- Boeing supplier Spirit AeroSystems said it was being innovative when it used soap as a lubricant.
- Besides the soap, FAA auditors say they saw Spirit mechanics use a hotel key card to check a door seal.
- Spirit said both practices were approved by Boeing and the FAA.
A supplier for Boeing said it tried using other household products like Vaseline and cornstarch as a lubricant before it settled on using liquid Dawn soap, The New York Times reported on Thursday.
In March, The Times reported that Federal Aviation Administration's (FAA) auditors saw Spirit AeroSystems' mechanics applying soap to a door seal.
The mechanics were also seen using a hotel key card to check a door seal, per an audit report obtained by The Times.
"People look at the hotel key card or Dawn soap and think this is sloppy. This is actually an innovative approach to solving for an efficient shop aid," Spirit spokesperson Joe Buccino told The Times.
According to Buccino, Spirit also tried using other household products such as Vaseline, cornstarch, and talcum powder as a lubricant before settling on liquid Dawn soap.
Buccino said the Dawn soap became their top choice because it didn't cause the door seal to degrade over time.
Spirit told The Times that Boeing had approved both practices. The company added that the soap and the key card-like device were documented for use under FAA's standards as factory tools, also known as shop aids.
The company's chief technology officer, Sean Black, told The Times that Spirit came up with the key card-like device after seeing workers using a hotel key card to check gaps.
"Our workers routinely find creative ways to make the process of building fuselages more efficient. In this case, workers created the door rigger seal tool, which allows our teams to test the door seals without any risk of degrading the seal over time," Black told the outlet.
A spokesperson for Boeing confirmed to The Times that it had indeed approved Spirit's use of the soap and key card-like device, while an FAA representative declined The Times' request for comment.
The audit, the FAA said, was part of its ongoing investigation into Boeing after a door plug on an Alaska Airlines flight blew out in January while the plane was still midair.
The controversy surrounding Spirit's unorthodox engineering practices takes place amid heightened scrutiny of the quality of Boeing's planes. The aircraft manufacturer has come under the spotlight following repeated quality assurance lapses.
On Wednesday, the head of the National Transportation Safety Board (NTSB) said in a Senate hearing that she was considering surveying every Boeing employee about the company's safety culture.
"I don't think there's anyone at Boeing, from Dave Calhoun down, that doesn't want to know what happened. They want to know, and they want to fix it, and we're there to help," NTSB chief Jennifer Homendy said.
Representatives for Boeing, Spirit, and the FAA did not immediately respond to a request for comment from Business Insider sent outside regular business hours.