Gauges are available to alert the pilot vibration limits in which engine sections?

• A. Gauges alert the pilot vibration limits in N1 only
• B. Gauges alert the pilot vibration limits in N2 only
• C. Gauges alert the pilot vibration limits in both N1 and N2
• D. Gauges alert the pilot vibration limits in neither

Answer: (C)

Vibration can show up in either rotating section of a multispool engine, so cockpit gauges are provided for both. The N1 spool (typically the low‑pressure system, including the fan and first stages of the compressor) and the N2 spool (the high‑pressure system, including the core compressor and turbines) can develop vibration independently due to different fault sources like blade wear, imbalance, or bearing issues. Monitoring both ensures that a problem in either the low‑pressure or high‑pressure side is detected early, and the crew can take appropriate action before damage progresses. Relying on a single spool’s gauge could miss issues on the other spool, which is why gauges alert vibration limits in both N1 and N2.