A single bolt that was improperly installed by U.S. aerospace company Boeing Co. caused South Korea's presidential jet to make an unprecedented emergency landing in March, Air Force investigators concluded on Wednesday.
The presidential jet, a Boeing 747-400 plane, with President Lee Myung-bak and first lady Kim Yoon-ok on board, was forced to land at Incheon International Airport, west of Seoul, on March 12 while heading for the United Arab Emirates for an official visit.
Although no passengers suffered injuries and the presidential jet resumed its flight about two hours after repairs on a malfunction in the plane's ventilation system, it marked the first emergency landing by a presidential jet in South Korea.
The investigation attributed the emergency landing to the bolt in the plane's air-distribution system that was "incorrectly installed by Boeing."
"We found that Boeing incorrectly installed the bolt when it manufactured the 747-400 plane," Air Force Col. Choi Young-hoon told reporters. "Boeing's faulty assembly is responsible for the landing incident."
The incorrectly assembled torque arm bolt caused one of three air-inlet doors of the plane's main cabin to rupture and produce noise, Choi said.
"To prevent the recurrence of such an accident, the Air Force will conduct monthly safety checks on the presidential jet," Choi said.
The South's Air Force and Boeing jointly carried out the investigation, Choi said.
In a statement, Boeing said it found the "incorrect orientation" of the bolt in the air-inlet door assembly, suggesting the problem may affect other 747-400 airplanes.
"We are revising the aircraft maintenance manual to more clearly identify the proper re-installation of the torque arm bolt," the statement said. "We will continue to review other fleet actions as appropriate."
"As a result, we are reviewing the data to determine possible actions for our production system and the in-service fleet," Boeing said.
The presidential office of Cheong Wa Dae leased the Boeing aircraft, manufactured in 2001, from Korean Air last year under a four-year contract worth 140 billion won ($130.2 million).
Kang Young-shik, executive vice president of Korean Air, said the company plans to ask Boeing to pay compensation for direct and indirect damage that the emergency landing caused.
Korean Air, South Korea's national flag carrier, is responsible for maintenance and in-flight services for the presidential jet, while the Air Force supervises maintenance work.
To hold Korean Air accountable for the incident, the Air Force will reduce the lease payments by 71 million won, officials said.
"The Air Force also sincerely apologizes to the public for neglecting its supervision and causing concerns over the incident surrounding the presidential jet," the Air Force said in a statement. (Yonhap)