Embraer E-Jet Fuel System

The fuel system of the Embraer E190 changed substantially between the generations. The first-generation E190 keeps all its fuel in two wing tanks and feeds each engine mainly with an ejector pump, which has no moving parts and needs no electrical power. The E190-E2 adds a centre tank whose pumps keep the wing tanks topped up, so that the engines are still fed from the wings. Both generations have a crossfeed to correct an imbalance, and both have a DC pump for the APU.

The architecture differs from that of the A320 as its FCOM describes it, where six main pumps in the inner and centre tanks feed the engines, and from the 737, whose centre tank feeds the engines directly through its own pumps. This article describes the E190 and the E190-E2 and names the model each figure belongs to, the other models being introduced in E-Jet family and flight deck; the general principles are in fuel feed, boost pumps and crossfeed and fuel tanks, venting and inerting.

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Tanks and capacities

On the first-generation E190, each wing tank is arranged from outboard to inboard as a surge (vent) tank, the main tank and a collector bay, which holds all the fuel pumps. Near each engine pylon there is a dry bay, so that the tank does not rupture if an engine rotor bursts.

The E190-E2's centre tank carries most of its fuel. It has one shutoff valve and two AC pumps, one working automatically, which feed both wing tanks at the same time and keep 2,100 to 2,200 kg in each; the engines are fed from the wing tanks through the collector tanks. The principle resembles that of later A320-family aircraft, the A320ceo delivered from 2014, the A320neo and the A321, which move their centre tank fuel into the wing tanks so that the engines are always fed from the wings. The E2 also has an on-board inert gas generation system (OBIGGS), which enriches air with nitrogen to minimise flammability, as the nitrogen generation system does on 737s fitted with one.

Feed and pumps

The first-generation E190 has four kinds of fuel pump:

The ejector pump uses motive flow, a stream of fuel under pressure, to entrain fuel from the collector bay towards the engine. It has no moving parts and needs no electrical power. The three scavenge pumps in each tank, also driven by motive flow, keep the collector bay full so that the feed stays constant. On the first-generation E190 the fuel reaches each engine by a simple path:

1. The scavenge pumps keep the collector bay full.
2. The ejector pump draws fuel from the collector bay.
3. The fuel passes the normally open engine fuel shutoff valve to the engine.

Since the motive flow comes from the engine, the AC pump provides the boost for the engine start. None of the primary pumps needs electrical power, the two AC pumps are on different buses, AC bus 1 and the AC ESS bus, and the DC pump is on DC ESS bus 2 (see E-Jet electrical system).

On the first-generation E190, with its switch in AUTO, an AC fuel pump runs for the start of the engine on its side, for the APU when no engine is running, when ENG 1 or ENG 2 FUEL LO PRESS appears, and during crossfeed. Its single DC fuel pump supplies the APU when an engine is not running, AC power is missing or no AC pump is available. On the E190-E2 the DC pump, in the right wing tank, is used for the APU start, and its FUEL DC PUMP switch has moved from the fuel control panel to the APU control panel.

On the first-generation E190, downstream of the ejector pump, the normally open engine fuel shutoff valve closes when the engine is commanded to stop or the fire handle is pulled.

Crossfeed

Opening the crossfeed valve lets both engines be fed from the same tank, which is how the crew correct a fuel imbalance; on the first-generation E190 the AC pump in AUTO runs during crossfeed. On the E190-E2:

• Crossfeed is not used during take-off and landing, and the before-landing flow includes checking that it is off.
• The FUEL IMBALANCE message appears at 360 kg or more, which is also the maximum imbalance in the limitations, and goes out at 45 kg or less.
• When the imbalance has fallen below 45 kg with the crossfeed still open, the FUEL EQUAL-XFEED OPEN advisory tells the crew to close it.

Fuel quantity and temperature indications

The fuel quantity of each tank and the total appear on the EICAS, with a fuel synoptic page on the MFD. The E190-E2 gained centre tank indications on both. Its thresholds are:

The thresholds fit together. FUEL LO LEVEL comes on below 400 kg in a wing tank, so with both wing tanks at that level about 800 kg remain, which the operating manual equates to about 30 minutes of flight. The amber total at 1,600 kg comes earlier, when twice that quantity is left.

For fuel temperature, the E190-E2's FUEL TANK LO TEMP caution is triggered by the fuel in the left tank at -37 °C or below. It leaves a margin above -44 °C, the minimum Jet A-1 temperature in the E190-E2 limitations.

Fuel that cannot be used, trapped fuel in the E190-E2's centre tank, is entered in the FMS on the FUEL MGMT page, reached from PERF and NEXT. Only the range value on the PERF CRUISE page is then adjusted, not the progress page.

Ground checks and fuel frost

The first-generation E190 has magnetic level indicators in the wings, so the quantity can be checked by dipstick on the ground. Transport Canada lists them as removed on the E190-E2, which matches the operating manual's note that the dipstick check is an E1 procedure.

Fuel cold-soaked at altitude can chill the wing so much that frost forms on it after landing, even in mild weather. The E190-E2 accepts this cold-soaked fuel frost on the upper wing only within the marked area, with no precipitation and no visible moisture, and with the temperature above 0 °C. The 3 mm frost allowance in the operating manual concerns the underside of the wing, not the upper surface (see aircraft ground de-icing and anti-icing).

Abnormal situations

The main fuel alerts and situations, and what lies behind them:

• FUEL LO LEVEL. On the E190-E2 it means less than 400 kg in a wing tank. On the first-generation E190 it can come on with less than 2,800 kg if the collector bay is no longer kept full, and attitude and g then matter.
• FUEL IMBALANCE. At 360 kg or more on the E190-E2 the crew balance the tanks with the crossfeed and close it again when FUEL EQUAL-XFEED OPEN appears.
• FUEL TANK LO TEMP. The left tank fuel has reached -37 °C on the E190-E2, 7 °C above the -44 °C Jet A-1 limit.
• Engine fire. Pulling the fire handle closes the engine fuel shutoff valve, as does an engine stop command, on the first-generation E190 (see E-Jet fire protection and oxygen).
• Electrical emergency. On the first-generation E190, with the RAT online at or above 130 kt, the RAT generator supplies the AC ESS bus and DC ESS buses 1 to 3, which carry the right AC pump and the DC pump, and the ejector pumps need no power at all.

Fuel limitations

The main fuel limitations, with the model each applies to:

• Usable fuel: 13,100 kg on the first-generation E190, 13,690 kg on the E190-E2.
• Maximum imbalance: 360 kg on the E190-E2.
• Fuel temperature: minimum -44 °C for Jet A-1 on the E190-E2.
• Crossfeed: not used during take-off and landing on the E190-E2.
• Cold-soaked fuel frost: on the E190-E2 upper wing, only within the marked area and in the conditions above.

The engines themselves, their fuel control and the APU are covered in E-Jet engines and APU; the electrical, hydraulic and flight controls articles describe the other main E-Jet systems.

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.