Neometrix / Air Data Test Sets / Air Data Test Set / NMX-ADT-53

NMX-ADT-53 · ENGINEERED-TO-ORDER CLASS — SPECIFY · CONNECT · LIMIT · RAISE · HOLD · PROVE

Air Data Test Set. Speed and height are just pressures.

Name: Air Data Test Set
Brand: Neometrix
SKU: NMX-ADT-53

A pitot-static system does not measure speed or height. It measures pressure, and the instruments turn that into speed and height.

So the test set is built around two pressures, static and pitot, held together, with limits on how fast they move and a hold at every point that shows a leak.

Discuss an air data test set Capability note (PDF)

A single portable air data test set in a clean test hall: a rugged grey steel case with a carrying handle and a smooth blank front panel on a small two-wheel trolley, with two plain black hoses running from stainless ports on its side to two stainless adapter fittings lying on the floor, and no people

Fig · 01 — A portable air data test set on its trolley, with its two hoses and adapters laid out — illustrative render.

The pressures

static and pitotheld together

The limits

rates and differencescapped in the set

The order

speed on last, off firstbuilt into the sequence

The hold

a timed leak holdat every point

Status

engineered to orderno set yet delivered

ISO 9001ISO 14001ISO 2533 standard atmosphere reference

Overview

Why a test set is judged by how steadily it holds, and how safely it moves.

Because an instrument can be wrecked in a second and a leak can hide for years. A set that is accurate but rough breaks capsules, and a set that moves gently but cannot hold hides leaks.

Fig · 02 — The set in one picture: height and speed are asked for, two pressures are set and held, and the instrument is read against them.

Speed and height are just pressures.

What the set is for

It tests the pitot-static instruments of an aircraft, and the pipework that feeds them, on the ground. The set makes the pressures a flight would make: a static pressure for height and a pitot pressure for speed. It suits altimeters, airspeed indicators and climb indicators, and the pitot and static lines they share.

Why speed and height are pressures

A pressure altimeter reads static pressure and turns it into height by the standard atmosphere. An airspeed indicator reads the difference between pitot and static pressure. A climb indicator reads how fast static pressure changes. A set that controls two pressures can stand in for all three on the ground.

Why rates and differences are limited

The sensing capsules are delicate. A sudden surge of pressure, or pitot pressure with the static side left open, can crush or over-range them. The set limits how fast each pressure moves and how far apart the two can be, so the set protects the instrument, not the operator's care.

Why the order matters

Airspeed is a difference, so the pitot hose is connected before the static channel is run. Height is raised first and speed is added second. At the end speed comes off first and height returns to ground last. The order is built into the sequence.

Why every point is held

A leak in a static or pitot line shows as drift in height or speed. Only a hold at a steady pressure tells a leak from an instrument error, so every test point carries a timed hold that reports the drift.

Why one offset is not enough

The standard atmosphere relates pressure to height by a curve, not a straight line. An error found at one height does not hold at another, so an instrument is tested at several points across its range.

The method

Specify, connect, limit, raise, hold, and prove.

Six steps in a fixed order. The two shaded steps are the ones a quick test skips.

FIG · 02AIR DATA TEST SET · SPECIFY / CONNECT / LIMIT / RAISE / HOLD / PROVE — SPEED AND HEIGHT ARE JUST PRESSURES

The step people underrate is the hold. A set that reaches the right number and cannot hold it has shown where the pressure was, not where it stays.

Fig · 03 — Three ways a test set lets you down: a rate that is too fast, one side alone, and no leak hold — a drawing of the idea, with no values.

1 · Specify

The instruments set the ranges and the rates, and the maintenance data sets the points. The customer states them, and the set does not guess them.

2 · Connect

The pitot hose goes on first, then the static hose, through keyed adapters that will not let a static hose fit a pitot port.

3 · Limit

The rate of climb, the rate of speed change, the speed and the difference between the two pressures are capped in the set before any pressure moves.

4 · Raise

Height is raised first and held. Speed is added only after that, and the difference is watched all the way up.

5 · Hold

Each test point carries a timed hold that reports the drift in height and speed, so a leak is told from an instrument error.

6 · Prove

Speed comes off first and height returns to ground last, at a controlled rate, and the record is handed over with the log.

Work content

What the set contains, element by element.

Read it as a checklist: a set missing a row will give a good reading and a wrong answer.

Two plain black flexible hoses laid in gentle curves on a grey steel bench, each ending in a plain stainless steel adapter fitting, one a smooth tapered nose and the other a short plain cylindrical plug, and no people

Fig · 04 — The connections: two hoses with stainless adapters, one a tapered nose and one a plain plug — illustrative render.

Element	What it does	What matters
Pressure source	provides vacuum and pressure	a pump sized for the instruments, with clean dry air and a trap that keeps moisture out
Static channel	holds the pressure that stands for height	a controlled channel with fine control near each test point and a steady hold
Pitot channel	holds the pressure that adds speed	a second controlled channel, so airspeed is the difference between two pressures and not a guess
Pressure controller	turns height and speed into pressure	applies the standard atmosphere, so the operator asks for height and speed and the set works out the pressures
Limits	protect the instrument	programmable limits on the rate of climb, the rate of speed change, the speed and the difference between the two pressures
Hoses & adapters	connect to the work	hoses and adapters for the instrument or the aircraft ports, keyed so a static hose cannot be fitted to a pitot port
Leak hold	proves a line is tight	a timed hold at each point that reports the drift in height and speed
Safe return	lets the instrument go	a return to ground that takes speed off first and then height, at a controlled rate
Control & logging	run and record	PLC or computer control of the test points, and a logger that keeps pressure, height, speed and hold drift for every point
Reference sensors	check the set itself	reference pressure sensors that are compared with a reference before each series of tests
Guarding	keeps people clear of pressure and vacuum	relief valves, a vented exhaust and guarded moving parts on the pump
Procedure	fixes the sequence	specify, connect, limit, raise, hold and prove, the same for every instrument and every aircraft
Testing & documentation	prove the set first	a leak test, a reference check and a run record the customer can inspect

The element that decides whether the reading is true is the pressure controller and its hold, because a set that cannot hold a pressure cannot tell a leak from an instrument error.

Fig · 05 — One set, three jobs: an instrument bench, the aircraft lines, and an air data computer, each fed the same two pressures.

Full specification — expand

System	A vacuum and pressure source with clean dry air; a static channel and a pitot channel, each controlled; a pressure controller that turns a commanded height and speed into pressures by the standard atmosphere; programmable limits on the rate of climb, the rate of speed change, the speed and the difference between the two pressures; hoses and keyed adapters for the instrument or the aircraft ports; a timed leak hold that reports the drift in height and speed; a safe return to ground; a PLC or computer control with a logger; reference pressure sensors; relief valves and guarding; a written test plan; and testing and documentation before handover
The One Idea	An air data test set is judged by how steadily it holds two pressures and how safely it moves them.
Why Speed And Height Are Pressures	A pressure altimeter reads static pressure and turns it into height by the standard atmosphere, an airspeed indicator reads the difference between pitot and static pressure, and a climb indicator reads how fast static pressure changes, so a set that controls two pressures can stand in for height, speed and climb on the ground
Why Rates And Differences Are Limited	The sensing capsules are delicate, and a sudden surge of pressure, or pitot pressure applied with the static side left open, can crush or over-range them, so the set limits how fast each pressure moves and how far apart the two can be
Why The Order Matters	Airspeed is a difference of two pressures, so the pitot hose is connected first, height is raised before speed is added, and speed is taken off before height returns to ground
Why Every Point Is Held	A leak in a static or pitot line reads as drift in height or speed, and only a hold at a steady pressure tells a leak from an instrument error, so every test point carries a timed hold
Why One Offset Is Not Enough	The standard atmosphere relates pressure to height by a curve and not a straight line, so an error found at one height does not hold at another and an instrument is tested at several points across its range
Standards	ISO 2533 is the public reference for the standard atmosphere that relates pressure to height. The aircraft maker's maintenance data and the aviation authority's rules set the test points, the rates, the hold times and the leak limits, and this page prints none of them. Approval of an instrument or an aircraft for use rests with the customer and the authority they name; none is claimed here
Configurations	A portable set with a case, hoses and a pump for the ramp, a bench set with a manifold for several instruments at once, and a programmed set whose points and holds are run and logged by a PLC
Scope Boundary	This set tests pitot-static instruments and lines with air pressure. It is not a bench that compares gauges with a dead-weight reference (see pressure calibration bench), not a rig that tests liquid circuits at pressure (see aerospace pressure and leak test rig) and not automatic test equipment for electronics (see modern universal automatic test equipment). It does not test electronics: no certification is claimed here
Status	Neometrix has quoted against successive air data test requirements, and no delivered air data test set is claimed.

Configurations

One method, three ways to supply the set.

The method, the record and the hold rule are shared. What changes is how much of the set is supplied and where it works.

Portable set

Case, hoses and pump

A rugged portable set for the ramp and the hangar floor, with hoses and adapters for the aircraft ports and a built-in leak hold.

Bench set

Pump, controller and manifold

A bench set for the instrument shop, with a manifold that tests several instruments at once and fine control near each point.

Programmed set

Pump, controller and PLC logger

A set whose test points and holds are run by a PLC or computer, with the pressures, height, speed and drift logged for every instrument.

Fig · 06 — Three ways to supply the set, one method: a portable set, a bench set, or a programmed set.

And the part that is not equipment at all, yet decides all three: the test plan. It fixes the test points, the rates, the holds and the way drift is reported, and it is written from the instrument's maintenance data, not from the set.

Where it is used

Wherever speed and height are read from pressure, and the pressure has to be right.

The common thread is an instrument that is only as true as the pressure it is given.

Maintenance lines

Where the pitot and static lines of an aircraft are leak-tested and its instruments are checked after work on the lines.

Instrument shops

Where altimeters, airspeed indicators and climb indicators are overhauled and tested on the bench, several at a time.

Air data computer test

Where a computer needs pressures at known heights and speeds while its outputs are read by other equipment.

Calibration and flight-test labs

Where pressure sensing is characterised across its range and an offset at one point must not be assumed at another.

Watch

See it in motion.

A short walkthrough video of the air data test set.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does an air data test set actually do?

It makes, on the ground, the two pressures a flight would make: a static pressure that stands for height, and a pitot pressure that, together with static, stands for speed. It holds them at commanded values, moves them at limited rates, and compares what the instrument shows with what the set knows it is feeding. It also holds a steady pressure in an aircraft's lines to show whether they leak. In short, it lets an altimeter, an airspeed indicator or a climb indicator be tested without leaving the hangar floor.

Q · 02 Why is airspeed a difference of two pressures, and why does the order matter?

An airspeed indicator reads the difference between pitot and static pressure, so a leak or an error in either line changes the airspeed. For the same reason, if static pressure is pumped down while the pitot side is left open, the difference grows and the instrument reads a speed that is not there. So the pitot hose is connected first, height is raised before speed is added, and speed is taken off before height returns to ground. The set builds that order into its sequence, so it does not depend on the operator's memory on a busy day.

Q · 03 How does a hold show a leak?

With a steady pressure applied to a static line, a tight line stays put. A leak lets air back in, so the pressure creeps toward ambient and the height read from it creeps down. In a pitot line a leak lets the speed read from it fall away. The set holds each point for a timed interval and reports the drift in height and speed, so a leak is told apart from an instrument error. A reading taken on the move cannot do that, which is why a spot reading is never enough.

Q · 04 Is this the same as the pressure calibration, leak test rig or automatic test equipment pages?

No, and the differences are worth stating precisely. The pressure calibration bench page compares gauges with a dead-weight reference. The aerospace pressure and leak test rig page tests liquid circuits at pressure. The modern universal automatic test equipment page tests electronics. This page makes the two pressures of a flight, static and pitot, on the ground, to test the instruments and lines that read them. It does not replace any of them, and it does not claim what they claim a second time.

Q · 05 What can the set not do?

It simulates height, speed and climb by pressure, and it does not fly. It cannot reproduce the effect of airflow over a probe or a port, so errors that depend on the airflow need other methods. It does not measure the electronics of a computer, only the pressures fed to it. It does not certify an instrument or itself: this page claims no certification or accreditation. No height, speed or pressure figure is printed here, and approval of an instrument or an aircraft for use rests with the customer and the authority they name; none is claimed here.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix has quoted against successive air data test requirements, and no delivered air data test set is claimed. What stands behind the offer is adjacent: Neometrix engineers pressure calibration benches (see the pressure calibration bench page), aerospace pressure and leak test rigs (see the aerospace pressure and leak test rig page) and pneumatic test rigs (see the general purpose pneumatic test rig page). The pressure controllers, transducers, vacuum pump, hoses and adapters are catalogue items, bought in, not invented. What Neometrix engineers is the set around them: the pneumatic plumbing and manifold, the limits and the sequence, the hold and the logging, the procedure and the records. So the honest position is that the set is engineered to order, the neighbouring disciplines are in the building, and the first set of this exact kind will be built around the customer's own instruments rather than taken off a shelf.

Q · 07 Which standards apply, and who sets the limits?

ISO 2533 is the public reference for the standard atmosphere that relates pressure to height, and a pressure altimeter is built on that relationship. The test points, the rates, the hold times and the leak limits come from the aircraft maker's maintenance data and the aviation authority's rules, not from the set. This page prints none of them. Acceptance of the finished set, including its proving runs 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 your instruments rather than the set. First, the instruments and the aircraft ports: what is tested, and the fittings on the work. Second, the ranges: the heights, speeds and climb rates, stated by the customer. Third, the limits and holds: the rates, the differences and the hold times from the maintenance data. Fourth, the connections: the hoses, the adapters and the room where the set will work. Fifth, the control and guarding: portable, bench or programmed, and the site's rules. Sixth, the record: the pressures, heights, speeds and drift you want kept. From that we come back with a set concept, a written test plan you can check, and a budgetary price.

The neighbouring test pages, and how they differ from this one.

Three neighbours: one compares gauges, one tests liquid circuits, one tests electronics.

↗ A gauge reference

Pressure Calibration Bench

A bench that compares gauges with a dead-weight reference - it calibrates gauges, it does not simulate height and speed.

↗ A liquid-circuit rig

Aerospace Pressure and Leak Test Rig

A rig that tests liquid circuits at pressure - liquids in pipework, not the instruments that read air pressure.

↗ An electronics tester

Modern Universal Automatic Test Equipment

Automatic test equipment for electronics - it tests modules electrically, not by the pressures they sense.

Browse all Neometrix product lines.

Get a quotation

Tell us the instruments, the ranges,
and the limits.

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

Enquire — air data test set Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — AIR DATA TEST SET SPECIFY · CONNECT · LIMIT · RAISE · HOLD · PROVE — SPEED AND HEIGHT ARE JUST PRESSURES ENGINEERED IN NOIDA · INDIA