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.

With the disclaimer that all the following may not be entirely accurate (as it was not my airline wot dun it). A BAE146 was being ferried with an engine inoperative and fan not locked. For whatever reason (maybe to use the TMS?) the Captain did not keep the thrust lever of the dead engine in fuel cut-off. They encountered ice, so selected ignition ON. Windmilling damage? If the resultant explosion was categorised as windmilling damage, or finger trouble, I know not.

Mach, not aware of that particular version, but at least one operator experimented with locally derived procedures to their detriment.

An issue with the 146 engine was the geared fan; the fan shaft / turbine could windmill relatively fast, whilst the core - oil pump, would be slower or even stop.
As I recall, after an in flight shutdown, if the core stopped or was below 7% the engine should not be relit, because of potential un-lubricated bearing failure.
The fan had to be secured for ferry flights.

146 Lockout
 

If you were to lockout a 146 engine, you locked out the fan, with a bar across the turbine, the core with a locking pin, disconnected the igniter boxes and took a lead off the start contactor.
The story that Mach refers to did happen, just a couple of wee details are different. The fan was locked, the core wasn’t, the igniters were not disconnected. So the core drove the fuel pumps etc, as it windmilled it pumped fuel into the combustor. I heard at the time the captain liked to keep all 4 throttles in a line like usual.
The rest of the story turned out just as Mach said…..

Yea, that's not a 'windmilling engine' damage - that's basically an attempted in-flight start with a locked low rotor (fuel on, ignition on, fan not turning). That's an almost guaranteed bad outcome (regardless of the engine type)...

That sounds like a very good way of forgetting that there's an inoperative engine on the aircraft...

On the Electra we used to put the throttle fully forward if an engine was shut down. Happened quite often.

I was on Beverleys in the sixties.
We'd been stuck in Lagos for a week or so with an engine failure, and we were going to Kinshasa via Douala in Cameroon. Unfortunately, having refuelled, the number four wouldn't start because of a duff starter motor. I explained to the Tower that we'd taxy out on three and get the no4 to start on the roll, and if it didn't start we'd taxy back and shut down.This was baffling to the Tower who hadn't got much English and reluctantly agreed it. Fortunately the No4 started and we were airborne (I didn't use the word 'moulins' ) !

Reminds me of a story on a 747 in the sand pit who had a similar problem ..engine didn’t start/ relight attempted on take off run which didn’t work/ take off abandoned/ all fuseable plugs blew on the gear/ aircraft stranded whilst a shed load of wheels flown out from LHR. ..(attempt with passengers on board of course).
Some stories you can’t make up.

There was a case at the Portland, Oregon airport - I'm going to say about 20 years ago - biz jet tried to windmill start an engine on the runway and it went very, very wrong (IIRC, the biz jet was a write-off).

BTW, if you're going to do an engine out ferry, SOP should be to pull the ignition and fuel breakers for that engine, especially if you're going to move that engines thrust lever...

There was a pretty notorious case at Boeing Everett maybe 30 years ago. Major operator's chief pilot came out to pick up a brand new 747-400 with Rolls engines. During a ground run, he pulled all four fire handles to shutdown the engines - but then pushed the fire handles back in without setting the fuel condition switches to 'CUTOFF' - re-introduced fuel (and auto-ignition) into a hot turbine as the engines were spooling down. Mother of all tailpipe fires resulted - four of them - along with four melted turbines.
Even through it was the operator's pilot who screwed up (and violated procedures) and toasted the engines (over a million dollars damage each to all four engines), no paperwork had yet been signed so the aircraft still belonged to Boeing - and Boeing had to eat it.
I heard the pilot in question was permanently banned from Boeing property...

If its the same one I'm thinking of, it was a fan and intake change only.
Metal bar through the middle of the chock made a mess. 😁

I remember hearing of a 747 engine run at Gatwick. Someone forgot to engage autostart, air and fuel switches to on. Not a lot of air quite a bit of fuel, a very hot start. Engine change.