Definition
The position of a fuel metering or mixture control lever when it is moved fully forward or to its maximum-flow stop, allowing the greatest fuel flow the system is set to deliver. In fuel system rigging and adjustment, the full-register position is the reference point used to verify that the control linkage and fuel metering unit reach their designed maximum-fuel setting together.
Plain English
The setting where the fuel control lever is pushed all the way to its maximum stop, calling for the most fuel the system is built to provide. It is the 'fully open' end of the lever's travel.
Context Anchor
Seen in magneto theory, ignition system troubleshooting, and maintenance discussions about how a magneto creates spark.
Derivation
Register' here comes from the older mechanical sense of a control or valve being 'registered' (set or aligned) to a specific position. 'Full-register' means the control is set all the way to its maximum mark — fully aligned with the maximum-flow stop.
Why Pilots Care
Although this is primarily a maintenance term, incorrect rigging at the full-register position can cause an engine to run too rich or too lean at full power, which directly affects takeoff performance, detonation margin, and engine longevity.
Analogy
It is like lining up two magnets face to face at their strongest pull. When they are fully lined up, the magnetic effect is strongest; when they move away from that alignment, the effect changes.
Intuition Check
Do not read “register” here as a book, list, or cockpit readout. In this term, it means mechanical alignment: the magnet is fully lined up with the matching metal parts in the magneto.
Example Sentence 1
With the mixture control set to the full-register position, the technician confirmed that the fuel metering unit reached its maximum-flow stop at the same time.
Example Sentence 2
Voltage is induced in the coil just after the full-register position when the points open.