cover-up to avoid the recall are as follows:○ A recall w ould cost the company a h uge amount of m oney that would hurt the company greatly. For
that reas on, the rel ated departments put pressure on the m arket qu ality department, an d the market
quality department had to obey.
○ If the true information was revealed, the people who caused the defects in manufacturing, designing,and engineering would be punished. Those people wanted to avoid that punishment.
Mitsubishi Motors Corp. became independent from Mitsubishi Heavy Industry Corp. in 1970. Most of
their market consists of members of the Mits ubishi group. This is tr ue not only for the c ommercial trailer
trucks an d buses o f Mitsubishi Fu so, but al so fo r pa ssenger cars. Mi tsubishi Motors so ld abo ut 35 8,000
cars including 230,000 light vehicles in Japan; half of those cars appear to have been sold to members of
the M itsubishi group. In f act, o ne pers on o ut of ten is som ehow rel ated to a Mi tsubishi gr oup in Ja pan.
Everyone in Japan had believed that companies having names with "Mitsubishi" would never fail. In thecase of Mitsubishi Motors, this belief led the company to take selfish and illegal actions.
People who know Mitsubishi Motors well testified to the media as followings:○

Executives care more about the company than the customers.

○ The authority is concentrated to the executives, and t he employees must wait for i nstructions fromthe executives.
There have been repeated incidents that have hurt Mitsubishi Motors's corporate governance, including
the problem of sexual harassment in a factory in the USA in 1996, the revelation of a relationship between
the company and a c orporate e xtortionist in 1997, and the cover-up of reca lls i n 2000. I n spi te of th ese
incidents, the Mitsubishi group had always supported Mitsubishi Motors. The Mitsubishi group had neverlet a Mitsubishi company fail. The social responsibility of Mitsubishi Motors was therefore kept vague. On
the other hand, Mitsubishi Motors was always afraid of the investors: Bank of Tokyo-Mitsubishi, Ltd. and
Mitsubishi Corporation.
5. Immediate Action
It is da ngerous to kee p m anufacturing unsafe pro ducts by gi ving priori ty to busi ness. When car
manufacturers find defects, they have to do everything that they can to ass ure safety, and then they must
give information about the defects to the public. Consumers would select the manufacturers who act in thisway.
6. Countermeasure
Mitsubishi Motors a nnounced a sc heme of management rec onstruction on May 2 1, 2 004. M arketingstrategy was discussed in a "cro ss fu nctional team", a g roup of ab out fi fty backbon e employees wi th th epresident and CEO Yoichiro Okazaki acting as the chairperson. This was a drastic change in the com pany
policy, which had been highly conservative.
At the same time, Mitsubishi Motors established a business ethics committee that included experts from4

Failure Knowledge Database / 100 Selected Cases

outside the company. This committee supervised the company compliance.
This scheme, however, di d no t work. O n January 2 8, 20 05, Mi tsubishi Motors announced a notherscheme ofmanagement reconstruction. M itsubishi H eavy Ind ustries, M itsubishi C orporation, a nd

Tokyo-Mitsubishi Bank added another 270 billion yen to their investment for Mitsubishi Motors, making
the s um of their new s upport, i ncluding loa ns, a t otal of 5 40 billion y en. T he f ormer investm ent f or th ereconstruction was 496 billion yen; the total shares of supporting companies are now over one trillion yen.
Mitsubishi H eavy Indus try increase d t he r ate of i nvestment for Mits ubishi M otors to 1 5% an d clarified
their initiative for recons truction support. The pr esident o f M itsubishi Heav y In dustry, Takashi Ni shioka,
became the CEO of Mi tsubishi Motors. It is c lear t hat the c ompany cont inues to re ly on i ts fa mily
(Mitsubishi group) as it has in the past.
On t he ot her hand, t he Mi nistry of Infr astructure a nd T ransport decided t o es tablish its ow n reca ll
inspector syste m. The inspectors are ten ex-e ngineers of car m anufacturing c ompanies. They go to t hescene of an a ccident if t he accident seem s to have been c aused by s ome ki nd of s tructural defe ct. Theyobserve the inspection process of manufacturers and at the same time they analyze the cause of the accident
themselves. The Ministry of Infrastructure and Transport will ask manufacturers for recalls according to theresults of their analysis.
It is, however, too late to make a recall after an accident has happened. The real solution for the problem
is to maintain the ethic of manufacturing safe products. If there is a concern about safety, countermeasures
should be made as soon as possible. This safety ethic is not only for the company as a whole, but it is also
something that each engineer has to keep in mind.
The failure of a tra iler truck's hub occurs due to metal fatigue. Mitsubishi Fuso studied extensively thefatigue life o f the fron t h ubs of heavy-duty trai ler trucks. Fi rst, th ey re considered the view point andprocedure for ev aluation t he fat igue life. Second, t hey changed t he size and m aterial of t he h ubs, using
thicker fla nges and l arger notches to decrease stre ss concentration, and a dopting a stro nger FCD600
material. Fi nally, t hey ev aluated t he new hub a nd c onfirmed that its fat igue l ife is lo ng enough forpermanent use. This result was reported to the Ministry of Infras tructure and Transport in July 2004, andthey made a recall to change the hubs to the new type. They are now investigating the rear hubs.
7. Knowledge
The biggest problem is that Mitsubishi Motors did not take further actions when the complaints that had
been hidden by the company were revealed in 2000.
When a com pany does som ething wrong, the company presi dent ap ologizes. However , the c ompany
does not always make what the pres ident says in his or her apology com e true. This event at Mitsubishi
Motors showed the importance of making specific improvements.
The problem is the way of internal control of a company. This event revealed that lying always fails.
The lies produced victims in society, and the company lost their credibility.
If a company believes that their customers would never abandon it, that company might become another
Mitsubishi Motors someday. Executives have to rethink what is in the best interests of their company.

5Failure Knowledge Database / 100 Selected Cases

8. Sequel
On May 2 0, 2004, the pre sident of Mi tsubishi Fus o admitted t he company's re sponsibility for th e
defects. However, Mitsubishi Motors had known about the defects eight years ago, but the company did not
do anything about it. They kept making repairs secretly (which is illegal) for a while, and then they stopped
even doing the repairs.
They repor ted that the to tal num ber of trailer tr ucks w ith defects w as abo ut 170,000 of he avy-duty
trailer truck "the great", which was produced from 1983 to 1996. Half of these trucks are still been driven.
If the cracking occurs at the clutch housing, the propeller shaft will vibrate, and the vibration might lead tofracture of the brakes. There have been over 70 reports of defects in the products of Mitsubishi Fuso Truck& Bus Corp. and Mitsubishi Motors.
The following timetable shows how this event developed.
- June/1996
First fracture accident of a clutch.
- 1994
A person was injured in an accident in Kanagawa- March-May/1996
Mitsubishi Motors held a meeting for considering a recall and disc overed the defect in the clutches.
They expected around 40 accidents to occur over 8-9 years, but they decided to make illegal repairs insecret.
- 1998A person was injured in Nagoya- July/2000
Disclosure of t he c over u p of t he d efect i n the clutches by M itsubishi Mo tors. Mitsubishi M otors
reported about 6 00,000 d efective c ars t o t he M inistry of Infrastruct ure a nd Transport. (For mer
cover-up case)- Sep./2000
The Ministry of Infrastructure and Transport prosecuted Mitsubishi Motors on suspicion of violating
the Road Trucking Vehicle Law (Former cover-up case).
- May/2001
The Tokyo summery court punished the executives of Mitsubishi Motors, including a vice-president.
(Former cover-up case)- Oct./2002
A refrigerated van lost control because of defects in its clutches in Yamaguchi prefecture. The driverdied.
- May/2004
Mitsubishi Fuso Truck & B us Corp. gave information about defects and reported recalls of defective
vehicles to the Ministry of Infrastructure and Transport.
- 10/June/2004

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Failure Knowledge Database / 100 Selected Cases

Ex-executives of Mitsubishi Motors were arrested in connection with the fatal accident in Yamaguchi
prefecture.
- 15/June/2004
The m anufacturing headquarters of Mi tsubishi Fuso l ost its ISO 9001 cert ification because of th e
cover-up c ase. In t he U SA and Euro pe, most of com panies request that t heir trading partners have
ISO9001 certification. The reasons for ca nceling the ISO9001 certification of Mitsubishi Fuso are as
follows:(1) The variation of the quality of products is wider than that required for certification.
(2) Making repair in secret is illegal.
(3) These facts have never been shown in screening.
- 18/June/2004
The M inistry of Infrastruc ture a nd Transport i nspected 37 cases that resulte d i n acci dents a nd/or
burning. T here w ere 1 40 cases in volving 1 7 m anufacturers i n t otal. T he first place belonged t o
Mitsubishi Fuso, which had 7 recalls and 85 accidents; in second place was Mitsubishi Motors with 6
recalls a nd 11 ac cidents. These m embers of t he Mitsubishi fam ily account ed for almost 70% of thecases. M itsubishi Fu so had 52 accidents b efore re porting th e hu b defect s and 21 acci dents before
reporting the clutch defect. Only two of the accidents were fatal.
Mitsubishi Fuso is e xpected to re port another 40 recalls and Mitsubishi is expected to re port another
25. As a result of postponing their response to the problems, the number of problems kept on growing.
- Oct./2004
First trial hearing for the Yamaguchi incident (at Yokohama district court)- Dec./2004
Mitsubishi Fuso submitted measures for preve nting a conceal knowledge of rec alls. The Ministry of
Infrastructure and Transport asked Mitsubishi Fuso for an additional report.
- Jan/2005
It w as reveal ed th at M itsubishi Fus o ha d prod uced 2, 800 bra nd new cars w ithout certification, and
2,000 of them had defects and needed to be recalled.
- 2/Feb/2005
Mitsubishi Fuso reported another 41 defects, and they finished their inspection.
As descri bed above, both t he " tire hub fracture of trailer tr ucks" an d the "cl utch fracture of tra iler
trucks" originated in the "former cover-up case" in July 2000.
9. On the Side
There are many other examples of similar problems in Japanese big companies.
The compliance of a com pany i nvolves not only obeying l aws but also the actions t hat t he com pany
takes to enhance the compliance depending on the industry standard and the corporate culture. Experts ofcorporate compliance suggest the following two measures to prevent scandals.
(1) Develop incentive to obey compliance7

Failure Knowledge Database / 100 Selected Cases

In Japan, the cost of compensation for a death is about 100 million yen. The cost of a rec all is muchmore. In the USA, punitive damage is admitted. One solution for the situation in Japan is as follows: Permit
companies i n crisis w ith e nough technology and manpower to obtain spe cial fu nds for reca lls under t hecondition that they obey compliance and make full disclosure.
(2) Establish a system for internal reporting and evaluation of information
Recent problems w ere reveale d t hrough internal rep orts. Ex ecutives ha ve to get information a boutproblems as soon as possible.
The following suggestion is added by authors:(3) Establish performance requirements and make effective use of nongovernmental standard
Laws cannot maintain the security of s ociety by themselves. People try to find ways to get around thelaws. Governmental law is not enough. Companies should make their own regulations and obey them.
10. Primary Scenario
01. Poor Value Perception
02. Poor Safety Awareness03. Lack of awareness of risks
04. Organizational Problems
05. Inflexible Management Structure
06. Acceptance of unreasonable demand
07. Malicious Act
08. Rule Violation
09. Conceal knowledge of recalls
10. Usage
11. Maintenance/Repair
12. No parts exchange
13. Defect of tire hub
14. Usage
15. Operation/Use
16. Trailer-truck
17. Failure
18. Fracture/Damage
19. Fatigue
20. Fracture of tire hub
21. Secondary Damage
22. External Damage
23. Drop of tire
24. Bodily Harm
25. Death8Failure Knowledge Database / 100 Selected Cases

26. Fatal accident
27. Loss to Organization
28. Social Loss
29. Loss of reliability

9Failure Knowledge Database / 100 Selected Cases

Fig. 1

Typical "super great" tractor.

Wheel

Tire

Brake drum
Hub bolt
Drum nut

Wheel nut

KnuckleHub

Fig. 2 Installation of a hub and a tire.

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Failure Knowledge Database / 100 Selected Cases

Body R

Wheel R

Drum R

Groove R
Fig. 3

Cross-sectional configuration of a hub.

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