The company asked the Federal Aviation Administration to ground the helicopters on May 29, after a broken adjustable collective link was discovered on a customer-owned aircraft. The part, which is supported by a second, back-up link, is an important component in the main rotor system. There were no accidents related to the broken link assembly.

Following FAA approval, and laboratory and flight tests of a new part, the helicopters were returned to flight status on Saturday.

After completing design analysis of a replacement part, McDonnell Douglas decided to proceed with the manufacturing process immediately.

"We authorized fabrication of the parts based on our analysis of the design," said Erv Hunter, vice president of the company's light helicopter division. "That decision allowed us to have the parts ready for installation on the aircraft just as soon as lab and flight tests were complete."

The action enabled operators to begin flying without delay, instead of waiting while new link assemblies were fabricated following the test program, Hunter said.

Hunter praised the manufacturer of the part, Eason & Waller Manufacturing and Precision Grinding, of Phoenix, Ariz., as performing beyond all expectations to supply replacements. "They added extra shifts at their plant to accommodate our requests," Hunter said.

Federal Aviation Administration officials monitored the design, manufacturing and test program, again saving steps and time for the operators, Hunter said.