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

AP4 Services
Aeroderivative Field Services

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.

Mechanical 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 Above Tasks

+Generator Minor Inspections & Maintenance

Controls Field Services

+DLE Mapping

+Exciter Troubleshooting

+Controls Troubleshooting and Logic Modifications

+Full Package Start-Up & Commissioning



AP4's parts division AP+M can provide a full range of replacement parts from basic consumables to combustion components.

MRO & Repair

AP+M's MRO capabilities include; hydraulic actuators (i.e. VBV, VSV VIGV actuators) and hydromechanical/pneumatic valves including Bleed Valves, CDP, Thrust Balance and Check Valves.

O&M Contracts

AP4 Services provides powerplant operations and maintenance (O&M) – including O&M supervision, maintenance planning & scheduling, engineering, consultancy, team training, and resident or outsourced engineers.



Using the latest technology, components, and lessons learned through decades of experience, AP4 Energy 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.