Pre-Operation Inspection Findings on a High-Hour Derrick
During a morning pre-operation inspection, a 2012 digger derrick with 6,800 hours shows four findings. The winch wire rope has three broken wires in one lay near the lower sheave and a kink 4 ft from the drum. The right outrigger cylinder rod has a thin oil film but no drip after cycling. The boom lift cylinder hose has a chafed outer jacket with the reinforcement visible but no leak. The outrigger warning alarm does not sound when the right rear outrigger is extended, although the light works. The operator wants to set three poles because the crew has a road closure permit valid only until 11 a.m. The supervisor says the wire rope damage is normal wear and the alarm can be checked at lunch. The machine annual inspection sticker is current.
1. Which findings require the machine to be removed from service before work, and why?
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The wire rope damage requires removal from service. Three broken wires in one lay plus a kink near the drum is not normal wear; a kink can indicate a shock load or improper spooling, and broken wires reduce strength and can damage sheaves. The chafed hose with reinforcement visible also requires removal from service or replacement before use, because the reinforcement is the pressure-containing layer and the hose can fail suddenly under boom lift pressure. The inoperative outrigger alarm is a safety-device failure: the light working does not prove the alarm will warn personnel when an outrigger is not properly deployed. The thin oil film on the outrigger rod is the only finding that may not automatically remove the machine from service if it is truly a film with no drip after cycling, but it must be cleaned, monitored, and evaluated against the manufacturer's criteria. The road closure permit does not override safety defects.
2. How should the operator document and return the machine to service after repairs?
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The operator should record each deficiency on the inspection form, tag the machine out of service, and notify the supervisor in writing. Repairs should be made by qualified personnel using the manufacturer's parts and procedures. After repair, the affected systems need a function check: cycle the outriggers and verify the alarm and light, pressure-test the hose and inspect for leaks, and inspect the wire rope installation and spooling. If the manufacturer or employer requires a load test or nondestructive inspection after wire-rope replacement, complete it before returning to work. The repair should be documented with the date, part replaced, technician, and test results. The operator should then perform a new pre-operation inspection and confirm the machine is complete before accepting it for service.
3. What is wrong with the supervisor's reasoning?
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The supervisor is treating schedule pressure as a reason to defer safety defects. 'Normal wear' is not a valid category for broken wires and a kink without comparing the condition to the removal criteria and the manufacturer's inspection requirements. Deferring the alarm to lunch assumes nothing will go wrong during the morning, but the alarm is specifically there to protect ground personnel during outrigger deployment. A current annual inspection sticker does not mean the machine is fit for the next shift; daily and pre-operation inspections exist to catch conditions that develop between inspections. The correct decision is to remove the machine from service until the defects are corrected, then reassess the schedule.