Machine Design

Safety Reviews Required When Modifying Equipment, too

Adding a computer to the forklift as a way of streamlining order-picking-forklift operations seemed like a great idea. That is, until one of the modified forklifts ran over a worker’s foot. The computer screen blocked the forklift operator’s view, and he didn’t see the person in his path. The end result was that part of the pedestrian’s leg had to be amputated.

When manufacturers do preliminary hazard analyses on their products, it is critical that they include the products’ intended uses and reasonably foreseeable misuses. However, there are some misuses that designers can’t be expected to predict. I often run into unexpected misuses when I investigate accidents. Many of them include situations where users without the technical expertise to safely modify equipment made changes the manufacturer didn’t predict or authorize.

Some industries and individual companies address unforeseeable modifications with a general warning. The warning tells users they must contact the manufacturer in writing, and receive written approval from the manufacturer, before making any modifications. Failure to do this voids the product warranty. In addition, if OSHA inspectors uncover an unauthorized modification, they can issue a citation including a fine or corrective action.

The warn-and-review approach is the one the forklift industry has adopted. In my opinion, it’s a good policy that protects the manufacturer and discourages forklift owners from unsafe practices.

In the case above, the forklift owner was a large publishing company. Operations personnel thought it would save time and money to have computer systems installed on their order-picking forklifts. The forklift-mounted computers meant operators did not have to go to a central place to drop off completed work orders and pick up new ones.

This sounds good on the surface, but no one did a human-factors study to determine where to locate the computer screen. It turned out the screen partially blocked the operator’s view of the forklift’s path and led to the accident mentioned earlier. The victim had to have the leg amputated between knee and ankle.

If the company had written to the forklift manufacturer about the proposed modification, the manufacturer probably could have warned about the possibility of a diminished field of view. A preliminary hazard analysis within the publishing company itself would have also raised a red flag.

Stay tuned for next month’s column where I’ll continue to discuss the hazards that go with product modifications when users don’t think them through or involve the manufacturer. Automotive products are among the most frequently modified, and the users who make changes or install third-party products are not always qualified to perform detailed hazard analyses of the changes they make. Even a seemingly innocuous modification, like installing a sound system, can have disastrous consequences without a proper safety review.

— Lanny Berke

Lanny Berke is a registered professional engineer and Certified Safety Professional involved in forensic engineering since 1972. Got a question about safety? You can reach Lanny at [email protected].

Edited by Jessica Shapiro

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