Topline: The world’s biggest planemaker, Boeing, faced another blow as it suggested that up to 50 of its 737 NG aircraft—a predecessor to the 737 MAX—have been grounded after several operators discovered cracks on the aircraft.

• Australia’s Qantas is the latest airline to ground one its 737 NG planes over the issue and set out to inspect 32 more, but it assured passengers that they should not be concerned. The firm’s head of engineering, Chris Snook, said: “We would never operate an aircraft unless it was completely safe to do so.”
• Earlier this month, authorities in South Korea said nine planes were grounded, five of which were operated by Korean Air. Southwest Airlines and Brazil’s Gol Linhas Aereas have also grounded some of its 737 NG fleet in order to carry out urgent inspections.
• Indonesian airlines Sriwijaya Air and Garuda Indonesia Airways grounded three 737 NG planes over the same issue, while Lion Air, which operated a 737 MAX plane that fatally crashed a year ago, found cracks on two of its 737 NG aircraft.
• According to AFP, Boeing reports that 5% of the 1,000 planes inspected so far had cracks and were undergoing repair.

Key background: Earlier this month, U.S. regulators ordered the inspection of hundreds of 737 NG planes in the U.S. that had completed more than 30,000 takeoff and landings (or cycles), after the planemaker reported problems with its pickle fork—the section which attaches the main body of the plane to the wings. But the recently grounded Qantas plane had flown less than 27,000 miles, according to the airline, with none of its 737 NG planes had completed 30,000 cycles. The Federal Aviation Administration is now seeking to widen the number of 737 NGs being inspected.

Issues with the 737 NG will be especially unwelcome as Boeing works to improve its safety reputation following two crashes involving its 737 MAX airliner that killed 346 people in five months. The 737 Max fleet has been grounded since March and is not expected to fly again until January 2020 at the earliest. Boeing has faced significant financial losses and seen one of its top executives, Kevin McAllister, fired. The firm’s CEO, Dennis Muilenberg, faced tough questioning from the House Transportation Committee on Wednesday.

Additional fact: The 737 NG (Next Generation) aircraft first flight was in 1997. More than 7,000 have been delivered to scores of airlines around the world.

Further reading: Here’s The New Evidence On 737 MAX Development Released At The House Boeing Hearing (Jeremy Bogaisky)

Boeing CEO Refuses Lawmakers’ Calls To Step Down In Combative House Hearing (Jeremy Bogaisky)

Lion Air Crash Report Faults Boeing 737 MAX Design Flaws, Pilot Errors (Isabel Togoh)