Parking With Thrust Reversers Deployed? — Tech Ops Forum

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Parking With Thrust Reversers Deployed?

c5load From United States of America, joined Sep 2008, 917 posts, RR: 0
Posted (2 years 8 months 2 weeks 6 days 2 hours ago) and read 2967 times:

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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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10 replies: All unread, jump to last

tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (2 years 8 months 2 weeks 6 days 2 hours ago) and read 2956 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.

Fly2HMO From , joined Dec 1969, posts, RR:
Reply 2, posted (2 years 8 months 2 weeks 6 days 2 hours ago) and read 2943 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.

packcheer From United States of America, joined Nov 2008, 323 posts, RR: 0
Reply 3, posted (2 years 8 months 2 weeks 5 days 22 hours ago) and read 2866 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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Fly2HMO From , joined Dec 1969, posts, RR:
Reply 4, posted (2 years 8 months 2 weeks 5 days 20 hours ago) and read 2805 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.

tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 5, posted (2 years 8 months 2 weeks 5 days 11 hours ago) and read 2682 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.

DashTrash From United States of America, joined Aug 2006, 1314 posts, RR: 4
Reply 6, posted (2 years 8 months 2 weeks 5 days 7 hours ago) and read 2600 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.

MD11Engineer From Germany, joined Oct 2003, 13344 posts, RR: 64
Reply 7, posted (2 years 8 months 2 weeks 5 days 5 hours ago) and read 2559 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

Fly2HMO From , joined Dec 1969, posts, RR:
Reply 8, posted (2 years 8 months 2 weeks 5 days 5 hours ago) and read 2552 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.

evil8er2006 From United States of America, joined Sep 2010, 11 posts, RR: 0
Reply 9, posted (2 years 8 months 2 weeks 5 days 5 hours ago) and read 2516 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.

Spacepope From Vatican City, joined Dec 1999, 2739 posts, RR: 1
Reply 10, posted (2 years 8 months 2 weeks 5 days 2 hours ago) and read 2454 times:

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

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