The electrical system on the B777 supplies 115 V AC and 28 V DC power. The main powersources are a left integrated drive generator (IDG) and a right IDG, powered by the left and rightengines respectively. An auxiliary power unit (APU) can supply power if either or both of the IDGsare unavailable. The SDU was powered by 115 V AC from the left AC bus which was normallysupplied by the left IDG. If power from the left IDG was lost, then a bus tie breaker would closeand power would be automatically transferred from the right AC bus. Similarly, if power was lostfrom the right AC bus, power would be automatically transferred from the left AC bus. This power

-

experience a power interruption sufficiently long to generate a log on request, it was consideredthat a loss of both AC buses or, a disabling of the automatic switching, would be required. At 00:19, the aircraft had been airborne for 7 hours and 38 minutes

18

and fuel exhaustion was adistinct possibility. When a fuel tank was deplete

-

spool-down and the electrical generator it was driving would drop off-line and no longer provideelectrical power to its associated AC bus. Accident investigations show that when fuel exhaustionhas occurred, typically one engine will flame-out before the other. In the case of MH370 it is likelythat one engine has flamed-out followed, within minutes, by the other engine.

Following the loss of AC power on both buses

19

, the SDU would have experienced a powerinterruption sufficiently long to force a shut-

20

(RAT) would

-start. The APUwould take approximately one minute to start-up and come

-

provided electrical power

21

to the SDU. After power became available, the SDU would takeapproximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM logat 0019.29.If engaged, the autopilot could have remained engaged following the first engine flame-out butwould have disengaged after the second engine flamed-out. By the time of the SATCOM log onmessage, the autopilot would have been disengaged for approximately 3 minutes and 40seconds. If there were no control inputs then it would be expected that eventually a spiral descentwould develop. In the event of control inputs, it is possible that, depending on altitude, the aircraftcould glide for 100+ NM

The electrical system on the B777 supplies 115 V AC and 28 V DC power. The main powersources are a left integrated drive generator (IDG) and a right IDG, powered by the left and rightengines respectively. An auxiliary power unit (APU) can supply power if either or both of the IDGsare unavailable. The SDU was powered by 115 V AC from the left AC bus which was normallysupplied by the left IDG. If power from the left IDG was lost, then a bus tie breaker would closeand power would be automatically transferred from the right AC bus. Similarly, if power was lostfrom the right AC bus, power would be automatically transferred from the left AC bus. This power

-

experience a power interruption sufficiently long to generate a log on request, it was consideredthat a loss of both AC buses or, a disabling of the automatic switching, would be required. At 00:19, the aircraft had been airborne for 7 hours and 38 minutes

18

and fuel exhaustion was adistinct possibility. When a fuel tank was deplete

-

spool-down and the electrical generator it was driving would drop off-line and no longer provideelectrical power to its associated AC bus. Accident investigations show that when fuel exhaustionhas occurred, typically one engine will flame-out before the other. In the case of MH370 it is likelythat one engine has flamed-out followed, within minutes, by the other engine.

Following the loss of AC power on both buses

19

, the SDU would have experienced a powerinterruption sufficiently long to force a shut-

20

(RAT) would

-start. The APUwould take approximately one minute to start-up and come

-

provided electrical power

21

to the SDU. After power became available, the SDU would takeapproximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM logat 0019.29.If engaged, the autopilot could have remained engaged following the first engine flame-out butwould have disengaged after the second engine flamed-out. By the time of the SATCOM log onmessage, the autopilot would have been disengaged for approximately 3 minutes and 40seconds. If there were no control inputs then it would be expected that eventually a spiral descentwould develop. In the event of control inputs, it is possible that, depending on altitude, the aircraftcould glide for 100+ NM

The electrical system on the B777 supplies 115 V AC and 28 V DC power. The main powersources are a left integrated drive generator (IDG) and a right IDG, powered by the left and rightengines respectively. An auxiliary power unit (APU) can supply power if either or both of the IDGsare unavailable. The SDU was powered by 115 V AC from the left AC bus which was normallysupplied by the left IDG. If power from the left IDG was lost, then a bus tie breaker would closeand power would be automatically transferred from the right AC bus. Similarly, if power was lostfrom the right AC bus, power would be automatically transferred from the left AC bus. This power

switching is brief and the SDU was designed to ‘hold

-

up’ during such power interruptions. To

experience a power interruption sufficiently long to generate a log on request, it was consideredthat a loss of both AC buses or, a disabling of the automatic switching, would be required. At 00:19, the aircraft had been airborne for 7 hours and 38 minutes

18

and fuel exhaustion was adistinct possibility. When a fuel tank was deplete

d, the corresponding engine would ‘flame

-

out’,

spool-down and the electrical generator it was driving would drop off-line and no longer provideelectrical power to its associated AC bus. Accident investigations show that when fuel exhaustionhas occurred, typically one engine will flame-out before the other. In the case of MH370 it is likelythat one engine has flamed-out followed, within minutes, by the other engine.

SDU power-up

Following the loss of AC power on both buses

19

, the SDU would have experienced a powerinterruption sufficiently long to force a shut-

down, the aircraft’s ram air turbine

20

(RAT) would

deploy from the fuselage into the aircraft’s slipstream and the APU would auto

-start. The APUwould take approximately one minute to start-up and come

‘on

-

line’ after which time it could have

provided electrical power

21

to the SDU. After power became available, the SDU would takeapproximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM log

The electrical system on the B777 supplies 115 V AC and 28 V DC power. The main powersources are a left integrated drive generator (IDG) and a right IDG, powered by the left and rightengines respectively. An auxiliary power unit (APU) can supply power if either or both of the IDGsare unavailable. The SDU was powered by 115 V AC from the left AC bus which was normallysupplied by the left IDG. If power from the left IDG was lost, then a bus tie breaker would closeand power would be automatically transferred from the right AC bus. Similarly, if power was lostfrom the right AC bus, power would be automatically transferred from the left AC bus. This power

switching is brief and the SDU was designed to ‘hold

-

up’ during such power interruptions. To

experience a power interruption sufficiently long to generate a log on request, it was consideredthat a loss of both AC buses or, a disabling of the automatic switching, would be required. At 00:19, the aircraft had been airborne for 7 hours and 38 minutes

18

and fuel exhaustion was adistinct possibility. When a fuel tank was deplete

d, the corresponding engine would ‘flame

-

out’,

spool-down and the electrical generator it was driving would drop off-line and no longer provideelectrical power to its associated AC bus. Accident investigations show that when fuel exhaustionhas occurred, typically one engine will flame-out before the other. In the case of MH370 it is likelythat one engine has flamed-out followed, within minutes, by the other engine.

SDU power-up

Following the loss of AC power on both buses

19

, the SDU would have experienced a powerinterruption sufficiently long to force a shut-

down, the aircraft’s ram air turbine

20

(RAT) would

deploy from the fuselage into the aircraft’s slipstream and the APU would auto

-start. The APUwould take approximately one minute to start-up and come

‘on

-

line’ after which time it could have

provided electrical power

21

to the SDU. After power became available, the SDU would takeapproximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM logat 0019.29.If engaged, the autopilot could have remained engaged following the first engine flame-out butwould have disengaged after the second engine flamed-out. By the time of the SATCOM log onmessage, the autopilot would have been disengaged for approximately 3 minutes and 40seconds. If there were no control inputs then it would be expected that eventually a spiral descentwould develop. In the event of control inputs, it is possible that, depending on altitude, the aircraftcould glide for 100+ NM

The electrical system on the B777 supplies 115 V AC and 28 V DC power. The main powersources are a left integrated drive generator (IDG) and a right IDG, powered by the left and rightengines respectively. An auxiliary power unit (APU) can supply power if either or both of the IDGsare unavailable. The SDU was powered by 115 V AC from the left AC bus which was normallysupplied by the left IDG. If power from the left IDG was lost, then a bus tie breaker would closeand power would be automatically transferred from the right AC bus. Similarly, if power was lostfrom the right AC bus, power would be automatically transferred from the left AC bus. This power

switching is brief and the SDU was designed to ‘hold

-

up’ during such power interruptions. To

experience a power interruption sufficiently long to generate a log on request, it was consideredthat a loss of both AC buses or, a disabling of the automatic switching, would be required. At 00:19, the aircraft had been airborne for 7 hours and 38 minutes

18

and fuel exhaustion was adistinct possibility. When a fuel tank was deplete

d, the corresponding engine would ‘flame

-

out’,

spool-down and the electrical generator it was driving would drop off-line and no longer provideelectrical power to its associated AC bus. Accident investigations show that when fuel exhaustionhas occurred, typically one engine will flame-out before the other. In the case of MH370 it is likelythat one engine has flamed-out followed, within minutes, by the other engine.

SDU power-up

Following the loss of AC power on both buses

19

, the SDU would have experienced a powerinterruption sufficiently long to force a shut-

down, the aircraft’s ram air turbine

20

(RAT) would

deploy from the fuselage into the aircraft’s slipstream and the APU would auto

-start. The APUwould take approximately one minute to start-up and come

‘on

-

line’ after which time it could have

provided electrical power

21

to the SDU. After power became available, the SDU would takeapproximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM logat 0019.29.If engaged, the autopilot could have remained engaged following the first engine flame-out butwould have disengaged after the second engine flamed-out. By the time of the SATCOM log onmessage, the autopilot would have been disengaged for approximately 3 minutes and 40seconds. If there were no control inputs then it would be expected that eventually a spiral descentwould develop. In the event of control inputs, it is possible that, depending on altitude, the aircraftcould glide for 100+ NM

The electrical system on the B777 supplies 115 V AC and 28 V DC power. The main powersources are a left integrated drive generator (IDG) and a right IDG, powered by the left and rightengines respectively. An auxiliary power unit (APU) can supply power if either or both of the IDGsare unavailable. The SDU was powered by 115 V AC from the left AC bus which was normallysupplied by the left IDG. If power from the left IDG was lost, then a bus tie breaker would closeand power would be automatically transferred from the right AC bus. Similarly, if power was lostfrom the right AC bus, power would be automatically transferred from the left AC bus. This power

switching is brief and the SDU was designed to ‘hold

-

up’ during such power interruptions. To

experience a power interruption sufficiently long to generate a log on request, it was consideredthat a loss of both AC buses or, a disabling of the automatic switching, would be required. At 00:19, the aircraft had been airborne for 7 hours and 38 minutes

18

and fuel exhaustion was adistinct possibility. When a fuel tank was deplete

d, the corresponding engine would ‘flame

-

out’,

spool-down and the electrical generator it was driving would drop off-line and no longer provideelectrical power to its associated AC bus. Accident investigations show that when fuel exhaustionhas occurred, typically one engine will flame-out before the other. In the case of MH370 it is likelythat one engine has flamed-out followed, within minutes, by the other engine.

SDU power-up

Following the loss of AC power on both buses

19

, the SDU would have experienced a powerinterruption sufficiently long to force a shut-

down, the aircraft’s ram air turbine

20

(RAT) would

deploy from the fuselage into the aircraft’s slipstream and the APU would auto

-start. The APUwould take approximately one minute to start-up and come

‘on

-

line’ after which time it could have

provided electrical power

21

to the SDU. After power became available, the SDU would takeapproximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM logat 0019.29.If engaged, the autopilot could have remained engaged following the first engine flame-out butwould have disengaged after the second engine flamed-out. By the time of the SATCOM log onmessage, the autopilot would have been disengaged for approximately 3 minutes and 40seconds. If there were no control inputs then it would be expected that eventually a spiral descentwould develop. In the event of control inputs, it is possible that, depending on altitude, the aircraftcould glide for 100+ NM

Mystery of Flight MH370