Interview Questions for RCA Cleaning

Root Cause Analysis (RCA) in cleaning isn’t just about fixing a mess; it’s about understanding why the mess happened in the first place. It’s a systematic approach to identifying the underlying causes of cleaning-related problems, preventing their recurrence, and improving overall cleaning effectiveness. Think of it like diagnosing a medical issue – you wouldn’t just treat the symptom (a rash), you’d investigate the underlying cause (an allergy).

In a cleaning context, RCA involves a structured investigation to determine the root cause of issues such as inadequate cleaning, persistent contamination, damage to surfaces, or inefficiencies in the cleaning process. This involves gathering data, analyzing the situation, and identifying the root cause(s), rather than simply addressing the immediate visible problem.

The ‘Five Whys’ is a simple yet powerful iterative interrogative technique used in RCA. It involves repeatedly asking ‘Why?’ to peel back layers of explanation and uncover the root cause. Let’s say a floor isn’t clean:

• Why 1: The floor is dirty because the cleaning solution wasn’t effective.
• Why 2: The cleaning solution wasn’t effective because it was diluted incorrectly.
• Why 3: It was diluted incorrectly because the instructions were unclear.
• Why 4: The instructions were unclear because they weren’t translated properly.
• Why 5: They weren’t translated properly because the translation service was outsourced to a less-qualified provider.

In this example, the root cause is the selection of an unqualified translation service. Simply re-cleaning the floor only addresses the symptom, not the underlying problem. The Five Whys helps systematically drill down to find the true root cause.

Corrective actions address the immediate problem, while preventative actions aim to stop it from happening again. Imagine a spill on the factory floor.

Corrective action: Cleaning up the spill immediately to prevent accidents. This is a short-term solution.

Preventative action: Investigating why the spill occurred (was there a leak? Was the material improperly handled?), implementing new safety protocols (better spill containment, improved material handling), and providing additional training to prevent future incidents. This addresses the root cause and prevents recurrence.

In RCA cleaning, both are crucial. Corrective actions deal with the present situation, while preventative actions prevent future occurrences, resulting in a more efficient and safer cleaning process.

Identifying potential cleaning process failures requires a proactive approach, combining observation with data analysis. Here’s a multi-pronged strategy:

• Regular Inspections: Conduct routine visual checks of cleaning equipment, supplies, and work areas for signs of wear, tear, or contamination.
• Data Monitoring: Track key cleaning metrics such as cleaning time, chemical usage, and defect rates. Unexpected deviations from the norm signal potential problems.
• Feedback Mechanisms: Establish channels for cleaning staff to report issues, near misses, or suggestions for improvement. Anonymous feedback systems can be particularly valuable.
• Process Mapping: Create visual representations of the cleaning process to identify bottlenecks, redundancies, or potential points of failure.
• Predictive Maintenance: Schedule preventative maintenance on cleaning equipment to reduce the likelihood of breakdowns.

Combining these methods allows for early identification of potential problems, enabling preventative actions and minimizing disruptions.

Common root causes of cleaning-related issues in manufacturing environments include:

• Inadequate Training: Staff may not have the necessary skills or knowledge to perform cleaning tasks effectively.
• Insufficient Resources: Lack of proper cleaning equipment, chemicals, or personal protective equipment (PPE) can compromise cleaning quality.
• Poorly Defined Procedures: Ambiguous or incomplete cleaning protocols can lead to inconsistencies and errors.
• Equipment Malfunction: Faulty cleaning machines can result in subpar cleaning and potential safety hazards.
• Lack of Cleaning Verification: Absence of a robust system to verify the effectiveness of cleaning can lead to undetected contamination.
• Environmental Factors: High humidity, temperature fluctuations, or dust levels can affect cleaning effectiveness.

Identifying the root cause often involves considering a combination of factors rather than a single isolated issue.

Data analysis is crucial for effective RCA in cleaning. In my experience, I’ve used data from various sources, including cleaning logs, equipment maintenance records, defect reports, and environmental monitoring data. I’ve employed statistical methods to identify trends and patterns, such as:

• Trend Analysis: Identifying increasing trends in cleaning times or defect rates that suggest underlying problems.
• Control Charts: Monitoring key performance indicators (KPIs) to detect significant deviations from established baselines.
• Regression Analysis: Investigating the relationship between different variables (e.g., cleaning chemical concentration and cleaning effectiveness) to identify causal relationships.

This data-driven approach goes beyond intuition; it provides objective evidence to support RCA conclusions and inform the implementation of effective corrective and preventative actions. For example, identifying a correlation between a specific cleaning chemical and an increase in equipment failures would point towards a potential root cause.

Thorough documentation of the RCA process is essential for transparency, accountability, and continuous improvement. My preferred method involves a structured report that includes:

• Problem Statement: A clear and concise description of the cleaning-related issue.
• Data Collection: Details of the data gathered (e.g., cleaning logs, photos, interviews).
• Root Cause Analysis: A detailed explanation of the steps taken to identify the root cause(s), including the use of techniques like the Five Whys.
• Corrective Actions: A description of immediate actions taken to resolve the problem.
• Preventative Actions: A plan to prevent future occurrences of the issue.
• Action Owners: Assignment of responsibilities for implementing corrective and preventative actions.
• Timeline: A schedule for completing actions and follow-up reviews.

I typically use a combination of written reports, flowcharts, and diagrams to create comprehensive documentation that is easily understandable and shareable across different teams.

Prioritizing corrective actions after a Root Cause Analysis (RCA) in cleaning validation involves a risk-based approach. We assess both the likelihood of the problem recurring (risk) and the potential impact on product quality, patient safety, or regulatory compliance. A simple risk matrix is often used. This matrix typically has axes representing the likelihood of occurrence and the severity of the impact. Each corrective action is then plotted on this matrix.

For example, a high-likelihood, high-impact issue (like a recurring contamination event) would be prioritized immediately above a low-likelihood, low-impact issue (like a minor procedural deviation). We use a combination of qualitative and quantitative data to populate this matrix. Qualitative data might come from expert opinions, historical data, and hazard analysis, while quantitative data might include defect rates, environmental monitoring results, and deviation frequency.

• High Risk, High Impact: Immediate action required. This may involve halting production, implementing emergency controls, and initiating a full-scale investigation.
• High Risk, Low Impact: Swift action needed. This might include improved training, process tweaks, and enhanced monitoring.
• Low Risk, High Impact: Action planned for the near term. This could involve implementing preventative maintenance or a more robust cleaning procedure.
• Low Risk, Low Impact: Action can be deferred, potentially incorporated into future process improvements.

Measuring the effectiveness of corrective actions post-RCA relies on a combination of methods. We monitor key indicators – both leading and lagging – to assess if the root cause has been truly addressed and whether the implemented solutions are sustainable. Leading indicators predict future problems (e.g., improved training scores, compliance with new procedures), while lagging indicators reflect past performance (e.g., reduced defect rates, improved environmental monitoring results).

For example, if a recurring cleaning failure was linked to inadequate training, post-RCA actions might include revised training materials, hands-on workshops, and competency assessments. The effectiveness would be gauged by tracking the improvements in training scores (leading indicator) and reductions in cleaning failures (lagging indicator) over a defined period. We also use statistical process control (SPC) charts to monitor cleaning validation data to ensure consistent performance over time and to detect any trends that indicate potential issues.

Cleaning validation techniques aim to demonstrate that cleaning procedures effectively remove residues from equipment and surfaces to acceptable levels. Common techniques include:

• Residue Analysis: This is the most common method, involving swabbing or rinsing equipment surfaces and analyzing the collected samples for residual drug product or cleaning agents using techniques like HPLC (High-Performance Liquid Chromatography), GC (Gas Chromatography), or spectrophotometry. The results are compared to pre-determined acceptance criteria.
• Visual Inspection: This is a basic but important method for detecting visible residues or debris. It serves as an initial screening step before more sophisticated analyses. It often involves a checklist and documented observations.
• Microbial Testing: This is particularly relevant in pharmaceutical and medical device industries. Tests are conducted to verify the absence of microorganisms that could contaminate subsequent products.
• ATP Bioluminescence: This rapid method uses ATP (adenosine triphosphate) detection to measure microbial contamination levels. Higher ATP levels indicate a greater presence of microorganisms.

The choice of technique depends on the specific product, equipment, and regulatory requirements.

My experience encompasses various cleaning methods, each suited to different applications:

• CIP (Clean-in-Place): This automated system uses chemicals, heat, and circulation to clean equipment without disassembly. Ideal for large-scale manufacturing processes and closed systems. It requires a high level of instrumentation and validation.
• COP (Clean-out-of-Place): This involves manual cleaning of equipment after disassembly. Suitable for smaller-scale operations or equipment with complex geometries. It requires rigorous documentation and standard operating procedures.
• Manual Cleaning: This is the most basic method involving manual scrubbing, rinsing, and wiping. Appropriate for simple surfaces but labor-intensive and less consistent compared to automated methods.
• Ultrasonic Cleaning: This method utilizes high-frequency sound waves to dislodge residues. Effective for intricate equipment and delicate components.

The selection of the most appropriate method considers factors like the type of residue, the material of the equipment, the level of automation, regulatory requirements, and cost considerations. For example, CIP is preferred for large bioreactors, while manual cleaning might be suitable for smaller laboratory glassware.

Handling conflicting information during an RCA requires a structured and objective approach. We begin by clearly documenting all perspectives, including dissenting opinions. We then carefully examine the underlying data and evidence supporting each viewpoint. This may involve reviewing documentation, conducting interviews, and repeating experiments or tests to validate data quality. If necessary, we involve a subject matter expert or convene a larger team to provide input and weigh the evidence objectively. The goal is not to force a consensus, but to analyze data thoroughly and arrive at a conclusion based on the best available evidence. Sometimes, the root cause may be multifactorial, encompassing elements of several proposed solutions.

In a previous role, we experienced persistent particulate contamination in a pharmaceutical filling line. Initial investigations focused on poor cleaning, but the problem persisted despite intensified cleaning efforts. The RCA employed a structured approach, including: reviewing batch records, conducting environmental monitoring, interviewing operators, and analyzing cleaning validation data.

The root cause was eventually identified as a faulty air filter in the cleanroom, allowing particulate matter to settle on the filling equipment. The solution involved replacing the faulty air filter, implementing a more rigorous filter replacement schedule, and improving cleanroom environmental monitoring protocols. Following the corrective action, the particulate contamination was eliminated, and the filling line productivity significantly increased.

Compliance with cleaning regulations and standards is paramount. We adhere to guidelines such as GMP (Good Manufacturing Practices), ISO 14644 (Cleanrooms and associated controlled environments), and relevant national and international regulations. This involves maintaining comprehensive documentation, including cleaning validation protocols and reports, standard operating procedures, training records, and deviation investigations. Regular internal audits, alongside external audits by regulatory agencies, ensure our adherence to established standards. We utilize a Quality Management System (QMS) to track and manage all aspects of cleaning and cleaning validation, ensuring compliance and continuous improvement. This includes the implementation of CAPA (Corrective and Preventative Action) procedures to address any deviations or issues promptly and effectively.

My familiarity with cleaning agents and their compatibility with various materials is extensive. I understand that selecting the wrong agent can damage equipment, compromise the cleaning process, or even create hazardous situations. My knowledge covers a wide range, from common solvents like isopropyl alcohol (IPA) and acetone, to specialized cleaning solutions for delicate materials like silicon wafers or optical lenses. I’m adept at understanding Material Safety Data Sheets (MSDS) to ensure safe handling and appropriate selection. For instance, IPA is excellent for cleaning many surfaces but can damage some plastics. Acetone is a powerful solvent but requires careful handling due to its flammability. For stainless steel, I might choose a specific alkaline cleaner optimized for its resistance to corrosion. For delicate optics, I might use a specially formulated low-residue cleaner. The selection process always prioritizes compatibility, efficacy and safety.

My experience includes working with various materials including metals (stainless steel, aluminum), polymers (polycarbonate, PTFE), and glass. I consider factors such as surface finish, material sensitivity, and the specific contaminants to be removed when selecting a cleaning agent. My approach is always risk-averse; I’d rather use a less aggressive cleaner than risk damage to the equipment or the environment.

Safety is paramount in RCA cleaning investigations. My protocols always begin with a thorough risk assessment, reviewing the MSDS for all cleaning agents and equipment used. This includes identifying potential hazards like flammability, toxicity, and reactivity. I always wear appropriate Personal Protective Equipment (PPE), including gloves, eye protection, lab coats, and sometimes respirators, depending on the cleaning agents and the environment. I work in well-ventilated areas whenever possible, and I adhere strictly to spill response protocols, having absorbent materials and neutralizing agents readily available. Furthermore, I ensure all equipment is properly grounded to prevent electrostatic discharge (ESD) damage, especially crucial when dealing with sensitive electronics. Finally, I maintain detailed records of all chemicals used, concentrations, and procedures followed, ensuring traceability and accountability.

Communicating findings effectively is crucial. I typically present my RCA cleaning investigation results through a concise, well-structured report. This report includes a clear executive summary highlighting key findings and recommendations. The main body details the methodology employed, the data collected, the analysis performed, and the conclusions drawn. I use visual aids such as charts, graphs, and images to make the information easily digestible. I prefer clear, non-technical language where possible, adjusting the complexity to suit the audience (e.g., technical details for engineers, a high-level overview for management). Finally, I incorporate recommendations for preventing similar occurrences in the future, often including detailed procedural changes or equipment upgrades. An example might be recommending a change in cleaning frequency or implementing a new cleaning validation procedure to ensure consistency and effectiveness. I always welcome questions and facilitate open discussion after presenting the report.

The RCA cleaning process benefits from several tools and software. For example, I use calibrated instruments like spectrophotometers to measure the cleanliness of surfaces. Particle counters assist in quantifying particulate contamination. Microscopy techniques (optical and SEM) help in identifying the type and source of contaminants. Data management software helps in organizing and analyzing the large datasets generated during the cleaning process. Furthermore, specialized cleaning validation software can assist in documenting and tracking cleaning procedures, ensuring compliance with regulatory requirements. In specific cases, I might use software for statistical process control (SPC) to monitor and improve cleaning efficiency. Specific tools depend on the investigation’s scope and the materials involved. For example, I might use swabs and wipes for surface sampling, and specific cleaning validation software to document and track the cleaning process.

Ensuring data accuracy and completeness is critical. This involves meticulously documenting all aspects of the cleaning process, starting with the initial assessment of the contamination. I use standardized procedures and checklists to ensure consistency and minimize errors. All measurements and observations are recorded with appropriate units and uncertainties, and data is double-checked for accuracy. Chain-of-custody protocols are followed for samples to maintain their integrity. Traceability is maintained throughout the process, allowing for review and verification. I employ statistical methods to analyze the data, identify outliers, and assess the significance of findings. Any discrepancies or anomalies are investigated thoroughly before drawing conclusions. For example, if a particle counter shows an unexpectedly high particle count, I would re-sample, check the calibration of the instrument and investigate potential sources of contamination.

Key Performance Indicators (KPIs) for evaluating cleaning effectiveness include:

• Contamination levels: Measured by particle counts, microbial counts, or chemical residue analysis. Lower levels indicate better cleaning.
• Cleaning cycle time: Shorter cycle times suggest efficiency improvements.
• Cleaning solution consumption: Lower consumption indicates optimized cleaning processes and reduced waste.
• Cleaning validation pass rate: A high pass rate indicates consistent and effective cleaning.
• Defect rates: Reduced defect rates in downstream processes suggest that the cleaning process is successfully removing contaminants that would otherwise cause defects.
• Cost per cleaning cycle: Minimizing cost while maintaining effectiveness is a key goal.

Monitoring these KPIs allows for continuous improvement of the cleaning process and ensures its effectiveness in maintaining product quality and preventing contamination.

My experience encompasses various cleaning validation documentation types, including:

• Cleaning validation protocols: These detailed documents outline the methods and procedures used for cleaning validation studies.
• Cleaning validation reports: These reports summarize the results of cleaning validation studies, including data analysis and conclusions.
• Standard Operating Procedures (SOPs): These documents describe the standard steps for routine cleaning processes. They are crucial for maintaining consistency and reproducibility.
• Cleaning logs or batch records: These documents record the details of each cleaning event, including dates, times, personnel involved, chemicals used and equipment cleaned.
• Deviations and investigations: Documentation of any deviations from standard cleaning procedures and the investigations undertaken to determine root cause and corrective actions.

Understanding these different document types and their interrelationships is vital for ensuring compliance and demonstrating the effectiveness and control of the cleaning processes. I’m experienced in generating these documents to meet regulatory requirements (e.g., FDA, GMP) for pharmaceutical and medical device industries.

Preventing recurring cleaning issues requires a proactive, multi-faceted approach. It starts with a thorough understanding of the root cause (RCA) of the initial problem. Once identified, we implement preventative measures tailored to that specific cause. This often involves a combination of strategies.

• Process Improvements: Modifying cleaning procedures to address weaknesses revealed by the RCA. For instance, if residue was found due to insufficient dwell time of the cleaning agent, we’d adjust the procedure to increase contact time. This might involve adding a pre-soak step, using a more effective cleaning agent, or adjusting the cleaning cycle parameters.

• Equipment Modification: If equipment design contributes to cleaning challenges, we might recommend modifications. For example, if dead-leg areas in a pipe system are causing persistent residue, we might propose redesigning the system to eliminate these areas.

• Training and Education: Properly trained personnel are critical. We provide refresher training to ensure cleaning staff understands the updated procedures and the importance of following them precisely.

• Enhanced Monitoring: Implementing more robust monitoring systems, such as regular visual inspections, swab tests, and more frequent cleaning validation studies, helps detect any deviations early.

• Documentation and Standardization: Maintaining meticulous records of cleaning procedures, deviations, and corrective actions allows for continuous improvement. Standardizing cleaning procedures across the facility promotes consistency.

For example, if a recurring issue was bacterial contamination in a specific piece of equipment, the RCA might reveal inadequate sanitization. Our preventative action would include implementing a stricter sanitization procedure with validated efficacy, retraining staff on the correct technique, and possibly updating the equipment to improve cleanability.

Time is always a critical factor in RCA cleaning investigations. My approach emphasizes efficiency without compromising thoroughness. I use a structured methodology to manage time effectively:

• Prioritization: We assess the impact of the cleaning issue. High-priority issues (e.g., those impacting product quality or safety) are addressed immediately, while lower-priority issues are tackled according to a planned schedule.

• Focused Investigation: Rather than a broad search, we use data-driven techniques and evidence-based reasoning to focus the investigation on the most likely causes. This might involve reviewing batch records, cleaning logs, or performing targeted sampling.

• Teamwork and Collaboration: Engaging relevant stakeholders (production, engineering, quality control) from the beginning helps us gather necessary information quickly and prevents duplicated effort. This collaborative approach also ensures that everyone understands the findings and the preventative actions.

• Use of Data Analysis Tools: Statistical software or data visualization tools can help analyze large datasets from cleaning records and quickly identify trends or patterns that pinpoint root causes.

• Regular Updates: Providing frequent updates to stakeholders ensures transparency and allows for timely intervention if needed. This also reduces the likelihood of the problem escalating.

For instance, if a cleaning issue arose during a critical production run, I’d immediately convene a team to assess the impact and implement temporary mitigation measures while simultaneously initiating the RCA investigation. This would involve prioritizing data collection and analysis from the affected production run to quickly identify the root cause and prevent further issues.

Balancing thoroughness and timely resolution in RCA cleaning is a delicate act. It’s crucial to avoid both rushing to conclusions and getting bogged down in unnecessary details. This balance is achieved through:

• Structured Approach: Using a defined RCA methodology (e.g., 5 Whys, Fishbone diagram) ensures a systematic approach, preventing wasted time on irrelevant leads.

• Data-Driven Decision Making: Instead of relying solely on intuition, we utilize objective data (e.g., cleaning validation reports, residue analysis) to guide the investigation, ensuring that conclusions are evidence-based.

• Setting Timelines and Milestones: Establish realistic but challenging timelines for each phase of the investigation. Regularly monitoring progress against these milestones ensures that we stay on track.

• Risk Assessment: Early in the process, we assess the potential risks associated with a delay. This helps prioritize the most critical aspects of the investigation and focus resources effectively.

• Escalation Protocols: Having clear escalation procedures in place for situations where the investigation is encountering significant roadblocks ensures timely resolution.

Imagine a cleaning validation failure. While a comprehensive investigation is needed, we’d prioritize identifying immediate threats to product quality or patient safety. We’d quickly implement temporary measures while proceeding with a thorough RCA to determine the long-term solution.

One significant challenge is dealing with situations where multiple contributing factors lead to cleaning failures. It can be difficult to isolate the primary root cause. For example, a residue issue might stem from a combination of inadequate cleaning procedures, unsuitable cleaning agents, and equipment design flaws.

To overcome this, I employ a systematic approach that includes:

• Data Correlation: Analyzing various datasets (cleaning logs, environmental monitoring, equipment performance data) to identify correlations between different factors and pinpoint the most likely combination of root causes.

• Experimental Design: Conducting controlled experiments to test hypotheses about potential root causes. For instance, we might test different cleaning agents or modify cleaning procedures to determine their individual impact on residue levels.

• Expert Consultation: Seeking expert opinions from specialists in cleaning validation, microbiology, or engineering to provide alternative perspectives and enhance problem-solving.

• Statistical Analysis: Employing statistical techniques to assess the relative contribution of different factors to the observed problem.

In one instance, we faced persistent bacterial contamination in a production line. Initially, we focused on cleaning procedures, but further investigation revealed that a poorly designed section of the equipment was harboring biofilm. By modifying the equipment design and implementing a more rigorous cleaning procedure, we solved the problem effectively.

Cleaning validation is the documented process of proving that a cleaning procedure consistently removes residues of manufacturing materials from equipment to a level deemed safe for subsequent processing, consistent with GMP guidelines. It’s not just about visual inspection; it’s about providing objective evidence that the cleaning process is effective.

Its importance is paramount, as inadequate cleaning can lead to several critical issues:

• Cross-contamination: Residues from previous batches can contaminate subsequent products, leading to product degradation, off-specifications, or even harmful products.

• Toxicity: Cleaning agent residues, if not properly removed, might be toxic to future products or pose risks to operators.

• Microbial contamination: Insufficient cleaning can result in microbial growth and contamination, leading to product spoilage, safety concerns, and regulatory non-compliance.

• Regulatory Compliance: Cleaning validation is crucial for demonstrating compliance with regulatory requirements (e.g., FDA, EMA) and maintaining product quality and safety.

Cleaning validation usually involves defining acceptance criteria (e.g., limits on residual levels), selecting appropriate analytical methods for residue detection, sampling plans, and establishing cleaning procedures. The process involves executing the cleaning procedure repeatedly and then testing for residual levels to verify that the method meets the pre-defined acceptance criteria.

Staying current in RCA cleaning and related technologies is essential for maintaining expertise. I actively engage in several strategies:

• Professional Organizations: I’m a member of professional organizations like the PDA (Parenteral Drug Association) which provides access to educational materials, conferences, and networking opportunities. These organizations often host seminars and workshops covering the latest advancements in cleaning and validation techniques.

• Industry Publications and Journals: Regularly reading journals such as Pharmaceutical Technology and other industry publications keeps me updated on the latest research, best practices, and regulatory changes.

• Conferences and Workshops: Attending industry conferences and workshops enables me to learn from leading experts and network with peers.

• Online Courses and Webinars: I leverage online learning platforms to access specialized training courses and webinars in RCA and cleaning validation techniques.

• Collaboration with Peers: Regularly discussing challenges and best practices with colleagues and peers from other facilities helps broaden perspectives and learn from others’ experiences.

For instance, I recently participated in a workshop on advanced analytical techniques for residue analysis, learning about new methods that can significantly enhance the speed and accuracy of cleaning validation studies.

When the root cause of a cleaning problem remains unclear despite initial investigations, a systematic approach is critical. This involves escalating the investigation and employing more advanced techniques:

• Expand the Scope of the Investigation: Broaden the investigation to include factors initially overlooked. This might involve reviewing additional batch records, examining different cleaning cycles, or collecting samples from different locations.

• Advanced Analytical Techniques: Employ more sophisticated analytical methods for residue detection and characterization. This might involve techniques like HPLC, GC-MS, or surface analysis techniques to identify trace levels of residues that might have been missed by simpler methods.

• Expert Consultation: Seeking input from specialized experts (e.g., material scientists, microbiologists) who can offer insights based on their specific area of expertise.

• Design of Experiments (DOE): If multiple factors are suspected, employ DOE to systematically test the impact of various factors (cleaning agent concentration, dwell time, temperature) on cleaning effectiveness, guiding us to the combination of factors most responsible.

• Failure Mode and Effects Analysis (FMEA): A proactive technique, FMEA can be retroactively applied to identify potential failure modes within the cleaning process that were previously unknown or underestimated. It focuses on identifying potential failures before they happen and assessing the consequences.

If a root cause remains elusive, it is essential to communicate transparently with relevant stakeholders about the ongoing investigation, highlighting the steps taken and the potential implications while continuing the more detailed investigation until a satisfactory root cause is discovered and implemented.