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Spray Deflector On B717, MD80s And MD90s?  
User currently offlineFerret From United States of America, joined Jun 2000, 123 posts, RR: 0
Posted (8 years 3 months 3 weeks 5 days 16 hours ago) and read 7734 times:

I have often seen the strange appendage to the nose gear of the Boeing 717s, MD-80s and MD-90s. It has been identified as a spray deflector.

I am curious why this is needed and why this is the only airframe that seems to need it. I would guess it is to prevent water spray ingestion into the engines, but it seems like that wouldn't be a problem for tail-mounted engines.

Any insight is appreciated.  Smile


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17 replies: All unread, jump to last
 
User currently offlineTWAL1011727 From United States of America, joined Mar 2006, 636 posts, RR: 0
Reply 1, posted (8 years 3 months 3 weeks 5 days 16 hours ago) and read 7687 times:

This has been discussed before.....

It is to help keep FOD from getting slung up over the wings into the engines. Yes...it does happen.

The B727 had chined nose gear tires to do the same job.
Do a B727 A/C search and look at some pictures and you'll see them.

KD


User currently offlineBH From United States of America, joined Jul 2001, 525 posts, RR: 1
Reply 2, posted (8 years 3 months 3 weeks 5 days 9 hours ago) and read 7586 times:

You hit the nail on the head of it's use. Recent test have concluded that thier is really no difference on the spray of water with or without the spray deflector.You may start seeing the trend of some of the airlines taking them off.It is also saves a bit of wieght (i guess not that much,but every bit helps).It also saves time on the replacement of the nose gear tires.

From what i am told by the MX guys in the field they take a hell of a beating and always have to be cared for.The Back spray deflectors will stay on.
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User currently offlineCaptRightseat From United States of America, joined Aug 2006, 1 posts, RR: 0
Reply 3, posted (8 years 3 months 3 weeks 5 days 9 hours ago) and read 7562 times:

What is the approximate weight of the part?

User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 4, posted (8 years 3 months 3 weeks 5 days 5 hours ago) and read 7452 times:

http://www.airliners.net/discussions...h_ops/read.main/155468/6/#ID155468
http://www.airliners.net/discussions...h_ops/read.main/157148/6/#ID157148
http://www.airliners.net/discussions...ech_ops/read.main/25649/6/#ID25649
regds
MEL



Think of the brighter side!
User currently offlineDogfighter2111 From United Kingdom, joined Nov 2004, 1968 posts, RR: 1
Reply 5, posted (8 years 3 months 3 weeks 4 days 23 hours ago) and read 7430 times:

Didn't Concorde have these fitted after the fatal AF Concorde crash, and if so I take it that it was for the same use?

Thanks
Mike


User currently offline2H4 From United States of America, joined Oct 2004, 8956 posts, RR: 60
Reply 6, posted (8 years 3 months 3 weeks 4 days 22 hours ago) and read 7418 times:
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Quoting Dogfighter2111 (Reply 5):
Didn't Concorde have these fitted after the fatal AF Concorde crash, and if so I take it that it was for the same use?

I believe the purpose of the Concorde's devices was to contain tire debris in the event of a puncture.




2H4





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User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 7, posted (8 years 3 months 3 weeks 4 days 22 hours ago) and read 7416 times:

Quoting Dogfighter2111 (Reply 5):
Didn't Concorde have these fitted after the fatal AF Concorde

http://www.findarticles.com/p/articl...m0CWU/is_2000_August_4/ai_63866114
The Link states it was a possible cause in the 90s.
regds
MEL



Think of the brighter side!
User currently offlineDogfighter2111 From United Kingdom, joined Nov 2004, 1968 posts, RR: 1
Reply 8, posted (8 years 3 months 3 weeks 4 days 22 hours ago) and read 7409 times:

Thanks for the info guys,

I was unaware that Concorde was fitted with these prior to the incident. I take it that work was carried out on these after the AF crash. The reason I say that is, that previously I was watching BBC News when Concorde was re-introduced and the new modifications list had the Deflectors on that list.

Thanks
Mike


User currently offlineDavid L From United Kingdom, joined May 1999, 9541 posts, RR: 42
Reply 9, posted (8 years 3 months 3 weeks 4 days 21 hours ago) and read 7391 times:

Quoting 2H4 (Reply 6):
Quoting Dogfighter2111 (Reply 5):
Didn't Concorde have these fitted after the fatal AF Concorde crash, and if so I take it that it was for the same use?

I believe the purpose of the Concorde's devices was to contain tire debris in the event of a puncture.

I think they were spray deflectors and made of glass fibre but later reinforced with something like steel bands to reduce the effects of shattering in the event of a burst tyre.


User currently offlineVC10 From United Kingdom, joined Nov 2001, 1412 posts, RR: 16
Reply 10, posted (8 years 3 months 3 weeks 4 days 16 hours ago) and read 7345 times:

Concorde had water deflectors fitted to the main landing gear and to the nose gear, and they were there to control water from the wheels. They were fitted all the time the aircraft were in service, ie 1976 onwards.

After an incident I believe in the 1980s a recommendation was made that the Main Wheel water deflectors should be strenghtened with metal reinforcing. This was only a recommendation and BA took it up.

Interestingly another rear engine aircraft, the VC-10, had rubber chines moulded into the wall of it's nose wheel tyres, again to try and suppress the water wave from these tyre, and so prevent water injestion by the engines.

littlevc10

[Edited 2006-08-26 21:46:59]

User currently offlineDavid L From United Kingdom, joined May 1999, 9541 posts, RR: 42
Reply 11, posted (8 years 3 months 3 weeks 4 days 16 hours ago) and read 7331 times:

Quoting VC10 (Reply 10):
They were fitted all the time the aircraft were in service, ie 1976 onwards.

I neglected to specify that. That was the whole point of my post. D'oh!


User currently offlineFilton From United Kingdom, joined May 2006, 51 posts, RR: 0
Reply 12, posted (6 years 7 months 1 week 4 days ago) and read 6603 times:

Nose wheel spray deflectors have been discussed quite a lot, but not so much main gear deflectors, such as these on the MD90:


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If they are to prevent spray/debris getting into the engine, why don't all rear engined aircraft have them?

I'm also interested in how they attach. Does anyone have any more detailed pictures - or perhaps a drawing from a maintenance manual?

Thanks...


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 13, posted (6 years 7 months 1 week 3 days 22 hours ago) and read 6579 times:



Quoting Filton (Reply 12):
If they are to prevent spray/debris getting into the engine, why don't all rear engined aircraft have them?

My guess is because all aircraft are slightly different and the debris trajectory varies.

Also as mentioned, the 727 has chines, which do the same things but in a different way.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineFilton From United Kingdom, joined May 2006, 51 posts, RR: 0
Reply 14, posted (6 years 7 months 1 week 3 days 4 hours ago) and read 6483 times:



Quoting Starlionblue (Reply 13):
My guess is because all aircraft are slightly different and the debris trajectory varies.

That makes sense, but it is one thing to have difference layouts of deflectors, as in the DC 9 & MD80, but quite another not to have any at all, like Fokker 70 etc.

Anyone know what these deflectors are made of? They look like pretty chunky lumps of metal to me - must be very heavy. Someone must have a close up pic!


User currently offlineDALMD88 From United States of America, joined Jul 2000, 2614 posts, RR: 14
Reply 15, posted (6 years 7 months 1 week 2 days 14 hours ago) and read 6396 times:



Quoting Filton (Reply 14):
Anyone know what these deflectors are made of? They look like pretty chunky lumps of metal to me - must be very heavy. Someone must have a close up pic

They are made of AL. They are a lot lighter than they look because of that. Most guys I work with hate changing a MD80 nose tire because of the added hassle of the deflector. It isn't that much more work, only two bolts in the back and the one on the axle. Most guys I think are just looking for something to bitch about. Hell, you don't even need to jack the gear. Simply turning the nose gear on a MadDog gets the tire off the ground.

There is also a little spray deflector on the main gear. It's just this batwing looking strip aft of the tires.


User currently offline777WT From United States of America, joined Jan 2005, 877 posts, RR: 1
Reply 16, posted (6 years 7 months 5 days 23 hours ago) and read 6206 times:

BH,

your images shows up with a red X.

Can you host it again?


User currently offlineJoseKMLB From United States of America, joined May 2008, 493 posts, RR: 0
Reply 17, posted (6 years 5 months 3 weeks 6 days 16 hours ago) and read 5751 times:



Quoting TWAL1011727 (Reply 1):
It is to help keep FOD from getting slung up over the wings into the engines. Yes...it does happen.

I was thinking the same thing.


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