A recent article developed by the Government Accounting Office (GAO) found that unplanned maintenance is often absorbed by revising target dates rather than being tracked as a distinct delay cause. 

This practice obscures the real drivers of schedule slip and prevents effective planning. To counter this, risk must be analyzed and quantified at the level of each individual maintenance task.

This article explores an approach that breaks that risk into three primary components:

1. Risk of a recurring finding 
2. Risk that required parts are unavailable 
3. Risk that needed support is not available

These are not abstract categories; they repeatedly translate into issues like:

• Missed targets
• Extended down time
• Misaligned resources 

Only by treating each of these as an explicit factor in every task can depots generate realistic schedules, resource plans and readiness forecasts.

1. Risk of a Recurring Finding

If an inspection consistently results in the same finding on every visit, the maintenance task itself must be re-evaluated. A chronic finding signals that the current approach—often inspect and defer via paperwork—is not aligned with actual fleet condition.

When recurring issues are formalized as planned work, metrics better reflect what is truly unplanned.

For instance, each time a frontline maintainer performs an inspection, they are effectively auditing the task by executing the step-by-step procedure. This real-time audit often reveals issues within the maintenance steps that must be corrected. 

Task-level implications of a recurring finding should trigger a formal review of the underlying task and its frequency and scope. This helps guide whether it should transition from inspect to inspect and repair or simply to repair. 

Once those issues are addressed, the improved task benefits all future maintenance actions that rely on the procedure.

Currently, common processes for this involve:

• Performing the same inspection each cycle
• Documenting the same discrepancy
• Requiring frontline personnel to repeatedly generate a 202 form
• Waiting each time for an engineering response

However, MROs and repair shops can increase efficiency by taking actions like:

• Converting that recurring discrepancy into a planned repair or modification
• Building that repair into the baseline work package and schedule

This can help achieve significant benefits, such as:

• Reduced uncertainty
• Shorter decision cycles
• Aligned maintenance tasks with the real aircraft behavior of the aircraft
• Improved data quality

2. Risk That Required Parts Are Unavailable

The article’s discussion of unplanned work naturally extends to supply-chain risk. Each task that may generate a part requirement carries its own logistics profile. Ignoring that profile leads directly to hidden delays.

For every part associated with a potential finding, the operation must ask the following:

• Is the part available from normal supply channels? 
• What is the lead time from vendors or depots? 
• Are there engineering, obsolescence, or qualification constraints? 

In practice, when parts are not readily available, units frequently resort to cannibalization.  This is the practice of removing serviceable parts from a potentially airworthy aircraft to support another. 

While this can be operationally necessary, it carries significant hidden cost and risk, such as:

• Incurring labor and downtime to remove the good part
• Requiring additional labor and downtime to reinstall a future replacement part
• Complicating maintenance and documentation on both aircraft

Cannibalization, therefore, often costs roughly twice as much in time, effort and disruption. When this is not explicitly recognized as part of the task’s risk profile, schedules are underestimated, and readiness is overstated.

For each maintenance task with a required or potential part demand based on the risk of finding and issue, planners should:

• Assign a parts-availability risk level (low/medium/high)
• Explicitly note whether cannibalization is likely
• Incorporate expected delays and costs into the baseline schedule and resource plan

This will ensure the individual tasks can be completed within the required schedule timeline. 

3. Risk That Needed Support Is Not Available

Even when a problem with an aircraft is known and the part is available, work can still stall if the necessary support is not in place at the right time.

This includes:

• Properly certificated personnel
• Specialized tooling and test equipment
• Facilities or dock space with the right capabilities
• Engineering and quality assurance support
• Necessary compliance paperwork for completing the task

For example, aircraft inspections in the military often use the following process:

1. Perform an inspection understanding that the inspection in the past has generated a finding most of the time
2. Generate a 202 form documenting the finding and send it off to the supporting organization
3. Discover only afterward that the required tooling, facility or qualified personnel will not be available when the work needs to occur

This introduces additional delays, rework in planning and, potentially, increased time out of service.

From a risk perspective, the true issue with these processes is that the maintenance system is not configured to respond to that finding in a timely way. 

This is why it’s key for MROs and repair shops to engage in predictive maintenance planning and work chronic issues into routine maintenance activities.