FAA Wants Boeing 737 MAX Engines Checked For Corrosion

The FAA has today issued a new Airworthiness Directive for some CFM LEAP-1B engines on the 737 MAX family of aircraft. The Directive relates to corrosion caused by the long storage of the planes, which in some cases could lead to degraded thrust. The fix is easy enough, and shouldn’t be a significant burden on the airlines affected.

Boeing 737 MAX, Production, Return To Service
Due to long periods of storage, some MAX engines are suffering corrosion. Photo: Vincenzo Pace – Simple Flying

Corrosion problems could cause reduced thrust

When aircraft are parked for a long time without use, it’s only natural that some parts might begin to show some wear and tear. The worldwide fleet of 737 MAX was grounded for more than two years, with many airlines choosing hot, dry storage spots in deserts to protect their assets.

But despite airlines’ best efforts to keep their fleet in good order, there have been some teething troubles as the type returns to the skies. Today, the Federal Aviation Administration (FAA) has issued a new Airworthiness Directive (AD) for the engines on the 737 MAX in relation to corrosion as a result of long storage.

The FAA’s document says that, for certain CFM LEAP-1B engines, there have been multiple reports of pressure sub-system (PSS) unit faults due to corrosion following storage. Specifically, it states,

“In April 2021, the FAA received a report from CFM, the engine manufacturer, of numerous instances of PSS unit faults. The manufacturer reported these faults have been occurring since October 2020 and are a result of pressure transducer corrosion following extended storage periods. The manufacturer’s investigation found that certain PSS units, identified by serial number, have been exposed to conditions that make pressure transducers in these units susceptible to an increased rate of faults.”

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The LEAP-1B powers the Boeing 737 MAX. Photo: CFM

While the fault is not thought to be dangerous, it can lead to reduced thrust, and therefore requires airline attention. However, it seems to be an easy enough problem to fix. Indeed, the FAA says it is only an issue during the first 15 hours of electrical power being provided to the PSS after storage.

As such, the AD requires that engines with fewer than 15 hours of electrical power supply to the PSS in the past 90 days have repeated checks before every flight. A second, and much simpler option, is for airlines to simply apply power to the PSS unit until it has accumulated at least 15 hours.

The FAA estimates that 158 engines of US registry are affected by the AD. This fault is unrelated to the electrical issue reported in late April.

The MAX continues to fly out of Washington and off to its new owners. Photo: flydubai

The MAX is flying out of Washington

Boeings recent earnings results highlighted the sterling efforts of the team to get the already-built inventory of MAX aircraft out to their customers. Since the FAA ungrounded the type in late 2020, 85 aircraft have been delivered to customers. 63 of these were delivered in the first quarter of the year.

To date, 31 airlines have returned the 737 MAX to revenue service, safely and without incident. While the situation in China remains something of a question mark on Boeing’s timetable, the planemaker is confident that the regulators will approve the narrowbody before the end of the year.

Have you flown a 737 MAX yet? What did you think? Let us know in the comments.