"This issue will take years to resolve," Trowbridge said.
Takata produced between 260 million and 285 million ammonium nitrate-based inflators worldwide between 2000 and 2015, of which nearly half wound up in U.S. vehicles, one of the former Takata managers told Reuters, citing the company's production records.
Takata supplied those inflators to more than a dozen automakers, according to company documents reviewed by Reuters. Its single largest client was Honda Motor, which still owns a minority stake in Takata and has recalled more than 8 million defective Takata inflators in the U.S.
Takata produced most of the inflators that regulators are now investigating at its main inflator plant in Monclova, Mexico or at plants in Georgia and Washington state, according to company documents. The documents noted persistent quality failures at those plants, which a former Takata official said contributed to inflator ruptures.
Last month, Takata told NHTSA in a filing that "manufacturing variability" may have contributed to the ruptures.
The manufacturing problems are detailed in dozens of internal Takata emails, spreadsheets and presentations reviewed by Reuters. The records show the problems are more pervasive and continued for a longer period than those previously reported. They extended beyond the Mexican plant to the factories in Georgia and Washington state, and they continued until at least 2014, company records show.
Among the issues: metal shavings inside some inflator parts; improperly welded inflator casings; bad propellant wafers, and bent or damaged parts.
Those problems eventually could allow moisture to contaminate the ammonium nitrate propellant, which in turn could lead to an inflator rupture, one of the former Takata managers told Reuters.
A 2006 internal log of quality issues noted problems with inflators sold to Mazda Motor, Ford Motor, BMW, Honda Motor, Daimler's Mercedes-Benz, and Toyota Motor. The log listed problems including metal shavings and contamination, broken or missing clips, and deformed or misaligned parts.
In a 2010 memo, a Takata manager expressed concern about "how to control moisture" in some inflators and worried that the company would not be able to assure the safety of the devices.
In an email the same year about pre-production quality testing of inflators built at the Monclova factory, a Takata manager expressed confusion to colleague about the causes of pervasive defects.
"I do not understand why we are failing every lot," he wrote.
In company documents, Takata engineers referred to the failures – when exploding inflators ruptured into metal fragments – as "ED," for "energetic disassembly."
The long-running scandal has overwhelmed the company's ability to furnish replacement parts as fast as automakers are forced to recall vehicles. A Takata competitor, airbag supplier Autoliv, is also making replacements for recalled Takata inflators and recently told investors it expects to continue making those parts through 2017, one year longer than originally planned. More recalls would add more delays.
Regulators have so far tried to direct replacement inflators to older vehicles that were operated in hot, humid parts of the country, because ammonium nitrate becomes unstable when contaminated by moisture and can cause the inflators to rupture.