Incident Report - Gold Coast, Australia

In the early hours of 9 December 2017, a Liebherr LTM1350-6.2 experienced an outrigger failure on the Gold Coast in Australia. The crane was being set up to complete a dual lift. During set up, the operator slewed to the front of the crane cab to configure the hook block with the correct reeving required when the rear left outrigger failed. This caused the outrigger to collapse.

Directly following the incident, a quarantine area was established around the machine to ensure the safety of all personnel working in the area. Universal Cranes immediately mobilised additional operatives and transport to site to assist with making the crane safe to de-rig. Upon investigation of the site, the initial cause of the collapse was suspected as failure to install the outrigger pin on the left rear outrigger, causing the inner jack box to be incorrectly positioned over the internal shear keys. This caused the outrigger box to collapse with the upper structure of the crane sitting down over the rear left outrigger.

The crane was transported back to Universal Cranes’ Brisbane depot where a visual inspection of the crane was carried out by the manufacturer and Universal Cranes’ mechanics. The damaged outrigger box was removed and stripped to enable confirmation of the cause of the incident.

This inspection confirmed the conclusion of the onsite assessment that the missing locating pin in the outrigger had allowed the inner box to load the area of the outer box which did not have shear keys available for the required load spread.

Furthermore, the factors that contributed to this incident were:

Outrigger Incident_Dec2017.jpg
  1. The mat under the left rear outrigger needed to be re-positioned as it was not in the correct position.

  2. The pins in the rear outrigger were not inserted.

  3. The left rear outrigger was not full extended.

There have been several measures put in place to prevent the reoccurrence of incidents of this nature:

  • A sensor system was installed onto the outriggers after the incident. This system displays the percentage each outrigger is extended on the computer in the top cab.

  • The Job Safety Analysis on the docket book has been modified with an additional check box ensuring the crane is set up as per manufacturer specifications, to be completed before work commences.

  • The commissioning and testing step in an internal SWMS document has been updated to include minimum checks that are specific to this crane and as per the manufacturer’s specifications in the operations manual:

    • The axle suspension is blocked

    • Outrigger beams and support cylinders have been extended according to the load chart

    • The outrigger beams are pinned and locked (2 pins per outrigger beam)

    • Outrigger cylinder pads are pinned and secured in the operating position

    • Adequate support underneath outriggers

    • The axles are relieved, which means the tyres do not touch the ground

    • The counterweight is attached and secured according to the data in the load chart

    • The hook block is correctly reeved as shown in the reeving plan

    • The correct function on LMI has been selected

    • All safety functions to be checked, including operation of anti-two blocks, boom limitations and anemometer

    • Prior to telescoping/extending boom test all outrigger pads with maximum counterweight load with the boom at the lowest possible angle; do this by slewing the counterweight over all 4 outrigger beams.

• A new policy states that outrigger pins must be installed regardless of whether they are structural or not. Stickers have been added to the outrigger beams and in the top cab of this crane to remind the operator.

Sally Austin