The FAA is investigating two separate Southwest Airlines incidents involving Boeing 787 Max 8s

The Federal Aviation Administration (FAA) is investigating after an April Southwest Airlines plane reportedly dropped to within 400 feet of the Pacific Ocean off the coast of a Hawaiian island before climbing to safety, Bloomberg reported.

The probe comes as the regulators look into a separate incident in May when a Southwest flight from Phoenix to Oakland sustained damage from a “Dutch roll,” an aircraft motion caused when the tail moves side-to-side and the wings move up and down. The airlines reported the roll and the damage a couple of weeks later, on June 7.

Both incidents included Boeing 787 Max 8 planes.