What is the most critical functional test to perform on a load moment indicator (LMI) system before operation?

The most critical functional test to perform on a load moment indicator (LMI) system before operation is to verify its accuracy by comparing the LMI's displayed load, radius, and boom angle readings with actual measurements obtained using calibrated measuring devices. An LMI is a safety device that monitors the crane's load, radius, and boom angle to prevent overloading and potential tipping. The test involves lifting a known weight at various boom angles and radii and comparing the LMI readings to the actual values. If the LMI readings deviate significantly from the actual measurements, the LMI must be recalibrated by a qualified technician before the crane is put into service. This ensures the LMI is accurately calculating the crane's capacity and providing reliable warnings to the operator. For example, if the LMI indicates a load of 10,000 lbs at a 40-foot radius, this should be verified with a calibrated load cell and measuring tape to confirm the accuracy of the system. Failing this test means the LMI cannot be trusted to prevent overloads, creating a significant safety hazard.