EXPOSED
Fitting crankshafts, torquing head bolts, aligning gears and verifying tolerances is hand work, not screen work, so language AI barely touches the core day. The real pressure is industrial robotics and fixture automation, which already own high-volume engine lines — what survives is low-volume, large, or variant-heavy builds (marine, industrial, rebuilds, prototypes) where tooling up a cell costs more than a skilled assembler. No license, no client relationship, and work instructions define most decisions, so the only moats are hands and physical presence.
Part 2020 shock, part continued decline in the years since.
Median pay $45,660 → $53,710 -5.9% in real terms
This line is counted by the Bureau of Labor Statistics — the one figure on this page that isn't a judgement of ours. Headcount moves on demand, offshoring, demographics and the business cycle, and automation is one term among several, often not the loudest.
So a falling line is not evidence that AI did it, and a rising one is not evidence that it won't. Both happen in this register: some occupations resist automation and shrink anyway, others are highly automatable and keep growing. The marked year is 2020.
BLS projection, 2024–2034
-21.1% 38,400 → 30,300 on the projections basis
Exposed, and shrinking
Both signals point the same way: the tasks are largely automatable and the BLS projects -21.1% by 2034. This is the case where the score and the forecast agree, and it is the one worth taking seriously.
Different clocks. The score is what current AI could do to this work today. The projection is how many of these jobs will exist in 2034. Everything between the two — how fast employers actually adopt, whether demand grows in the meantime — is why they can point opposite ways without either being wrong.
~2,800 openings a year on average, including replacing people who leave.
FitterAssemblerValve MakerMotor SetterSubassemblerValve SetterEngine BuilderCell TechnicianCrane AssemblerMachine BuilderMotor InstallerEngine AssemblerMotors AssemblerAssembler ErectorMachine AssemblerProduct AssemblerTurbine AssemblerInjector AssemblerGenerator AssemblerRace Engine BuilderAssembly Line WorkerCompressor AssemblerJet Engine AssemblerMechanical Assembler
Holding it up: task resistance . Weakest point: liability shield .
Mixed — a routine tier and a judgment tier At 13 the score credits what a robot cell still can't do cheaply — feeling a bearing preload, chasing an interference fit on a rebuilt block, working from a marked-up print on a one-off marine or genset build — but it stops short of 14+ because the repetitive torque sequences, gasket placement and press-fit operations that fill a high-volume shift are already done by fixture automation and torque robots on the big lines.
Some physical or field component An 11 reflects that you're standing at a bench or line with air tools, hoists, presses and micrometers on physical parts — real force, real reach, real dexterity — but the environment is a controlled indoor plant floor with fixed stations, part kitting and defined lighting, not the unpredictable field conditions of a millwright crawling inside a running facility.
No licence, no signature requirement A 2 is because nothing you install requires you to hold a license or sign off in your own name; the plant's quality inspector, the engineering spec and the manufacturer's warranty absorb the consequence of a bad build, and your traceability stamp on a work order is a shop record, not personal legal exposure.
Executes defined procedures on defined inputs At 5, most calls are already made for you by the build sheet, torque spec and go/no-go gauge; the discretion that keeps this above the floor is the decision to stop the line, tag a part out of tolerance, or flag a fit problem before it becomes scrap — real judgment, but exercised inside documented procedure rather than owning the outcome.
The verdict above describes this occupation as a whole. Almost nobody does the typical version of a job — tick what's actually in your week and see how your own mix sits.
Your task mix speaks to task resistance (13/20 here) — how much of the day's work current AI already does. That is the dimension the boxes above are about.
It cannot move the other three. Liability shield (2/20) is whether the law requires a licensed human to sign. Trust premium (3/20) is whether buyers specifically pay for a person. Judgment and accountability (5/20) is whether the role exists to own consequential calls. Those are facts about the occupation's standing, not about which tasks are in your week — a paralegal who does only trial exhibits still holds no licence. Together they are 10 of this occupation's 34 points (29%).
Embodiment (11/20) is also a property of the work rather than the worker, but we don't tag individual tasks as physical or not, so the picker can't tell you anything about it. That's a limit of this tool, not a claim.
Did we get the list right? Tell us what's missing — the tasks are written from the outside, and you're reading this from the inside.
The moves above are yours to make. This is the other half: what would have to change in the world for the occupation itself to score higher. None of it is in any one person's gift, but it is where the floor actually comes from. Scores here are not a one-way ratchet. Only two of the five dimensions — task resistance and embodiment — track what machines can do. The other three track law, what buyers will pay for, and who is answerable, and those move in both directions, often in response to the same pressure AI creates. If every lever below landed, this occupation would score around 49/100, still EXPOSED.
Task-mix shift as high-volume cells finish automating: what remains is prototype/first-article builds, rebuild teardown where wear diagnosis and reuse/scrap calls are unstructured, and variant-heavy marine/industrial engines where BOMs and fits change per unit. This tier resists both robotics and instruction-following AI because the build sequence is not stable enough to fixture.
Concentration into large-displacement and field work — locomotive, marine, stationary gensets, wind gearbox rebuilds — where the machine cannot be brought to a cell and assembly happens in situ with confined-space and overhead access. Field-service engine assembly is already a distinct pay tier at EMD/Caterpillar dealers.
If insurers or OEM warranty programs require a named assembler-of-record accountable for torque-sequence and clearance decisions on critical rotating assemblies — the way turbine and nuclear pump rebuilds already carry traveler sign-off per build step — the role owns consequential calls rather than executing instructions.
Airworthiness-style sign-off spreading beyond aviation: FAA Part 65 A&P certification already makes a named licensed human personally responsible for engine assembly and return-to-service. An analogous mandatory stamped sign-off in marine propulsion (USCG/ABS surveyor-witnessed assembly of critical rotating assemblies) or in EPA/CARB emissions-critical rebuild certification would attach a named human to the torque record.
The limit. Even with every lever, this stays a mid-scoring occupation: the headcount trend is set by robotics capex in high-volume plants, not by any of these moats. Trust premium has no realistic route — buyers purchase an engine, not an assembler, and no end customer knows or pays for who built it.
| Detroit-Warren-Dearborn, MI | 3,330 | $64,820 +21% |
| Greenville-Anderson-Greer, SC | 1,020 | $46,950 -13% |
| Los Angeles-Long Beach-Anaheim, CA | 660 | $46,620 -13% |
| Chicago-Naperville-Elgin, IL-IN | 540 | $49,630 -8% |
| Grand Rapids-Wyoming-Kentwood, MI | 460 | $53,570 +0% |
| Virginia Beach-Chesapeake-Norfolk, VA-NC | 360 | $36,030 -33% |
| Boston-Cambridge-Newton, MA-NH | 310 | $48,990 -9% |
| Toledo, OH | 310 | $75,770 +41% |
| Seattle-Tacoma-Bellevue, WA | 210 | $102,530 +91% |
| Indianapolis-Carmel-Greenwood, IN | 200 | $80,200 +49% |
| Oshkosh-Neenah, WI | 90 | $80,170 +49% |
We have no reported case of a named organisation automating this occupation. Not one deployment, not one announcement.
That is worth saying out loud next to a score of 34. The verdict above is about what the work exposes — what current AI could do to these tasks. It is not a claim that anyone has done it. For this occupation those two things have come apart completely: the capability argument is on this page, and the evidence column is empty.
Has AI actually changed your work? One tap, anonymous, and the running tally is public. Nothing else is asked of you.
Rather than check back: get the digest and we'll tell you what changed — or watch a single occupation from its own page.