LOSS OF BOTH ENGINE DRIVEN GENERATORS

Make sure you are not dealing with a single or dual engine failure! Advance thrust levers and verify engine response. ENG FAIL should not be displayed.

Verify MCP settings - values may have dropped back to defaults, such as speed 100 kts, altitude 50,000 feet or QNH setting 1,013.25 hPa - Altimeter setting 29.92 "Hg.

ON TAKEOFF
Do not reject takeoff if airspeed is above 80 kts! The antiskid system is inoperative (V1 with antiskid inoperative is roughly 20 kts lower), automatically and the autobrake RTO function is inoperative.

F/O flight instruments are lost. If the F/O was pilot flying, controls should be transferred to the captain on ground before or at rotation. The F/O can assist in speed readings.

On early NG the captain's PFD is not powered either. Switch the flight deck dome light to bright during ground run and read V1 and VR from the standby airspeed indicator. If you do not manage to read the standby ASI or you do not remember VR, rotate the airplane when reaching the last 3,000 feet of remaining runway (red-white centerline lights)

After lift-off :

• Electrical trim is inoperative - place cutout switches to off and use manual trim
• Flap Position Indicator is inoperative - maintain takeoff flaps setting, maintain airspeed between yellow bars on speedtape or aim for the actual flap placard limit speed minus 10kts.
• The airplane is unpressurized, level-of fat minumum safe altitude
• The aural altitude alert to level-off is inoperative and the A/T has disconnected
• Advise ATC and request radar vectors, do not continue RNAV without F/D

IN CLIMB OR CRUISE

There is no need for an immediate rushed descent, except that chances for a successful APU start increase below 25,000 feet. consider maintaining level flight until completion of the initial steps of the NNC, i.e. the attempt to reconnect the generators. If neither generator can be reconnected, start your descent. Advise ATC that you have lost P-RNAV and RVSM capability.

The outflow valve remains stuck in its last position. If climb is discontinued, engine bleed air output may be insufficient to maintain cabin pressurization and the cabin pressure altitude may reach 10,000 feet and above. Control the outflow valve in MAN.

ON FINAL APPROACH

If flaps are 15 or more, consider continuing approach, except for landing on short or contaminated runway, since antiskid and autobrakes are inoperative.

• maintain target speed according to the actual flap setting
• extend speedbrakes manually upon landing
• maintain directional control on the runway with nose wheel steering tiller

Refer to FCTM 8.x [Approach and Landing on Standby Power] for more information

ELECTRICAL POWER SYSTEM

AC and DC Standby Busses automatically switch to the backup source. If automatic switch-over does not occur, place the Standby Power switch to BAT by memory. Accomplish the NNC [STANDBY POWER OFF] when convenient. After restoring one engine generator or after placing the APU generator on bus, both TRANSFER BUS OFF amber lights must be extinguished! If a TRANSFER BUS OFF amber light remains illuminated, a fault occurred in the automatic bus transfer system. Place the Bus Transfer switch to OFF and back to AUTO and accomplish the NNC [TRANSFER BUS OFF].
If one of the generators shows a DRIVE amber light, this is probably the origin for the dual generator failure. One generator mechanically failed(e.g. shaft shear or high oil temperature) and the remaining generator was temporarily overloaded, causing both generators to trip off. Accomplish the NNC [DRIVE] to disconnect the generator from the engine and to avoid damage to the engine or accessory gear box, unless the associated engine is no longer running.

If the engine generators do not show any amber light, a fault or short in the electrical power system must be suspected. Even if one or both engine generators can be restored, there is still a chance for the problem to re-occur, unless the of the faulty component or electric bus has tripped. Verify the circuit breaker panels.

A tripped should only be reset if the associated system is identified as not being the cause of the electrical fault and only if required for safe continuation of the flight. Bear in mind that shorts in the electrical system may produce smoke or even smoldering fire !

APU ------------------------------------------------------- START
Each APU start attempt reduces battery endurance by approximately 7 minutes.
Only one APU start attempt is recommended, especially on airplanes with single battery.
The probability of a successful APU start is higher below 25,000 feet.

The APU DC pump logic requires both Center Tank Fuel Pump switches be in the ON position (SB 737-28-1152). The DC pump does not operate when the switches are in the OFF position. Select both Center Tank fuel pumps ON to increase chances for a successful APU start.

IRS MODE selector(s) ----------------------------------ATT
Alignment : climb and descend are allowed, but the wings must be kept level and the airplane may not accelerate or decelerate for 30 to 60 seconds.

Heading : Obtain the heading from the remaining IRS or use the magnetic compass reading corrected for deviation. The HDG> prompt on the FMC POS INIT page is only displayed after attitude recovery. Enter the magnetic heading in the FMC with 3 digits or via the ISDU keyboard on the aft OVHD panel :

• place the SYS DSPL selector to the failed IRS (Left or Right)
• place the DSPL SEL selector to HDG/STS
• enter magnetic heading with 4 digits (Litton) or H+3 digits (Honeywell)

Updating : The IRS drifts like a conventional gyro. The heading should be updated every 15 minutes and prior to starting the approach.

Note : If the FAULT amber light remains illuminated in ATT, Consider cycling the IRS to OFF and back to ATT in-flight. (alignment takes up to 120 seconds)

IF ONLY ONE TRANSFER BUS IS RECOVERED
If only one Transfer Bus is restored and only one engine generator or the APU generator is available, you must land at the nearest suitable airport. Advise ATC.

If only one Transfer Bust is restored but two generators (including the APU generator) are available, you can continue the flight to destination, as you have two sources.

IF BOTH TRANSFER BUSSES REMAIN UNPOWERED
Advise ATC and request an immediate diversion. Land within 30 minutes or 60 minutes with dual battery installed. Above 30,000 feet thrust deterioration or engine flameout may occur, because the fuel pumps are unpowered.

Refer to FCOM 6.20.x [All Generators Inop] + [Basic Equipment Operating] for the complete list of all systems that remain available with the battery as the only electrical source. The following items require special attention :

General
Automatic Passenger Oxygen Control and Release inoperative
Manual control is available
Air/Gnd Relay(s) operate(s) normally
Strobe lights are inoperative. Position lights function only with the switch in STEADY. However, switch off lights to conserve battery.

Air Systems
The Auto and Alternate modes are inoperative. At lower altitude select MANUAL DC and open outflow valve to land unpressurized.

Anti-Ice, Rain (As wired)
Pitot and pitot static heat INOP : avoid icing conditions
Temperature probe heat INOP : refer to NNC [Airspeed Unreliable] and PI [General - Flight with Unreliable Airspeed]
Window heat all INOP : speed 250 KIAS below 10,000 feet due to birdstrike risk - pull windshield air control for window defogging
Engine and Wing Anti-Ice are inoperative : avoid icing conditions

Automatic Flight
Autopilot A and B are inoperative - Autothrottle is inoperative

Communications
VHF 1 and PA available for both Captain and F/O
Transponder ATC 2 is inoperative, select ATC 1.
ATC 1 may have standby power (as wired), advise ATC.

Engines, APU
Engine reversers available upon landing
Right ignition is available. Place selector switch to Right.
Limit the use of engine ignition to conserve battery voltage!
All engine parameters remain compact displayed on the UDU
The EEC's are powered by a built-in alternator (Engine N2 RPM must be above 15%)

Flight Controls
All TE-LE flaps indications INOP. TE and LE flaps are available, however, without asymmetry protection due to FSEU power loss.
Extend the flaps step by step and monitor control wheel for any roll.
Flaps maneuvering indications on the speed tape remain valid
The bottom of the upper red bar is equal to the placard speed of the actual flap setting, so it can be used as a TE flap indicator!
TE Flap Alternate Electric Motor is inoperative
Speed brakes auto extension INOP. Extend manually upon landing
Electric trim is inoperative - Use manual trim

Flight Instruments Displays
Standby magnetic compass light, dome light(s), emergency instrument flood lights available.
Standby ALT/ASI indicator relies completely on pitot static and does not require any battery power. ISFD has its own dedicated battery.
Both RA inoperative - VHF NAV 2 inoperative

Flight Management Navigation
Verify FMC for possible PERF data loss and LEGS active waypoint
If power to Transfer Bus 2 is not restored within 5 minutes, the right IRS is lost. A high voltage peak may even cause both IRS to fault.
ALL PFD/ND displays are affected and ISFD (as installed) heading data input is lost. Accomplish the NNC [IRS FAULT] for one or both IRS.

Fuel
All fuel pumps are inoperative. Center tank fuel can no longer be used, but you have to land within 30 or 60 minutes anyway.
The fuel crossfeed valve remains operative.
Fuel quantity indication remains available

Hydraulics
(optional) Hydraulic quantity and pressure are displayed on UDU

Landing Gear
Autobrakes are inoperative - Outboard Antiskid are inoperative
Landing gear normal green/red indication
Refer to PI [Adivisory Info - Nono-Normal Configuration Landing Distance] for antiskid inoperative and add 55 meters / 170 feet for manual speedbrakes
SOP - Landing minimums CAT I - Verify Lower Landing Minimum Requirements Table
Rudder pedal nose wheel steering is inoperative ! nose wheel steering remains available via the nose wheel steering tiller.

ATC
Use "clicks" to reply to ATC in order to preserve battery endurance

SUBSEQUENT FAILURE(S)

STANDBY POWER BUS FAIL

If the STANDBY PWR OFF amber light remains illuminated after completion of the associated NNC, it is just not your day... Many basic functions, such as primary attitude indication (including stall warning and stick shaker), all navigation (VOR, ILS, ADF, FMC, GPS), all communication (VHF, HF, transponder), fuel quantity and partial engine indications are lost.

• Use standby instruments (if powered) for attitude, altitude and airspeed flying Basic attitude and thrust settings can be obtained from PI [General - Flight with Unreliable Airspeed]
• Avoid icing conditions (engine ignition, pitot heat, anti-ice are all inoperative)
• Choose an airfield that allows a visual approach.
• The timer-clock serves as fuel indicator : on most flights you carry fuel for the planned flight time + 45 minutes. You can take that as a reference, however, keep in mind that fuel endurance is substantially reduced if the filed flight altitude cannot be maintained.