Two ceiling fixers sustained serious injuries when the mobile aluminium scaffold they were working from collapsed. The working platform of the scaffold was approximately 1.8m high, 3m long and 600mm wide. Persons using the scaffold had no prior instruction or training in the assembly and use of a mobile scaffold less than 4m in height. Both ceiling fixers inspected the mobile scaffold prior to use and noticed that the leg lock collars attached to the threaded stems of the castors showed signs of some physical damage and a build-up of dirt. The scaffold collapsed after one of the ceiling fixers made his way to one end of the working platform. The leg lock failed, which allowed the castor stem to retract into the vertical frame at one end of the scaffold.

• Damage sustained to the mobile scaffold was not identified as a potential hazard.
• An accumulation of dirt was visible around the locking collar of the threaded leg, which may have prevented the collar from extending to the full height distance required to firmly secure the threaded leg.