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Air Tank Corrosion Sparks Fire Retardant Concerns

TUESDAY, MAY 7, 2024

A recent inspection conducted by the United States Forest Service reportedly found signs of corrosion inside air tankers using mineral production company Compass Minerals’ magnesium chloride-based aerial fire retardants.

Compass Materials stated that the findings have led to the USFS making the decision to pass on a contract with Compass for the upcoming 2024 fire season.  

What Happened

In December 2022, Fortress North America—which is owned by Compass Minerals—was the first company in over twenty years to have its long-term aerial fire retardants added to the USFS’ Qualified Product List. Its products, FR-100 Powder and FR-200 Liquid Concentrate, had reportedly passed the USFS’ tests for environmental impact, toxicity, corrosion and burn retardation efficacy.

Afterwards, Fortress reportedly signed a contract with the USFS in May 2023 to provide mobile-deployed fire-retardant air tanker bases for the wildfire season. However, the negotiations for the 2024 season created new reasons to reassess the use of magnesium chloride-based retardants.

The inspections were reportedly part of the USFS’ Integrated Operational Field Evaluation (I-OFE) conducted during the winter, identifying corrosion in areas with accumulations of magnesium chloride-based retardants from Fortress North America company.

The findings from this inspection reportedly raised aircraft safety concerns, resulting in the USFS’ decision to inform Compass Minerals in March this year that it would be “unable to define the scope and associated terms and conditions of a new contract.”

The inspections also reportedly kickstarted a detailed safety assessment by the National Transportation Safety Board and the National Institute of Standards and Technology on two air tankers affected by the retardants. 

“While we are disappointed with the findings of the initial inspection, we share the USFS’ prioritization of safety above all other factors,” said Edward C. Dowling Jr., President and CEO of Compass.

“As we work collaboratively with the USFS, NTSB, and NIST on the more detailed assessment to be conducted, we have to assume based on this new information that Fortress’ proprietary, magnesium chloride-based aerial fire-retardant formulation will not be utilized for the foreseeable future in the fight against wildfires.”

As a result of the USFS’ decision, and the ongoing safety assessments, Compass plans to develop and qualify non-magnesium chloride-based aerial fire-retardant products.

The USFS’ decision to pause the use of magnesium chloride-based aerial fire retardants for the 2024 wildfire season reportedly highlighted the challenges of balancing firefighting efficacy with safety and environmental considerations.

Nic Lynn, Vice President of Operations at Missoula-based Neptune Aviation, explained that the company’s Tanker 02 used the magnesium chloride retardant from Compass Minerals last year. The plane is one of Neptune’s nine active BAe-146 quad-jet tankers.

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According to Lynn, it has not flown since it returned to Missoula from San Bernardino, California, in December 2023, though the company’s other aircrafts were not affected. Although Tanker 02 is currently grounded during the investigation, Lynn added that it “will be operational for the fire season.”

Additionally, Kevin McLaughlin, Director of Production and Certification at Oregon-based Erickson Aero Tanker, said that the company’s Tanker 106 used Compass Minerals’ retardant last year and would be grounded for the 2024 fire season.

Tanker 106 reportedly last flew Dec. 14, 2023, when it returned to Madras, Oregon, from Porterville, California. However, six other aircrafts in Erickson’s fleet—all MD-87 jets like Tanker 106—were reportedly unaffected.

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Lynn and McLaughlin had reportedly declined to comment on the specifics of the damage to the aircraft, pointing out the ongoing investigation.

According to the report, the findings of corrosion were serious enough to ground aircrafts and led the United Aerial Firefighters Association to ask the USFS to pause the testing and certification of new retardants until it can create new testing processes to mitigate a potentially corrosive retardant from getting on the Qualified Products List.

Additionally, the association reportedly asked the agency to wait for the NTSB and NIST investigation report to be released.

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“As it must, the USFS prioritized the safety of aircraft, aerial firefighters, and the public, however, this development underscores the urgent need to reassess and update the current process for adding new products to the USFS Qualified Products List,” stated UAFA Executive Director Paul Petersen.


Tagged categories: Chlorides; Chlorides; Corrosion; Corrosion protection; Environmental Controls; Environmental Protection; Fire; Fireproofing; Health & Safety; Health and safety; Inspection; National Institute of Standards & Technology; NTSB (National Transportation Safety Board); Program/Project Management; Research; Research and development; Safety; Tanks


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