The death of a Chinese worker who fell 19 storeys after being hit by a tower crane's load could have been due to a fault in the crane's design, a Ministry of Manpower (MOM) investigation revealed yesterday in a coroner's court.
This prompted the State Coroner to call for an advisory to be issued at once to warn users of the crane in Singapore. Mr Liu Debao, a construction worker from Shandong, was pushed off an unfinished HDB building in Fernvale Street on Jan 23 last year.
The 40-year-old was struck by a prefabricated bathroom unit when the crane lifting it suddenly swung towards him at high speed.
It pinned him against some mesh barricades, which gave way. He then tumbled about 51m to the ground, where he was pronounced dead. The crane in question was manufactured in China by Shandong Guohong Zhonggong Mechanical Co. There are 14 cranes of the Guohong QTZ250 model in Singapore.
MOM senior investigation officer Wong Zhi Wun explained in court that a momentary loose wire connection in the crane's slewing control system could have potentially caused the accident.
Simulation tests found that when the disconnection occurred, the crane would start swinging at full speed, even if the operator released the joystick to stop it.
The crane operator, Mr Yao Fujun, also told investigators he had slewed the crane only slightly towards Mr Liu, but the bathroom unit suddenly surged towards his colleague at top speed.
According to Mr Wong, an inspection of the crane afterwards found no loose connections. But the wires could have been "intermittently loosened due to vibrations" during its operations.
He added that two other crane operators using the same model later came forward to claim they had experienced the same thing.
When they stopped and restarted the cranes, however, the problem ceased, so they did not think of reporting it until the accident.
While the investigation did not conclusively pin the blame on the crane design, Mr Wong said it cast "significant doubt" on the accident having been deliberately caused by the crane operator.
State Coroner Marvin Bay recommended that an advisory be sent out "without further delay".
He said: "If this happens once, it is tragic. If it happens twice, it is difficult to justify." He will release his findings on June 4.