Windmilling damage?
 

Question about windmilling engines in general, and the GE-90 in particular.
If you shut an engine down in flight and leave it windmilling for a few hours, is there any risk of damage to the engine?

For that length of time - yes, but since you probably had a reason (I would hope) to shut it down - it's kind of a moot point.

There are some photos around the internet of 747s either ferrying on three engines, or using the extra inboard engine mount to carry an inop engine - usually with straps preventing the fan from turning. I suspect that's to prevent damage from windmilling possibly without oil pressure to lubricate the bearings.

If you shut it down for oil loss/low oil pressure - definitely yes.
If it still has oil, the windmilling of the engine will drive the oil pump at sufficient speed to provide oil to the bearings, so the risk of damage is minimal.
The AMM has guidance for what actions are required for an extended engine windmill and what minimum windmill oil pressures you need to avoid damage.

Tdracer….thank you so much, that makes sense. And gubes with what a crew were told by mtce.

When we used the 5th pod ( extra inboard mount) we took the fan blades out.

With the GE CF-6 (predecessor to the GE90), if you shut the engine down and pull the fire handle then the hydraulic pump will be damaged with prolonged windmilling as the hydraulics have a valve that closes starving the pump of fluid.

And what about the extra drag from fan blades that are subject to friction from a lack of oil? Is it significant?

If it is an inflight shut down, windmilling, fuel was feed to that engine every so oftern for short periods. I believe it helped keep the fuel pumps? Lubricated. IIRC
as long as there is oil pressure there is no problem, with bearings etc.
On a 3 engine fairy, or pod, the fan needs to be strapped.

“On a 3 engine fairy”
Not entirely sure I’ve even seen one with one engine…

If you're spelling police I am in real trouble. Can't spell see.
I am no ferry either.

This doesn’t make any sense to me. Please elaborate.

Just checked back to admit that there are plenty of single engine Ferries and Faireys, but I’ve never seen a Faerie or a Fairy that had an attached ICE.

There does appear, on perusal of the internet, a Thomas the Tank Engine character (steam engine) that is, in fact a “Witch-Fairy” so that probably counts as a single fairy engine…

Let me try my best. There are 4 engined jet aircraft, still around but getting fewer by the year.
If there is an inflight shutdown for eg, of an engine, involving a 4 engined aircraft. Then provided the crew are qualified and the country the aircraft in which the 3 engine takeoff is intended, allowes, the aircraft maybe be flown to a suitable maintenance facility, for an engine change.
More cost effective than having a replacement engine flown out and fitted.

I got all of that, I was talking about the assertion that one or the other of us had a problem spelling “see”
I’ve wasted enough of everyone’s time on this thread, I abjectly apologize for the drift, and if Mr. Jones would be kind enough to message me an explanation, I’d be grateful. Meanwhile I’ll simply be quiet and go back to my usual haunts.

Appoligies. Communication problem on my part.

I remember a wonderful contraption consisting of ropes and wooden blocks being used on the TriStar spare engine pod to stop the RB211's fan windmilling in flight, so clearly prolonged rotation of a dead engine was considered an issue.

One of the “interesting” aspects of the BA flight that departed LAX and had an engine surge, declared an emergency then decided to continue to LHR on three but ended up landing in MAN having put out a mayday due to miss management of the fuel system was that during engine certification they had to show that a good engine could be windmilled for 2 (or 3?) hours without damage. Wondered what 11 hours did to a damaged engine.

On the subject of which, I understand to prevent windmilling on the ground on a Tri-Star one day a rubber chock was inserted.

This solution worked quite well until, alas, the ground run was required. The mighty 211 had no problem shredding the chock.

One engine change later....

Vulcan with sand bags- multiple engine changes.