PE Mechanical Exam Structure

The PE Mechanical exam is a computer-based, open-book exam (NCEES PE Mechanical Reference Handbook only) consisting of 80 multiple-choice questions in 5.5 hours. Like the PE Civil exam, it is divided into three modules and you select the one that best matches your practice area:

  • HVAC and Refrigeration — heating, cooling, psychrometrics, refrigeration cycles, heat transfer, energy codes
  • Machine Design and Materials — stress analysis, fatigue, power transmission, bearings, shafts, and material selection
  • Thermal and Fluid Systems (TFS) — thermodynamics, fluid mechanics, heat exchangers, pump systems, and power cycles

HVAC and Refrigeration Module

This is the most popular module among practicing mechanical engineers in commercial building design. Key topic areas include psychrometric processes (sensible heating, cooling and dehumidification, humidification, mixing), refrigeration cycles (vapor compression, COP calculations), ASHRAE standards (load calculations per ASHRAE 62.1, 90.1, energy efficiency), heat transfer through building envelopes, and cooling/heating load methodologies.

Know the psychrometric chart cold — the exam will present problems where you must read or calculate wet-bulb, dry-bulb, dew point, and relative humidity relationships. Practice reading the chart quickly and understand what each line represents.

Machine Design and Materials Module

This module covers topics more common to manufacturing and product design engineers. Key areas: stress and strain analysis, combined loading, fatigue analysis using S-N curves and Goodman diagram, columns (Euler and Johnson buckling), pressure vessels, bolted joints, welded connections, bearings (L10 life calculations), gears, belts and chains, shafts, clutches and brakes, and material properties.

The NCEES handbook has extensive tables for material properties, stress concentration factors, and S-N curves. Knowing where to find these quickly is critical.

Thermal and Fluid Systems Module

TFS covers thermodynamics (first and second law, Rankine and Brayton cycles, entropy), fluid mechanics (Bernoulli, pipe flow, Moody chart, pump systems), heat transfer (conduction, convection, radiation, heat exchanger NTU-effectiveness method), and combined systems (cogeneration, waste heat recovery).

Pump affinity laws (Q ∝ N, H ∝ N², P ∝ N³) and system curve analysis appear frequently. Know how to plot a pump curve and system curve intersection and how parallel/series pump configurations change the operating point.

Study Resources

The most widely used PE Mechanical prep courses are PPI (School of Professional Engineers), School of PE, and Brightwood Engineering. PPI's Practice Problems for the PE Mechanical Exam is the most comprehensive problem bank. Supplement with ASHRAE handbooks (Fundamentals and HVAC Applications) for the HVAC module — while these can't be brought in, studying them builds the conceptual understanding needed to use the NCEES handbook effectively during the exam.

Passing Score and Statistics

NCEES does not publish the exact cut score, but PE Mechanical pass rates for first-time takers range from 65–75% depending on the module. HVAC and Refrigeration tends to have strong pass rates among engineers actively practicing in that field. The biggest cause of failure is insufficient practice problem work — reading and understanding is not the same as being able to solve problems under time pressure.