EASA Executive Director Patrick Ky said after the Iowa meeting, "we think there is still some work to be done", according to Janet Northcote, a spokeswoman for the agency.
Boeing spoke person Gordon Johndroe stated Wednesday the corporate "provided technical documentation to the regulators as a part of the software program validation course". The documentation was complete, and it was presented in a format in line with earlier submissions.
One source briefed on the matter characterized the problem differently and stated Boeing's documents had gaps, was substandard, and meant regulators couldn't complete the audit, a vital step before the airplane will be certified to return to service. There was no indication of any need to revise the software package based on the audit, sources said. Boeing shares ended down about 1%.
Muilenberg told a New York Times conference he thought about it, but decided it wasn't in his character. Boeing has said it is targeting FAA approval this year. Depending on how long it takes to satisfy FAA and EASA, it could push back a certification flight test and regulators' final decision on lifting the flight ban by a few days or even weeks, said the person.
The company said it had given software updates for the 737 Max simulators, especially for the controversial maneuvering characteristics augmentation system (CMAS), said to be the cause behind the two crashes.
Boeing's fastest-selling jetliner has been grounded worldwide since March, cutting off a key source of cash for Boeing while forcing airlines to cancel thousands of flights. Southwest Airlines is being more conservative, keeping the Max out of its schedule until February 8.
American Airlines CEO Doug Parker says his airline is feeling more confident that its grounded Boeing 737 Max jets will soon be approved to fly again.
Documentation requirements are central to certification for increasingly complex aircraft software, and can become a source of delays.