By David Shepardson

WASHINGTON (Reuters) - Boeing Co <BA.N> has released hundreds of internal messages that contained harshly critical comments about the development of the 737 MAX, including one that said the plane was "designed by clowns who in turn are supervised by monkeys".

The messages, disclosed on Thursday, show attempts to duck regulatory scrutiny with employees disparaging the plane, the company, the Federal Aviation Administration and foreign aviation regulators.

In an instant messaging exchange on Feb. 8, 2018 - when the plane was in the air and eight months before the first of two fatal crashes, an employee asks another: "Would you put your family on a MAX simulator trained aircraft? I wouldn't".

The second employee responds: "No".

The 737 MAX has been grounded since March after an Ethiopian Airlines flight nose-dived, just five months after similar Lion Air crash. The two disasters killed 346.

In particular, some of the communications reveal efforts by Boeing to avoid making pilot simulator training - an expensive and time-consuming process - a requirement for the 737 MAX.

The plane maker just this week changed tack, saying it would recommend pilots do simulator training before they resume flying the 737 MAX - a major shift from its longheld position that computer-based training was sufficient as the plane was similar to its predecessor, the 737 NG.

The release of the messages, which highlight an aggressive cost-cutting culture and disrespect towards the FAA, is set to deepen the crisis at Boeing which is struggling to get its best-selling plane back in the air and restore public confidence.

The FAA said, however, that the messages do not raise new safety concerns although "the tone and content of some of the language contained in the documents is disappointing".

Boeing said the communications "do not reflect the company we are and need to be, and they are completely unacceptable".

For a factbox on excerpts from employees' messages, click on https://www.reuters.com/article/us-boeing-737max-factbox/factbox-in-boeing-internal-messages-employees-distrust-the-737-max-and-mock-regulators-idUSKBN1Z90NP

PEARLY GATES CLOSED

The disclosure, which Boeing said was in the interest of transparency with the FAA, prompted renewed outrage from U.S. lawmakers and puts more pressure on Boeing's new CEO David Calhoun to overhaul the company's culture when he takes the reins on Monday.

House Transportation Committee Chairman Peter DeFazio, who has been investigating the MAX, said the messages "paint a deeply disturbing picture of the lengths Boeing was apparently willing to go to in order to evade scrutiny from regulators, flight crews, and the flying public, even as its own employees were sounding alarms internally."