GE Aerospace, whose joint venture made the engines of the Boeing airplane that crashed in the deadliest aviation disaster on South Korean soil, joined the investigation as Seoul extended by a week special inspections of all 101 Boeing 737-800 jets.

A widely used Boeing aircraft, the 737-800, was involved in Sunday’s crash-landing of a Jeju Air flight that killed 179 people.

Investigators on Saturday expect to compile the complete transcript from the cockpit voice recorder recovered from the wreckage of the Jeju Air Boeing 737-800 that crashed on Sunday in South Korea, the transport ministry said in a statement.

For decades, Boeing has maintained a role as one of the giants of American manufacturing. But the the past year's repeated troubles have been damaging.

Boeing shares were down as much as 6% Monday morning. Authorities in Korea believe a bird strike could have been a factor in the fatal crash.

South Korean officials are struggling to determine what caused a deadly plane crash that killed nearly 180 people on board, with the nation saddened, shocked and ashamed over the country’s worst aviation disaster in decades.