Check hierarchy rules

Check hierarchy defines how smaller checks, (also known as lighter checks or inclusive task definitions) are included when larger checks, (also known as heavier checks or primary task definitions) are performed. Put another way, when a heavy check is performed it already includes all the work normally performed as part of a lighter check. Therefore, you automatically get credit for the lighter check.

In addition, check hierarchy rules can also contain more than a single task definition primary to a single task definition inclusive. That is, a check hierarchy rule will support task chains for either the primary or inclusive task definitions.

When the smaller checks are included in the visit, check yield may be sacrificed beyond the defined MinYield and MaxYield defined in the Task Definition template. The next instance of the inclusive task will be scheduled from the visit end date of the visit that the primary task is assigned to.

A check hierarchy rule is composed of two check hierarchy types: a primary check hierarchy and an inclusive check hierarchy. The primary tasks can contain a partial chain. The inclusive tasks must contain the entire chain. A partial chain means a subset of tasks from a task chain as defined within the task definition. This could be a single member of a chain, or every odd visit, or the first half of the tasks.

If an inclusive task has a wider applicability (more aircraft have it as applicable) than the primary task, Fleet Planner creates the check hierarchy visit -- provided the primary and inclusive task have cross-over applicability.

The check hierarchy rules template defines when the smaller checks (inclusive task definitions) are included in larger checks (primary task definitions). Check hierarchy rules are defined in the following table:
Check hierarchy rules
  Primary check hierarchy Inclusive check hierarchy
Supports chain Yes Yes
Supports partial chain Yes No
Supports repeating task definition Yes Yes
Supports one-time task definition Yes Yes

  • When using a chain for the inclusive group in a rule the engine will find one of the inclusive tasks to include with the primary task. It will select an inclusive task with overlapping yield range. If none of the inclusive tasks has overlapping yield it will select the next available future inclusive task. If a rule uses a chain for both the primary tasks and the inclusive tasks each member of the primary task chain will include one task from the inclusive task chain. Again, based on overlapping yield or next available future task.

  • When a chained task definition is used for the primary task definitions, either a single member of the chain is permitted or the whole set of tasks from the chain (if appropriate).

  • When a rule uses a one-time task for the inclusive task the engine will merge it with whichever primary task has overlapping yield. If no primary task has overlapping yield it will be merged with the first available primary task scheduled before the one time task's due date.

  • Specifying a one-time task to merge into a repeating primary task is not a supported scenario.

  • When a retirement visit is scheduled and it includes a task that has one or more inclusive tasks as defined by existing check hierarchy rules, then the retirement visit will also include the corresponding inclusive tasks. If these inclusive tasks were not forecast due to the retirement date’s proximity to the plan’s forecast end date, then they will be generated automatically to satisfy the check hierarchy rules.

check_hierarchy_rules.csv
Column name Required Data type or format Description and business rules
Name Yes Text field A check hierarchy rule name

  • is required.

  • must be unique.
Primary Task Definitions Yes Text field

Task ID of the primary (larger) task that includes the inclusive (smaller) task.

Must be listed in the Task Definition template.

If there are multiple task definitions in the same group, they must be part of the same chain (but not necessarily all members of the chain).

Inclusive Task Definitions Yes Text field

Task ID of the inclusive (smaller) task.

Must be listed in the Task Definition template.

If there are multiple task definitions in the same group, they must be a single and complete chain.

  • You cannot have two rules with different names but the same task definitions.

  • A task definition may not appear in both the primary and inclusive column for the same check hierarchy rule.

  • You cannot have circular dependencies between task definitions among existing rules and new or edited rules.