Oct. 31 (UPI) -- Already suffering financially with its 737 Max fleet out of service, plane maker Boeing said Thursday dozens of its "Next Generation"-variant 737s have been grounded due to cracks in the airframe.
Boeing said as many as 50 747NGs worldwide have been grounded. Qantas said it would inspect 33 of the planes this week.
Qantas said it is waiting for replacement parts from Boeing, and must train maintenance crews how to remove and replace the forks. Boeing said in a statement it's "coordinating with our customers and suppliers on repair plans." The process is expected to take several weeks.
The Australian Licensed Aircraft Engineers Association said all 75 of Qantas' "Next Generation" models should be grounded until they are inspected.
"Boeing had previously thought the cracks were only occurring on aircraft with over 35,000 landings," association secretary Steve Purvinas said. "The issue has now been identified on two Qantas aircraft with as few as 27,000 landings and Qantas are yet to inspect the majority of its 737 fleet."
Qantas head of engineering Chris Snook called the grounding "completely irresponsible."
"Our checks are well advanced and will be finished by tomorrow -- months ahead of schedule," he said.
Southwest Airlines said earlier this month it had withdrawn two of its NG models from service after finding cracks.
The NG is the second Boeing 737 model to be grounded, following the global withdrawal of its Max fleet last spring. The U.S. aviation giant is working on a software fix for the models' automated flight system. The only U.S. carriers to fly the Max -- American, Southwest and United -- said the planes will remain grounded until January, at the earliest.
Boeing CEO Dennis Muilenburg testified in the House and Senate this week to address the planes.
"We know we made mistakes and got some things wrong," he told the Senate commerce committee Tuesday. "We own that. We understand and deserve this scrutiny."