Anonymised hypothetical
A hypothetical drone-arm revision record
One load case and cycle target carry through the first proposal, the initial failure, the local reinforcement, and the retest; the missed mass target stays in the record.
The hypothetical acceptance criteria are an 8% minimum mass reduction, no more than 2.0 mm tip deflection under a 120 N upward load, and no visible delamination or insert loosening after 10,000 combined cycles at 120 N and 3.0 N·m.
Those figures belong only to this scenario. They provide a fixed basis for comparing the initial design and the revision.
Initial proposal
The arm starts with a [0/+45/-45/0]s layup and a bonded aluminium root insert with 14 mm of overlap. The midspan is thinned to approach the mass target.
The review record identifies tip deflection, the root bond line, and the layup termination as the three locations to inspect before combined-cycle testing.
The first test stops at cycle 6,400
At cycle 6,400, local debonding appeared at the end of the root-insert bond line. The test stops. The inspection note locates the issue at the end of the bond line without assigning the failure to the carbon-fibre material itself.
Revision
The change is to add two local ±45° reinforcement plies across the end of the bond line and increase the insert overlap from 14 mm to 20 mm. The midspan layup remains unchanged.
The added root material changes the mass calculation, so the revised record does not carry over the initial estimate.
Retest
The revised sample completes 10,000 combined cycles, and no visible debonding or insert loosening was observed. Tip deflection under the 120 N upward load is 1.8 mm.
The connection and deflection criteria are met. Mass reduction reaches 6.5%, short of the 8% target. The revision addresses the observed connection issue, while mass remains open for another iteration.