"Boeing doesn't know what it doesn't know," he said.
But Conner said several times during the press conference that Boeing is confident that the outsourcing process is not responsible for any of the recent problems.
John Goglia, a former aircraft mechanic who was also a member of the National Transportation Safety Board, told CNN he also believes the plane is safe and would have no problems flying one himself.
"Every single airplane that I ever worked on that was brand new had tons of problems almost all of which were minor in nature," he said. But he said the problems are numerous enough to raise some concerns.
"These events don't seem to be repeating -- there's a lot of them -- but they appear to be quality control more than they are design," he said.
-- CNN's Marnie Hunter and CNN Wires staff contributed to this story