Federal safety investigators bypassed aviation regulators on Tuesday and urged leading helicopter manufacturers to install so-called black boxes that would help determine the cause of crashes such as the one that killed former NBA star Kobe Bryant. The National Transportation Safety Board appealed directly to six manufacturers after the Federal Aviation Administration failed to act on the board's recommendations to require the devices on most helicopters. The safety board said turbine-powered helicopters should record data, audio and images during flight. The NTSB identified seven crash investigations between 2011 and 2017 in which it said the lack of recorder information slowed its ability to find potential safety issues.