Analysis of a Root Cause Analysis

Note: RCA के बारे में मैं हमेशा कहूंगा की RCA यानि रुट कोज़ एनालिसिस तभी या साथ- साथ हो जाना चाहिए जब आप किसी स्टॉपेज या फेलियर के लिए करेक्टिव एक्शन लेकर प्लांट को रीस्टार्ट करते हो। बाद में किया गया RCA  बेकार है। यह पहली बात है। 

दूसरी और उससे भी ज्यादा जरुरी बात यह है की जो बंदा RCA कर रहा है उसी के ऊपर RCA का आख़री एक्शन आकर रुकेगा। अगर ऐसा नहीं हो तो मान लीजिये की या तो  RCA अधूरा या गलत है या फिर RCA किसी ओर बंदे ने किया है।  

Regarding RCA - Root Cause Analysis - I would always assert that it should be conducted either simultaneously with, or immediately following, the implementation of corrective actions taken to restart the plant after a stoppage or failure. An RCA performed at a later stage is futile. That is the first point.

The second, and even more critical, point is that the final action resulting from the RCA must ultimately rest with the very individual who conducted the analysis. If this is not the case, you can assume that the RCA is either incomplete or flawed OR that it was performed by the wrong person entirely.

Here, for an example, I have done an ANALYSIS of a ROOT CAUSE ANALYSIS which was done for a stoppage of the plant, 2 days later and that too after reminders. 

Major Weaknesses in this RCA

1. Root cause is still too generic

The statement: “Actual screw load exceeded motor capacity” is not the real root cause.

This only describes what happened, not why it happened repeatedly.

The RCA should further investigate:

• Why did load increase?
• Was material moisture high?
• Was screw pitch unsuitable?
• Was buildup occurring?
• Was bearing partially seized?
• Was alignment poor?
• Was there process choking upstream?
• Was feed control unstable?
• Was design calculation incorrect?

Without this, the RCA remains at a “symptom level”.

2. No evidence or measurements included

A strong RCA should contain data such as:

• Motor rated current vs actual current
• Load trend
• Conveyor load %
• Ampere history
• Motor temperature
• Gearbox condition
• Bearing inspection findings
• VFD frequency
• Process conditions during trip

Currently the RCA is mostly opinion-based.

3. Oversized motor may hide the problem

Changing motor from:

2.2 kW → 3.7 kW

may solve the symptom temporarily, but it can also:

• transfer overload to gearbox,
• increase mechanical stress,
• mask process issues.

Before upgrading motor size, there should be:

• load calculation,
• torque calculation,
• design validation.

Otherwise this becomes “problem shifting”.

4. No distinction between:

• Root Cause
• Contributing Cause
• Corrective Action
• Preventive Action

These are mixed together.

Example: “High friction/material resistance” could be: a contributing cause,

not necessarily the final root cause.

5. No verification of corrective action effectiveness

A proper RCA should answer:

• Did current reduce after motor replacement?
• Is screw load now stable?
• What is the new operating margin?
• Has the issue recurred?
• For how many days/months monitored?

Without validation, RCA closure is weak.

6. Human and system factors missing

The RCA only focuses on equipment.

But effective industrial RCA should also check:

• Maintenance factors
• Lubrication frequency
• Inspection quality
• PM checklist adequacy
• Operational factors
• Sudden feeding practices
• Material consistency
• Start-up sequence
• Design factors
• Original motor sizing basis
• Safety factor used
• Historical overload pattern

What a Stronger RCA Would Look Like

A more mature RCA would include:

A. Problem Statement

Precise event description with time and impact.

Example: “PC coal firing screw conveyor tripped at 12:55 PM due to overload causing kiln stoppage for 15 minutes.”

B. Evidence Section

Include:

• Current trend graph
• Photographs
• Inspection findings
• Bearing condition
• Material condition

C. Technical Analysis

Example:

• Actual load torque estimated at X Nm
• Motor rated torque only Y Nm
• Material buildup increased drag by Z%

D. Root Cause Classification

Separate:

Type                         Example

Immediate Cause         Motor overload

Contributing Cause Material buildup

Root Cause                 Undersized motor selection + inadequate cleaning frequency

System Cause         No periodic load monitoring

E. SMART Corrective Actions

Instead of: “Monitor current regularly”

write:

“Electrical department shall record screw motor current once per shift for 30 days and review trend weekly.”

This makes accountability measurable.

Most Important Improvement Needed

The biggest improvement required is:

Move from “failure description” to “failure mechanism analysis”.

Currently the RCA mostly explains: what happened.

A stronger RCA explains: why the system allowed it to happen.

That difference separates an average RCA from a high-quality engineering RCA.

Final Assessment

Area                                 Rating

Logical flow                         7/10

Technical depth                 5/10

Evidence-based analysis         3/10

Corrective actions                 6/10

Preventive robustness             5/10

Overall effectiveness         6/10

This RCA is acceptable for a basic plant-level closure, but not yet strong enough for a reliability-engineering standard or management review aimed at preventing recurrence permanently.