Spirit AeroSystems has disclosed more detail about a newly implemented 737 fuselage inspection process that executives say has initially slowed deliveries but will ultimately better prepare the company for future production rate increases.

On 1 March, Boeing started requiring that 737 fuselages be fully inspected for possible defects or other problems prior to Spirit shipping them from its Wichita production site to the narrowbody’s final assembly line in Renton, Washington.

The aircraft manufacturer intends the inspections to reduce or eliminate fuselage-related “travelled work” – meaning work completed later than planned during production.

Boeing implemented the inspection requirement amid intense pressure to improve quality following the 5 January in-flight failure of a 737 Max 9’s mid-cabin door-plug.

737 assembly c Spirit AeroSystems

Source: Spirit AeroSystems

Spirit AeroSystems and Boeing are now jointly inspecting, prior to delivery, 737 fuselages coming out of Spirit’s Wichita assembly site

“The decision was made to fundamentally change the inspection process,” Spirit chief executive Pat Shanahan said on 7 May during the company’s first-quarter earnings call.

He notes that Boeing and Spirit teams are now jointly inspecting fuselages coming out of the manufacturer’s Wichita facility. “Today, working shoulder to shoulder with a standardised 26-zone product-verification process, the teams verify product conformity on the 737.”

Ideally, the changes will ensure that fuselages arriving in Renton are ready to go, meaning Boeing can “load [them] into their first position and immediately put floors down”, Shanahan adds. “We cannot travel any work that would disrupt their ability to start on day one.”

Boeing executives have said in recent months that anything that disrupts production – such as the need to complete work out of the normal cycle – opens a door for possible quality problems.

Indeed, prior to delivering the 737 Max involved in the 5 January incident, workers in Renton had removed its left-side door-plug so representatives of Spirit could fix a rivet problem, according to the National Transportation Safety Board’s preliminary report. The Boeing team replaced the plug but apparently never installed bolts intended to secure it, leading to the in-flight failure.

Shanahan says the new inspection process prevented Spirit from delivering 45 fuselages produced during the first quarter, which “in effect paused our ability to receive payment for completed fuselages”. Boeing did, however, throw Spirit financial support in the form of a $425 million loan, which Spirit expects to repay in the third quarter.

Spirit now anticipates completing 31 737 fuselages monthly for the rest of this year, far lower than its previous plan.

The inspections have already driven a 15% “improvement in quality” and will enable Spirit to deliver more production-conforming fuselages when output increases, Shanahan says. “This all supports rate 42, rate 47 and beyond.”