NMX‑RPT‑30 / Rev 00 / aerospace mechanism test / frame · engagement · flow 2026 · Product Page

NMX-RPT-30 · ENGINEERED TO ORDER — RETRACTABLE REFUELLING PROBE TEST RIGS

Every probe passes on a bench. This rig is built to make one fail.

Name: Retractable Refuelling Probe Test Rig
Brand: Neometrix

A refuelling probe has to extend out of a moving aircraft, meet a receiving coupling that is also moving, hold a fuel-tight joint while both aircraft manoeuvre, and stow again afterwards. There is exactly one good place to discover what it cannot do, and it is on the ground. So the rig mounts the article at a representative interface rather than in something conveniently stiffer; cycles it past its declared life, including the emergency cases; drives the engagement as what it actually is — an impact at closing speed with the misalignment dialled in, not a gentle docking; and flows fluid through the joint while the article is loaded, moving and cold, because a probe that seals on a static bench and weeps mid-stroke has passed the wrong test. Equipment of this class has been quoted against successive retractable refuelling probe qualification programmes for a defence research organisation; no delivered refuelling probe test rig is claimed — the class is engineered to order.

Enquire — probe test rigs Capability sheet (PDF)

Illustrative of the class — a structural test rig in a clean laboratory bay: a heavy welded steel portal reaction frame painted fresh grey, with a long straight polished stainless steel tube held horizontally at its root in a thick machined steel interface bracket bolted through the frame, two large hydraulic actuators with bright clevis ends and chrome rods attached to the tube through machined load-spreading collars, a bright cylindrical inline load cell between each actuator rod and its clevis, black hydraulic hoses running in a tidy parallel bundle to a manifold block, a yellow-framed mesh safety guard standing open at one side, no people and no readable markings

Fig · 01 The frame — the article held at a representative interface, loaded through collars, and reacted into steel

Proves

a limitnot a habit

Engagement

an impactoff-axis, at speed

Flowed

while movingloaded and cold

Reacted into

a real interfaceairframe stiffness

Status

engineered to orderquoted class

ISO 9001 / 14001 Engineered to order Aerospace test rig franchise Multi-axis load & flow Noida · India

Overview

The rig's job is to be the last cheap failure.

Everything a refuelling probe does happens between two aircraft in close formation with fuel moving between them. A qualification rig exists so that the first time the mechanism reaches its limit, it does so bolted to a steel frame in a laboratory.

Illustrative of the class — the engagement end of a test rig in a clean laboratory: a machined steel coupling fixture with a central circular receptacle mounted on a low carriage running on two parallel hardened steel linear rails bolted to a machined baseplate, facing the rounded tip of a polished stainless steel tube held opposite, a graduated adjustable angle plate with curved slots and clamping bolts beneath the fixture so it can be set off-axis, a bright cylindrical load cell mounted behind the receptacle, thin instrumentation cables clipped along the baseplate edge, no people and no readable markings

Fig · 02 The engagement carriage — a coupling fixture on rails, and a graduated plate that puts the error in on purpose

The engagement is an impact, not a connection. The two aircraft are closing on each other, the hose and its receiving coupling are trailing in disturbed air, and the pilot is aiming a tube at a target that moves. Contact therefore arrives with energy and with error — angular and lateral misalignment are not faults in the manoeuvre, they are the normal condition of it. A rig that slides a nozzle gently into a socket has proven nothing that the aircraft will ever ask. So the engagement end runs on rails, arrives at a representative closing speed, and the misalignment is set deliberately on a graduated plate so the same wrong angle can be repeated a thousand times.

How you hold it decides what you learn. Probe loads do not stop at the probe — they react into the aircraft attachment, which deflects. Mount the article in a fixture far stiffer than the airframe and the bending moments redistribute, the deflections shrink, and the fatigue life that comes out belongs to the rig rather than to the aeroplane. So the interface is engineered to represent real attachment stiffness, and the reaction frame behind it is stiff enough not to join in. It is the same principle the site's iron bird argues at whole-aircraft scale: the structure that holds the article is part of the instrument.

And the hard cases happen together, not in turn. Seals harden when cold, clearances close, greases stiffen, and a joint that is perfectly tight on a static bench at room temperature can weep mid-stroke at altitude temperature under load. Testing each condition separately passes articles that fail when the conditions combine, so fluid flows while the article is loaded, while it is moving, and while it is cold-soaked, with leak detection running throughout.

Equipment of this class has been quoted against successive retractable refuelling probe qualification programmes for a defence research organisation, covering both telescopic and actuated types. No delivered refuelling probe test rig is claimed: the class is engineered to order, and the record is stated as it stands.

Representative

Held as the aircraft holds it

Interface stiffness reproduced, not idealised — so the fatigue result belongs to the aircraft.

Realistic

Error dialled in, not out

Closing speed and misalignment set on a graduated plate — the wrong angle, repeatable a thousand times.

Combined

Fluid, motion and cold at once

Because a joint that seals static and weeps mid-stroke has passed the wrong test.

Architecture

Mount, cycle, engage, flow.

The schematic follows the test — the article mounted as the aircraft mounts it, cycled past its life, engaged off-axis at speed, and flowed while it moves — then the rig underneath: frame and interface, actuation, engagement carriage, fluid and acquisition.

FIG · 03PROBE TEST RIG ARCHITECTURE · FRAME + INTERFACE / ACTUATION + CYCLING / ENGAGEMENT CARRIAGE / FLOW + CONDITIONING + DAQ

Fig · 03 The limit found on the ground, where it costs money rather than an aircraft

Arc · 01

Frame & Interface

Reaction frame plus a representative attachment — the aircraft-side stiffness reproduced, so the load path is the real one.

Arc · 02

Actuation & Cycling

Deploy and stow, timed and counted beyond life — the actuator's own duty measured, and the emergency retraction cases run.

Arc · 03

Engagement Carriage

Coupling fixture on rails, graduated misalignment, inline load cell — contact at closing speed, with the error set on purpose.

Arc · 04

Flow, Conditioning & DAQ

Fluid at pressure, cold-soak, leak detection — load, position, pressure and flow tied to a single time base.

Qualifying a probe, or a mechanism like one? Send the load envelope, the cycle life, the engagement conditions and the fluid and temperature range — a clause-by-clause compliance matrix within two working days · [email protected]

Send tender spec

Specifications

Reference rigs, built to the qualification plan.

The parameters below describe reference rigs. Frame size, actuator ratings, carriage stroke and speed, fluid capacity and channel counts all follow from three givens: the probe's load envelope and cycle life, the engagement conditions to be reproduced, and the fluid, pressure and temperature range the programme has to defend.

Illustrative of the class — a fluid conditioning skid on a clean laboratory floor: a fresh-grey painted steel baseplate frame carrying a horizontal pump with an electric motor on machined mounting pads, bright stainless steel pipework running between two tall cylindrical filter housings, a polished inline flow meter body flanged into the pipe run, a compact manifold of hand valves with black handles, a plain light-grey control cabinet with a blank closed door at one end, a shallow stainless drip tray beneath the skid and a braided earth bonding strap clamped to the frame, no people and no readable markings

Fig · 04 The fluid side — conditioned, filtered, metered, and watched for the leak that only appears mid-stroke

Where probe test rigs go wrong

A fixture stiffer than the aircraft — the commonest and most expensive error, because the rig quietly becomes the subject of its own test and the fatigue life reported belongs to a structure that never flies. Engagement modelled as a gentle push — no closing speed, no impact energy, no misalignment, so the one event the probe exists to survive is the one event never reproduced. Conditions tested in turn — a static leak check, then a cold check, then a motion check, and an article that passes all three but weeps when they combine. Cycles counted without load — endurance that proves only that the mechanism still moves, not that it still moves under the spectrum it will meet. Instrumentation on separate time bases — a load peak that cannot be tied to the position that caused it, which turns a diagnosis back into an argument. And the rig's own hazard case left as an afterthought — flammable fluid beside stored hydraulic energy and electrical power, with bonding, containment and interlocks bolted on at the end.

So the discipline runs the other way. The interface is engineered to represent the aircraft attachment, and the frame behind it is stiff enough not to participate. The engagement is driven at closing speed on rails, with angular and lateral misalignment set on a graduated plate and recorded with every run. Fluid, motion and temperature are applied together, with continuous leak detection rather than a check at the end. Cycling runs under load, past the declared life, with the emergency retraction cases included. Every channel — load, position, cycles, pressure, flow, temperature — is acquired on one time base. And the safety case is designed in from the first drawing, because that is what makes it possible to run the machine hard.

Full specification — expand

System	Retractable refuelling probe test rig — reaction frame & interface, actuation & cycling, engagement carriage, fluid conditioning & acquisition
Governing Idea	Find the failure on the ground — load beyond the envelope and cycle beyond life; a rig that never breaks anything has proven a habit, not a limit
The Engagement	An impact, not a docking — contact at representative closing speed, with angular and lateral misalignment set deliberately and repeatably
The Mounting Rule	Represent the airframe, or you test the fixture — interface stiffness reproduced rather than idealised, because probe loads react into the aircraft attachment
Article Types	Telescopic and actuated retractable probes — and mechanisms of the same character: deploy, engage, hold, retract
Load Application	Axial, side and bending load through machined load-spreading collars; limit load and ultimate cases reacted into the frame; loads applied in combination, not one axis at a time
Cycling	Deploy and stow beyond declared service cycles, timed and counted under load, including emergency retraction cases and post-cycle function checks
Flow	Fluid at pressure through the coupling while the article is loaded, moving and cold-soaked, with continuous leak detection rather than an end-of-test check
Conditioning	Cold-soak and altitude conditioning — seals harden, clearances close and greases stiffen, and all three change what the joint does
Instrumentation	Load, position, cycle count, pressure, flow and temperature acquired on a single time base, so a load peak can be tied to the position that caused it
Safety Case	Flammable fluid beside stored hydraulic energy and electrical power — bonding, containment, drip trays, ventilation, interlocks and guarding designed in from the start
Acceptance	Qualification and acceptance test procedures written and run against the agreed test plan, with rig calibration traceable and in date
The Split	The site's fuel contents gauging probe test rig handles the site's other “probe”, and it is a different article entirely — a measurement sensor calibrated for accuracy, not a mechanism loaded towards destruction. The landing gear shock absorber is the closest cousin: another retractable aircraft mechanism that extends, absorbs an impact and retracts, and is judged on all three. The iron bird proves whole systems in true geometry; this proves one mechanism to its limit
Scope Boundary	Ours: reaction frame & interface, actuation & cycling, engagement carriage & misalignment provisions, multi-axis load application, fluid conditioning & leak detection, cold & altitude conditioning, instrumentation & acquisition, the safety case, installation, commissioning, documentation, training, spares & AMC — including build to the customer's specification. Bought-in certified: actuators, load cells, flow instruments, acquisition hardware. The customer's: the probes, their qualification requirements and their acceptance limits
Status	Engineered to order — equipment of this class quoted against successive retractable refuelling probe qualification programmes for a defence research organisation; no delivered refuelling probe test rig is claimed

PDF · 1 page

Retractable Refuelling Probe Test Rig — Capability Sheet

Tender Response

Send load envelope, cycle life & engagement conditions — compliance matrix in two working days

Variants

One discipline, four rigs.

What changes is the question — will it survive, will it engage, will it last, or is this particular one good.

Var · 01

Full Qualification Rigs

Multi-axis load, cycling, engagement and flow in one frame — the campaign rig that has to answer everything.

Var · 02

Engagement & Contact Rigs

Closing speed, impact energy and misalignment — the one event the probe exists to survive, reproduced on demand.

Var · 03

Endurance Cycling Rigs

Deploy and stow under load, past the declared life — long, unattended running with the spectrum applied.

Var · 04

Acceptance & Functional Stands

Short, repeatable pass-fail runs for production or post-overhaul — tempo without losing the discipline.

Applications

Wherever a mechanism must deploy and be trusted.

The programmes that develop these mechanisms, and the shops that must return them to service.

A · 01Probe development programmes

A · 02Qualification & certification campaigns

A · 03Airframe interface load validation

A · 04Overhaul & post-repair acceptance

A · 05Production end-of-line functional test

A · 06Cold & altitude environmental qualification

FAQ

Common questions.

Plain-language answers from the engineering team.

Q · 01 Why does a refuelling probe need a rig of its own?

Because it is asked to do four different jobs, and failing any one of them is serious. It is a structure that projects into the airstream and carries aerodynamic load whenever it is deployed. It is a mechanism that has to extend and retract reliably, including in a hurry when something has gone wrong. It is a fuel joint that has to seal at pressure while both ends of it are moving relative to each other. And it is an impact absorber, because engagement is a collision with a moving target and misalignment is normal rather than exceptional. Each of those duties has its own failure mode — fatigue cracking at the root, an actuation jam, a seal that weeps under load and temperature, damage from a hard or badly aligned contact — and they interact, so proving them one at a time on separate benches leaves the combinations untested. Testing at the aircraft level is the alternative, and it is enormously expensive, comes far too late to change the design, and puts the discovery of a limit in the worst possible place: airborne, in close formation, with fuel flowing. A dedicated rig moves that discovery onto the ground, early, where the consequence of finding a limit is a repair and a design change rather than an incident.

Q · 02 Why does the mounting interface matter so much?

Because a probe is a cantilever, and what happens at the root decides what happens everywhere else. Loads applied at the tip — aerodynamic drag, side force, and the axial and off-axis forces of engagement — travel back down the article as a bending moment that grows towards the attachment, and then pass into the aircraft structure, which deflects. That deflection is part of the real system: it changes how the load is shared, where the peak stress sits, and how the whole assembly responds dynamically to a sharp input like a contact. Bolt the article into a massive, rigid laboratory fixture and all of that changes. The root becomes stiffer than reality, so the moment distribution shifts and the peak stress may appear somewhere it never does in service. The dynamic response changes, so a resonance seen on the rig may not exist on the aircraft, or one that matters in the air may be entirely absent here. Worst of all, the fatigue life that comes out of a long cycling campaign is then the fatigue life of the wrong boundary condition — and it usually errs optimistic, which is the dangerous direction. So the interface is engineered rather than improvised: attachment geometry as fitted, representative local stiffness, and the reaction frame behind it stiff enough that it contributes nothing of its own. The rule is the same one the axle cell and the iron bird both argue — the structure that holds the article is part of the instrument.

Q · 03 How do you reproduce an engagement on a laboratory floor?

By treating it as what it physically is: a controlled collision with a deliberate aiming error. The receiving coupling fixture is carried on a carriage running on hardened linear rails, so relative motion between the two halves is real motion rather than a slow squeeze, and it can be driven to a representative closing speed so the contact carries the right energy. The aiming error is the part people leave out, and it is the part that breaks things: real engagements arrive with angular and lateral misalignment, so the fixture sits on a graduated angle plate with curved slots, letting a specific angle and offset be set, clamped, recorded, and then repeated identically for as many contacts as the test plan demands. An inline load cell behind the receptacle captures the contact force history, which is what tells you whether the tip, its sealing face and the mechanism behind them are absorbing the event the way the design intended. Around that, the interesting cases are the ugly ones: contact at the extreme of the misalignment envelope, repeated contacts in quick succession, a glancing strike that loads the article sideways, and engagement attempts that miss and scrape. Those are the events that produce real damage in service, and they are exactly the ones that a gentle, well-aligned laboratory push will never produce.

Q · 04 Why must fluid, motion and cold happen at the same time?

Because sealing is a dynamic property, and testing it statically measures something else. A seal works by being compressed against a counterface with the right contact pressure; anything that changes that pressure changes whether it seals. Temperature changes it profoundly — elastomers stiffen and lose resilience as they get cold, so a seal that follows a small surface irregularity easily at room temperature may bridge it at altitude temperature; metals shrink at different rates, so clearances that were correct move; greases thicken and increase the force needed to move the mechanism at all. Motion changes it too: a joint at rest has settled into one position, while a joint mid-stroke is being asked to seal across a surface that is sliding, possibly with a slight lateral load pushing it off-centre. And load changes it, because bending in the article distorts the housing that carries the seal. Each effect on its own is often survivable; combined, they are where leaks actually occur. Since the consequence in service is fuel escaping in an airstream, the rig applies all three together and watches with continuous leak detection throughout the run rather than inspecting for wetness at the end — an end-of-test check cannot tell you a joint wept for two seconds at the coldest point of a stroke, which is precisely the finding that matters.

Q · 05 How is this different from your other probe rig and your landing gear work?

Different articles, and in one case a completely different meaning of the same word. The site's fuel contents gauging probe test rig also has “probe” in its name, but its article is a measurement sensor — a capacitance element that sits in a tank and reports how much fuel is present. Its rig is about accuracy: known quantities, known attitudes, calibration against a reference, and the question is how closely the reading matches truth. Nothing is loaded towards destruction and nothing is cycled to failure. This rig's article is a mechanism and a structure, and the question is the opposite one: where does it break, and does it stay sealed until it does. The landing gear shock absorber is the genuine cousin — another retractable aircraft mechanism that deploys, absorbs a substantial impact, holds a fluid seal under load, and retracts again, judged on all four counts, with the same rig questions about representative mounting, cycling under load and instrumentation on a common time base. And the iron bird sits one level above all of them: whole systems in true geometry, proving interactions rather than limits. Component rigs find where a part fails; the integration rig finds where correct parts disagree.

Q · 06 What do you build, what is bought in — and what is claimed?

Divided honestly. What Neometrix provides: the reaction frame and the interface, engineered to represent the aircraft attachment stiffness rather than to be conveniently rigid; the actuation and cycling arrangement with timing, cycle counting, load-holding and the emergency retraction cases; the engagement carriage on its rails with the graduated misalignment provisions and contact-speed control; multi-axis load application through machined load-spreading collars, with limit and ultimate cases reacted into the frame; the fluid conditioning and leak detection — supply, filtration, pressure and flow control, containment and drip management; cold-soak and altitude conditioning; the instrumentation and acquisition that puts load, position, cycles, pressure, flow and temperature on a single time base; the safety case around flammable fluid, stored hydraulic energy and electrical power — bonding, ventilation, interlocks and guarding; and installation, commissioning, documentation, training, spares and AMC, including build to the customer's own specification, which is how requirements of this class are framed. What is bought-in certified: actuators and their power units, load cells, pressure and flow instruments, and acquisition hardware — proprietary products of established makers, integrated rather than imitated. What is the customer's: the probes themselves, their qualification requirements, and the acceptance limits those requirements are anchored to. And the record, stated plainly: equipment of this class has been quoted against successive retractable refuelling probe qualification programmes for a defence research organisation, covering telescopic and actuated types. No delivered refuelling probe test rig is claimed; the class is engineered to order, around the mechanism it has to judge.

↗

The aerospace proving family from Neometrix.

One sensor, one mechanism, one whole aircraft — three different questions.

↗ Accuracy

Fuel Contents Gauging Probe Test Rig

The site's other “probe” — a sensor judged on accuracy, not a mechanism judged on limits.

↗ Mechanism

Landing Gear Shock Absorber

The closest cousin — deploys, absorbs an impact, seals under load, retracts.

↗ Systems

Iron Bird — Systems Integration Rig

One level up — where correct parts disagree with each other.

Browse all Neometrix product lines.

Get a quotation

Send the load envelope
and the cycle life.

The projects desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — probe test rigs Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED TO ORDER — RETRACTABLE REFUELLING PROBE TEST RIGS FIND THE FAILURE ON THE GROUND · THE ENGAGEMENT IS AN IMPACT · REPRESENT THE AIRFRAME, OR YOU TEST THE FIXTURE ENGINEERED IN NOIDA · INDIA

Every probe passes on a bench. This rig is built to make one fail.

The rig's job is to be the last cheap failure.

Held as the aircraft holds it

Error dialled in, not out

Fluid, motion and cold at once

Mount, cycle, engage, flow.

Frame & Interface

Actuation & Cycling

Engagement Carriage

Flow, Conditioning & DAQ

Reference rigs, built to the qualification plan.

Where probe test rigs go wrong

One discipline, four rigs.

Full Qualification Rigs

Engagement & Contact Rigs

Endurance Cycling Rigs

Acceptance & Functional Stands

Wherever a mechanism must deploy and be trusted.

Common questions.

The aerospace proving family from Neometrix.

Fuel Contents Gauging Probe Test Rig

Landing Gear Shock Absorber

Iron Bird — Systems Integration Rig

Send the load envelope
and the cycle life.

Similar Products

Share This Page

Every probe passes on a bench. This rig is built to make one fail.

The rig's job is to be the last cheap failure.

Held as the aircraft holds it

Error dialled in, not out

Fluid, motion and cold at once

Mount, cycle, engage, flow.

Frame & Interface

Actuation & Cycling

Engagement Carriage

Flow, Conditioning & DAQ

Reference rigs, built to the qualification plan.

Where probe test rigs go wrong

One discipline, four rigs.

Full Qualification Rigs

Engagement & Contact Rigs

Endurance Cycling Rigs

Acceptance & Functional Stands

Wherever a mechanism must deploy and be trusted.

Common questions.

The aerospace proving family from Neometrix.

Fuel Contents Gauging Probe Test Rig

Landing Gear Shock Absorber

Iron Bird — Systems Integration Rig

Send the load envelopeand the cycle life.

Similar Products

Share This Page

Send the load envelope
and the cycle life.