The explosion of a stratospheric balloon during ground testing by World View Enterprises at Spaceport Tucson last December caused more than $475,000 in damages to the company’s county-owned building, more than double the initial estimates, according to a new report to the Pima County Board of Supervisors.

World View’s insurance carrier paid the full cost of the repairs, which were initially pegged at about $200,000, according to a memo to the board prepared by County Administrator Chuck Huckelberry in response to queries from Supervisor Ally Miller.

The matter is to be discussed at the supervisors’ meeting on Tuesday, Aug. 7.

World View’s own independent investigation found that the explosion was caused by static electricity and that the company’s preflight safety review “incorrectly assessed both the probability and possible consequences of an explosive event during deflation.”

The company has hired a safety director and is instituting new training, operating and workplace procedures to avoid such incidents in the future, World View CEO Jane Poynter said in a letter to the supervisors.

World View is ramping up flights on its stratospheric balloons for research payloads for NASA and other customers and plans to eventually offer passengers rides to the stratosphere.

In the Dec. 17 incident, a hydrogen-filled balloon exploded while it was being deflated after a fill test at World View headquarters and Spaceport Tucson, south of Tucson International Airport. No serious injuries were reported.

Miller, a staunch opponent of World View’s lease deal with the county, submitted a list of a dozen questions to county administrators, covering investigations of the incident, damages and injuries, hazardous materials handling and insurance.

Some specific responses:

  • The Federal Aviation Administration, the National Transportation Safety Board and the Occupational Safety and Health Administration were notified of the incident. Since no one was killed, neither the FAA nor the NTSB visited the site.

OSHA conducted an inspection of the site and closed the case with no findings in January.

  • There was no damage to Spaceport Tucson — which essentially consists of a round concrete launch pad 700 feet in diameter — and no damage claims were filed with the county by neighboring residents or agencies.
  • Three World View employees received medical attention for hearing issues such as ear-ringing, which was reported to OSHA, and counseling was offered to any employees who experienced trauma from the event.
  • World View was not cited by OSHA for mishandling hazardous materials, and the company has complied with federal regulatory standards and its lease with the county in its handling of hydrogen.
  • Helium and hydrogen used as lift gases are not stored on-site for extended periods, but delivered and stored briefly as needed for flights.
  • Though it was a ground test, the event was coordinated with the FAA and Tucson International Airport, and a notice to pilots was issued noting that the tethered balloon would extend about 300 feet into the air.
  • World View’s $1 million insurance policy on the site — which Miller called “woefully inadequate” — was reviewed by Huckelberry and the county’s director of risk management and was deemed adequate.

World View’s three-member independent incident review team was headed by N. Wayne Hale Jr., a former NASA official whose more than 30 years with the space agency included stints as flight director and head of the space shuttle program.

The team, which also included a retired NASA chief engineer and a scientist who has supported NASA’s scientific balloon program for decades, spent five days on-site in February gathering data and interviewing 26 of the company’s 70 employees.

Besides hiring a safety director, the review team recommended that World View improve its hazardous-materials and risk-management processes, get more analysis and support for hydrogen gas operations, refine operations crew scheduling rules, improve balloon design and improve its communications and culture as the company moves from research and development to production and operations.

Contact senior reporter David Wichner at dwichner@tucson.com or 573-4181. On Twitter: @dwichner. On Facebook: Facebook.com/DailyStarBiz

Senior reporter covering business and technology for the Arizona Daily Star/Tucson.com