Boeing doesn't expect regulators to allow its grounded 737 Max fleet to return to service until the summer at the earliest, an announcement that sent the company's stock plunging more than 5% Tuesday and temporarily halted trading of its shares on the New York Stock Exchange.

Boeing on Tuesday announced a new, later time frame for getting the troubled aircraft back into the air. It has been grounded since March, following the second of two 737 Max crashes in less than six months. Boeing now doesn't expect to get the green light from regulators until June or July, according to reporting from CBS News' Kris Van Cleave.

The company is also reportedly looking into borrowing as much as $10 billion to cover the growing expenses of grounding the 737 Max and recertification of the jet by federal aviation officials, as well as other costs of the two crashes.

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Until a few weeks ago, Boeing officials had been confident they would get that approval before the end of 2019. But then-CEO Dennis Muilenburg left the company last month when it became apparent it would not meet that deadline.

The FAA reportedly had been frustrated with Boeing sticking with its previous time frame for getting federal clearance for the plane, with regulators having given the company indications the process would take much longer.

The FAA told CBS News in a statement on Tuesday it has "set no timeframe" for when the work needed to approve the jet will be completed.

Industry officials familiar with Boeing's thinking told CBS News' Kris Van Cleave that the later timeline is not due to a new issue with the airplane, but rather is based on the time it's taken the company to meet certain certification milestones thus far.

American, Southwest, and United airlines in recent weeks had all removed the 737 Max from their flight schedules until at least early June. The airlines had hoped to have the plane back in service ahead of the busy summer travel season, but that looks less likely.

The news comes as new Boeing CEO David Calhoun is visiting the company's plants in Everett and Renton, Washington, today to meet with employees across various commercial airline product lines. He's also set to host a webcast for all employees on Wednesday before taking reporter questions for the first time.

Boeing shares were down about 4% after trading resumed Tuesday afternoon to around $311 a share.

Last week, the company disclosed an additional software glitch in the new Max software that Boeing was working to resolve. Sources say they hope that to be fixed in a few weeks. The company is set to announce its 2019 earnings next Wednesday.