Air Systems

Question 1

(756,) Describe the function of the Compartment Temperature (COMPT
TEMP) controls and indicators.

Answer 1

Compartment Temperature selectors
 AUTO – Provides automatic compartment temperature control.
 OFF – Closes the associated compartment trim air valve and
illuminates the compartment temperature INOP light.

Note: The INOP light also illuminates for a fault in the associated zone
temperature controller.

(767 only) Flight Deck (FLT DK) Manual (MAN) control:
 MAN –
- Provides manual control of the compartment trim air valve.
- The selector is spring loaded to the 6 o’clock position while in
manual.

Note: Selecting the MAN position does not illuminate the compartment
temperature INOP light. (Control is still available)

Question 2

(756) Recall the meaning of a Left or Right Engine (L/R ENG) bleed OFF light.

Answer 2

Engine Bleed Air OFF lights
 Illuminated (amber) – engine bleed air valve is closed:
- Closes automatically due to a system fault
- Closed if the switch is OFF
- Closed if the engine is not operating.

Question 3

(756) Recall the indications of a dual auto pressurization controller failure.

Answer 3

AUTO Inoperative (INOP) light Illuminated (amber) –

 AUTO 1 and AUTO 2 CABIN ALTITUDE CONTROL mode
selector (MODE SELECT) functions are inoperative

 MAN mode selected

Question 4

(767 Only) Recall the meaning of the Cargo Heat Overheat (OVHT) light.

Answer 4

Cargo Heat Overheat (OVHT) lights illuminated (amber) –

 The cargo compartment temperature is above the standard control range

 The shutoff valve has been signaled closed.

Question 5

(756) Describe the function of the trim air system

Answer 5

 The trim air control system adds warm air to the pack output air.
 The pack controllers regulate the pack output air temperature to
satisfy the temperature requirement of the compartment requiring
the coolest air.
 If the TRIM AIR switch is OFF or the trim air system is
inoperative, the packs attempt to maintain all compartments at an
average temperature.

TRIM AIR switch
 ON – the trim air valve is commanded open.
 Off (ON not visible) – the trim air valve is commanded closed.

TRIM AIR OFF light
 Illuminated (amber) – the TRIM AIR switch is off.

Question 6

(756) Describe the function of the gasper system.

Answer 6

Gasper System (as installed)
 The gasper system draws air from the forward cabin overhead air conditioning ducts and discharges it from gasper outlets in the
passenger service units located above each passenger seat.

Note:

• The 757 has no flight deck control for the gasper system.
• The 767 has a flight deck switch to control the gasper system.

Question 7

(756) Recall the pressurization panel landing altitude (LDG ALT) must be reset in the indicator during a diversion.

Answer 7

Set to diversion field LDG ALT

Question 8

(756) Discuss the purpose of the recirculation fans.

Answer 8

 The recirculation fans maintain overall cabin air circulation while
allowing a reduction of cabin air ventilation, permitting the packs to be operated at a reduced flow. This reduces bleed air demand from the engines, reducing fuel burn.

Note: On the 757 only, the Left Recirculation Fan (L RECIRC FAN) switch should not be turned off because of its equipment cooling
function.

Question 9

(756) Explain how to manually control the cabin

altitude.

Answer 9

 Position the cabin altitude mode selector (MODE SELECT) to manual (MAN)
 Move the cabin altitude MANUAL control to CLIMB or DESCEND as needed to control the cabin rate and altitude.

Question 10

(767 Only) Recall the location, functions and preflight position of the BULK CARGO HEAT selector.

Answer 10

BULK CARGO HEAT selector
 The BULK CARGO HEAT selector is located on the P-61 accessory panel

 Normal (NORM) - standard cargo heating range.
 Ventilation (VENT) - requests a higher temperature control range
than NORM and turns on a ventilating fan for the bulk cargo compartment .

Note: The preflight position for all Delta operations is VENT

Question 11

(767 Only) Recall the functions of the equipment cooling selector positions.

Answer 11

 Automatic (AUTO) – automatically controls the equipment cooling system.
 Standby (STBY) – positions the equipment cooling system for inboard air flow.
 Override (OVRD) – positions the equipment cooling system for reverse air flow and arms the NO COOLING light.

Question 12

(756) Explain the meaning of a PACK OFF light.

Answer 12

PACK OFF lights
Illuminated (amber) –.The pack valve is closed.

Note: The Pack is OFF.

Question 13

(756) Explain the meaning of a PACK Inoperative (INOP) light.

Answer 13

Illuminated (amber) –
 A pack outlet overheat has been detected
 A fault in the automatic control system has been detected.

Question 14

(767 only and as installed) Explain the meaning of an illuminated GASPER OFF light.

Answer 14

 Illuminated (amber) – the GASPER fan switch is ON but the fan is not operating.

Question 15

(756) Explain the meaning of an illuminated Recirculation Fan (RECIRC FAN) INOP light.

Answer 15

 Illuminated (amber) –

• The recirculation fan is failed or is not operating.
• The RECIRC FAN switch is off.

Question 16

(756) Explain the meaning of an illuminated Equipment Cooling (EQUIP COOLING) OVHT light on both the 757 and 767.

Answer 16

(757) Equipment Cooling Overheat (OVHT) light
 Illuminated (amber) – insufficient airflow due to:
- Insufficient airflow during ground operations
- The supply fan is inoperative, or
- The alternate supply fan is inoperative

(767) Equipment Cooling Overheat (OVHT) light
 Illuminated (amber) – high temperature or low airflow in the equipment cooling system.

Question 17

(756) Explain the function of the OFF, AUTO and STBY positions of the pack control selectors.

Answer 17

PACK Control selectors
 OFF – closes the pack valve.
 AUTO – the pack is automatically controlled.
 STBY –
- N (normal) – regulates the pack outlet temperature to a
constant, moderate temperature.
- C (cool) – sets the pack to full cold operation.
- W (warm) – sets the pack to full warm operation.

Note: The automatic controller is bypassed in the standby position.

Question 18

(756) Explain the meaning of an illuminated CABIN ALTITUDE light on the overhead panel and an illuminated CABIN ALT light on the center forward (discrete) panel.

Answer 18

 Illuminated (red) –
- The cabin altitude has exceeded 10,000 feet
- The light extinguishes when the cabin altitude descends below
8,500 feet.

Question 19

(756) Explain the operation of the cabin altitude AUTO RATE control

Answer 19

 Functions only if AUTO 1 or AUTO 2 is selected
 Rotate – sets the limit for cabin altitude rate of climb or descent during auto control
 The index mark is the proper preflight position

Question 20

(767 Only) Explain the meaning of an illuminated NO COOLING light on the
EQUIP COOLING panel

Answer 20

 Illuminated (amber) –

• Active in the OVRD position only
• No reverse air flow through the E/E compartment avionics

Question 21

(756) Recall the meaning of an illuminated compartment temperature INOP light.

Answer 21

 Illuminated (amber):
- The compartment temperature control is selected OFF
or
- A fault has occurred in the zone temperature controller while operating in AUTO
or
-The TRIM AIR switch is selected OFF.

Note: Selecting the TRIM AIR switch OFF will cause all compartment temperature INOP lights to illuminate.

Question 22

(767 Only) Explain why the center isolation (C ISLN) switch is guarded.

Answer 22

 To protect the air source to the ADP (Air Driven Pump)

Question 23

(756) Recall the meaning of an illuminated DUCT LEAK light.

Answer 23

 Illuminated (amber) – a high temperature bleed air leak is detected

Question 24

(756) Recall the meaning of an illuminated Engine BLEED light.

Answer 24

 “Bleed Air Malfunction” is the Delta recommended answer.

 The Volume II detailed answers are also acceptable.

Question 25

(756) Recall the meaning of an illuminated Engine HI STAGE / OVHT light.

Answer 25

Engine HIGH STAGE / OVHT lights
 “Bleed Air Malfunction” is the Delta recommended answer.
 The Volume II detailed answers are also acceptable.