The aircraft flew back yesterday to Lhr minus a winglet, they are removable. Like the B744 aircraft, cleared to operate with one winglet missing.
Presume damaged tip will be repaired and refitted.

Which, of course, means that someone, or many, have probably predicted a scrape but nothing was done.
I'm having an attack of déjà vu.

I flew a type which was authorised to do that.
ONE missing was an Acceptable Defect but TWO was not - never understood that. Probably hadn't been considered, researched, demonstrated and certificated on the basis that to lose one winglet may be regarded as a misfortune; to lose both looks like carelessness :E

It really doesn't matter how many peanuts you feed your monkeys if you hire fools.

Here's what two very well paid monkeys did to an innocent 747 (not to mention the well charted brick outhouse they clobbered).

http://www.thetimes.co.uk/tto/multim..._2_495433b.jpg

Basil
 

I flew the B747- 400 which had the same MEL restrictions. Ok to fly with one missing but not both. Any engineering types here to explain why??

ONE missing was an Acceptable Defect but TWO was not - never understood that. Probably hadn't been considered, researched, demonstrated and certificated on the basis that to lose one winglet may be regarded as a misfortune; to lose both looks like carelessness - Basil

A historical precedent, admittedly in respect of a different form of travel, may be found here https://www.youtube.com/watch?v=RghKdGn8h5A :ok:

Jack

I was told by someone who should know that it was due to cost reasons in certification. There is no engineering reason why it would be unsafe to fly with 2 missing winglets.

Reason for no dispatch with 2 winglets missing
 

I was told that the reason you cannot dispatch with both winglets missing, on the 744 at least, was that it was due to the decrease in static wick dischargers. I can't verify that but it was from a colleague who is good on this sort of thing.

Anyone confirm or deny?

There are B744s flying with no winglets fitted, domestically in Japan/Korea and some cargo ones in the US bringing parts to Everett for assembly I think. Fitting winglets to them only saves fuel if the sector is longer than a few hours, roughly 5 IIRC

To certify the CDL for missing winglets, the OEM has to flight test the configuration.

To save cash for an option no one want to pay for, typically only 1 winglet removed is tested. If an airline wants 2 removed they can pay for the flight testing to the OEM. Basically it involves revising the performance numbers i,e, measure the increased fuel burn.

PS. I would be surprised static wicks would be an issue in this. The aircraft should have sufficient elsewhere to compensate. I think around up to 1 in 7 may be missing per typical design.

Static Wicks:

According to one 744 CDL, and I paraphrase: 60 installed, despatch allowable with 23 fitted (45 needed if operation requires use of HF and/or ADF). Various comments about distribution of wicks :rolleyes:

That's what I've heard.