Reference Trees are on their way out of AMOS. Since 25.12, the legacy Reference Tree programs (APN 27 and APN 246) are retired. Configuration Management, aligned with ATA Spec 2400, is now how aircraft and assembly configurations are controlled.
You do not have to rebuild every configuration by hand. A migration task converts existing Reference Trees into Allowed Configurations, and AMOS 26.6 makes the assignment step smarter. But the result depends almost entirely on the quality of the data you feed it.
How the migration task works
The migration runs as a scheduler task in three steps:
Match. An aircraft Reference Tree has no direct link to an aircraft, so AMOS scores every aircraft against each tree. The score depends on where it finds the registration or aircraft type: in the tree title, the description or the tree group. Only trees that reach your chosen confidence level are converted. Assembly trees are matched on their root part number.
Create. AMOS builds the Allowed Configurations for the tree and its sub-assemblies. A registration match gives a tail-specific configuration and a type match gives a fleet configuration. Functional Position (FP) codes come from the pattern you set in APN 3125.
Assign (optional). AMOS assigns each configuration to its aircraft or assembly and moves installed rotables into their FPs.
Scores are lowered for aircraft and assemblies that already have a configuration, so repeat runs do not create duplicates.
Two things that decide the result
How your trees are named. A tree with the registration in its title is matched with full confidence. A tree named after the aircraft type becomes a fleet configuration. Trees named “Copy of…” or “test”, or duplicate revisions of the same aircraft, leave you with a bad choice: a low threshold that creates unwanted configurations, or a high one that leaves gaps.
How well your positions line up. In the 25.12 logic, a rotable only moves into a Functional Position when its existing position code matches the new FP code exactly. The same position coded LH on one tail and LEFT on another, or left blank, means that rotable stays uncontrolled and has to be mapped by hand in Configuration Assignment (APN 3658).
Run it in stages, assign with care
The task can be run as often as you like, and several controlled runs usually beat one big one. A common pattern is to convert the trees that clearly carry a registration first, with a high confidence level. Then run again at a lower level to pick up type-level trees as fleet configurations, and review the task log before each further step. Aim for fleet configurations, and handle tail differences as conditional effectivities inside an FP.
Assignment is where migration reaches daily operations. Once an assembly is assigned, the configuration checker replaces the Reference Tree check during label booking. A partly transferred assembly will show missing items. Component Booking shows a warning rather than a blocker for migrated assemblies, so an assembly can be installed while its check result is still wrong. Test auto-assignment outside production first. Before go-live, also check spare assemblies likely to be installed soon in Configuration Control (APN 3128).
What AMOS 26.6 improves
AMOS 26.6 addresses the weakest point of the earlier logic: assignment on exact matches only.
Rule-based scoring. Assignment uses weighted rules and an automatic assignment threshold, both of which you can adjust. You can see the score behind each decision.
Smarter matching. Partial codes (3rh → 3RN.2) and dictionary equivalents (LH → LEFT) are recognised.
Controlled roll-out. Assignment runs on demand, in batches, and never changes existing assignments.
Safety net after upgrade. The check is paused for auto-assigned assemblies and comes back on with the next booking. AMOSmonitoring shows how much of the fleet is fully, partly or not yet controlled.
Better matching helps, but it does not fix poor data. Clean names and positions still decide how much is left to fix by hand.
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Five checks before you start
Clean up the tree list. Deactivate obsolete, duplicate and test trees, and pick one best tree per tail or type.
Fix the names. Put the registration in the title of tail trees and the aircraft type in the title of fleet trees.
Harmonise positions. Align position codes across tails, fill blanks, and set the FP generator in APN 3125 to reproduce them.
Review what carries over. Check the alternates that will be imported, and remove consumables and repairables from the trees.
Prepare the processes. Test receiving, label booking and material allocation with Configuration Management. Then schedule the daily configuration check.
How EXSYN can help
The migration task does the conversion. Your data decides whether you end up with a controlled fleet or a long list of manual fixes. EXSYN profiles your Reference Trees and position codes, cleans and harmonises them in bulk, and helps you plan and validate the migration runs before go-live.
Planning a move to Configuration Management or an upgrade to AMOS 26.6? Book a 1-on-1 meeting with EXSYN AMOS team for a data readiness check.
