Beleaguered airline manufacturer Boeing  (BA) - Get Report received additional negative scrutiny on Friday after The Wall Street Journal reported that the company limited input from its test pilots on flight control systems for its now-grounded 737 MAX jet fleet - contrary to established practice.

Sources told the Journal that Boeing test pilots and senior pilots involved in the MAX's development were not given detailed briefings about how fast or steeply the automated system known as MCAS could push down a plane's nose. They were also not informed that the system relied on a single sensor rather than two to verify the accuracy of incoming data about the angle of a plane's nose.

The extent of pilots' lack of involvement had not been previously reported.

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Chicago-based Boeing's MAX fleet has been grounded globally following two crashes in Indonesia and Ethiopia over a five-month period that claimed 346 lives. Boeing and the Federal Aviation Administration have been working together on a software fix for the MCAS system and make it less reliant on automation.

Shares of Boeing were up 0.2% on Friday.