Removing 747 Engines

[Sky Wave]

Apologies if this has been covered before.

EAAC have been juggling engines on their 4 x 747-200's parked at EGHH and very often they've left aircraft without any engines on the wings at all.

I know that I've seen pictures of the early 747 role outs with concrete blocks on the wings to save stressing the wing spar whilst they were waiting for their engines.

I was wondering if EAAC's practice is detrimental to the life of the airframe or if you can remove all engines for a certain amount of time only.

Perhaps they get around it by filling the wing tanks with fuel??

Can anyone shed any light on this?

Cheers

[ft]

I'd say the concrete blocks are more to keep the W&B in check than to avoid stressing the wing spar.

[N1 Vibes]

Gent's

it's routine to remove all 4 donks during major checks, say C and D checks. Don't think there is a special requirement to hang bricks on-wing then.

Brgd's

N1 Vibes

[Sky Wave]

Thinking logically, the weight of the aircraft is supported by the wings in flight so it really shouldn't matter if the wings are a bit light.

Cheers anyway.

I'm still wondering why they bothered with concrete blocks at Boeing when the 74's first came out. The mass & balance suggestion could be an answer but I understood they did it with all of them, surely you could have calculated the M & B and wouldn't have needed to put concrete blocks on every aircraft. Can anyone confirm if it was done for that reason?

[NSEU]

Perhaps an old wives tale? I was also told, many many years ago that it was to prevent stress.

N1 Vibes... Re C & D checks. I would check BMM 7-11-05 prior to removing engines whilst the aircraft is on jacks (due W&B considerations).

Rgds.
NSEU

[SMOC]

They probably have placed ballast in the fwd cargo which I have seen done before, I've also seen the nose wheel tied down.

Rgds SMOC