American aircraft manufacturer Boeing has suspended test flights of the new 737 MAX due to concerns over the engines used on the plane.
The new comes days before Boeing was due to make its first delivery of the aircraft to customers.
American Airlines and Southwest in the United States and Shandong Airlines in China are among those who have placed orders.
However, despite the delay, Boeing said it was sticking with plans to begin MAX deliveries this month.
Production of the jets is also set to continue.
Indian airline SpiceJet earlier this year placed an order for 205 new planes from Boeing.
The deal is valued around $22 billion, with the first Max 737 planes to be delivered to SpiceJet in 2018.
Boeing confirmed it was notified last week of a potential issue involving turbine engine discs manufactured by a supplier to CFM International.
CFM is the joint venture between US firm General Electric and French-based Safran.
Boeing added it had not experienced any problems with the discs during more than 2,000 hours of testing, with the suspension purely a precaution.