Yesterday brought yet more bad news for Boeing as it received a multi-million-dollar fine from the Federal Aviation Administration. The FAA has accused Boeing of knowingly installing faulty parts on around 133 Boeing 737s in 2018 and 2019.

2019 is drawing to a close, but the year continues to torment Boeing with more accusations of faulty components and failings in the company’s quality assurance processes. The FAA published a press release yesterday, outlining the details of its claims against Boeing.

Faulty slat tracks

According to the FAA, Boeing installed faulty slat tracks, which are part of the slat mechanism on the leading edge of the aircraft’s wings, on numerous Boeing 737s. In total, approximately 133 Boeing 737s were installed with the faulty components across a period stretching between 2018 and 2019.

According to the FAA, the faulty slat tracks were affected by an issue known as ‘hydrogen embrittlement’, which can occur during the cadmium-titanium plating process. As a result of this hydrogen embrittlement, the slat tracks should not have been approved for use.

Boeing 737 NG wing
Slat tracks guide the slats on the leading edge of an aircraft's wing. Photo: Altair78 via Wikimedia Commons

The faulty slat tracks were processed by one of Boeing’s third-party suppliers, Southwest United Industries, which carried out the cadmium-titanium plating. Southwest United Industries then delivered the plated slat tracks to Spirit AeroSystems, which then supplied them to Boeing.

Southwest United Industries detected the hydrogen embrittlement in the batch of slat tracks, informing the manufacturer of the components, Kencoa Aerospace. Kencoa Aerospace then informed Spirit AeroSystems about the embrittlement. Boeing was then in turn informed of the issue by Spirit AeroSystems in September 2018.

The FAA did not become aware of the slat track issues until much later. Once it did, it issued an Airworthiness Directive which came into effect on 10 June 2019.

Where did Boeing go wrong?

Despite being made aware of the hydrogen embrittlement which was detected in the batch of slat tracks, Boeing continued to install them on Boeing 737 MAX and Boeing 737 NG models.

The FAA also claims that during the period between 10 October 2018 and 2 May 2019, Boeing knowingly certified 85 aircraft which had potentially been fitted with slat tracks from the faulty batch.

The slat track issue was further complicated by the fact that Southwest United Industries failed to apply a protective coating over the identification numbers on the slat tracks themselves. This meant that it was hard to identify which slat tracks had been affected.

Although the hydrogen embrittlement was not a result of manufacturing errors on Boeing’s part, the FAA alleges that Boeing failed in its duty to properly oversee the quality assurance processes of its suppliers.

Boeing 737 MAX
The slat tracks were affected by hydrogen embrittlement. Photo: pjs2005 via Wikimedia Commons

As a result, the FAA has issued a civil penalty against Boeing which amounts to a total of $3,916,871. Boeing has 30 days to respond to the penalty notice.

Flight Global has quoted Boeing with regards to the issue:

"We are committed to continuing to strengthen our processes to ensure that quality issues in our production system are promptly identified, elevated and resolved."

Boeing has also said that "All affected 737 NGs have been inspected and all slat track installations determined to be required have been completed on the NGs."