Boeing has asked Ryanair to send extra engineers to oversee quality checks of its planes "on the ground" following the Alaska Airlines incident.
Ryanair's boss told the BBC that quality was improving but the incident had shown there was "more to be done".
It comes after an unused door fell off a Boeing 737 Max 9 operated by US-based Alaska Airlines.
Ryanair does not use Boeing's 737 Max 9 aircraft but operates the Max 8 variant and has Max 10s on order.
The airline is one of Boeing's biggest customers for the 737 Max family, with more than 100 in service and due to have some 400 more by 2034.
Ryanair's chief executive Michael O'Leary said that he expects delivery delays to affect its capacity.
Asked in an interview with the BBC if he had complete confidence in Boeing's quality control processes after the incident which saw an unused door fall off, the Ryanair boss said "no".
But he added that his airline did now have "more confidence" in plane maker Boeing.
Mr O'Leary also said that a delivery of 12 planes towards the end of last year had been "in terms of defects the best deliveries we've had in three years".
He acknowledged what happened with the Alaska Airlines flight had been serious but said the industry always learned from incidents.
Mr O'Leary said that Boeing made good planes, but compared the relationship to a marriage: "I can be in love with you and still occasionally criticise some of your personal habits. I think that's the same with Boeing."
He suggested that the management team at Boeing "needs to be improved" following the incident, although he gave his support for Boeing's current chief executive David Calhoun, stating that he is "doing a stellar job in very tough circumstances".
Mr O'Leary added: "We don't need more senior management changes in Boeing."
On Monday, Boeing announced that an outside party would also be brought in to assess its production practices.