Embraer E-Jet Air Conditioning, Bleed Air and Pressurisation
On the Embraer E190-E2, the air management system (AMS) controls the bleed air from the engines, the APU or a ground cart and the two air conditioning packs it feeds, while a two-channel cabin pressure controller drives the outflow valve that sets the cabin altitude.
On the Embraer E190-E2 one controller runs most of the air systems. The air management system (AMS) controls the bleed air and the air conditioning, detects hot air leaks, monitors the crew oxygen, controls the wing and engine anti-ice, and performs fault detection and isolation for the smoke detectors. Cabin pressure has its own two-channel controller, which drives the outflow valve.
Figures are those of the E190-E2 unless another model is named. Anti-icing is covered in E-Jet ice and rain protection and crew oxygen in E-Jet fire protection and oxygen; the principles are in bleed air and pneumatic systems, air conditioning packs and pressurisation principles and control.
The air management system
The AMS controller has two redundant channels, left and right, and either of them can control the entire system on its own: one channel per side does not mean that each channel controls only its own side. The failure of one channel therefore gives only the AMS CTRL FAULT advisory, while AMS CTRL FAIL, a caution, means that both channels have failed.
The pneumatic system supplies four consumers: engine starting, wing and engine anti-ice, the environmental control system (ECS), and the pressurisation of the water system. The hydraulic reservoirs are not among them.
Bleed air sources and crossbleed
Bleed air comes from the engines, the APU or a high-pressure ground cart:
- The APU feeds the left side of the system through a check valve. Its air is used mainly for air conditioning and engine starting, and never for anti-icing.
- A ground cart connects to the right side, through a port on the lower section of the fairing and a check valve, and is used mainly for engine starting.
In AUTO the APU bleed supplies the system only when it is available, there is no leak in the APU or the left bleed duct, engine 1 bleed is not available, since engine 1 would have priority, and anti-ice is not operating. APU bleed is not limited to the ground: it may supply the air conditioning up to 15,000 ft. On the ground with one engine and the APU running, the APU bleed has priority if the crossbleed is operating, the opposite engine's bleed pressure is below the minimum for an engine start, the speed is below 50 kt and anti-ice is not requested.
The crossbleed valve is electrically controlled, pneumatically operated and normally closed. In AUTO it opens when one side has pressure and the other has no bleed air, when ENG 2 start is selected in flight, or when ENG 1 start is selected in flight with the APU bleed off. Through the open crossbleed, one engine can provide enough bleed air for both packs.
Exam tip: APU bleed enters on the left, the ground cart on the right. Selecting ENG 2 start in flight opens the crossbleed; selecting one pack off with both engine bleeds normal does not.
Hot air leak detection is part of the AMS. BLEED 1 (2) LEAK, a caution with an amber striped bar, appears when the monitored temperature exceeds 125 °C. Once the temperature is below 80 °C, the BLEED button can be cycled.
Air conditioning packs
A single pack can supply all the air conditioning and pressurisation. The AMS closes a pack when it has no bleed source, when it is selected off, when its bleed duct has a leak, when the pack itself has a fault, or when its associated engine is being started. Single-side pneumatic operation with one pack inoperative is limited to 31,000 ft.
When both packs have failed or been switched off, for example to remove smoke, emergency ram air ventilates the aircraft below 25,000 ft. If the emergency ram air vent valve fails closed, the RAM AIR FAULT advisory appears.
Exam tip: one pack is enough for air conditioning and pressurisation, but one pack inoperative in single-side pneumatic operation limits the E190-E2 to 31,000 ft. Emergency ram air needs both packs off or failed and works below 25,000 ft.
Temperature control and distribution
The E2 has a "smart" ECS whose performance depends on the number of passengers. Transport Canada's operational evaluation report likewise lists cabin automatic temperature control by passenger count, set on the MCDU, among the E2's differences.
Gasper air is conditioned air delivered to the pilots and passengers through eyeball outlets. It comes from the right pack and the right recirculation fan, through a gasper shutoff valve.
The electronics bays are cooled with cabin and cockpit air. The forward bay takes cockpit air and the centre bay cabin air, and three fans in parallel serve them: fan 1 runs while fans 2 and 3 stand by. The aft bay has no fan and relies on air flowing from the passenger cabin.
The forward cargo compartment is ventilated by a fan with air from the recirculation bay. When smoke is detected there, the fan stops and the shutoff valve closes. CRG FWD VENT FAIL, a caution, means that the fan has failed, or that the valve is open while smoke is detected. Cargo fire protection is covered in E-Jet fire protection and oxygen.
Pressurisation control
The cabin pressure controller (CPC) is in the forward avionics compartment. Its two identical, independent channels work as master and standby and swap roles after each flight. PRESN AUTO FAULT, an advisory, means one channel has failed and the other keeps pressurisation working normally; the failure of both channels gives a caution instead.
In AUTO the CPCS works from the gross weight, the cruise altitude and the landing field elevation of the destination. Values received from the FMS are shown in green; a value set on the pressurisation panel is shown in cyan with an "M". Without FMS data the CPCS uses the ambient pressure and a default gross weight.
On the ground the CPCS works through three modes before take-off:
| Mode | Condition and target |
|---|---|
| GND | Outflow valve fully open, -0.01 psid |
| TAXI | From doors closed and N2 above 60 %, targets +0.11 psid |
| T/O | With take-off thrust set on the ground, targets +0.15 psid |
At the gate the outflow valve is fully open in GND mode. Once the doors are closed and N2 is above 60 %, TAXI mode aims for a small positive differential, and setting take-off thrust raises the target to +0.15 psid, so the cabin is already slightly pressurised when the aircraft lifts off.
Manual mode, outflow valve and dump
In MANUAL mode both CPC channels go to standby, and one of them, selected automatically, drives the outflow valve on the crew's UP and DOWN commands.
Selecting DUMP drives the outflow valve fully open and disables the packs and the recirculation fans; normal operation can be restored afterwards. DUMP works only in AUTO mode. The cabin then climbs at about 2,000 fpm up to a cabin altitude of 12,400 ft, where the outflow valve closes.
Exam tip: DUMP needs AUTO, opens the outflow valve fully and switches off the packs and recirculation fans. The cabin climbs at about 2,000 fpm and stops at 12,400 ft.
Warnings and limitations
CABIN ALTITUDE HI, a master warning, comes on at a cabin altitude of 9,700 ft or more. For airports above 9,400 ft elevation, it is instead set at a cabin altitude 500 ft above the airport. The 8,000 ft figure is the maximum cabin altitude limitation, not the warning threshold. See pressurisation safety valves and warnings.
| Limit, E190-E2 | Value |
|---|---|
| Maximum cabin altitude | 8,000 ft |
| Maximum differential pressure, up to 37,000 ft | 7.8 psid |
| Maximum differential pressure, above 37,000 ft | 8.4 psid |
| Positive pressure relief valve setting | 8.6 psi |
| Maximum overpressure | 8.77 psi |
| One pack inoperative, single-side pneumatic operation | 31,000 ft |
| APU bleed for air conditioning | Up to 15,000 ft |
| Emergency ram air | Below 25,000 ft |
The higher differential applies above 37,000 ft, up to the maximum operating altitude of 41,000 ft, which the EASA type-certificate data sheets give for every E-Jet model. Cruising at FL390, for example, the E190-E2 may use the full 8.4 psid; at FL330 it is limited to 7.8 psid, and with one pack inoperative in single-side pneumatic operation it may not be there at all.
The main air system messages are:
| Message, E190-E2 | Meaning |
|---|---|
| AMS CTRL FAULT, advisory | One AMS controller channel failed |
| AMS CTRL FAIL, caution | Both AMS controller channels failed |
| BLEED 1 (2) LEAK, caution | Monitored temperature above 125 °C |
| RAM AIR FAULT, advisory | Emergency ram air vent valve failed closed |
| CRG FWD VENT FAIL, caution | Forward cargo fan failed, or valve open with smoke detected |
| PRESN AUTO FAULT, advisory | One CPC channel failed |
| CABIN ALTITUDE HI, warning | Cabin altitude 9,700 ft or more |
For comparison with other types, see A320 pressurisation and B737 pressurisation.
Frequently asked questions
What is the maximum cabin altitude and differential pressure of the E190-E2?
The maximum cabin altitude is 8,000 ft. The maximum differential pressure is 7.8 psid up to 37,000 ft and 8.4 psid above, while the positive pressure relief valve is set at 8.6 psi and the maximum overpressure is 8.77 psi. The CABIN ALTITUDE HI master warning comes on at a cabin altitude of 9,700 ft, or 500 ft above the airport for airports above 9,400 ft.
Where does APU bleed air enter the E-Jet pneumatic system?
On the E190-E2 the APU feeds the left side of the pneumatic system through a check valve, and it is used mainly for air conditioning and engine starting, never for anti-icing. A high-pressure ground cart connects to the right side. In AUTO the APU bleed is used only when engine 1 bleed is not available, there is no leak in the APU or left duct and anti-ice is off, and it may supply the air conditioning up to 15,000 ft.
Can the E190-E2 fly with one air conditioning pack?
Yes. A single pack can supply all the air conditioning and pressurisation, and one engine can provide enough bleed air for both packs through the crossbleed valve. With one pack inoperative in single-side pneumatic operation, however, the E190-E2 is limited to 31,000 ft. If both packs fail or are switched off, emergency ram air ventilates the aircraft below 25,000 ft.
What does cabin DUMP do on the E190-E2?
On the E190-E2, DUMP drives the outflow valve fully open and disables the packs and the recirculation fans. It works only in AUTO pressurisation mode. The cabin then climbs at about 2,000 fpm up to 12,400 ft, where the outflow valve closes again. Normal operation can be restored afterwards.
How does the E190-E2 cabin pressure controller work?
The controller has two identical, independent channels, one master and one standby, which swap roles after each flight. In AUTO it uses the gross weight, the cruise altitude and the destination's landing field elevation, from the FMS or set on the panel. In MANUAL both channels go to standby and one, chosen automatically, drives the outflow valve on the crew's UP and DOWN commands. One channel failed gives PRESN AUTO FAULT.
Test yourself on Embraer E-Jet Air Conditioning, Bleed Air and Pressurisation
The v1prep banks cover this topic in the E-Jet type-rating bank, with a worked explanation for every answer. EASA ATPL, PPL, IR and CPL, the FAA written tests and type ratings for the A320, 737, A220, 787, ATR 72 and E-Jet.
Start practising →Sources and further reading
- 14 CFR 25.841, Pressurized cabins
- 14 CFR 25.831, Ventilation
- 14 CFR 25.1438, Pressurization and pneumatic systems
- EASA Easy Access Rules for Large Aeroplanes (CS-25), CS 25.831 Ventilation and CS 25.841 Pressurised cabins
- FAA Aviation Maintenance Technician Handbook, Airframe (FAA-H-8083-31B), Chapter 16, Cabin Environmental Control Systems
- EASA Type-Certificate Data Sheet EASA.IM.A.071, Embraer ERJ 190 (ERJ 190-100, -200, -300 and -400)
- Transport Canada Civil Aviation, Operational Evaluation Report, Embraer E-Jets (E1 and E2), Revision 1, 2023
Library articles are written for study and exam preparation. They do not replace your aircraft's approved documentation, your operator's procedures or the regulations themselves.