Pilots want answers on how Boeing will rebuild trust with its partners when CEO Dennis Muilenburg appears before Congress on Tuesday and Wednesday to answer questions about the deadly crashes and grounding of the company's 737 Max planes.

"Safety culture doesn’t work unless there's trust. Without trust, that airplane will not fly," Dennis Tajer, spokesman for the Allied Pilots Association and an American Airlines pilot, told FOX Business.

On the anniversary of the first of two deadly crashes involving the 737 Max, Muilenburg will tell Congress that the aircraft company knows it made mistakes and is throwing everything into fixing the plane.

In their final report on the first crash, Indonesia investigators said last week that Boeing's design of a key flight-control system made the plane vulnerable if a single sensor failed — disregarding the aviation industry's long reliance on redundant systems to prevent disaster. They also faulted Lion Air, which operated the plane, and U.S. regulators who approved it for flight.