Although the cause of this month’s crash of a China Eastern Airlines plane remains unknown, lawyers who previously sued over the 737 Max 8 said there are early signs of a possibly defective Boeing aircraft.

China Eastern Airlines Flight 5735 was headed from Kunming to Guangzhou on March 21 when it nosedived from 29,000 feet, crashing into the mountains of Southern China and killing all 132 people on board. Chinese investigators have located the aircraft’s black boxes but have made no conclusions about the cause of the crash.