AP4 Group – Full-Service Heavy-Duty & Aeroderivative Industrial Gas Turbine Maintenance Provider.

About AP4 Power Services

AP4 Power Services is an aeroderivative field service provider of mechanical & controls field engineers.

Our field service engineers can provide 24/7 support to safely diagnose and complete both mechanical and controls troubleshooting & maintenance, from planned outages and project execution to unplanned outages and emergency call-outs.

Field Services

  • Full Borescope Inspections
  • Quarterly, Semi-Annual & Annual Package Inspections
  • Full Alignments and Alignment Verification
  • Vibration Troubleshooting
  • VSV Bushing Change Out & HPC Top Case Repairs
  • HP Recoup & Thrust Balance Checks
  • Fuel Nozzle Installation & Exchanges
  • Troubleshooting all Aspects of Package and Engine Problems
  • Preventive and Corrective Maintenance & Inspection
  • Gas Turbine Removal & Re-Installation (R&R)
  • Gas Turbine Preservation
  • Implementation of Service Bulletins
  • Provide Parts & Supporting Tooling for the Above Tasks
  • Generator Minor Inspections & Maintenance
  • Controls Field Services
  • DLE Mapping
  • Exciter Troubleshooting
  • Controls Troubleshooting and Logic Modifications
  • Full Package Start-Up & Commissioning

Our Solutions

Large Frame Controls Services Upgrades

AP4 Power Services specializes in controls, excitation, and LCI systems on GE™ heavy-duty gas and steam turbines. These services include a wide variety of controls maintenance, troubleshooting, and system upgrades. Our OEM-trained field engineers are here to ensure your equipment operations are reliable and efficient.

Turbine System Upgrades

Power plant personnel look to AP4 Power Services when they are seeking a trusted non-OEM service provider that can help develop and implement customized controls system projects. We are a trusted installation partner for many non-OEM equipment vendors throughout the industry.

Aeroderivative Field Services

From basic troubleshooting to DLE Mapping and mechanical service and maintenance, AP4 Power Services can meet all of your aeroderivative needs. Our expert team of Controls & Mechanical Field Engineers are ready and able to provide the on-site support you require.

Industry Benefits


Using the latest technology, components, and lessons learned through decades of experience, AP4 Power Services can ensure complete reliability for both start-up and continuous operation.


This is the key to success in today’s competitive power markets. Heat Rate, Capacity, Start-Up, and Maintenance Costs are critical to the success of aging power plants.


Spending good money where it makes the most difference! We understand that O&M budgets are shrinking, so we work with the plants to understand where and when to repair, replace, or upgrade for maximum return.


Aging systems can continue to provide reliable service for many years to come with the proper service, maintenance, and repairs. Push your upgrades out 5-10 years with confidence.