“I'm so upset, I just don't know where to begin.” That was how one member of the National Transportation Safety Board (NTSB) reacted to a staff presentation of the investigation into a fatal dump truck crash.
The crash occurred when an overloaded, medium-duty dump truck lost its brakes on a steep downgrade and collided with four vehicles waiting at a busy intersection at the base of the grade. A 21-yr.-old employee of a small landscaping/farm supply firm was driving the truck; he'd been on the job just 10 days.
The NTSB investigation determined that the probable cause of the crash was lack of oversight by the firm's management, which resulted in an untrained driver improperly operating an overloaded, air brake-equipped vehicle with inadequately maintained brakes.
Misdiagnosis of the truck's underlying brake problems by fleet mechanics was listed as a contributory factor; another was insufficient information about automatic slack adjusters (ASAs) and inadequate warnings about the safety problems caused by manual adjustment.
The NTSB member's comment reflected her frustration with two issues in particular. The first was the lack of industry knowledge about recommended operating and maintenance practices for ASAs, despite the fact that they have been required on all new trucks since 1994. The second was the lack of effective national and state safety oversight of smaller interstate/intrastate fleets.
I share her frustration on both topics and am asking for your help, particularly with the first.
NTSB findings indicate that the truck had a history of brake defects. It had been placed out of service during a roadside inspection and failed a state vehicle inspection. In both cases the rear axle brakes were cited as defective because the push rod travel was more than the permitted maximum.
Remedial action was limited to adjustment of the ASAs. To make matters worse, drivers and mechanics reported that they had routinely adjusted the ASAs during the year leading up to the accident.
By now, I hope you're as angry as I am. But just in case you're not, let me point out that ASAs operate very differently than their manual predecessors: They're designed to adjust brake push rod travel automatically to compensate for normal brake lining wear.
Unfortunately, worn hardware (clevis pins, sockets, etc.) restricts the ability of an ASA to maintain push travel within prescribed limits. This is what happened to the dump truck. The problem is compounded when mechanics and drivers try to correct it by adjusting the ASA. Such a fix is short-lived, dangerous and, in the case of this crash, fatal.
I know what you're thinking: This is an isolated incident that's only getting attention because of the NTSB investigation. Sadly, that's not the case.
Ask your mechanics and drivers whether or not it's okay to “adjust” an ASA. I think you'll be surprised by the answers. When NTSB conducted an informal survey of mechanics, drivers and roadside inspection officers, it found the vast majority considered this to be an acceptable — even routine — practice.
I urge you to immediately begin assessing your drivers' and mechanics' knowledge of ASAs and air brakes and follow up with appropriate training and testing.
This is the seventh time in six years that I've written about the tragic consequences of defective brakes. Please help me stem the tide of needless death and injury.
Jim York is the manager of Zurich Service Corp.'s Risk Engineering Transportation Team, based in Schaumburg, IL.