By David Morgan
WASHINGTON (Reuters) - Takata Corp (7312.T), which is recalling 34 million defective air bag inflators, has proposed a plan to address concerns about the safety of the replacement parts it is providing to consumers - but the details are not available to the public.
A proposed Takata testing plan, which the National Highway Traffic Safety Administration posted to its website on Tuesday, totals 37 pages. But the auto safety watchdog agency agreed to make 35 pages blank, after the Japanese manufacturer requested confidentiality over contents that include proprietary information.
"It is not public information because it is confidential business information," said NHTSA spokesman Gordon Trowbridge.
Takata's testing plans attempt to deal with two central questions for regulators, lawmakers and safety advocates: whether the air bag inflators now being used to replace defective parts are safe -- and for how long.
The recall, which U.S. officials have described as the largest in U.S. history, involves millions of vehicles made by 11 automakers and equipped with Takata air bag inflators that can explode with too much force, spraying shrapnel into passenger compartments. The devices have been linked to at least eight deaths and more than 100 injuries.
The cause of the defect remains a mystery. But Takata and safety regulators suspect the inflators' ammonium nitrate-based propellant may play a role, especially after several years. A Takata executive stirred new safety concerns in Congress this year when he disclosed to lawmakers that the company continues to use a less volatile form of the chemical in new air bag inflators.
In its proposal to NHTSA, the manufacturer said its testing plan would "inform Takata's assessment of the service life and safety of unrecalled and replacement inflators containing phase-stabilized ammonium nitrate." Takata would also provide NHTSA with access to testing data on a rolling basis.
Trowbridge said NHTSA is still analyzing the proposal.
The agency has said it will hold a public hearing this fall on the Takata recall, in which regulators intend to play a coordinating role.
The manufacturer also proposed a digital advertising campaign to encourage U.S. car owners to get their Takata air bags replaced. The campaign would begin in states with high humidity, where most problems have occurred, and eventually spread nationwide, with ads directing consumers to a central recall website.
Takata said it would also use direct mailings to reach car owners through auto insurance channels.
(Reporting by David Morgan; Editing by Phil Berlowitz)