RAM Preventive & Predictive Maintenance 3

Question 1

In ultrasonic predictive maintenance, what physical phenomenon is being detected when monitoring for compressed air leaks or bearing defects?

Accepted Answer

High-frequency acoustic emissions above 20 kHz generated by turbulence or stress

Answer

Ultrasonic testing detects high-frequency sound waves (typically 20–100 kHz) produced by gas turbulence at leak points or stress-wave emissions from bearing defects and electrical arcing.

Question 2

What does a 'fast Fourier transform' (FFT) spectrum analyzer do in a vibration-based predictive maintenance program?

Accepted Answer

Converts time-domain vibration waveform data into a frequency-domain spectrum

Answer

FFT converts a time-domain vibration signal into a frequency-domain spectrum, revealing the amplitude of each frequency component and enabling identification of specific fault frequencies.

Question 3

A predictive maintenance program uses motor current signature analysis (MCSA). Which fault is this technique specifically effective at detecting?

Accepted Answer

Rotor bar cracks or broken rotor bars in induction motors

Answer

MCSA detects anomalies in the stator current spectrum; broken or cracked rotor bars produce characteristic sidebands around the supply frequency at specific slip-related intervals.

Question 4

Which parameter is used to define the 'age exploration' strategy in RCM when no historical failure data exists for a component?

Accepted Answer

A conservative initial interval that is extended only if no failures are found at inspection

Answer

When failure data is absent, RCM recommends starting with a conservative (short) interval and extending it incrementally—'age exploration'—based on the condition found at each inspection.

Question 5

ISO 10816-3 vibration severity standards classify machinery vibration based on which measurement?

Accepted Answer

Peak vibration velocity in mm/s measured on the bearing housing

Answer

ISO 10816-3 specifies evaluation zones (A through D) for industrial machines based on the broadband RMS vibration velocity (mm/s) measured on non-rotating parts such as bearing housings.

(RAM) Reliability, Availability, and Maintainability Certified Professional Practice Test

(RAM) Reliability, Availability, and Maintainability Certified Professional Practice Test

RAM Preventive & Predictive Maintenance 3