The company took the grounding action following discovery of a broken adjustable collective drive link during a post-flight inspection on May 8, 1997. The drive link assembly is a component of the rotor head system. A second, dual-path, fixed link assembly continued to function in the May 8 incident and is not impacted by this action.

McDonnell Douglas issued a notice of the incident to operators of the helicopter on May 9 and began immediate investigation and testing of the drive link to determine the cause. At the same time, the company sent operators replacement link assemblies with instructions to replace the part. Subsequent laboratory tests revealed that the drive link assembly requires redesign. Time required to design, test, manufacture and distribute new link assemblies is not known.

"We've taken this action because our number one priority is the safety of the people who operate and fly in our aircraft," said Erv Hunter, vice president of the company's light helicopter division.