SHARE

Boeing 737 Max supplier Spirit AeroSystems is defending its controversial decision to use Dawn dish soap as a lubricant for the aircraft’s door seals. Spirit’s use of soap and other odd, everyday objects like hotel key cards and wet cheesecloths to perform maintenance drew immediate public scrutiny last month. Now, Spirit claims both the dish soap and key card use cases were not only justified, but innovative.

[ Related: Dish soap, hotel key cards, and confusion: Boeing FAA audit unearths dozens of issues ]

During its six-week audit, an FAA investigator claimed they saw Spirit mechanics apply Dawn dish soap (yes, the kind sitting in household kitchens) to a 737 Max door seal to act as a lubricant. Separately, the investigator also witnessed a Spirit mechanic using a generic hotel key card to check a door seal. Spirit defended both of those practices in a recent interview with The New York Times

Speaking with the Times, a Spirit spokesperson claims the company opted to use the dish soap because its particular chemical properties would not degrade the door seal’s materials over time. Once applied, the soap was intended to help prevent tears or bulges from occurring during the seal’s installation. It turns out dish soap wasn’t the first household product Spirit considered for the job either. 

“Spirit workers did not land on the dish soap on the first try. [The Spirit spokesperson] said that other common products had been used in the past — including Vaseline, cornstarch and talcum powder — but that they ran the risk of degrading the seal over time.”

Spirit similarly defended its use of the key card, claiming it was used to measure the gap between the seal and the door plug. The company claims mechanics tried to use other tools first but discovered they weren’t flexible enough to measure the gap without damaging the seal. The key card was. 

Spirit claims it has since developed its own in-house tools that function like the key card which it calls a “door rigger seal tool.” Each of these use cases, Spirit claims, authorized by engineers at Boeing as appropriate “shop aids.” 

“People look at the hotel key card or Dawn soap and think this is sloppy,” Spirit spokesman Joe Buccino said during a recent interview with the Times. “This is actually an innovative approach to solving for an efficient shop aid.” 

A Boeing spokesperson told the Times the company had indeed approved both the soap and key card-like tool as shop aids. When reached for comment, Boeing confirmed the Times’ reporting but declined to comment further.  An FAA spokesperson told PopSci it could not comment on the audit because it is part of an ongoing investigation into the two companies. 

The FAA began its investigation into the two companies after a door plug blew off a 737 Max plane during an Alaskan Airlines flight in January. Since then, passengers onboard Boeing aircraft have endured a sudden nose-dive, a mid-air wheel detachment, and, most recently, the frightening loss of an engine cover. The repeated safety incidents have sparked multiple federal investigations. Dave Calhoun, the company’s former CEO since January 2020, resigned last month.