Question 7 of 7: Foundry Overhead-Crane Casting Drop — Causes, Corrective Actions, and Follow-Up

Question 7: Foundry Overhead-Crane Casting Drop — Causes, Corrective Actions, and Follow-Up (20 marks: 6/8/6)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Causes of the Accident

The narrative describes a single mechanical failure sequence — the hoist eyebolt assembly failed, the casting fell, and the falling load then caused the cables to snap — but a system-safety reading (Question 1(i)) requires tracing that mechanical event back through every contributing area, not stopping at "the eyebolt broke":

• Overloaded or fatigued eyebolt/lifting hardware — the eyebolt assembly may have been rated below the actual load (3,000 lb plus dynamic/shock loading from acceleration and any swing), improperly seated (side-loaded rather than loaded in-line, which drastically reduces an eyebolt's rated capacity), or degraded by prior use, corrosion, or an undocumented overload event.
• Inadequate or expired inspection of lifting hardware — rigging, hooks, eyebolts, and hoist cables require scheduled inspection (visual pre-use plus periodic certified inspection); a failed component reaching service use points to either no inspection program, an inspection interval too long for the duty cycle, or an inspection that missed a visible defect (deformation, thread wear, cracking).
• Incorrect rigging configuration for the specific casting — a foundry casting's centre of gravity and lift points are not always obvious from its shape; an eyebolt loaded off-axis, or a single-point lift on a load that needed a spreader bar/multiple lift points, imposes forces well beyond the hardware's straight-pull rating.
• No secondary restraint against a single-point-of-failure lift — the entire load path depended on one eyebolt assembly with no independent backup (a safety sling, a secondary chain), so a single hardware failure had nothing to arrest the fall.
• Absence of an exclusion zone / worker positioned under or beside the suspended load's fall path — the employee was struck, indicating he was within range of the load and cables when they released, rather than positioned clear of the suspended-load path as crane-operating procedure requires.
• Possible crane maintenance/certification gap — periodic crane and rigging certification (load testing, cable condition) is required specifically to catch this class of failure before it occurs in service.

(ii) Corrective Actions Required

1. Engineering — correct the rigging design — specify lifting hardware (eyebolts, shackles, slings) rated with an adequate safety factor for the actual maximum load including dynamic effects, always loaded in the orientation it is rated for (in-line, not side-loaded), and use multi-point rigging or a spreader bar matched to each casting's geometry and centre of gravity rather than a single-point lift wherever the load shape makes that unreliable.
2. Engineering — add redundancy to the load path — a secondary restraint (independently rated safety chain or sling) so that a single-component failure does not result in an uncontrolled fall of the entire load.
3. Inspection and maintenance program — implement (or tighten) a scheduled, documented pre-use and periodic certified inspection of all lifting hardware and the crane itself, with defective components removed from service immediately rather than returned to use pending "monitoring."
4. Administrative controls — establish and enforce an exclusion zone / no-work-under-suspended-loads rule, with the operator and any ground personnel trained to keep clear of the load's swing and fall path at all times during a lift.
5. Training — retrain crane operators and riggers on load calculation, correct rigging selection and orientation for irregular castings, and pre-lift inspection of hardware.
6. PPE — retain and reinforce the head-protection requirement — the incident record itself shows the protective head gear already in place prevented a fatality; continue mandatory hard-hat use in the lifting area as a last-line control, without treating it as a substitute for the engineering and procedural fixes above.

(iii) Follow-Up Action Required

• Formal incident investigation and report — root-cause analysis (fault tree or 5-Whys, Question 1(iii)/Question 2(i)) documenting the failed component, its inspection history, the rigging configuration used, and every contributing factor identified in part (i), not just "eyebolt failed."
• Engineering examination of the failed hardware — metallurgical/failure analysis of the fractured eyebolt assembly and any damaged cable to determine whether the failure mode was overload, fatigue, material defect, or improper installation, which determines which corrective action in part (ii) actually addresses the root cause.
• Inspect and re-certify all similar lifting hardware in service at the facility, not only the failed unit, since the same rigging error or hardware defect may be present on other cranes/lifts.
• Review and update the rigging procedure and JSA for moving this class of casting, incorporating the corrective actions from part (ii) into a written, trained-on procedure.
• Medical follow-up for the injured employee, and incident recording/reporting to the workplace's joint health and safety committee and, where the severity threshold is met, to the jurisdiction's OHS regulator.
• Communicate lessons learned across all shifts and crews using overhead cranes, so the corrective action is not confined to the specific workstation where the incident occurred.