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BOEING 767 SYSTEMS REVIEW

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Copyright Smartcockpit.com Ludovic ANDRE / version 00

AUXILIARY POWER UNIT (APU) 1. GENERAL ¡ APU is a single shaft gas turbine located in the unpressurized tailcone ¡ Fuel for the APU normally comes from the Left Main Tank - Left FWD AC fuel boost pump is used when AC ground service power is available - APU DC fuel pump is used when no AC power is available. 2. LIMITS ¡ Maximum 3 starts within 60 minutes. ¡ BLEED until 17500 ft ¡ ELECTRICAL until 43100 ft (has always priority on Bleed air) Electrical + 2 Packs on ground 3. START ¡ On ground, APU and Airplane batteries are required. ¡ APU battery supplies power to : - starter - air inlet door - APU control circuitry ¡ Aircraft battery supplies power to : - Fire Protection - APU fuel valve - DC fuel pump - APU control circuitry when heavy starter load ¡ Sequence : - Selector to start - APU fuel valve opens ( FAULT and RUN light flashes during ops > SELF TEST) - APU inlet door starts to open - DC pumps starts in left tank - Electric starter engages - Acceleration to normal speed (white) = APU is at operating speed (available for electrical & bleed)

4. SHUTDOWN Switch OFF : - BLEED valve closes (if OPEN) - Time delay feature for cooling = 60 seconds after bleed valve has been closed (between

0 and 120 ") - Inadvertent shutdown with RUN remaining ON = resume back to normal by momentarily selecting START

- RUN light extinguishes and FAULT light momentarily ON indicating APU fuel valve closure - Resets FAULT circuitry

RUN

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BOEING 767 SYSTEMS REVIEW

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Copyright Smartcockpit.com Ludovic ANDRE / version 00

5. PROTECTION Battery Switch OFF : - On ground = shutdown with delay protection but without FIRE DETECTION - In flight = no result (amber) + EICAS APU FAULT + auto shut-down = Fault or Fire sensed (inhibited when APU selector is OFF) OR (amber) + EICAS APU FUEL VAL + auto shut-down = Fuel valve not in correct position

6. NICE TO KNOW ¡ Average APU fuel consumption = 115 kg / h (ground) & 90 kg / h (flight) ¡ No Fire system test required before starting the APU. ¡ When rotating APU selector ON (for start), always verify APU FAULT LIGHT cycles ON then OFF, then rotate

APU selector to START and let it spring back to ON.

FAULT

FAULT

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BOEING 767 SYSTEMS REVIEW

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Copyright Smartcockpit.com Ludovic ANDRE / version 00

APU DIAGRAM

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BOEING 767 SYSTEMS REVIEW

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Copyright Smartcockpit.com Ludovic ANDRE / version 00

APU FIRE DETECTION