Boeing 737 wing parts at the center of a Federal Aviation Administration alert earlier this week were manufactured by a Spirit AeroSystems sub-tier supplier, Boeing said by email.
Boeing spokesman Bernard Choi said by phone that the company is “not commenting on the supplier” including giving its name. But he did say that Spirit discovered the possible problem with the parts during testing.
The parts, slat track assemblies, are used to guide an airplane’s slats, which help with take-off and landing.
Spirit AeroSystems directed questions about the potentially faulty parts and their supplier to Boeing. Spirit makes about 70 percent of the 737 including the fuselage at its Wichita plant.
The FAA on Sunday alerted airlines and international aviation regulators that the slat track assemblies on more than 300 Boeing 737s could crack or fail because of how they were made. The affected airplanes include older model 737 NGs and the new 737 Max — the Boeing model grounded worldwide earlier this year following deadly crashes in Indonesia and Ethiopia.
Choi said one batch of 148 parts were found to “have an issue with hydrogen embrittlement” — meaning hydrogen was introduced into the metal during manufacturing — so they do not conform to Boeing’s standards.
Boeing said in a statement that it had identified 21 737 NGs and 20 Max aircraft that probably have the parts. Airlines are being asked to inspect them on another 112 NGs and 159 Maxes.
Boeing’s statement said the company doesn’t know of any in-service issues with the faulty batch of slat tracks and plans to replace them, which should take a day or two.