A gas turbine that ran 8,000 hours isn't due for the same inspection as one that ran 8,000 hours with 400 starts — because every start-stop cycle punishes the hot section far more than steady running. Track fired hours alone and a peaker unit reaches its combustion inspection worn out and overdue, while a baseload unit gets inspected too early. The right clock is equivalent operating hours. OXMAINT AI is AI-powered maintenance management software (CMMS) that counts EOH per turbine — hours, starts, trips and firing weighted together — and drives every inspection, borescope and condition alert from it. Book a demo to see EOH-based scheduling.
Power Generation · Gas Turbine Maintenance
Schedule the Turbine on Equivalent Hours, Not the Calendar
Fired hours tell half the story; starts and trips age the hot section far faster. OXMAINT AI tracks equivalent operating hours per unit and pins every combustion, hot-gas-path and major inspection to it — with borescope findings, vibration and temperature trended alongside — so the turbine is opened up exactly when it needs to be.
- 1Count EOH
- 2Trigger the inspection
- 3Log borescope findings
- 4Trend & predict
What one start really costs
10–20equiv. hours
of thermal shock added by a single start-stop cycle
Fired hoursthe base count
+ startsthermal cycling
+ trips & peak firingextra stress
= Equivalent Operating Hours, the true clock. Source: OxMaint gas-turbine maintenance guidance.
Why Starts Age a Turbine Faster Than Hours
A baseload unit and a peaker can log the same fired hours and be in completely different condition. The difference is thermal cycling — and it's why EOH, not the calendar, protects the hot section. Start a free trial to count it correctly.
Baseload unit
Runs long and steady, few starts. Fired hours and EOH stay close — the turbine ages roughly with the clock.
EOH ≈ fired hours
Peaker unit
Starts and stops constantly. Each cycle adds 10–20 equivalent hours, so EOH races ahead of fired hours — and inspections come due sooner.
EOH ≫ fired hours
Each start adds roughly 10–20 equivalent hours of thermal shock, which is why high-start peaker units reach inspection thresholds well before their raw fired hours suggest. Source: OxMaint gas-turbine maintenance guide.
The Three Inspection Milestones
Gas turbine maintenance builds toward three progressively deeper inspections, each triggered by EOH or factored starts. Track the count and none of them sneaks up on you. Book a demo to map your intervals.
Combustion Inspection~8,000–12,000 fired hrs
Fuel nozzles, combustion liners, transition pieces, crossfire tubes and flame detectors — the early-wear check, done a couple of times before each HGPI.
Hot Gas Path Inspection~24,000 hrs / 800 factored starts
Full CI scope plus turbine blades, nozzles and shrouds, with the casing opened for rotor access — the mid-life deep look.
Major Inspection~40,000–48,000 fired hrs
Flange-to-flange teardown — compressor, rotor and bearings — where rotor replacement or life-extension is decided.
Intervals are typical OEM-style ranges; your exact thresholds depend on the frame, duty and OEM programme. CI runs on fired hours, HGPI on hours or factored starts, MI at the deep overhaul point. Source: OxMaint gas-turbine inspection guidance.
Never Miss an EOH Threshold Again
See how OXMAINT AI recalculates EOH continuously and raises the combustion, hot-gas-path or major inspection as the count crosses each threshold — with the scope attached.
Borescope: The Look Inside Between Overhauls
You don't tear down a turbine to know how it's doing — you borescope it. Structured, digital findings between major inspections catch blade and combustor wear early. Start a free trial to log borescope findings.
Blades & vanes
Cracking, coating loss, tip rub and erosion on the hot-section aerofoils.
Combustors
Liner and transition-piece condition — the first parts to show thermal distress.
Fuel nozzles
Fouling, wear and spray-pattern clues that drive combustion trouble.
Digital record
Findings logged to the unit with images, so wear is trended over time, not re-found each visit.
The Early-Warning Layer: Condition Monitoring
Between scheduled inspections, a handful of trended readings protect the schedule — flagging trouble before it forces an unplanned outage. Book a demo to trend them per unit.
Vibration
Rising or shifting vibration is the earliest sign of rotor imbalance, bearing wear or blade damage.
Exhaust temp spread
An uneven exhaust-temperature profile points to a combustor or fuel-nozzle problem before it worsens.
Compressor efficiency
A falling compressor performance signals fouling — a candidate for an online or offline wash.
Lube oil & bearings
Oil analysis and bearing temperature catch mechanical wear before it reaches a trip.
Condition parameters per gas-turbine maintenance practice — vibration, exhaust temperature spread, compressor efficiency, lube-oil and bearing data as the early-warning layer that protects the inspection schedule. Source: OxMaint gas-turbine guide.
How OXMAINT AI Runs Gas Turbine Maintenance
OXMAINT AI is maintenance management software that counts EOH, triggers the right inspection, holds borescope and condition data, and turns a developing trend into a work order — the whole turbine programme on one record. Start a free trial to load your turbines.
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1
Count
Recalculate EOH from hours, starts, trips and firing continuously, per unit.
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2
Trigger
Raise the combustion, hot-gas-path or major inspection as EOH crosses each threshold.
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3
Inspect
Capture borescope findings and readings on structured digital checklists tied to the asset.
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4
Predict
Trend vibration, temperature and efficiency so a developing fault becomes a planned work order.
Frequently Asked Questions
What are equivalent operating hours?
A weighted count that adds fired hours, starts, trips and firing severity into one number — so a high-start turbine's real wear is captured, not just its running time.
Start a free trial to track EOH.
How much does one start count?
Roughly 10–20 equivalent hours of thermal shock, which is why peaker units that cycle often reach their inspections far sooner than their fired hours imply.
Book a demo to see the math.
What are the three main gas turbine inspections?
Combustion inspection (~8,000–12,000 fired hours), hot-gas-path inspection (~24,000 hours or 800 factored starts), and major inspection (~40,000–48,000 hours), each deeper than the last.
Start a free trial to schedule them.
Where does the borescope fit in?
Between the major inspections — a scheduled internal look at blades, combustors and nozzles that catches wear early without a teardown.
Book a demo to see the checklist.
Can OXMAINT AI predict turbine problems?
By trending vibration, exhaust temperature spread and compressor efficiency, it surfaces a developing fault as a planned work order before it forces an unplanned outage.
Start a free trial to trend them.
Run the Turbine on the Clock That Actually Matters
Count EOH, trigger every inspection on time, log borescope findings and trend condition — the whole gas turbine programme on one platform.
