A task force has been set up to investigate whether two air bridges that collapsed at Chek Lap Kok airport on Sunday failed because of the bolts connecting different parts of the platforms, the Airport Authority says.
Ricky Leung Wing-kee, general manager of technical services for the authority, said initial investigations pointed to the bolts as the cause of the collapse.
Leung said a conclusion would not be reached until the investigation finished in three months.
The bolts were fixed components in the air bridges and were not touched during daily operations.
At about 6pm on Sunday, after all passengers and crew had boarded a Cathay Pacific flight to Nagoya, the rear bridge connected to one of the doors of the Airbus A330 fell on its side. As it toppled over, it upset the front bridge, causing that to fall as well, the authority said. An airport worker was injured.
There are 99 air bridges at Terminal 1, and the authority said it carried out an overnight inspection of the facilities after the incident.
Twenty of the bridges use bolts similar to the ones in question. Nine rear bridges with the bolt design have been suspended from use as a precautionary measure, although the authority said they had passed ultrasonic inspections. The nine front bridges with such bolts remain in use. Terminal 1 now has 88 air bridges in operation for its 49 gates.
Leung said air bridges with bolts were introduced in 1999 and 2000 and they could be used for about 20 years.
There was no indication the air bridges were worn out; they passed a regular check conducted late last month.
"Maintenance work is conducted on the air bridges weekly, monthly and quarterly, and the collapsed bridges had just passed the monthly check carried out on March 27. Nothing unusual was discovered," he said.
"For the monthly test, besides seeing whether an air bridge can generally function well, we will conduct a detailed inspection of the components, including the bolts."
Leung said the maintenance budget for the airport rose from HK$324 million in 2006-07 to HK$528 million in 2011-12.
The investigation will be led by engineer Edmund Leung Kwong-ho. Other members of the task force include representatives from Cathay Pacific, Hong Kong Airport Services, the ground-handling company that operated the collapsed air bridges, and Jardine Engineering, which is the maintenance contractor of the air bridges.
Specialists from Bukaka, the Indonesian manufacturer of the air bridge, will also assist the investigation.
Meanwhile, Ng Chi-kee, executive director of airport operations with the authority, said they had enough manpower for maintenance work. The amount of time needed to conduct regular checks had not been a problem, Ng said.
"We place a lot of importance on maintenance and safety, and we do not have any restriction on maintenance time," he said. "If there is a need, we will stop any [process] to conduct a detailed examination."