The Wednesday Morning Ritual
Every Wednesday at 9 AM, Ahmed walks to Pump P-447, opens the inspection panel, checks the bearing temperature, listens for unusual vibration, closes the panel, and marks the PM complete in Maximo.
P-447 runs 24/7 in a water treatment plant.
The PM happens every Wednesday because that’s what the schedule says.
Here’s the problem: that bearing will fail based on operating hours, not calendar days.
The bearing doesn’t know it’s Wednesday.
The Calendar-Based PM Illusion
Real example from a manufacturing plant in Egypt, 2025:
Motor M-203 was scheduled for monthly lubrication. It runs 16 hours per day, so monthly PM equals every 480 operating hours.
Except production varied:
- January: 520 operating hours
- February: 380 operating hours
- March: 610 operating hours
February’s PM happened too early. The bearing still had lubrication.
March’s PM happened too late. The bearing ran dry for 130 hours.
Result: bearing failed in April.
The PM schedule said “monthly.” The bearing needed “every 500 operating hours.”
What Meter-Based Scheduling Looks Like
Instead of “PM every 30 days,” you use “PM every 500 operating hours.”
Maximo setup: Create a meter on the asset (RUNHOURS), link the PM to that meter (Frequency: 500 hours).
Maximo generates the PM when the meter reaches 500, 1000, 1500.
Real example from a hospital HVAC system in Saudi Arabia, 2024:
Chiller package with 4 compressors. Old schedule: monthly filter change for all 4 units.
Problem: units ran different hours.
- Compressor 1: 720 hours/month (constant use)
- Compressor 2: 480 hours/month (office hours only)
- Compressor 3: 620 hours/month (high use)
- Compressor 4: 290 hours/month (backup)
Changed to meter-based: PM triggers every 600 operating hours per compressor.
Result after 12 months:
- Compressor 1: 12 filter changes (was 12)
- Compressor 2: 8 filter changes (was 12, saved 4)
- Compressor 3: 10 filter changes (was 12, saved 2)
- Compressor 4: 5 filter changes (was 12, saved 7)
Savings: 13 unnecessary changes × $180 = $2,340 Labor savings: 9.75 hours freed up
Small example. Multiply across 200 assets.
The Condition-Based Alternative
Some equipment shouldn’t have scheduled PMs at all.
Example from a university campus in Saudi Arabia, 2025:
12 cooling tower fans. Old schedule: monthly inspection × 12 fans = 144 inspections per year.
Changed to condition-based: vibration sensors on all 12 fans, automated alert when threshold exceeded.
Result after 18 months:
- Inspections triggered: 31 (vs 216 scheduled)
- Failures caught early: 6
- Failures missed: 0
- Labor hours saved: 185 hours × $45/hour = $8,325
Key insight: 185 of those 216 inspections found nothing wrong.
Condition monitoring found 6 real problems early.
The Four PM Strategies
Calendar-Based: Best for regulatory compliance (fire extinguisher annual inspection).
Meter-Based: Best for measurable runtime (generator oil change every 500 hours).
Condition-Based: Best for critical assets with sensors (bearing replacement when vibration threshold exceeded).
Hybrid: Best for critical equipment (pump inspected every 1000 hours OR every 6 months, whichever comes first).
How to Audit Your PM Schedule
Pull PM effectiveness data:
ASSETNUM, PMNUM,
COUNT(*) AS PM_COUNT,
SUM(CASE WHEN FINDING = ‘ISSUE_FOUND’ THEN 1 ELSE 0 END) AS ISSUES_FOUND
FROM WORKORDER
WHERE WORKTYPE = ‘PM’ AND STATUSDATE > ‘2024-01-01’
GROUP BY ASSETNUM, PMNUM
Look for:
- PMs with 0 issues found in 12+ completions → Too frequent
- PMs where issues found over 80% of time → Too infrequent
Calculate PM waste:
Conveyor system in Egypt:
- PM: Monthly belt tension check
- Labor: 30 minutes, Rate: $35/hour
- Issues found in 12 months: 0
Waste = 12 × 0.5 × $35 = $210 per year per conveyor
18 conveyors = $3,780 annual waste on one PM task.
The PM Frequency Formula
Optimal PM Frequency = MTBF × 0.5 to 0.7
Example: Pump bearing MTBF = 8,000 operating hours
Optimal PM: 8,000 × 0.6 = 4,800 operating hours
Real case from power generation in Egypt, 2025:
Turbine blade inspection. Previous: Every 6 months.
Failure history: MTBF = 4,200 hours
New schedule: Every 2,500 operating hours
Result: Caught 2 early-stage blade cracks before catastrophic failure. Previous schedule would have missed both.
What to Do Sunday
Week 1: List your top 20 most expensive assets.
Week 2: Check PM effectiveness for each.
Week 3: Calculate failure frequency.
Week 4: Pick 5 assets where operating hours vary. Test meter-based scheduling for 90 days.
The Real Numbers
Manufacturing plant, 450 assets, 2024:
Calendar-based: 3,600 PMs per year, $181,440 labor cost
After audit: 40% of PMs found zero issues in 12+ months.
Optimization: Eliminated 920 PMs annually
New cost: $135,072
Annual savings: $46,368
Payback: 4 months
Final Thought
If your PM schedule was designed around a calendar instead of how equipment actually degrades, you’re maintaining a schedule, not maintaining equipment.
The calendar doesn’t care if your bearing fails.
Your operating hours, vibration levels, and temperature do.
Need a PM effectiveness audit? Contact Innexa for a PM schedule optimization review.
About Innexa IT Solutions
Innexa works exclusively with IBM Maximo and Maximo Application Suite for asset-intensive organizations across Egypt and the GCC. We support clients in building asset performance capabilities through disciplined data practices, integration clarity, and practical execution roadmaps grounded in real operational environments.
