Airlines worldwide must inspect 312 of Boeing's 737 family of aircraft, including some of the grounded 737 Max, because they have wing components that are prone to cracking and must be repaired within 10 days, US aviation regulators said Sunday. Boeing informed the Federal Aviation Administration that so-called leading edge slat tracks may not have been properly manufactured and pose a safety risk, the agency said in an emailed statement. The parts allow the wing to expand to create more lift during takeoff and landing. The FAA plans to issue an order calling for operators of the planes worldwide to identify whether the deficient parts were installed and to replace them, if needed. A complete failure wouldn’t lead to a loss of the aircraft, the FAA said, but could cause damage during flight. Boeing has notified operators of the planes about the needed repairs and is sending replacement parts to help minimise the time aircraft are out of service, the company said in a statement. The slat tracks in question were made by a supplier to Spirit AeroSystems Holdings, Boeing said in an email. Boeing has identified 148 parts made by a subcontractor that are affected. The parts may be on a total of 179 737 Max aircraft and 133 737 NG planes worldwide, including 33 Max and 32 NG aircraft in the US, the FAA said. The NG, or Next Generation, 737s are a predecessor to the Max family. The deficient parts may be on fewer of the identified planes, Boeing said. While the full number of jets must be inspected, 20 Max and 21 NG aircraft are “most likely” to have the suspect parts installed, according to the company. The 737 Max has been grounded worldwide since March 13 after two fatal crashes tied to a malfunction that caused a flight control system to repeatedly drive down the plane’s nose. Boeing is finalizing a software fix along with proposed new training that will be required before the planes fly again.