LZ129
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Why No Spinner Painting On LH 748?

Tue Feb 12, 2013 9:47 pm

I've been an avid but silent follower of the insightful discussions on a-net for a long time now and I decided to join you and start getting some of my own questions out there.

On that note: I've noticed that LH's 747-8I are the only a/c in their fleet not to have spinner paintings. Does anybody here have an idea why they chose to go without them? I know it is available since Air Bridge Cargo have a spiral on the spinners of their 747-8F engines. And while we're at it, does anybody have a non-hear-say source for what the actual purpose of spinner paintings is? I've heard both that it's supposed to warn ground crew that the engine is on and that it's supposed to deter birds but I never found a credible source for either one of those claims.
 
ak907
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RE: Why No Spinner Painting On LH 748?

Tue Feb 12, 2013 10:58 pm

To warn the ground crew. As a ramper I can tell you they do help, especially on the four engine planes like the 747. It helps when the plane is taxiing to the parking spot with two engines shutoff, making it real easy to see when they are off. They don't really help when the plane is on the spot with the engines running, because you will hear it long before you see it.
 
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HAWK21M
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RE: Why No Spinner Painting On LH 748?

Sat Feb 16, 2013 10:11 am

The Spinner indicates to the Ground personnell that the Engine is Not stationary.....Not sure if the Bird logic applies as the response time of the bird might not be that swift in Air.

About why no painting spiral on the Spinner of the B748i......I'm curious to know too.
I may not win often, but I damn well never lose!!! ;)
 
LZ129
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RE: Why No Spinner Painting On LH 748?

Sat Feb 16, 2013 11:53 am

Do you have a link for me, maybe to a technical manual of some sort, that can prove that the spinner painting's funciton is to warn the ground crew? As I mentioned, I've heard that, too, but I also heard the bird-story... There is a rumour that JAL once tested this by flying the same type of aircraft - some with a spinner painting, some without - on the same routes and supposedly in the end the ones with spinner paintings, on average, had fewer bird strikes than the ones without. But again, that is only a rumour and therefore not what I'm really looking for.

And as for the 748i: No matter which of the two is the actual purpose of the spinner painting, it seems odd that LH decided to not apply them only on that type of a/c...
 
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747classic
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RE: Why No Spinner Painting On LH 748?

Sat Feb 16, 2013 4:41 pm

The spinner is normally painted to allow the ground crew to observe a positive N1 (fan) rotation during engine start in difficult visual (night) conditions. The ground engineer has to monitor the Fan from a position near the nose wheel.

With some older engine types, especially during an engine start with a tailwind (negative N1), it is still required to give a "positive N1" call to the cockpit crew during the start sequence.

With the introduction of FADEC controlled engines with an auto start function no "positive N1" call is mandatory anymore.
Only during a manual start this call is required in some non-normal procedures. (failure of the N1 indication).

Because the 747-8 is the first 747 series with a full time automatic starting system without the possibility of manual starting, no operational need for a spinner painting has been left anymore.

Of course the airline can paint the spinner, but it has no operational function anymore.

[Edited 2013-02-16 09:31:50]
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
tepidhalibut
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RE: Why No Spinner Painting On LH 748?

Sat Feb 16, 2013 7:29 pm

Quoting LZ129 (Reply 3):
Do you have a link for me, maybe to a technical manual of some sort, that can prove that the spinner painting's funciton is to warn the ground crew?

Take it from an engineer at with experience with an engine company.... it's there for maintenance engineers' safety.

We often get newbies asking if it's really necessary - "I mean, it's obvious it's spinning, isn't it?" I then point out that it may not be as obvious at 2.00 am, at the end of a long shift, with ear defenders on. And for the cost of a pot of paint....why not? if it saves one engineer from climbing into the front of a running engine....

So, why a spiral? It doesn't have to be. I've seen some engines with just a radial strip, but a spiral is snazzier, and gives an easier interpretation of the direction of spinning.

As to the bird scaring effect - I'm personally not convinced by that, but if it's a side effect - then great. But it's not the primary purpose of the spiral.
 
LZ129
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RE: Why No Spinner Painting On LH 748?

Sat Feb 16, 2013 7:54 pm

Quoting 747classic (Reply 4):
Because the 747-8 is the first 747 series with a full time automatic starting system without the possibility of manual starting, no operational need for a spinner painting has been left anymore.

Do you know if the Airbus A380 has such a system as well? Because LH's A380 have spinner paintings.

Quoting 747classic (Reply 4):
The spinner is normally painted to allow the ground crew to observe a positive N1 (fan) rotation during engine start in difficult visual (night) conditions.
Quoting TepidHalibut (Reply 5):
Take it from an engineer at with experience with an engine company.... it's there for maintenance engineers' safety.

It seems to me, it might serve several functions afterall 
 
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HAWK21M
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RE: Why No Spinner Painting On LH 748?

Mon Feb 18, 2013 8:44 am

A spinning engine can mean a windmilling one on the ground too.........better to be safe.....the added cost isn't much to debate over.
I may not win often, but I damn well never lose!!! ;)
 
FlyDeltaJets
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RE: Why No Spinner Painting On LH 748?

Fri Mar 01, 2013 5:09 am

Quoting LZ129 (Reply 3):
Do you have a link for me, maybe to a technical manual of some sort, that can prove that the spinner painting's funciton is to warn the ground crew?


Big version: Width: 1280 Height: 960 File size: 1918kb


[Edited 2013-02-28 21:17:52]
The only valid opinions are those based in facts
 
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747classic
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RE: Why No Spinner Painting On LH 748?

Fri Mar 01, 2013 10:43 am

As stated in this ramp manual a painted spinner is benificial, but the alternative means is also mentioned " or wait until you can count the individual fanblades."

So, there is no legal requirement to paint the spinner for the safety of the ground crew. However, it can be done at the request of an airline to improve the safety standard during ground operation.

The primary funcion of a painted spinner is the requirement to observe a (positive) fan rotation from the nose wheel position by the ground engineer under certain conditions during a manual engine start.

.

[Edited 2013-03-01 03:34:25]
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
Yikes!
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RE: Why No Spinner Painting On LH 748?

Sun Mar 03, 2013 6:11 am

There used to be an argument that not only spinner spirals, but fan blade/propeller spiral paint jobs could have a wildlife avoidance benefit. So far though, there have been no studies verifying this theory.

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