The cracks were spotted in the “pickle fork” part of the plane, which is the part where the wings meet the fuselage (or body) of the aircraft. The Guardian reported that 737 planes must be checked after 30,000 cycles for these cracks. The airline said that the cracks could have happened anywhere between 22,600 and 30,000 cycles. The three affected planes each had at least 27,000 cycles completed, but the airline does not have any planes that have completed more than 30,000 cycles, the Guardian reported.
For reference, a cycle is a successful take-off and landing, or a single flight, according to the Guardian.
According to CNN Business, the cracks were found on heavily used planes. On Friday, Qantas said in a press conference that it would not ground all 737s in their fleet. Instead, the airline has checked the planes in its fleet that had completed at least 22,600 cycles, the Guardian reported.
“We are focused, right now, on those in scope, which is the 33 that have done between 22,600 cycles and 30,000 cycles,” said Andrew David, the head of Qantas Domestic, in a statement to the Guardian. “Any between 22,600 and 30,000 cycles needed to be checked within seven months … and we’ve done them within seven days, as soon as we found the first one.”
Chris Snook, head of Qantas Engineering, said in a statement to CNN Business that the airline would “never operate an aircraft unless it was completely safe to do so.” He also added, “Even when a crack is present, it does not immediately compromise the safety of the aircraft.”
According to Skift, Boeing said in a statement that only five percent of aircraft, worldwide, which required urgent checks had cracks. The 737 NG planes (737-700, 737-800 and 737-900) are older versions of the company’s 737 Max planes, which have been grounded by several airlines after crashes in Indonesia and Ethiopia, according to Skift.
Snook told CNN Business that all inspections would be completed by Friday. The affected planes are expected to return to service by the end of the year, the Guardian reported.
Earlier in October, airlines Southwest and Brazil’s Gol Linhas Aereas also had to ground a combined total of 13 Boeing 737 NG planes due to similar cracks in the pickle fork of the aircraft wings.