Neometrix / Aircraft Fuel System Test Rigs / Aircraft Fuel System Test Rig / NMX-FST-39

NMX-FST-39 · ENGINEERED-TO-ORDER CLASS — FILL · TILT · FEED · WATCH

Aircraft Fuel System Test Rig. A fuel system does not fail when the tank runs dry. It fails when a manoeuvre uncovers the pickup for an instant, with fuel still inside.

Name: Aircraft Fuel System Test Rig
SKU: NMX-FST-39

A fuel tank sitting full and level on a bench proves almost nothing. The moment that actually matters is a low tank in a hard turn, when the fuel surface can slide away from the pickup just long enough to let air in.

So this rig fills a tank to a chosen state, tilts it to a chosen attitude, and draws fuel off at the rate an engine would actually ask for, while it watches the feed, the gauging and the vent together.

Discuss a fuel system test rig Capability note (PDF)

An aircraft fuel system test rig: a plain metal tank on a tilting circular attitude platform, joined by pipes to a pump skid and a plain grey instrument cabinet, and no people

Fig · 01 — An aircraft fuel system test rig: a tank on a tilting attitude fixture, plumbed to a pump skid and a plain instrument cabinet — illustrative render.

The state

full, ordinary or lowchosen before every trial

The attitude

climb, dive, bank or slipset by a tilting fixture

The feed

drawn off at engine demandwatched for continuity

The record

feed, gauging, ventread together, not one at a time

Status

engineered to orderno rig yet delivered

ISO 9001ISO 1400114 CFR Part 25 Subpart E / CS-25 §25.951 referenceRTCA DO-160 referenceISO/IEC 17025 calibration reference

Overview

Why a fuel system is proved by the attitude it is hardest in, not the one it is easiest in.

Because a pickup that never sees air on the bench can still see air the first time it is asked to feed fuel in a real manoeuvre.

Fig · 02 — The rig in one picture: a chosen fuel state and attitude feed the trial, which is watched for feed, gauging and vent behaviour together.

Level and full proves little. Tilted and low is the real question.

What the rig is for

It proves that a fuel system keeps feeding, keeps its gauge honest, and keeps its tank breathing, across the fuel states and the attitudes the aircraft will actually see, not just level and full.

Why attitude is the real test

A fuel system must deliver fuel at the rate an engine needs under every likely flight condition. A climb, a dive, a bank or a sideslip can each move the fuel surface away from a pickup that was placed for level flight.

Why low fuel is the hard case

A full tank has fuel almost everywhere the pickup could be. A low tank only has fuel where the surface happens to sit, so a low state combined with a demanding attitude is where a pickup is genuinely tested.

Why air cannot be waved away

Any air that gets into a fuel system must not be allowed to cost the engine power. Proving continuous feed under attitude is therefore a safety question, not only a performance one.

Why gauging gets its own test

Feeding fuel and measuring how much is left are two different problems. A gauge that reads correctly level can still be checked for honesty when the tank is tilted or the fuel is low.

Why the vent is watched too

A tank that cannot breathe will eventually stop feeding properly, or worse. The vent system is read on every trial, not treated as a detail beside the feed line.

The test

Mount, fill, tilt, feed, watch, record and repeat.

Six steps in a fixed order. The middle two are what a level, full tank never has to answer for.

FIG · 02AIRCRAFT FUEL SYSTEM TEST RIG · MOUNT / FILL / TILT / FEED / WATCH / RECORD & REPEAT — THE SYSTEM IS PROVED WHERE IT IS WEAKEST

The step people underrate is the low-fuel trial. A tank that has only been tested full has only been tested in its easiest state.

Fig · 03 — Three attitudes that test the pickup: climb, bank and dive, each moving the fuel surface a different way — a drawing of the idea, with no values.

1 · Mount

Tanks, pumps and valves are plumbed to the aircraft's own fuel-system schematic.

2 · Fill

The system is filled to a chosen state, full, ordinary or low, before anything else is done.

3 · Tilt

The attitude fixture sets a chosen climb, dive, bank or sideslip, and holds it steady for the trial.

4 · Feed

Fuel is drawn off at the rate an engine would actually ask for, not a convenient rate for the bench.

5 · Watch

Feed pressure, gauge reading and vent pressure are read together, so the three questions share one clock.

6 · Record & repeat

The result is logged, then a new fuel state or attitude is set and the trial is run again.

Work content

What the rig contains, element by element.

Read it as a checklist: a rig missing a row will buy that row back later, usually as a result nobody trusts in the air.

A single plain metal fuel tank on a steel cradle, with a feed pipe and a vent pipe leaving its underside and a round inspection port on top, and no people

Fig · 04 — A single fuel tank on its stand, plumbed for feed and gauging, ready to be fitted to the attitude fixture — illustrative render.

Element	What it does	What matters
Tanks or tank simulators	hold the fuel to the aircraft's own geometry	the pickup sits exactly where it sits in the aircraft
Boost & transfer pumps	move fuel to the engines and between tanks	sized and controlled as the aircraft's own system is
Cross-feed & shut-off valves	route fuel between subsystems	operated in the sequence the aircraft's system uses
Fuel quantity gauging	reads how much fuel is present	checked for honesty, not just installed
Vent system	keeps the tank near atmospheric pressure	watched on every trial, not only when something goes wrong
Attitude fixture	tilts the tanks to a chosen climb, dive, bank or sideslip	holds the attitude steady for the length of the trial
Engine-side demand simulation	draws fuel off at a realistic rate	matched to what an engine would actually ask for
Instrumentation	reads feed pressure, gauge output and vent pressure	fast enough to catch a momentary loss of feed
Control & data acquisition	runs the sequence and logs every reading	the same sequence every time, against limits from the aircraft's own schematic
Calibration	keeps every reading trustworthy	traceable, and checked before it is relied on
Testing & documentation	prove the rig, then every trial	a calibrated rig, and a report for every run

The element that decides whether a trial means anything is not a machine. It is the attitude chosen for it. A rig that only ever runs level and full is measuring the one condition that was never in doubt.

Fig · 05 — One rig, three fuel states: full, ordinary and low, all on the same tanks and pickups.

Full specification — expand

Rig	Tanks or tank simulators built to the aircraft's own geometry; boost and transfer pumps; cross-feed and shut-off valves; a fuel quantity gauging installation; a vent system kept near atmospheric pressure; an attitude fixture that tilts the tanks to a chosen climb, dive, bank or sideslip; an engine-side demand simulation; instrumentation and data acquisition; and testing and documentation before handover
The One Idea	A fuel system does not fail when the tank runs dry. It fails when a manoeuvre uncovers the pickup for an instant, with fuel still inside
Why Attitude Matters	A fuel system must deliver fuel at the rate an engine needs under every likely flight condition, and a climb, a dive, a bank or a sideslip can all move the fuel surface away from a pickup that is perfectly placed for level flight
Why Low Fuel Is the Hard Case	A full tank has fuel everywhere; a low tank has fuel only where the surface happens to be, so the combination of a low fuel state and a demanding attitude is where a pickup is actually tested
Why Air Cannot Be Ignored	A fuel system must be arranged so that any air introduced into it does not cause the engine to lose power, so proving continuous feed under attitude is a safety question, not only a performance one
Why Gauging Is Tested Separately	A fuel quantity gauge and the fuel feed are two different problems, and a gauge that reads correctly while level can still be tested for honesty when the tank is tilted or the fuel is low
Why the Vent Is Not an Afterthought	A tank that cannot breathe will eventually stop feeding fuel properly or be damaged by pressure, so the vent system is watched on every trial, not only the feed line
Standards	14 CFR Part 25 Subpart E and the equivalent CS-25, in particular section 25.951, are the public references for how a fuel system must perform under every likely operating condition. RTCA DO-160 is the public reference for environmental qualification of airborne equipment, and ISO/IEC 17025 for calibration. None of them sets the fuel states or attitudes a particular aircraft's rig must cover: that is set by the customer against their own aircraft. Acceptance of the finished rig rests with the customer and their inspection authority
Configurations	A single-tank rig for feed and gauging, a multi-tank rig with transfer and cross-feed, and a full-system rig mounted on a tilting attitude table
Scope Boundary	This is the rig that proves a fuel system's feed, gauging and venting under attitude. It is not the whole aircraft's systems integration structure (see Iron Bird aircraft systems integration rig), not a calibration rig for one named fuel pump model (see test equipment for aircraft fuel pump), and not a hydrogen fuel system rig (see hydrogen fuel system component test system)
Status	Neometrix engineers aircraft fuel system test rigs to order, and no delivered aircraft fuel system test rig is claimed.

Configurations

One method, three ways to supply the rig.

The steps, the instrumentation and the record are shared. What changes is how many tanks the rig must take, and whether it can set an attitude.

Single-tank rig

One tank, feed and gauging

A compact rig for one tank, for proving feed and gauging on a single fuel source.

Multi-tank rig

Transfer and cross-feed

Several tanks with cross-feed valves and transfer pumps, for systems that move fuel between tanks in flight.

Full-system rig

On a tilting attitude table

The complete fuel system mounted on a fixture that can hold a chosen climb, dive, bank or sideslip for the length of a trial.

Fig · 06 — Three ways to supply the rig, one method: a single-tank rig, a multi-tank rig, or a full-system rig on an attitude table.

And the part that is not equipment at all, yet decides all three: the test plan — which fuel states and attitudes are covered, in what order, and the rule for judging feed, gauging and vent behaviour, so that every trial is read the same way.

Where it is used

Wherever a fuel system has to be proved before it flies.

The common thread is a fuel system whose failure would show up only in the air, at the worst possible moment.

New aircraft programmes

Where a fuel system design is proved on the ground before it is committed to flight test.

Modification and upgrade

Where a tank, pump or gauging change has to be re-proved against the whole system.

Component qualification

Where a new pump, valve or probe is proved installed in a system, not only on its own bench.

Investigation

Where a reported feed or gauging problem is reproduced on the ground rather than guessed at.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 Why does a full, level tank prove so little?

Because a full tank has fuel everywhere the pickup could possibly be, so almost any arrangement will feed successfully from it. The question a fuel system actually has to answer is what happens when the tank is not full and the aircraft is not level: a climb, a dive, a bank or a sideslip can all move the fuel surface away from a pickup that was placed correctly for level flight. Public airworthiness requirements for large aeroplane fuel systems say plainly that fuel must be delivered at the rate and pressure the engine needs under every likely operating condition, including manoeuvres for which certification is sought, and that testing is expected wherever it cannot be shown by analysis alone. A bench test that never leaves level and full has not engaged with that requirement at all.

Q · 02 What actually happens when a manoeuvre uncovers the pickup?

The fuel surface tilts with the aircraft, and if the tank is not full enough, the surface can move away from the pickup point for the fraction of a manoeuvre. If that happens, air rather than fuel enters the feed line. Public requirements for aeroplane fuel systems state that any air introduced into the system must not be allowed to cause a loss of engine power, so a system that momentarily draws air has to be designed, and proved, to cope with it without the engine faltering. That is precisely the condition this rig is built to create on purpose and on the ground, rather than let it be discovered for the first time in the air.

Q · 03 Why is fuel gauging tested separately from fuel feed?

Because they depend on different physics and can fail independently. Feed depends on whether fuel actually reaches the pickup and the pump. Gauging, commonly done with capacitance probes, depends on the probes correctly sensing how much fuel is in the tank and where its surface is, which changes with the tank's shape and the aircraft's attitude in exactly the way the fuel surface itself does. A gauge that is accurate with the aircraft level and the tank full can become optimistic or pessimistic once the tank is tilted or nearly empty, at precisely the moment an honest reading matters most to the crew. So this rig checks the gauge's reading against the fuel actually present, across the same states and attitudes it uses to test feed.

Q · 04 What does the vent system have to do with any of this?

A fuel tank has to breathe. As fuel is drawn out, the space above it must fill with air or vapour at close to atmospheric pressure, and as altitude or temperature changes, that same space has to relieve pressure or vacuum without damaging the tank or stopping fuel flow. A vent system that is blocked, undersized or wrongly arranged can starve the feed just as effectively as a mispositioned pickup, even though the tank itself may hold plenty of fuel. That is why this rig reads vent behaviour on every trial rather than treating the vent as a fitting that either works or does not.

Q · 05 Is this the same as the Iron Bird rig, the fuel pump test equipment, or the hydrogen fuel rig?

No, and the differences are worth stating precisely. The Iron Bird aircraft systems integration rig page is the whole aircraft's hydraulic, flight-control, landing-gear and electrical systems laid out on one ground structure; its own description does not list the fuel system among what it covers. The test equipment for aircraft fuel pump page is a calibration rig built around one named fuel pump and controller model, not a whole fuel system with tanks, gauging and a vent. The hydrogen fuel system component test system page is about a different fuel chemistry entirely. This page does not replace any of them, and it does not claim what they claim a second time.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers aircraft fuel system test rigs to order, and no delivered aircraft fuel system test rig is claimed. What stands behind the offer is adjacent: Neometrix engineers the fluid loops, pumps, valves and instrumentation behind other fuel and hydraulic test equipment (see the test equipment for aircraft fuel pump page) and the structural fixtures and geometry-critical build behind whole-aircraft ground rigs (see the Iron Bird aircraft systems integration rig page). Tanks or tank simulators, pumps, valves and gauging probes are proven catalogue items or customer-furnished articles, not invented. What Neometrix engineers is the rig structure, the attitude fixture, the plumbing to the aircraft's own schematic, the instrumentation, the data acquisition and the documentation. So the honest position is that the rig is engineered to order, the neighbouring disciplines are in the building, and the first rig of this exact kind will be built around the customer's own aircraft and fuel system rather than lifted off a shelf.

Q · 07 Which standards apply, and who sets the fuel states and attitudes to test?

14 CFR Part 25 Subpart E and the equivalent CS-25, and in particular section 25.951, are the public references for how a large aeroplane's fuel system must perform under every likely operating condition, and for the expectation that testing is used where analysis alone cannot show compliance. RTCA DO-160 is the public reference for the environmental qualification of airborne equipment, and ISO/IEC 17025 for calibration. None of them names the specific fuel states or attitudes a particular aircraft's rig must cover: that is set by the customer against their own aircraft's design and its own certification or qualification basis, and this page prints none of it. Acceptance of the finished rig, including its proving tests before handover, rests with the customer and whatever authority they name.

Q · 08 What do you need from us to quote?

Six things, and most of them describe the aircraft's fuel system rather than the rig. First, the schematic: the tanks, pumps, valves and gauging as the aircraft's own system defines them. Second, the states: which fuel levels must be tested. Third, the attitudes: which climb, dive, bank or sideslip conditions matter for this aircraft. Fourth, the demand: the flow the engine or engines actually draw. Fifth, the configuration: a single-tank rig, a multi-tank rig, or a full-system rig on an attitude table. Sixth, the site: the power, fuel handling and floor space the facility can offer. From that we come back with a layout drawing, a written test plan you can check, and a budgetary price.

The neighbouring aircraft-system rigs, and how they differ from this one.

Three neighbours in the same family of aircraft ground test equipment.

↗ The whole aircraft

Iron Bird — Aircraft Systems Integration Rig

The full-scale ground structure for hydraulic, flight-control, landing-gear and electrical systems - not built around fuel.

↗ One pump, not a system

Test Equipment for Aircraft Fuel Pump

A calibration rig for one named fuel pump and controller model, not a whole fuel system.

↗ A different fuel entirely

Hydrogen Fuel System Component Test System

Hydrogen fuel system components - a different fuel chemistry, not conventional aviation fuel.

Browse all Neometrix product lines.

Get a quotation

Tell us the schematic, the states,
and the attitudes that matter.

The projects desk replies within two working days with a layout drawing, a written test plan you can check, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — fuel system test rig Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — AIRCRAFT FUEL SYSTEM TEST RIG MOUNT · FILL · TILT · FEED · WATCH · RECORD & REPEAT — THE SYSTEM IS PROVED WHERE IT IS WEAKEST ENGINEERED IN NOIDA · INDIA