A stretched 747-400 with one new engine

Treat the 747-8 as a heavily modernised, stretched 747-400 rather than a clean-sheet design: same type certificate, same conventional bleed-air and hydraulic philosophy, but new engines, more electrical capability and subtle systems upgrades everywhere.

Key facts
Type certificate	Shares A20WE with the 747-400 (derivative, not a new type)
Engines	GEnx-2B only - ~13% better fuel burn than the -400's CF6
APU	PW901C with two 120 kVA generators (vs -400's two 90 kVA)
Not bleedless	Conventional pneumatic/hydraulic architecture - not a 787-style more-electric aircraft

Compared with the 747-400, the -8 looks different first: a fuselage about 5.6 m longer, raked wingtips instead of winglets, and GEnx-2B engines whose shared core and 80 percent of line-replaceable units come from the 787's GEnx-1B.

Systems changes include increased electrical generation, an upgraded PW901C auxiliary power unit, a larger main-deck flight-attendant rest (up to ten berths adjacent to door 5 in some cabins) and an optional second flight-deck position that gives -8 crews the same pilot type rating as the -400.

Deliveries total 155 (48 Intercontinental, 107 Freighter) against 694 of the -400 family, ending 54 years of 747 production in January 2023.

Not a new aeroplane, a new powerplant

The single most important thing to understand about the 747-8 is that it is a derivative, not a clean sheet. It flies on the same type certificate as the 747-400, which is why it could be certified so quickly in 2011, and it retains the entire conventional systems architecture - bleed air, hydraulics, a conventional flight deck. The only GEnx-powered 747 is the 747-8, and the GEnx-2B was the sole engine on it.

Where the -8 did change was in what the new engine made possible. The GEnx-2B delivered enough thrust and efficiency that the fuselage could be stretched about 5.6 m and the wing redesigned with raked wingtips, and that in turn is why the aircraft flew to a higher maximum takeoff weight. The 747-8F and 747-8 Intercontinental are, in systems terms, the 747-400 with a more efficient core, a bigger wing, and a longer body.

The one thing it did not do

The 747-8 was sometimes criticised for not being the aircraft the 787 was. That critique is fair at the level of philosophy: the 747-8 kept bleed air, kept a conventional flight deck, and kept most of the -400's system, so its fuel-burn advantage came from the engine and the aerodynamics, not from a more-electric architecture. It was a smart, low-risk evolution of a certified airframe rather than a revolution - which is exactly what Boeing intended when it chose to keep the 747-400 certificate alive.

Production end

The 747-8 line delivered 155 aircraft - 48 Intercontinental and 107 Freighter - against 694 of the -400 family, and ended 54 years of 747 manufacturing in January 2023. For the engine and the differences the GEnx brought, see engine thrust ratings.

Related

• Fuel system
• Hydraulic systems
• Electrical system
• 747-8 systems differences