Overhead

The Overhead Panel: Warning lights & indications

The overhead is divided into four vertical channels from left to right: A, B, C, & D. This photo is of an upper lights test. (All lights have two bulbs and during the test they alternate illuminating.) Right click on the photo and open in another window as the photo can then be zoomed for detail. When the associated lights illuminate on the overhead panel they indicate:

Channel A

CARGO EXTG1 7 EXTG2- low pressure is detected in the associated fire bottle
L/R Pitot- associated pitot heat power lost
L/R Alpha- alpha vane heating power lost
OAT- illuminates if temp probe heating power lost (when airborne and nosegear is uplocked)
STBY PITOT- heating lost or switch is off (24v R ESS bus)
L/R FRONT & L/R SIDE - illuminates steady when a controller fault or a partial/complete power loss occurs. Lights cycle when the related overheat temp sensor is controlling window heating
L/R PROP- fault detected in related prop heating system, loss of heating
L/R INTAKE- heating/ice protection for the engine intake duct has failed
L/R AIR VALVE- elec solenoid valve for eng anti-ice bleed air did not open when engine anti-ice was turned on OR did not close when engine anti-ice was turned off
L/R AC GEN- associated 115v AC wild generator is offline
DE ICE OV TEMP- de-ice boot bleed air downstream of regulators >150 degree C
TIMER- air pressure problem to deice boots or timer power loss/malfunction

Channel B

X FEED ON - illuminates when the fuel cross feed valve is open
L/R VALVE CLOSED - related fuel shutoff valve is closed (by fire handle only)
L/R FUEL FILTER - illuminates when the related fuel filter becomes clogged *bypass impending*
L/R MAIN PUMP - associated main fuel pump pressure is low (<6psi)
L/R LOW LEVEL - associated fuel tank is below 300lbs (+/- 70lbs)
L/R STBY PRESS - illuminates when standby pump pressurizes the engine feedline (crossfeed or directly)
CONN VALVE OPEN - the fuel tank interconnect valve between main fuel tanks is open
L/R OIL BYPASS - illuminates when oil filter is clogged
L/R CHIP DETECT - illuminates when metal particles are detected in the oil system
L/R FUEL LOW TEMP - illuminates when engine fuel temp is too low (<4C)
NO BAT START - illuminates when bat temp reaches 57C.

Channel C

INVERTER - Illuminates when the 115v output of the selected inverter fails or switch is off (Failure of the 26v output does not have an alert but will result in VOR & RMI flags.)
L/R ESS BUS - respective ESS buss is not powered
L/R BAT HOT - battery has overheated (71C), relay opens automatically & disconnects from the gen bus
L/R BAT - respective battery relay is open
EMER PWR - bus is not powered OR emergency battery voltage <24v
BUS TIE CONN - illuminates when the relay connecting the GEN buses (28V) is closed
L/R MAIN BUS - associated main bus is not powered
L/R GEN OV TEMP - respective gen has overheated (>150C) *must be manually taken offline*
L/R GEN - generator is disconnected from the gen bus
EXT PWR ON - illuminates (white) when power is selected ON or is available
EMER - emergency flight attendant call
CALL - normal F/A call button.

Channel D

L/R DUCT OV TEMP - Air Cycle Machine compressor discharge air too hot (>225C), distribution duct is overheating (>82C) *related engine bleed valve automatically closes
L/R RECIRC _ illuminated when the recirculation fan is operating at less than 80% *not connected to CWP
L/R BLD AIR LEAK - hot air leak in bleed line is detected (>205C)
L/R BLD FAULT - illuminates if bleed air temperature is too hot (>288C), pressure is to high (>43.5psi) OR engine bleed valve does not close when selected
L/R BLD CLOSED - associated engine bleed valve closed
L/R HP HIGH - valve received a signal to close and failed to close
CARGO DOOR - cargo door open
MAIN DOOR - main entry door open
MAIN DOOR HANDLE - main door handle not locked
CREW HATCH - cockpit crew hatch open
FUELING - (blue) under wing fuel panel is powered or fuel/defuel valve is open