Overview
This lecture explores the engineering, maintenance, and lifespan of the Boeing 747 (Jumbo Jet), including its complete overhaul, key systems, and what happens when it is decommissioned.
Introduction to the Boeing 747
- The Boeing 747 is a two-deck aircraft capable of carrying over 500 passengers.
- It is known as the Jumbo Jet and revolutionized air travel due to its size and engineering.
- The featured aircraft, Victor X-ray, has flown 36 million miles over 14 years.
Maintenance and Overhaul Process
- Every six years, 747s undergo a total strip-down and meticulous inspection.
- Maintenance involves checking over 20,000 parts and completing 12,000 tasks in about 30,000 working hours.
- Delays in maintenance can have significant financial impacts on airline operations.
Safety and Inspection
- Safety is the highest priority; every component, down to kettles, is tested.
- Landing gear is tested for emergency deployment using gravity.
- The fuselage and wings are examined for cracks and structural fatigue.
Aircraft Systems and Engineering Details
- The flight deck transitioned from requiring three crew members to two, thanks to automation.
- Redundant systems ensure operation if primary systems fail.
- Cabins are pressurized to simulate altitudes of 6,000–8,000 feet for passenger comfort.
- Airframe flexing can cause fatigue; regular inspections are essential.
Wing and Flight Principles
- Wingspan is about 211 feet; made of aluminium and carbon fiber.
- Lift is explained by both Bernoulli’s principle and Newton’s third law (deflecting air downward causes upward force).
- Flaps increase wing surface to allow low-speed flight and are carefully inspected and removed for maintenance.
Engines and Fuel
- Each engine produces over 60,000 pounds of thrust; engines are removed and inspected.
- Titanium fan blades are hollow and checked for damage; proper balancing is critical.
- The aircraft contains eight fuel tanks, holding up to 216,000 liters.
Cabin Features and Tests
- Seats are removed, refurbished, and checked for durability.
- Escape chutes must inflate in three seconds; precise refolding is required.
- Even toilets and kettles undergo electrical and performance testing due to strict regulations.
Electronics and Avionics
- Modern 747s use advanced computers and electronics for flight control, replacing manual flight engineer roles.
- Autopilot can control much of the flight but still relies on pilots for crucial actions like flap and landing gear deployment.
End of Life and Recycling
- When no longer economical to repair, 747s are dismantled for parts; engines and avionics have high resale value.
- Remaining aluminum is recycled into products like cans or bike frames.
- Some flight decks are preserved for use in simulators.
Key Terms & Definitions
- Fuselage — Main body structure of the aircraft.
- Avionics — Electronic systems on the aircraft, such as flight controls and communications.
- Flaps — Hinged surfaces on wings used to control lift at lower speeds.
- Autopilot — Computer system that assists or replaces manual flight control by pilots.
- Pressurization — Maintaining cabin air pressure above that outside at altitude.
- Black box — Flight data and voice recorder used for post-incident analysis.
Action Items / Next Steps
- Review principles of flight (Bernoulli and Newton).
- Study aircraft maintenance schedules and safety protocols.
- Know major aircraft components and their functions for exams.