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Partially Polished Nacelle On KLM MD-11

Posted: Thu Jun 20, 2013 2:32 pm
by CrimsonNL
Hi guys,

One of KLM's last 6 MD-11's, PH-KCD, has been flying around with an interesting pattern on the nacelle of engine #2. You can recognize her beacause of thise from a distance without seeing the registration. The nacelle has several "stripes" of metal which look to be polished, whatever it is it's much brighter then the metal around it. Can anyone tell me what the purpose of this is? I've never seen it before on any other MD-11, or any airliner that I can remember.


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Photo © Aaron Willis
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Photo © Gilbert Hechema



Thanks and regards,

Martijn

RE: Partially Polished Nacelle On KLM MD-11

Posted: Thu Jun 20, 2013 2:59 pm
by n901wa
It's been a long time since I been inside/outside a MD-11 nbr 2 intake, and even longer in a GE powered one. But it looks like the stripes line up with the round access panels that were on the outside of the intake. Maybe a repair of some sort? Not sure, but some info that might help you. Sorry, I am not of more help.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Thu Jun 20, 2013 8:28 pm
by SpaceshipDC10
Can it be some kind of aluminum tape or looking like used to mark specific points for some sort of airflow test ? The idea of tape came from the time Swiss began operations with Swissair titled aircraft where the 'air' part was covered.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Thu Jun 20, 2013 11:50 pm
by JAGflyer
My first thought is that some sort of repair was carried out which involved riveting new sections or doubler/tripler panels over an area that sustained damage. Due to the symetrical nature of the nacelle's shiny areas, I'm not sure if this is an accident repair or perhaps something to do with where specific mounting screws are.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 7:19 am
by Horstroad
Quoting SpaceshipDC10 (Reply 2):
Can it be some kind of aluminum tape

I would not tape anything on the engine nose cowl, especially not metal tape. the adhesive will fail sooner or later... engine A/I probably won't delay that.

looks like some kind of repair.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 2:04 pm
by klemmi85

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 2:17 pm
by 747classic
Quoting SpaceshipDC10 (Reply 2):
Can it be some kind of aluminum tape or looking like used to mark specific points for some sort of airflow test ?

Highly unlikely that tests are performed, seen the very limited time that the last active MD11 aircraft will remain in the KLM fleet. (phase out will be completed in 1-2 years)

Probably a repaired or modified nose cowl was installed.
The repaired patches (exactly located above the stringers?) or doubler plates are probably new or have been polished.
After a few months airline service the polished plates will also be blackened (oxidised) like the surrounding nose cowl structure and the repairs will hardly be noticed anymore.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 2:39 pm
by CrimsonNL
Quoting 747classic (Reply 6):
After a few months airline service the polished plates will also be blackened (oxidised) like the surrounding nose cowl structure and the repairs will hardly be noticed anymore


I've been browsing through the data base and pictures of KCD with these "stripes" go back as far as late 2011! I found 2 more excellent shots including a nice close-up.



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Photo © Stefan Sonnenberg
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Photo © Jason Wood



Martijn

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 9:40 pm
by SpaceshipDC10
It would have surprised me too if the tape suggestion I did was right. On the close-up picture it's really visible that it's something more substantial than just tape.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 10:20 pm
by flyingturtle
I've seen a (perhaps) similar thing on the 320 engine.



On the engine pylon, you see a brighter part and at the sides, one that has a much darker grey. The brighter one has a rough surface, while the grey one seems to be smooth.

Why is that?



David

RE: Partially Polished Nacelle On KLM MD-11

Posted: Fri Jun 21, 2013 11:02 pm
by CALTECH
Quoting flyingturtle (Reply 9):
Why is that?

Color difference between Aluminum and titanium.

As far as the KLM Florence Nightengale MD-11, looks like a repair or reinforcement of the inlet. KLM would know.

Video below.

http://www.youtube.com/watch?v=5PaZy...NbQg&feature=player_embedded#at=70

http://www.youtube.com/watch?v=jAfQw...bYMM&feature=player_embedded#at=67

[Edited 2013-06-21 16:19:52]

RE: Partially Polished Nacelle On KLM MD-11

Posted: Sat Jun 22, 2013 4:53 pm
by flyingturtle
Quoting CALTECH (Reply 10):
Color difference between Aluminum and titanium.

Thank you! (But now I'm super-officially stupid, because I own a titanium cooking pot for camping. It has the very same color.)


David

RE: Partially Polished Nacelle On KLM MD-11

Posted: Sun Jun 23, 2013 10:09 pm
by AA737-823
Quoting flyingturtle (Reply 11):
Thank you! (But now I'm super-officially stupid, because I own a titanium cooking pot for camping. It has the very same color.)

The alloys in your "titanium" cooking pot are most likely different alloys than those used on the A320 pylon.
Parts of the Airbus pylons get hot, and so titanium is used here, as I understand it. Conversely, Boeing typically employs cool pylons (except 757s and 747s with RB211 engines, which have precoolers in the pylons as well). You'll notice that a 747 with Rolls Royce engines doesn't have any "Boeing gray" paint on the pylons.

Anyhow, I suspect your cooking pot maybe have different coloration than the pylon due to different chemical makeups of the "titanium" alloys.

RE: Partially Polished Nacelle On KLM MD-11

Posted: Tue Jun 25, 2013 4:38 pm
by bikerthai
Quoting AA737-823 (Reply 12):
The alloys in your "titanium" cooking pot are most likely different alloys than those used on the A320 pylon.

Typically the aircraft titanium alloy used is Ti 6AL-4V. There are some newer grade titanium that may be used with supper plastic forming. For cookware, I think pure titanium may be used as it is easier to form.

Titanium typically do not have any finish as the surface is already corrosion resistant/proof. Aluminum, specially skin aluminum will have a layer of pure aluminum cladding on the surface that will make it shinier.

I think you can anodize titanium to give it a permanent shine (I heard that some customized titanium bicycle frames are anodized for this purpose). Otherwise a regular titanium surface will readily attract fingerprints.

bt

RE: Partially Polished Nacelle On KLM MD-11

Posted: Mon Jul 01, 2013 2:21 pm
by CALTECH
Quoting CrimsonNL (Thread starter):
The nacelle has several "stripes" of metal which look to be polished, whatever it is it's much brighter then the metal around it. Can anyone tell me what the purpose of this is? I've never seen it before on any other MD-11, or any airliner that I can remember.

Some photos of a 757 nacelle and slat with polishing and repairs in place.

http://i297.photobucket.com/albums/mm233/CALTECHphoto/010_zps6446dba1.jpg

http://i297.photobucket.com/albums/mm233/CALTECHphoto/011_zps20c5f2c1.jpg

http://i297.photobucket.com/albums/mm233/CALTECHphoto/013_zps2a05ffa4.jpg