The National Transportation Safety Board (NTSB) is advising motorcoach operators to inspect all buses equipped with automatic slack adjusters manufactured by Haldex Brake Products for fractured or disconnected control arms.
The NTSB issued its safety recommendation in a report on a 1998 motorcoach crash in which eight passengers were killed and 15 others, including the driver, were seriously injured.
The 1992 Van Hool N.V. coach, operated by Bruins Transportation of Brooklyn, N.Y., was transporting 22 passengers from New York City to casinos in Atlantic City, N.J., when the driver lost control of the vehicle during a lane change on the Garden State Parkway near Old Bridge, N.J. The bus careened off the roadway and overturned into a ravine.
Although brake performance was not determined to be a factor in the crash, NTSB investigators discovered that the right-side brake was grossly out of adjustment. Further examination revealed that the automatic slack adjuster on the brake had a fractured control arm. Based on wear patterns, the control arm was broken for some time. A brake inspection less than a month before the accident did not catch the problem.
Follow-up testing by NTSB investigators at Haldex's corporate facility in Grain Valley, Mo., showed that slack adjusters with broken control arms can lead to a rapid loss of adjustment at the affected wheel.
In its report, the safety board recommended that the American Bus Association and the United Motorcoach Association notify their members of this potential problem and urged them to inspect all vehicles with automatic slack adjusters for fractured or disconnected control arms. This self-inspection is particularly important because the location of the slack adjusters, especially on motorcoaches, makes it difficult for commercial vehicle inspectors to examine the control arm.
The NTSB also recommended that the National Highway Traffic Safety Administration monitor the progress of Haldex in correcting the problem of rapid deadjustment of brakes caused by a fractured or disconnected control arm.