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Parking With Thrust Reversers Deployed?  
User currently offlinec5load From United States of America, joined Sep 2008, 917 posts, RR: 0
Posted (3 years 11 months 4 weeks 23 hours ago) and read 3809 times:

I have seen it many times on the C-17 that it parks with the thrust reversers in the deployed position. Do civilian airliners do this at any point? Is it possibly an engine cooldown measure?


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User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (3 years 11 months 4 weeks 23 hours ago) and read 3798 times:

Quoting c5load (Thread starter):
Do civilian airliners do this at any point?

Not by normal procedures...they might do it for maintenance or in the event of a failure.

Quoting c5load (Thread starter):
Is it possibly an engine cooldown measure?

Not on a modern civilian airliner...it might work on a C-17 since they've got core reversers.

Tom.


User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 2, posted (3 years 11 months 4 weeks 23 hours ago) and read 3785 times:

Quoting tdscanuck (Reply 1):
it might work on a C-17 since they've got core reversers.

Wouldn't an engine cool down better if it was just allowed to windmill freely?

Leaving the reverser deployed arrests windmilling from what I've noticed.


User currently offlinepackcheer From United States of America, joined Nov 2008, 329 posts, RR: 0
Reply 3, posted (3 years 11 months 4 weeks 19 hours ago) and read 3708 times:

Well maybe you've hit the nail on the head. Maybe the C-17 leaving the reversers open won't harm anything, but will prevent the engine from windmilling, so they use that instead of having to put something in the fan blades (I've seen some airlines use a long 2 x 4 when the aircraft is at the gate).


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User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 4, posted (3 years 11 months 4 weeks 17 hours ago) and read 3647 times:

Quoting packcheer (Reply 3):
(I've seen some airlines use a long 2 x 4 when the aircraft is at the gate).

Now that's crude. The one I see often at airshows is bungee cords or even seatbelt extenders tied across a fan blade and a stator  I'm assuming the only real benefit to that is so stupid people don't stick their hands in there and get mauled.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 5, posted (3 years 11 months 4 weeks 8 hours ago) and read 3524 times:

Quoting Fly2HMO (Reply 2):

Wouldn't an engine cool down better if it was just allowed to windmill freely?

Windmilling doesn't do that much for the core...the N1 spool is spinning but most of the guts aren't. The core is heavily insulated, so airflow is limited. In a commercial reverser, windmilling is all you get so it's probably better than nothing.

Opening a core revereser, like a C-17, would actually give you an airflow path to the core, which might give you convective cooling and/or make the windmilling more effective.

This is wild speculation on my part...I have no idea what the real reason is.

Quoting Fly2HMO (Reply 4):
The one I see often at airshows is bungee cords or even seatbelt extenders tied across a fan blade and a stator

You should have seen the A400M guys securing their props at Farnborough this year...it was like Cirque Du Soleil came to town and they were starting to put the tent up.

Tom.


User currently offlineDashTrash From United States of America, joined Aug 2006, 1527 posts, RR: 2
Reply 6, posted (3 years 11 months 4 weeks 4 hours ago) and read 3442 times:

Quoting Fly2HMO (Reply 4):
I'm assuming the only real benefit to that is so stupid people don't stick their hands in there and get mauled.

When an engine is windmilling it it turning with zero oil pressure. Preventing the windmilling reduces engine wear since there is no lubrication going on.


User currently offlineMD11Engineer From Germany, joined Oct 2003, 14004 posts, RR: 62
Reply 7, posted (3 years 11 months 4 weeks 2 hours ago) and read 3401 times:

On older IL-76 aircraft (and possibly other Russian aircraft) it was standard practice to deploy the bucket type reversers when the aircraft was parked to prevent windmilling.

Jan


User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 8, posted (3 years 11 months 4 weeks 2 hours ago) and read 3394 times:

Quoting DashTrash (Reply 6):

When an engine is windmilling it it turning with zero oil pressure. Preventing the windmilling reduces engine wear since there is no lubrication going on.

I figured that too but I remember asking that question eons ago here and everybody said the wear is negligible.


User currently offlineevil8er2006 From United States of America, joined Sep 2010, 13 posts, RR: 0
Reply 9, posted (3 years 11 months 4 weeks 2 hours ago) and read 3358 times:

Quoting packcheer (Reply 3):
Maybe the C-17 leaving the reversers open won't harm anything, but will prevent the engine from windmilling, so they use that instead of having to put something in the fan blades...

Pretty much correct. Also, if you have a tailwind above a certain wind speed, the flight manual recommends placing the TRs in reverse to help with starting the engine.


User currently offlineSpacepope From Vatican City, joined Dec 1999, 2923 posts, RR: 1
Reply 10, posted (3 years 11 months 3 weeks 6 days 23 hours ago) and read 3296 times:

I remember TWA used to park their -9s with the buckets closed at STL, like this:

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And of course the IL-76 was also mentioned already:

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