Yamaha Motor Co., Ltd. has revealed two incidents of improper handling during certification tests following an internal investigation prompted by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). The company reported these findings and outlined corrective actions to MLIT on May 31, 2024.
Yamaha deeply regretted these incidents and extended its apologies to customers, suppliers, business partners, and stakeholders for any breach of trust.
Investigation and Findings
From February to May 2024, Yamaha conducted a thorough investigation involving a questionnaire survey of employees responsible for certification tests and document preparation over the past decade. The survey aimed to uncover any misconduct. Additionally, internal certification test reports were cross-referenced with application documents, and interviews were conducted with involved parties. An external investigation organization, led by Yamaha’s Integrated Auditing Division, ensured the investigation’s independence and impartiality.
The investigation revealed two primary issues:
- Improper Noise Testing: Tests were conducted under conditions that deviated from regulatory specifications. During noise testing, the engine output was altered to prevent equipment damage from heat, which was not in line with the regulations.
- Sound Pressure Testing for Horns: Application documents incorrectly listed Vehicle Identification Numbers (VINs) of vehicles other than those tested. This occurred due to a misunderstanding of the application rules.
Corrective Actions
Yamaha has retested the affected models and confirmed their compliance with safety and performance standards. Shipments of these products have been suspended pending retest report resubmissions and further consultations with relevant authorities.
Details of the Incidents
Noise Testing: The improper testing involved using a muffler with sound-absorbing glass wool. Testers adjusted the engine output to avoid equipment damage, mistakenly believing this adjustment would not impact the results. Retesting under correct conditions confirmed compliance with standards. However, shipments remain suspended until authorities approve the resubmitted reports.
Sound Pressure Testing for Horns: Application documents mistakenly listed VINs of vehicles other than those tested due to an incorrect understanding of the rules. Yamaha is taking steps to correct these submissions after consulting with authorities. There is no issue with the actual use of the vehicles concerned.
Root Causes
The investigation identified several causes for these issues:
- Noise Testing: A misunderstanding of the law led to changes in test conditions without recognizing the importance of strict compliance.
- Sound Pressure Testing: Inadequate internal communication of rules resulted in incorrect application submissions.
Preventive Measures
To prevent recurrence, Yamaha will:
- Clearly separate certification work from development work.
- Provide regular training on legal compliance and the importance of the testing process.
- Designate specific departments responsible for ensuring legal compliance.
- Maintain meticulous records and ensure consistency between internal reports and application documents.
- Implement a thorough check system for application documents and internal reports to avoid simple cross-checking.
- Clarify and disseminate the company’s interpretation of laws and regulations regarding vehicle conditioning for certification testing.
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