The Federal Aviation Administration (FAA) has proposed a new Airworthiness Directive (AD) for Boeing 737 MAX aircraft following multiple reports of faulty wires impacting the type’s spoilers, according to Aviation Week. This wiring issue can cause uncommanded rolls in flight that could lead to losses of control.
Spoilers are panels on top of wings that can extend upward to decrease (or “spoil”) lift and increase drag. They are secondary control surfaces that can have a number of impacts, such as helping pilots slow down, descend, or equalize the drag on both wings during commanded turns. Importantly, if spoilers deploy on one wing but not the other, the imbalance in lift and drag on both wings will roll the airplane into a turn.
The FAA says an investigation identified the potential that spoilers might deploy on one of an aircraft’s wings, reach their limit, and jam, causing the plane to exceed its full lateral control capability. In other words, the aircraft would enter a roll so steep that there would not be enough rudder authority to keep the nose aligned with the turn, potentially leading to a loss of control.
Per the FAA’s document, Boeing says this issue is due to “non-conforming installation of spoiler wire bundles that occurred during production.” 737 MAX operators were first made aware of the issue in July 2023 in which Boeing called for one-off inspections “of the clearance between the spoiler control wire bundles and the adjacent structure.”
According to Aviation Week’s report, the FAA’s new proposal is based on Boeing recommendations but does not specify a timeline to complete maintenance inspections. Airworthiness Directives generally require maintenance checks on a certain timeline, with inspections either being done once or completed on a timeline defined by flight hours or calendar segments.
This is the latest of a number of high-profile setbacks for the MAX family. In recent days, the Department of Justice (DOJ) has started an investigation into whether Boeing complied with the terms of its settlement after the MCAS crashes in 2018 and 2019. The NTSB also publicized an incident where a 737 MAX 8’s rudder pedals got stuck during landing in Newark last month.
