How to Pass FRC Robot Inspection: Full Walkthrough

Robot inspection is a pass/fail gate, not a design review. Under rule I102 in the 2026 manual, your team cannot play a Qualification or Playoff match — or earn Ranking Points from one — until your robot has passed a complete inspection. Inspectors are volunteers working down a published checklist, and every line on it points at a numbered rule you can read weeks before you get on the bus.

That is the whole secret: the test is open-book, and the book is free. FIRST publishes the exact checklist inspectors use on the same Season Materials page as the game manual — for 2026, a two-page PDF called the 2026 FRC Inspection Checklist. Walk your robot through it in your shop and you will find your problems on a Tuesday in the build room, not in a pit forty minutes before your first match.

The failures that actually cost teams their Thursday are boring and predictable: bumpers built to the wrong dimension, a robot three pounds overweight, a main breaker buried behind a superstructure, wire too thin for the breaker protecting it. Almost none of it is about whether your robot is good. It is about whether you measured.

One warning before any numbers. Inspection rules are reissued every season and the numbers move. The weight limit dropped from 125 lb to 115 lb for the 2025 season; for 2026 the starting-configuration box shrank hard, from a 120 in perimeter and 42 in height to 110.0 in and 30 in. Legal radios and control-system firmware change almost yearly too. Every figure below comes from the 2026 REBUILT manual (version TU22) and the 2026 checklist (Rev. 0). When the 2027 manual drops in January, read it yourself: this page maps the categories and their traps; it does not replace the manual.

How inspection actually runs at an event

Inspectors circulate through pits on Thursday, or Friday morning at a two-day district event. You do not queue at a booth — they come to you, and they work in blocks, so the process can pause for your practice match or a shift change and you may see several different inspectors. That is normal.

• A student must be present. I107 requires at least one student team member to accompany the robot for any inspection effort. Mentors alone are not enough.
• The robot shows up off. I106 requires it presented powered off, pneumatics unpressurized, and stored-energy devices in their lowest state — battery out is the norm. Power and air come on only for the portions that require it.
• You can ask for a different inspector, or invite the Lead Robot Inspector (LRI) in. The LRI has final authority on the legality of any component, mechanism, or robot at that event. Ask early — LRIs would much rather answer a question Thursday morning than fail you Friday.
• Practice matches don't require a passing inspection. You may play them before you pass, provided the robot is safe — bumpers approximately meeting the coverage, height, and cross-section requirements. The FTA, LRI, or Head Referee can pull you at any time.
• You sign for it. The checklist ends with a Team Compliance Statement a mentor and team captain both sign, attesting the robot was built after Kickoff and its major mechanisms are the team's own work (I101).

Inspectors can re-inspect at any point; passing Thursday is not a permanent certificate. For the specific ways teams blow this, we keep a running list of common inspection failures.

Frame perimeter, starting configuration, and extension

The frame perimeter is defined by a piece of string. R101 asks you to wrap a string around the outermost parts of the robot (bumpers off) at bumper-zone height and pull it taut. Whatever that string traces is your perimeter — if your chassis is U-shaped, the string spans the gap and the notch is inside the perimeter. It must be fixed and non-articulated; only minor protrusions up to 0.25 in (0.64 cm), such as bolt heads, rivets, and weld beads, are excluded.

Starting configuration is a size box. In 2026 it could not exceed a 110.0 in (2.794 m) perimeter or 30 in (76.2 cm) in height (R104), and nothing could stick out past the vertical projection of the perimeter except bumpers and minor protrusions (R102). Shave your CAD numbers — a chassis designed to exactly 110.0 in fails if your tube stock runs long or a rivet sits proud.

Extension is measured in-match but demonstrated at inspection. In 2026, robots could extend up to 12 in (30.48 cm) beyond the perimeter (R105), in only one direction at a time (R106), to a total height of 30.0 in (76.2 cm) (R107). Expect to be asked to demonstrate that your robot constrains itself, in hardware or software; "our drivers just won't do that" is not a constraint. R106 also treats a circular perimeter section as having infinite sides, so a round chassis cannot extend over a "corner."

For a fuller treatment, see our guide to FRC robot size and weight rules.

Bumpers: where most teams actually fail

Bumpers are the most common inspection failure, and the reason is almost always the same — a team built to last year's dimensions, or to the number printed on the checklist rather than the one in the manual.

Here is the trap almost nobody explains. The manual prints nominal dimensions; the checklist prints those same dimensions with the ±0.25 in inspection tolerance already applied. So 2026's R403 said bumpers must not extend more than 4.0 in from the frame perimeter, while the corresponding checklist line read 4.25 in. Both are correct. But design to 4.25 in and you have spent your entire tolerance budget before cutting a single piece of plywood, so any manufacturing error fails you. Build to the nominal number and keep the tolerance for stack-up.

The 2026 nominal requirements:

Easy things to miss:

• Legal padding is a specific list: solid pool noodles or backer rod, solid closed-cell polyethylene foam at 1.5–3.0 lb/ft³, solid closed-cell EVA foam at 2.0–6.0 lb/ft³, or foam floor tiles. Mixed types and layers are fine, and you don't have to cut one open to prove it.
• Mitered corners do not "fill" a corner. R406 is explicit that two segments meeting at a miter fail, because the cloth cover sits between them. You need continuous uncompressed padding wrapping the corner.
• No wedges. R407 bans wedge-like profiles — soft foam toward the top, heavily rounded single-radius profiles, and tapered or stepped padding all invite scrutiny.
• Bumpers must come off. R410 exists so inspectors can weigh the robot; the guideline is two people in under five minutes. If yours take a hex-driver marathon, you will be slow at every re-inspection.
• The bumper zone is relative to whatever you're driving on, not the carpet in absolute terms. Bumpers must also stay passive (R409) — no moving or electrical elements.

Full construction detail is in our FRC bumpers guide.

Weight: what counts, what doesn't, and how to weigh at home

2026 used three separate numbers, and conflating them is a common source of pit panic:

• R103 — 115.0 lb (52.16 kg): the robot in any single match configuration.
• R408 — 135.0 lb (61.23 kg): the robot with bumpers installed.
• I103 — 150.0 lb (68.04 kg): everything presented at inspection, including all swappable mechanisms you intend to use without re-inspection.

That last one is the useful one. You may bring more mechanisms to inspection than can legally fit on the robot at once, up to the I103 ceiling, then swap between them freely between matches — provided every configuration you play still satisfies R103.

Excluded from robot weight under R103: bumpers; the battery and its half of the Anderson quick-disconnect pair, including wire, cable lugs, connecting bolts, and insulation; and event-provided location-detection tags. Everything else counts — every zip tie, camera, piece of tape, and decoration.

Weighing at home: check your scale against a known mass, then weigh in your heaviest legal configuration, bumpers off and battery out, exactly as the inspector will. Leave 3–5 lb of margin — between your last shop weigh-in and your first match you will add a camera mount, a stiffener, and a bracket, and teams that arrive at exactly the limit arrive overweight. Weigh each swappable mechanism separately and write the number on the part in marker.

Electrical: breaker, wire gauge, fusing, and the isolation test

This is the longest block on the checklist, and the easiest to pre-pass if you are systematic.

The main power path. In 2026, the run from battery to Anderson SB connector to 120 A main breaker to the power distribution device had to be 6 AWG (7 SWG / 16 mm²) copper or larger (R609); copper-clad aluminum counts as copper. Every terminal on the battery, the main breaker, and their connections must be fully insulated at all times (R607) — not "once we put the cover on."

The main breaker must be reachable. R612 requires the single 120 A breaker to be quickly and safely accessible from outside the robot. Behind an access panel, under a moving mechanism, or buried mid-frame all fail. Label it — field staff may need to find it in a hurry.

Everything must be inspectable. R613 covers the PD, its wiring, and all breakers; they need not be visible in starting configuration, but you must be able to make them viewable on demand. R618 allows only one wire per PD terminal — to feed several devices from one circuit, use a splice or terminal block.

Breaker and wire sizing must agree. This is the line item that catches good teams. The 2026 minimums:

Wire attached to a legal device by its manufacturer is exempt, provided it is protected by the smallest breaker or fuse that lets the device work. If your wire is unmarked, be prepared to prove the gauge — our wire gauge calculator sizes a run for you, and the full walkthrough is in how to wire an FRC robot. On colors, R624 required red, yellow, white, brown, or black-with-stripe for positive supply and black or blue for common.

The frame is not a wire. R611 requires isolation from the frame, checked by measuring greater than 120 Ω between either battery post at the PD and any point on the robot. Inspectors will put a multimeter on this. The usual culprits are grounded-case sensors, decorative LED strips, and some encoders — conductive housings that quietly bond control ground to the chassis. Test it yourself before you leave; it takes ninety seconds.

Power the roboRIO and radio correctly. R615 requires roboRIO power directly from a non-switched, protected PD output with a 10 A fuse or breaker and nothing else on that circuit. In 2026 the legal radio was the Vivid Hosting VH-109 (R702), configured with your team's encryption key at the kiosk at each event and mounted so its LEDs are visible to field staff, not merely during inspection (R708).

Pneumatics: relief valve, pressure limits, and venting

No pneumatics means this section is skipped entirely. If you do use them, six parts are required (R805 in 2026): a legal compressor, a relief valve, a pressure switch, at least one vent plug, stored- and working-pressure gauges, and one primary working-pressure regulator.

• Stored pressure ≤ 120.0 psi (R807), with the compressor shutting off at or below that under roboRIO control.
• Working pressure ≤ 60.0 psi (R808), through a single primary adjustable, relieving regulator.
• Relief valve set to 125.0 psi (R811), attached directly to the compressor or via hard fittings to its output port. Teams are explicitly required to check and adjust this — the valve may arrive uncalibrated, and inspectors know it.
• Component ratings (R802): upstream of the regulator, rated ≥ 125.0 psi; downstream, ≥ 70.0 psi.
• Compressor flow ≤ nominal 1.1 cfm (519.1 cm³/s) at 12 VDC, one compressor only (R806).
• Vent plug visible, easily accessible, and able to vent all stored pressure to atmosphere (R813).

The functional check happens live: with the system empty, the compressor should start when the robot is enabled, stop at or below 120 psi, and hold working pressure at or below 60 psi. The inspector then disables the robot, opens the main breaker, confirms every LED is dark, and has you actuate the vent plug until both gauges read zero. A vent plug behind a panel or needing a wrench fails a rule that is genuinely about keeping people safe. More in our pneumatics guide.

Software and Driver Station checks

• Firmware and image versions. In 2026 the roboRIO needed image 2026_v1.2 or later (R701) and Driver Station software 26.0 or newer (R901). These get revised mid-season — re-image before your event, not the night before your first match.
• Team number set everywhere. roboRIO, Driver Station, and radio must all be configured to your team number (R705), and the radio programmed at the event kiosk for that event.
• The robot signal light. One or two RSLs (R709), mounted so the light is easily visible standing 36.0 in (91.44 cm) from at least one side, plugged into the roboRIO's RSL terminals. On the 855PB-B12ME522 you must jumper the "La" and "Lb" terminals for solid-light operation.
• No stray wireless. R707 and R905 — no wireless to, from, or within the robot or operator console, and no radios in the pit. Turn off Wi-Fi and Bluetooth on the driver station laptop. This one fails teams every season.
• Operator console. In 2026: no longer than 60.0 in, no deeper than 16.0 in, no more than 78.0 in above the floor (R904); no AC inverters (R907); a visible diagnostic display (R902); and the FMS Ethernet cable connected directly to the driver station device, not through a switch (R903).

Modifications between matches and re-inspection

This is where teams accidentally break a rule while trying to be helpful. The default: if you change the robot after it passed, it must be re-inspected before it plays again (I104). The exceptions, which do not require re-inspection unless they significantly change size, weight, legality, or safety:

• adding, moving, or removing fasteners (cable ties, tape, rivets)
• adding, moving, or removing labels or markings
• revising robot code — you can push software all weekend
• replacing a COTS component with an identical COTS component
• replacing a mechanism with an identical one (same size, weight, material)
• reconfiguring the robot with a subset of mechanisms already inspected under I103

That last bullet is why the I103 allowance matters. Mechanisms you bring to your initial inspection can be swapped in and out all event with no re-inspection; mechanisms you build Friday night cannot. Bring the spare arm to inspection Thursday even if you don't plan to use it.

Don't game it, though. I105 forbids using repeated re-inspection to sidestep the I103 cap. Returning to a previous configuration after a failed upgrade is explicitly fine; cycling between two heavy mechanisms that together exceed the limit is not, and the LRI will ask you to pick one. Everyone also gets re-weighed before playoffs, specifically to catch modifications that should have triggered a re-inspection.

A print-and-carry pre-inspection checklist

Run this in your shop the week before your event with the current year's official checklist open beside it. Assign one student per block.

Size and weight

• Weighed in heaviest configuration, bumpers off, battery out — 3–5 lb under the limit
• Robot plus bumpers, and all swappable mechanisms together, under their respective limits
• Perimeter measured with a taut string; starting height measured
• Extension limits enforced in code, and you can demonstrate it

Bumpers

• Built to nominal manual dimensions, not the tolerance-applied checklist numbers
• Padding legal; corners filled with uncompressed foam, no miters
• Red and blue sets both fit and weighed; numbers on three or more sides
• Two people can swap them in under five minutes — timed, not assumed

Electrical

• Main breaker accessible from outside and labeled
• Every breaker matched to wire gauge; PD and breakers viewable on demand
• Frame isolation measured with a multimeter, above the required resistance
• Battery secured for any orientation; every terminal insulated
• RSL visible from 36 in and flashing in sync with the roboRIO

Pneumatics

• Relief valve checked and set; both gauges installed and readable
• Compressor cuts off under the stored limit; regulator under the working limit
• Vent plug accessible without tools, drains to zero on both gauges

Software and console

• roboRIO re-imaged, Driver Station updated, team number set on all three devices
• Laptop Wi-Fi and Bluetooth disabled
• Operator console within size limits, display visible, no inverter

Pack the tools re-inspection needs — a tape measure, a multimeter, and a scale earn their space. Our pit checklist and packing list covers the rest.

Frequently asked questions

Can we compete in practice matches before passing inspection?**

Yes. Robots may play scheduled practice matches before passing, provided the robot is safe — which the 2026 manual defined as functional bumpers approximately meeting the coverage, height, and cross-section requirements. The FTA, LRI, or Head Referee can stop you at any time. You cannot play a Qualification or Playoff match, or earn points from one, until you pass a complete inspection.

Do bumpers and the battery count toward the robot weight limit?

No. In 2026, R103 excluded bumpers, the battery with its half of the Anderson quick-disconnect pair (wire, cable lugs, connecting bolts, insulation), and event-provided location-detection tags. Everything else counts, including zip ties, tape, and decorations. A separate limit covered the robot with bumpers installed — 135.0 lb in 2026 — so light bumpers still matter.

What happens if we fail inspection?

Nothing punitive. The inspector tells you which line failed and which rule it maps to; you fix it and get re-inspected. Most failures are small: a bumper gap, a wire gauge, an inaccessible breaker. This is exactly why teams self-inspect at home — an issue found in your shop costs an hour, the same issue found in the pit costs match time. If you disagree with a call, ask for the LRI.

Can we change the robot between matches without being re-inspected?

Only within the listed exceptions: code revisions, fasteners, labels, identical COTS replacements, identical mechanism replacements, and reconfiguring with a subset of mechanisms already presented at inspection. Anything else needs re-inspection before you play again. The practical move is to bring every mechanism you might use to your initial inspection, so swaps are free all event.

How tight are the bumper measurement tolerances?

In 2026, bumper dimensions were measured with a ±0.25 in tolerance — maximums got +0.25 in, minimums −0.25 in. Critically, the official checklist prints the numbers with that tolerance already applied while the manual prints nominal values, which is why the two documents can appear to disagree. Design to the nominal dimension so the tolerance absorbs manufacturing error instead of being consumed by your design.

**Does someone from our team have to be there for inspection?

Yes — at least one student team member must accompany the robot for any inspection effort, with exceptions only for major conflicts such as religious holidays, major testing, or transportation issues. Send a student who knows the robot's electrical and pneumatic layout; they will be asked to point at things.