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Status Report, Vol. 42, No. 7 | June 15, 2007 Subscribe

Door latch standard is strengthened but still requires work

Nearly 17 years after the Institute first asked the federal government to require better locks and latches on vehicle doors, the National Highway Traffic Safety Administration (NHTSA) has toughened a standard issued in 1967 as one of the initial federal auto safety rules. The move should help reduce the likelihood that doors on minivans, cargo vans, and 12-15-passenger vans will open during nonrollover crashes. But the standard still doesn't require latches and their mountings to withstand the complex loadings in some severe crashes.

Under the new rule that was issued earlier this year, sliding doors such as those on minivans and hinged cargo doors will be required to have a backup latching position known as a secondary latch. This secondary latch is intended to hold the door partially closed if the latch mechanism isn't fully engaged. The vehicles covered by the rule previously weren't required to have a secondary door latch, even though other passenger vehicles were.

Alternatively, the sliding doors on vans could meet the new requirements if the van has a visual warning system to signal that a door isn't fully closed. In addition, Federal Motor Vehicle Safety Standard 206 requirements will apply to 12-15-passenger vans for the first time. The changes take effect for vehicles made after September 1, 2009.

NHTSA stopped short of mandating a test to assess latch performance in severe crashes, including rollovers, where complex loading conditions can cause doors to open. A test procedure the agency developed to address the issue proved difficult to use in some vehicles and so was scrapped from the final rule. NHTSA says it's working on a new test.

"We hope the agency will quickly present a suitable regulatory test to gauge how latches perform in severe crashes and address door retention issues in rollover crashes," says Institute president Adrian Lund.

He adds that "rulemaking in these areas is long overdue. NHTSA acknowledges that when doors open during crashes, it's most often because the supporting structure fails, not the latch mechanism."

The Institute in 1990 petitioned the agency for a tougher test that would ensure that door latch assemblies and their mountings would hold up structurally in a severe crash. The Institute recommended testing the entire system including the latch, striker, and the structures to which they are attached, noting that the effectiveness of strong latches can be undercut by weak door or vehicle structures, which can fail when a lock is exposed to stress.

Whether the standard is strengthened or not, it should apply to all vehicle doors, including back doors, the Institute also told NHTSA. The agency denied the Institute's petition, and it wasn't until 1995 that the rule was revised to cover back doors in cars, hatchbacks, passenger vans, and SUVs but not sliding doors.

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