As automakers battle for their survival in the wake of the largest drop in vehicle sales ever, a new threat is looming from the suppliers the automakers rely on for everything from whole interiors to transmission and axle assemblies.

The health of these suppliers was one of the major concerns automakers expressed back in December as a reason filing for bankruptcy would be so disruptive to the whole nation’s economy.

Now the health of those suppliers has risen to the fore of the concern in Detroit. On Wednesday, auditors for one of the biggest suppliers, American Axle, cited concerns in an SEC filing that the company may not be able to “continue as a going concern,” given the problems at General Motors and Chrysler, two of its biggest customers. Uh oh, this sounds familiar from someplace else.

On Tuesday, Laura Marcero, a partner in auditing firm Grant Thornton LLP, said as many as 500 suppliers across the U.S. may be at risk of failure in this year’s carpocalypse. She went on to outline ways suppliers can attempt to protect themselves. But the sheer number of suppliers that could be at risk captured the attention of most news outlets.  

Since most suppliers work for several automakers, the failure of one supplier could delay or even shut down production across the industry, even impacting some automakers that weren’t otherwise in financial trouble. That could hamper any effort at for the ailing automakers to recover, with or without government loans. While the national media focuses its attention on the Detroit 3, they arguably are the tip of the iceberg.

—Eric Evarts