Boeing 747-400 winglets

I don’t think certification standards differ too much. For the few domestic version Boeing does not make a new certification. More likely is that they certify a -400D with increased landing weight with tests made for -400. They then reduce the cycles from 25,000 to 12,000 and schedule a complete inspection/replacement of the landing gear after 12,000 cycles to prove the further usage of the aircraft. 12,000 cycles translate into 6 years of service for 6 cycles a day.
I don’t know how much cycles are OK for a B747, but I know that domestic usage is limited to less than 10 years for -400. Another possibility would be mixed use for long haul and short haul.
However, any -400D will find itself in the desert long before its “mates of the production line” arrive there.

That a 400D will be retired long before a standard 400 is not surprising and if anything expected with the high usage on short sectors.

I trust by that you mean the 400D not the standard 400!

I don’t think certification standards differ too much. For the few domestic version Boeing does not make a new certification. More likely is that they certify a -400D with increased landing weight with tests made for -400. They then reduce the cycles from 25,000 to 12,000 and schedule a complete inspection/replacement of the landing gear after 12,000 cycles to prove the further usage of the aircraft. 12,000 cycles translate into 6 years of service for 6 cycles a day.
I don’t know how much cycles are OK for a B747, but I know that domestic usage is limited to less than 10 years for -400. Another possibility would be mixed use for long haul and short haul.
However, any -400D will find itself in the desert long before its “mates of the production line” arrive there.

The B747-400 is just certified for more than approx. 25,000 cycles. ………..

I trust by that you mean the 400D not the standard 400!

There is more to this story. Although the 400D didn’t come with winglets as standard (the winglets only offer fuel benefits in cruise, and the japanese domestic flights only lasted upto an hour, so more up and down than up, across and down), this model was designed to be converted to normal configuration at a certain point in their life, and so the winglets would be added subsequently. I know ANA had a 400D upgraded back to normal standard, I’m not sure if JAL has done any yet. The basis of this was that it would increase the revenue earning life of the aircraft by reducing the number of cycles (which through pressurisation and take-off/landings reduce the life of the airframe).

The B747-400 is just certified for more than approx. 25,000 cycles. Consequently the airframes have to be phased out after less than 10 years of service. One can assume that normally these aircraft do 5 to 8 cycles a day, if not more.
The winglets are also not needed because these aircraft never take off with MTOW. The fuel is much lower, hence you will hardly find a B747-400D taking off with 390 tons, more likely seems 330 tons and less. But on the other side the stresses on the landing gear are much higher.

A B747-400 without winglets would have serious blow on flight performance. The wing-lets were adapted because originally the wing of the B747 was adapted to the original weight of 330 tons, maybe with some room for growth.

There is more to this story. Although the 400D didn’t come with winglets as standard (the winglets only offer fuel benefits in cruise, and the japanese domestic flights only lasted upto an hour, so more up and down than up, across and down), this model was designed to be converted to normal configuration at a certain point in their life, and so the winglets would be added subsequently. I know ANA had a 400D upgraded back to normal standard, I’m not sure if JAL has done any yet. The basis of this was that it would increase the revenue earning life of the aircraft by reducing the number of cycles (which through pressurisation and take-off/landings reduce the life of the airframe).

Thanks for clearing that one up chaps.

thats most probably the B747-400D (d for domestic) – high capacity layout for ANA and JAL on their domestic routes. i believe that these are the only two airlines that have the variant, and it did not come with winglets.

EDIT – damn. you beat me to it 😀

Japan Airlines and ANA have both domestic versions of the 747 which come without winglets. On the shortroutes these aircraft are used, the winglets will not show any benefits.