TUMWATER — A Spokane aerospace company is paying one of the largest penalties ever in an appeal settlement over safety and health violations at a Newport manufacturing plant, according to the Washington Department of Labor & Industries.

The settlement also requires Zodiac Cabin & Structures Support LLC to continue to be listed as a “severe violator,” L&I announced on Thursday.

The department said 17 employees were injured in the July 2015 explosion. An L&I investigation completed in January 2016 found 17 willful violations, one for each worker who was injured and hospitalized. The company was also cited for 21 serious violations.

As part of the original citation, Zodiac was required to fix all serious hazards in the facility. That work has been completed, L&I reports.

Zodiac appealed the citation. While the appeal was pending, the employer and L&I agreed to mediation and reached a settlement.

The final willful violation affirms that the company used defective equipment and didn’t ensure safe procedures were used when processing flammable materials in its industrial curing oven, as advised in a consulting engineer’s report. This directly led to the explosion, according to L&I.

Along with upholding the severity level of each violation, the settlement requires Zodiac to pay a final penalty of $500,000 related to one willful violation affecting 17 workers, and the serious violations. The company was originally fined more than $1.3 million.

As a result of the willful violation, Zodiac Cabin & Structures Support LLC has been identified as a severe violator and will be subject to follow-up inspections to determine if the conditions still exist in the future.

Penalty money paid as a result of a citation is placed in the workers’ compensation supplemental pension fund, helping workers and families of those who have died on the job.

A message seeking comment from Zodiac Aerospace was not immediately returned on Thursday.

Keith Kinnaird can be reached by email at kkinnaird@bonnercountydailybee.com and follow him on Twitter @KeithDailyBee.com.