A heavy-duty equipment technician is performing a diagnostic check on a hydraulic excavator in a busy shop. The technician notices that the high-pressure hydraulic lines are leaking slightly. What is the immediate and most critical safety action the technician should take before further investigation or repair?

Question: A heavy-duty equipment technician is performing a diagnostic check on a hydraulic excavator in a busy shop. The technician notices that the high-pressure hydraulic lines are leaking slightly. What is the immediate and most critical safety action the technician should take before further investigation or repair?

Answer options: ✅ Shut down the engine, activate the parking brake, and relieve all stored hydraulic pressure.

• Place an absorbent pad under the leak and continue the diagnostic check.
• Tighten the visible fittings on the hydraulic lines to stop the leak.
• Notify the supervisor and continue working, being careful to avoid the spray.

Correct answer: Shut down the engine, activate the parking brake, and relieve all stored hydraulic pressure.

Explanation: High-pressure hydraulic fluid can cause severe injury (e.g., injection injuries) if it contacts the skin. The immediate and most critical action is to shut down the system and relieve all stored energy to eliminate the hazard. Continuing to diagnose, attempting to tighten fittings under pressure, or working around the leak without depressurizing are dangerous practices.