Aviation glossary · Limits and countersBack-to-Birth
BTB trace
Documentary evidence tracing a life-limited part from manufacture through every installation, removal and period of operation, so that its accumulated life can be proven rather than estimated.
Why it matters
A gap anywhere in the chain devalues the part, because the life that cannot be proven has to be assumed used. Lessors will not accept an aircraft whose LLPs have broken traces.
In AerSynx
A component is one record that moves with the part: removing it from an aircraft does not archive it and create a new one, so its history stays continuous across installations. Technical Records →