Air Systems Flashcards
Explain the meaning of an illuminated BLEED TRIP OFF light
Excessive engine bleed air temperature or pressure:
- related engine bleed air valve closes automatically
- requires reset (there’s a trip reset button)
VOL 2 / 2.1.1 & 2.2.2.2
Describe the function of the Temperature Selectors
AUTO - provides automatic temperature control for associated zones. Rotating the control towards C (cool) or W (warm) manually sets the desired temperature
OFF - closes the associated trim air modulating valve
Memory aid:
- these controls suck
- they are SELECTORS, not to be confused with the CONTROLLERS
- there’s 3 of them, CONT CAB, FWD CABIN, AFT CABIN
VOL 2 / 2.1.2
Explain the function of the ISOLATION VALVE switch
CLOSE - closes the isolation valve (when the valve is closed, it ISOLATES the left side from right side)
OPEN - opens the isolation valve
AUTO - isolation valve CLOSES automatically if:
- both engine BLEED air switches are ON AND
- both air conditioning PACK switches are in AUTO or HIGH
isolation valve OPENS automatically if:
- either engine BLEED air or air conditioning PACK switch is positioned to OFF
Note: Auto function is based on the position of the switches themselves, not the actual valves (ok cool, Boeing). If any of the four corner switches are OFF, the isolation valve opens, otherwise it’s always closed.
Extra note: When engine bleeds are on, you want the valve closed to isolate the 2 sides of the system so you don’t get a DUAL BLEED light.
VOL 2 / 2.1.1
Explain the function of the TRIP RESET switch
As long as the overheat/over pressure condition no longer exists, when TRIP RESET is pushed, it:
- resets BLEED TRIP OFF, PACK and ZONE TEMP lights
- related engine bleed valve opens or, related pack valve opens, or mixed air valve opens
- light remains illuminated until reset
Note: the TRIP RESET button does NOT reset a WING-BODY OVERHEAT light
Extra note: the WING-BODY OVERHEAT light doesn’t reset because there’s no one specific valve that can close to isolate the leak. There’s a handful of sensors scattered in the ducting, on each side of the aircraft, that can sense an overheat condition. Nerd out on where those sensor are in VOL 2 / 2.2.3.1
VOL 2 / 2.1.1 (10)
Describe the associated alerting with an E&E bay over temperature on the ground
If an over temperature occurs on the ground, alerting is provided through the crew call horn in the nose wheel well
VOL 2 / 2.3.4.4 Last sentence
Explain the function of the Pressurization Mode Selector
AUTO - pressurization system controlled automatically (normal switch position)
ALTN - pressurization system controlled automatically using ALTN controller (backup controller to AUTO)
MAN - pressurization system controlled manually by outflow valve switch, both auto controllers bypassed (YOU are the pressurization system controller)
VOL 2 / 2.1.5 (11)
At what altitude does the cabin altitude warning horn sound?
Intermittent Cabin Altitude Warning Horn sounds when cabin altitude reaches 10,000ft
VOL 2 / 2.1.4 (3)
Explain the function of the cabin ALT HORN CUTOUT Switch
… it shuts the fucking horn off.
Push it and it cuts out the intermittent cabin altitude warning horn.
VOL 2 / 2.1.4 & 15.2.4.1
Explain the meaning of an illuminated WING-BODY OVERHEAT light
Either light means there’s a leak in the ducting aka blowing hot air on a sensor. The sensors are located in the below areas.
Memory aid: AWAKE AWE
Left WING-BODY OVERHEAT light:
- A: Air conditioning bay (left)
- W: Wing leading edge inboard (left)
- A: APU bleed air duct
- K: Keel beam
- E: Engine strut (left)
Right WING-BODY OVERHEAT light
- A: Air conditioning bay (right)
- W: Wing leading edge inboard (right)
- E: Engine strut (right)
VOL 2 / 2.2.3.1 Image
Explain the function of the AIR TEMP Source Selector
No one truly knows.
SUPPLY DUCT - selects appropriate zone supply duct temperatures
PASS CAB - selects forward or aft passenger cabin temperature
PACK - selects left or right pack temperatures
VOL 2 / 2.1.2 (6)
Explain the meaning of an illuminated PACK light
- Indicates pack trip off (overheat condition) OR
- Failure of both primary and standby pack controls (controllers, not selectors)
- During MASTER CAUTION recall, indicates failure of either primary or standby pack control (single channel failure). Extinguishes when Master Caution is reset
VOL 2 / 2.1.2 (9) & 2.3.2.3
Explain the meaning of an illuminated ZONE TEMP light in the following areas
CONT CAB
- indicates a duct temperature overheat (single channel failure of primary or standby controller) or
- failure of the flight deck primary AND standby temperature controls (dual channel failure)
FWD CAB or AFT CAB
- indicates duct temperature overheat
During Master Caution light recall
- CONT CAB indicates failure of the flight deck primary OR standby temperature controls (single channel failure)
- Either FWD CAB or AFT CAB indicates failure of the associate zone temperature control
- Lights will extinguish when Master Caution is reset
VOL 2 / 2.1.2 (2) & 2.3.3
Explain the meaning of an illuminated OFF SCHED DESCENT
The airplane descended before reaching the planned cruise altitude set in the FLT ALT indicator.
You set the wrong cruise altitude. Or you leveled at a lower altitude and made that your final for turbulence and never adjusted it down to your altitude. It’s not a very smart computer.
Note: if a flight is aborted in climb and returns to the takeoff airport, the controller programs the cabin to land at the takeoff field elevation without further pilot inputs. If the FLT ALT indicator is changed, the automatic abort capability to the original takeoff field elevation is lost.
VOL 2 / 2.1.5 (2)
Recall the function of the TRIM AIR Switch
ON - trim air pressure regulating and shutoff valve signaled open
OFF - trim air pressure regulating and shutoff valve signaled closed
Additional info: Zone temperature is controlled by introducing the proper amount of trim air to the zone supply ducts. The quantity of trim air is regulated by individual trim air modulating valves.
VOL 2 / 2.1.2 (7) & 2.3.3
Recall the function of the RECIRC FAN
- Reduces the air conditioning system pack load and the engine bleed air demand
- Air from the passenger cabin and electrical equipment bay is drawn to the forward cargo bay where it is filtered and re-circulated to the mix manifold
VOL 2 / 2.3.4.3
Explain the function of the EQUIP COOLING SUPPLY Switch
NORM - normal cooling supply fan activated
ALT - alternate cooling supply fan activated
Note: the equipment cooling system cools the electronic equipment in the flight deck and E&E bay because electronic equipment gets hot as shit. I don’t wanna catch on fire. The system consists of a supply duct and an exhaust duct. Each duct has a normal fan and an alternate fan. Supply duct sends cool air in. The exhaust duct discards warm air. This is arguably the most simple system on the 737.
VOL 2 / 2.1.3 (1) & 2.3.4.4
Explain the function of the EQUIP COOLING EXHAUST Switch
NORM - normal cooling exhaust fan activated
ALT - alternate cooling exhaust fan activated
Note: the equipment cooling system cools the electronic equipment in the flight deck and E&E bay because electronic equipment gets hot as shit. I don’t wanna catch on fire. The system consists of a supply duct and an exhaust duct. Each duct has a normal fan and an alternate fan. Supply duct sends cool air in. The exhaust duct discards warm air. This is arguably the most simple system on the 737.
VOL 2 / 2.1.3 (3) & 2.3.4.4
Explain the meaning of an Equipment Cooling Supply OFF Light (left light)
Illuminated (amber) - no airflow from selected cooling supply fan.
Note: that backup fan better work or else we landing asap.
VOL 2 / 2.1.3 (2)
