Boeing’s top engineer insists the 25 May incident involving a Southwest Airlines 737 Max 8 which experienced ‘Dutch Roll’ was due to factors specific to the aircraft involved rather than the jet’s design or to its production system.
Speaking during a 18 June Senate hearing, Boeing chief engineer Howard McKenzie also revealed more detail about an issue involving 787 fasteners.
McKenzie says Boeing believes there is a “unique circumstance” around the Southwest narrowbody “that has nothing to do with design or manufacturing”, but cautioned that the National Transportation Safety Board still needs to complete its investigation.
“We are pulling together the data that we have, and it does not indicate that there is anything that is of fleet concern here,” he adds.
The NTSB is investigating the incident, saying the jet experienced an “oscillation event” and that a later inspection revealed structural damage. The Southwest pilots described the movements as a “Dutch roll”, which involves a combination of yawing and rolling. But much about the incident remains unknown.
Senators pressed McKenzie during the hearing, called by the subcommittee to probe Boeing’s quality and safety issues.
“The Dutch roll is an oscillation due to the rudder actuator responding to a particular circumstance that it is in,” McKenzie says. “Thus far… the data we have indicates that this airplane underwent some unique circumstance that is particular to this airplane”.
“We are supporting the NTSB with our design resources,” he adds.
Lawmakers also asked McKenzie about a separate problem involving improperly torqued fasteners on 787s. Boeing disclosed the issue last week, saying it has started inspecting undelivered jets.
McKenzie says the fasteners were tightened to the correct torque, but using the wrong method.
“The subtlety here is that they were torqued using the head side of the fastener as opposed to the nut side. It is a matter of what’s being held and what’s being turned,” he says.
Boeing has been studying the issue for all three 787 variants to identify possible safety risks. It has completed one of those analyses, and the results were “completely acceptable”, McKenzie says. “It is fine the way it is. The torque is applied properly. All the fasteners are installed.”
The Federal Aviation Administration is also reportedly investigating the fastener issue.
