Blackout Mid-Lift and the Failed Brake
You are landing a 3.4 t precast beam when the site power fails. The crane is a hammerhead with a 45 m jib, trolley at 30 m, and the beam is 1.5 m above its bearing. The crane has a diesel generator backup but it did not start automatically. The beam is held by the hoist brake, and you can hear the brake slipping and the load creeping down. Two riggers are on the slab near the beam, one within 2 m of the landing point. Wind is 20 km/h. The site emergency plan says 'contact the crane coordinator' but the coordinator is off site.
1. What are your immediate actions in the first minute, and in what order?
Read the worked answer
The priority order is people, then load, then equipment.
- Clear the area under and around the load. Sound the horn and shout to the two riggers to move away from the beam and out from under it. A creeping load with a slipping brake can drop without warning. This comes before anything else.
- Try to arrest the creep. Apply the hoist brake fully and check whether the creep is the brake releasing or the load overpowering it. If the crane has a manual brake release/apply or a mechanical load-holding device, use it per the manufacturer's procedure. Do not attempt to lower the load under manual control unless the procedure is known and the area is clear.
- Start the backup power if the procedure allows and the generator is available, so the hoist can be powered to lower the beam to the ground or the bearing. Confirm the area is clear first.
- Isolate and secure. If the load cannot be lowered, keep the area evacuated, barricade it, and keep the crane controls attended. Do not leave the crane with a suspended load.
- Communicate. Call the site emergency contact; if the coordinator is off site, escalate to the principal contractor's nominated emergency contact and the crane supplier. The emergency plan's single point of contact has failed and that must be reported.
The exam point is that clearing people precedes trying to save the load, and that a slipping brake is treated as a load that may fall.
2. After the incident, what must be reported and what must happen before the crane returns to service?
Read the worked answer
This is a dangerous occurrence, not a routine breakdown, and it is treated as an incident.
Reporting:
- Notify the site's emergency and incident process immediately, and record times, load, radius, wind, what was heard and seen, and the actions taken.
- Report to the crane supplier and to the principal contractor. In most jurisdictions a failure of a load-holding brake on a crane, or a load dropping/creeping in a way that could have injured someone, is notifiable to the regulator; the site's incident procedure determines who lodges it and by when. It should not be left to the operator alone, but the operator must ensure it is escalated, not assume someone else will.
- Preserve the scene and the crane's data/records. Do not reset or test the brake in a way that destroys evidence.
Before return to service:
- The hoist brake must be inspected and repaired by a competent person, with the cause of the slip identified - not just adjusted.
- The generator's failure to auto-start must be diagnosed and fixed, and the backup-start procedure tested.
- The emergency plan must be revised so there is always an available coordinator or a named deputy.
- A post-incident review with the rigging crew, and a check that the exclusion zone under the landing point was adequate in the first place.
- Written clearance from the competent person before the crane lifts again.