737-400 Specifications & Systems

Question 1

Tell me about the Boeing 737-400.

Answer 1

Length: 119' 7"
Height: 36' 3"
Wingspan: 94' 9"
Operating Empty Weight: 77,100 Lbs.
Maximum Zero Fuel Weight: 113,000 Lbs.
Maximum Landing Weight: 121,000 Lbs.
Maximum Takeoff Weight: 143,500 Lbs.

Question 2

Tell me about the engines on the Boeing 737-400.

Answer 2

Maximum Taxi Weight: 144,000 Lbs.
Engines: GE-Snecma CFM56-3B2
Thrust: 22,000 Lbs. Sea Level Static Thrust
Seating Capacity: 1st Class = 8, Economy = 138
Certified in Transport Category: FAR Pt 25 & Pt 36
Approved Operations: VFR, IFR, Icing- Not Severe Icing
Flight Crew: 2 Pilots, 3 Attendants
Tailwind Component: 10 Knots Approved

Question 3

What is the maximum runway slope for the Boeing 737-400?

Answer 3

Runway Slope: + or - 2% Maximum
Maximum Operating Altitude: 37,000 ft. Pressure Altitude
Maximum TakeOff & Landing Altitude: 8,400 ft. Pressure Altitude
Maximum Flight Operating Latitudes: 73° N to 60° S
Maximum Differential Pressure: 8.65 PSI
Maximum Cabin Differential Pressure for TakeOff & Landing: .125 PSI
Maximum Operating Altitude for APU: 25,000 ft.

Question 4

What is the maximum fuel capacity of the Boeing 737-400?

Answer 4

Maximum Fuel Capacity
Main Tanks(Wings): 10,643 Lbs. Each
Center Tank: 16,422 Lbs.
Lateral Fuel Imbalance between Main Tanks 1 & 2: Must be scheduled to be Zero
Random Fuel Imbalance: Must NOT exceed 1,000 Lbs. for Taxi, TakeOff, Flight, Landing

Question 5

Tell me more.

Answer 5

Main Tanks 1 & 2 Must be full if Center Tank contains 1,000 Lbs. or more
Landing Gear: Nose Wheel is Rudder controlled over 60 Knots, Steering Wheel controlled under 60 Knots Maximum for Taxiing
Anti Skid System: Wheel Speed Sensors detect Rotation Speed and are Modulated by Computer system, Temperature sensitive, Thermal Plug Sensor Brakes must be cool enough to operate or aircraft cannot GO. Prevents tire lock-up, skidding and longer stopping distances.

Question 6

Tell me about the fire systems on the Boeing 737-400.

Answer 6

3 Main Fire Bottles: Freon charged, 2 for Main Engines(Located in Landing Gear Well) can feed either Engine, 1 By APU, 4 pairs of detectors(2 loops, 4 detectors each) for each Engine, 1 in Wheel well, 1 by APU

Question 7

Describe the fuel system of the Boeing 737-400.

Answer 7

3 Tanks, 2 Main Tanks @ 10,643 Lbs. Each, 1 Center Tank @ 16,422 Lbs., 8 Fuel Pumps, 2 Electric Pumps in each tank, 1 gear driven pump on each Engine Cross feed valve feeds both engines from either Wing Tank, Must use Center Tank first, Scavenger Pump in Center Tank Pumps last 1,000 Lbs. of fuel into #1 Wing Tank, APU is fed from #1 Wing Tank, Fuel Temperature Gauge in #1 Wing Tank, Fueling & De-Fueling Valves on #2 Wing Tank

Question 8

Describe the hydraulic systems on a Boeing 737-400.

Answer 8

Hydraulic Systems : 3 systems @ 3,000 PSI
A System: Gear Driven Pump With Electric A/C Motor backup
B System: Same as A System - Operates Auto-Slats, Flaps & Leading Edge Devices
A&B Systems Operate: Rudder, Ailerons, Elevator, Landing Gear
A System Operates: #1 Thrust Reverser, AutoPilot- A, Ground Spoilers, Inboard Flight Spoilers, Alternate Brakes
B System Operates: #2 Thrust Reverser, AutoPilot-B, Outboard Flight Spoilers, Yaw Damper, Normal Brakes, Trailing Edge Flaps

Question 9

How many pumps?

Answer 9

6 Pumps Including PTU
Standby System Operates: Rudder, Thrust Reversers, Flaps, Auto-Slats, Leading Edge Devices
Power Transfer Unit (PTU): Powered by System A to Pressurize System B and to operate Flaps, Auto-Slats, Leading Edge Devices
Stand Pipes in Hydraulic Tanks to keep enough fluid for Secondary Pumps in case the #1 Pump fails or leaks.

Question 10

Tell me more about the hydraulic systems on the Boeing 737-400..

Answer 10

2 Main Systems and a standby, Each main System is driven with an Engine and an Electrical pump as a backup, Standby System is Electric Only, System A operates Ailerons, Elevator, Rudder, Landing Gear, AutoPilot A, Thrust Reversers, B System operates the Ailerons, Elevator, Rudder, Landing Gear, AutoPilot B, Thrust Reversers, as well as Flaps, Auto Slats and Leading Edge Devices, Standby System operates the Rudder, Thrust Reversers, Flaps, Auto Slats, Leading Edge Devices. The System contains a Power Transfer Unit operated by the A system, which pressurizes the B system to operate the Flaps and Leading Edge Devices

Question 11

Tell me about the electrical system on the Boeing 737-400.

Answer 11

3 Generators: 1 Generator drive(Transmission) on each Engine attached to shear shaft, 115 volts A/C @ 400 Hz constant
APU: Direct driven Generator(APU runs at one speed) also 115 volts A/C @ 400 Hz
Generator Bus #1: #1 Engine
Generator Bus #2: #2 Engine
Generator Buses: Cross Feed to Transfer Buses, 2 main 115 volt A/C Buses (Fuel Pumps)
3 Transformer/Rectifiers: 115 v A/C to 28 v D/C to 2 D/C Buses
Battery to Battery Charger and Hot Battery Bus to Battery Bus to Inverter(28 v D/C to 115 v A/C) for Emergency use to operate some Fuel Pumps, Hydraulics, Etc.

Question 12

Tell me more about the electrical system on the Boeing 737-400.

Answer 12

Description of Electrical System
3 Generators, 3 Transformer/Rectifiers, 2 Generator Buses, 2 Main Buses, 2 D/C Buses, 2 Transfer Buses, 1 Battery, 1 Battery Charger, 1 Inverter, T/R’s Convert 115 v A/C to 28 v D/C, Inverter Converts 28 v D/C to 115 v A/C

Question 13

Tell me about the air conditioning system on the 737-400.

Answer 13

Hot Air from 5th and 9th stages of each Engine and/or the APU (Pre conditioned air from ground source straight into Mix Manifold when at terminal), Hot Air goes to 2 A/C packs to be conditioned, and trim air system, Left Pack to Cockpit and Mix Manifold, Right Pack to Mix Manifold Only, which feeds the Main Cabin(Forward and Aft), Trim Air Feeds Hot Air into each cabin mix line to adjust temperature. Re-circulating Fans(in forward cargo hold) pump air back to Mix Manifold to re-condition and re-circulate air back into cabin.

Question 14

Tell me about the PACKS on a Boeing 737-400.

Answer 14

Hot Air goes to Primary Heat Exchanger to be cooled, to the Air Cycle Machine and gets compressed(gets hot again), to the Secondary Heat Exchanger, to the High Pressure Water Separator and back to the Air Cycle Machine(Turbine Portion) and back through the Water Separator and then to the Mix Manifold.

Question 15

Tell me about the trim air system on a Boeing 737-400.

Answer 15

Flows Hot Air into the Cabin Mix Lines(after Mix Manifold) and can be regulated to control Cabin Temperature.

Question 16

Tell me about the auxiliary power unit (APU) on a Boeing 737-400.

Answer 16

Location: Tail Cone of the Aircraft
Provides: Backup Electrical, Additional Bleed Air, Engine starting through Pneumatic Starters
APU can be started with Battery power, Runs at one speed only
Fuel Source: #1 Fuel Tank
Fuel Consumption: 200-300 Lbs./Hr.

Question 17

Tell me about the out-flow valves & relief valves on a Boeing 737-400.

Answer 17

Keeps Cabin Pressure regulated at 8.65 PSI
Pressure Relief Valve: Releases Excess Cabin Pressure
If Main & Forward Out-Flow Valves are Inoperative, They have A/C or D/C as backup.
Negative Pressure Relief Valve: Allows Pressure into Aircraft below 8,000 ft.

Question 18

Tell me about the emergency equipment on a Boeing 737-400.

Answer 18

Emergency Equipment

Megaphone, First Aid Kit, Crash Axe, CO2 Extinguisher, Water Extinguisher, Dry Chemical Extinguisher, BCF Extinguisher, Smoke Hood, Life Vests, Flashlights
Fire Extinguisher Types: 
Class A: Combustible Materials
Class B: Flammable Liquids
Class C: Live Electrical
Emergency Equipment
Megaphone, First Aid Kit, Crash Axe, CO2 Extinguisher, Water Extinguisher, Dry Chemical Extinguisher, BCF Extinguisher, Smoke Hood, Life Vests, Flashlights
Fire Extinguisher Types: 
Class A: Combustible Materials
Class B: Flammable Liquids
Class C: Live Electrical

Question 19

Tell me about the weight restrictions on a Boeing 737-400.

Answer 19

Weight Restrictions

TakeOff Weight: Weight at Brake Release- Determined by Runway Length, Temperature, Altitude, Tire Speed Limits, Brake Energy Limits, Obstacle Clearance, Enroute Clearance, & Operating Requirements
Climb Rate: 3° = 48’ per Nautical Mile
Maximum Approach, Landing, Climb Weight for Altitude & Temperature are determined from Maximum Landing Weight & Climb Rate Charts