PDA

View Full Version : RB211s starting


Capt. Greaseon
18th Sep 2010, 23:58
Just thought the L1011 lovers would like this. If only all engines sounded like this on start!!!!



YouTube - L-1011 Engine Start Part 1 N700TS (Aircraft leaving Roswell and heading to Kansas City) 01-30-2010 (http://www.youtube.com/watch?v=F8dezbfQC4I&feature=related)

Is is because the RB211 have three spools we get this deep sound when they start?

barit1
19th Sep 2010, 21:18
It's the combustor organ-pipe resonance, isn't it? And I'm amazed the EPA didn't make them control/capture all that unburned fuel! :=

lomapaseo
20th Sep 2010, 00:29
It's the combustor organ-pipe resonance, isn't it? And I'm amazed the EPA didn't make them control/capture all that unburned fuel!

It strikes me that if it were unburned fuel there would have been many incidents of toasted aft fuselages on L1011's. if it were to light off externally

I'll go with typical steam and smoke out of the exhaust until the smokeless combustor does its thing.

Any old hands on here like 411 and rampers who know?

N1 Vibes
20th Sep 2010, 02:30
Capt Greason,

I would suggest that the fuel system has previously been inhibited with something like Aeroshell 1. We used to use this in the test-cells, to preserve the delicate fuel components from corrosion, before engines went back to the customer for storage.

When you try to relight an engine for the 1st time that's been inhibited, the Aeroshell 1, which is actually a very thin 'oil', burns like they are announcing the new pope at the vatican. Until it clears from the fuel system you will get smoke like this and the engine will not fully 'fire-up', because the mixture is about 50:50 of oil to kerosene.

Hope this answers.

Best Regards,

N1 Vibes

EW73
20th Sep 2010, 03:13
I recall that when starting these RB211s, if you don't get that resonating sound, as you occasionally didn't, the engine would always go on to suffer from a stagnated start with rising EGT.

I always listened specifically for that sound, and if I didn't get it when I needed to, I closed the start lever, allowed it to run back down on the starter, then when stabilized, re-introduce the fuel/ignition, worked every time.
If I allowed it to continue to the stagnated indication, the resulting EGT would be much higher and would therefore take much longer to cool back prior to restart.

Did that for years in Air Pacific in those very nice (leased QF) 747-200s they used to run.

EW73

gas path
20th Sep 2010, 17:38
I too would go along with the inhibiting oil. I've also had the fire brigade come out on more than one occasion when someone has seen the smoke!:uhoh:. However with a protracted (hung) start like that even when it 'lit up' I guess it would warrant a look at the HPC stg 1 for a couple of bent blades! :suspect:

411A
20th Sep 2010, 22:51
Any old hands on here like 411 ....
You called?:}
And ,yes to the following...

I recall that when starting these RB211s, if you don't get that resonating sound, as you occasionally didn't, the engine would always go on to suffer from a stagnated start with rising EGT.


and...
I always listened specifically for that sound, and if I didn't get it when I needed to, I closed the start lever, allowed it to run back down on the starter, then when stabilized, re-introduce the fuel/ignition, worked every time.
If I allowed it to continue to the stagnated indication, the resulting EGT would be much higher and would therefore take much longer to cool back prior to restart.



Spot on.
The unusual 'sound' is flame propagation in the burner cans, whilst starting.
-524B series, anyway.
Can't say about the other RB.211 varients....haven't operated those.

Capt. Greaseon
21st Sep 2010, 13:36
Thanks for the replies, all I can say it is by far my favorite sound in aviation. Wish there were more of them still around.:hmm:

rudderrudderrat
26th Sep 2010, 10:48
Hi,
And I'm amazed the EPA didn't make them control/capture all that unburned fuel.
All that blueish white smoke is oil fumes. The original 211-22B had their "Labyrinth" oil seals made using IP bleed air. I'm afraid to say some were very smoky on start up (they were not really two stroke) but once IP air was available they stopped burning engine oil.

Beeline
26th Sep 2010, 21:02
I agree with rudderrudderrat, The fuel tanks must have been filled with inhibiting fluid for that long a wet cycle!

Dengue_Dude
26th Sep 2010, 21:20
Our SOP was to motor the engine to 10%N3 to motor that spool through a stall on each start.

Gave a characteristic noise akin to a rumble each start.

Is that the sound you mean?

That was on RB211-524 and -22Bs

grounded27
26th Sep 2010, 21:44
Love that triple spool sound, you can really hear (video did not capture the lower frequencies heard) all three spools humming as they catch up with eachother.

Peter Fanelli
26th Sep 2010, 21:47
You can keep your RB211 noise, this is how an aircraft engine should sound...


YouTube - Wright 3350 Radial Engine (http://www.youtube.com/watch?v=2d4HQ8ZM_2k)

Swedish Steve
27th Sep 2010, 08:24
All that blueish white smoke is oil fumes.

Well I tend to disagree.
When I started on the Tristar I worked in the Middle East. We didn't have masses of smoke out the back.

then I moved to Stockholm, and the TWA crews used to put the fuel/ign on at very low N3, and the smoke poured out. I have always thought it was unburnt fuel in the cold air.

Our SOP was to motor the engine to 10%N3 to motor that spool through a stall on each start.

That is what causes the smoke!.
After 6 years starting engines in BAH, we always ran the engine up to max N3, or at least 20pc N3, or we got a hot start.

In ARN we had a Tristar that only flew on weekends. So on Friday mornings we opened it up, and swept the snow out of the Nbr 2 intake and started it up. OAT around M10deg.It took about four minutes of starter motor before the starter cut out. Oil pressure off the clock high, and oil qty zero, and a fog bank behind us.

The problem with the -22 was that the fuel flow difference between no acceleration, and a stall was tiny. It seemed that we did mods to the start bleed system every 6 months. You never could remember which valve was controlled by which switch, and what the master sw did at the third detent. (except get you nearer to a hot start). With each new RB211 variant it gets better, and now the Trent 800 starts in seconds. (well 30 secs to idle).

barit1
27th Sep 2010, 17:04
With each new RB211 variant it gets better, and now the Trent 800 starts in seconds. (well 30 secs to idle).

...which is the norm for CF6.

lomapaseo
27th Sep 2010, 20:15
all this talk about the sounds an engine makes. Reminds me of the sound of the non RB211,s including the Pratts and GE's where after hearing the whoosh and the whistle of the start sequence you hear that satisfying whoomp as the burner lights and pressurizes the aft end of the machine.

Of course a less than satisying sound is the start sequence being energized by morons in the cockpit engaging the starter when you have your hands inside the fan on an engine. Turns out they were trying to get some airconditioning going on a hot day in MNL and hit the wrong switch. A couple of guys came rolling out of the inlet pretty quick :)

Capt. Inop
28th Sep 2010, 02:05
Of course a less than satisying sound is the start sequence being energized by morons in the cockpit engaging the starter when you have your hands inside the fan on an engine. Turns out they were trying to get some airconditioning going on a hot day in MNL and hit the wrong switch. A couple of guys came rolling out of the inlet pretty quick

With your experiece and knowledge concerning turbofan and turbojet engines i doubt you would put your hands anywhere near N1 stage unless any source
of bleed air was unavailable. Anyway, from the moment that you hear the starter and to the fan starts sucking in big objects there's plenty of time to get out of the intake and walk to a safe distance.

Dealing with aircraft engines on the line with anyone on the flightdeck, expect at least one moron flippin switches.

grounded27
28th Sep 2010, 09:10
With your experiece and knowledge concerning turbofan and turbojet engines i doubt you would put your hands anywhere near N1 stage unless any source
of bleed air was unavailable. Anyway, from the moment that you hear the starter and to the fan starts sucking in big objects there's plenty of time to get out of the intake and walk to a safe distance.



Dunno about modern high bypass engines but the JT-9 could start with the fan (N1) strapped, heard of the fan being held during a dry motor.

barit1
28th Sep 2010, 15:25
There have been cases of large fans started with N1 frozen (ice in the LPT, thermal lockup, etc.) and no harm done if it's only a short period, not above idle.

One potential concern is lack of seal pressurizing air drawn from a fan/LPC stage, thus possible oil loss; so such operation should not exceed OEM limits (possibly 30 seconds or so).

Gas Bags
28th Sep 2010, 15:49
There have been cases of large fans started with N1 frozen (ice in the LPT, thermal lockup, etc.) and no harm done if it's only a short period, not above idle.

One potential concern is lack of seal pressurizing air drawn from a fan/LPC stage, thus possible oil loss; so such operation should not exceed OEM limits (possibly 30 seconds or so).


Please enlighten us as to the OEM limits for the abnormal start you are referring to.

If I had such a start I would be extremely concerned and abort the start well before idle.

This is a windup surely.

lomapaseo
28th Sep 2010, 17:04
Please enlighten us as to the OEM limits for the abnormal start you are referring to.

If I had such a start I would be extremely concerned and abort the start well before idle.

This is a windup surely.

I like the play on words "this is a windup surely" :)

One of the reasons that you may not get the fan turning during start is that the blade tips have managed to windmill backwards jamming the tips into their fan case. The start sequence turns the non fan compressor rotor and its only the air from this rotor flowing through the aft turbine that begins to add torque to spin the fan. Until the engine actually stabilizes at idle the rotors are not well matched in RPM differences (not a biggie since you aren't expecting much power).

The key to a good start is what the EGT is telling you (burner stabilization) and the engine reaching a stabilzed (at idle) match between spool RPMs.

On the other hand if there are any concerns they would be stated in the FCOMs etc. by the manufacturer

Perhaps there is a corralary somwhere in the turboprop world of starting vs the prop speed

TURIN
28th Sep 2010, 19:05
With your experiece and knowledge concerning turbofan and turbojet engines i doubt you would put your hands anywhere near N1 stage unless any source of bleed air was unavailable.

You are right Capt Inop, however on a live aircraft full of passengers the APU will be running and the packs doing all they can to keep them happy.
The luxury of isolating the engines/start valve etc is often not available when slots are at a premium and the station manager is standing behind you impatiently tapping his/her foot.

It is the way of the new world unfortunately. :sad:

spannersatcx
28th Sep 2010, 19:28
station manager is standing behind you impatiently tapping his/her foot.

Just ignore them, I do!:ok:

Old Fella
3rd Oct 2010, 05:26
The RB211 series DO NOT NORMALLY exhibit such volumes of smoke on start. It seems obvious to me that these engines had been inhibited for long term storage and that they had not been started in quite a while. Normally fuel is introduced at either Max motoring RPM or 25% N3. It was also not clear if only No 3 was being started in the video clip. If so, the start was probably slower than usual due to pressure loss (APU output) because of the distance of the APU from No 3 Engine. L1011 APU's were not particularly efficient at best.

rudderrudderrat
3rd Oct 2010, 12:47
Hi Old Fella,

I agree. Even a brand new Trent will smoke as the preservative oil is burned off.
787-first-trent (http://www.flightglobal.com/blogs/flightblogger/2009/05/live-coverage-787-first-trent2.html)
"ZA001 started its Rolls-Royce Trent 1000 engines for the first time. White smoke was seen coming from the engine as storage oil was burnt off as the engines were spooled up."

411A
3rd Oct 2010, 13:11
The RB211 series DO NOT NORMALLY exhibit such volumes of smoke on start.
I have to smile when I see these statements.;)

What it should read is...'do not normally exhibit such volumes of smoke, unless the ambient temperature at the airfield is quite low, and the engine has been cold soaked.'
Very common to see these engines smoke on startup, under the above scenario.
In addition, also under these circumstances, a wing engine will normally spool up faster, during start.
The proximity of the number two engine to the APU is immaterial.

lomapaseo
3rd Oct 2010, 13:49
What it should read is...'do not normally exhibit such volumes of smoke, unless the ambient temperature at the airfield is quite low, and the engine has been cold soaked.'
Very common to see these engines smoke on startup, under the above scenario.
In addition, also under these circumstances, a wing engine will normally spool up faster, during start.
The proximity of the number two engine to the APU is immaterial.

Come to think of it, that is the only time I have seen RB211 engines on L1011's smoke on start up. Does give credence to the labryinth seal theory though.

We still don't have a confirmation from what it smells like (fuel or oil) from somebody standing directly behind one though :}

ZQA297/30
3rd Oct 2010, 18:07
I used to operate L-1011s from the Caribbean to LHR, where the aircraft turned around in about 2 hrs. No smoke on summertime starts at LHR, but every once in a while when it was really cold at LHR,there would be a cloud of smoke that smelled strongly of kerosene. Noticed it with other operators too. Also operated to YYZ where it was colder, but not as many "smokers". Beats me!

grounded27
3rd Oct 2010, 19:37
We still don't have a confirmation from what it smells like (fuel or oil) from somebody standing directly behind one though

Have no doubt it is fuel, it is there when it is warm out as well, just in more of a gasious form thus transparent.

Old Fella
4th Oct 2010, 08:49
Pleased you were able to smile 411A. I also have operated L1011 and RB211 powered B747's in very cold conditions (Kimpo in mid-winter as well as Narita, Osaka etc). I have never witnessed that amount of smoke on start from any engine regardless of ambient conditions. The engine start shown on the YouTube clip took almost 3 minutes to stabilize at idle, inordinately long and smoking for about two minutes hence my DO NOT NORMALLY statement. I also would debate your claim that a wing engine, if started in isolation using only APU bleed air, will spool up quicker than No 2.

VR-HFX
4th Oct 2010, 10:25
411

I'm with Old Fella. Never seen this amount of smoke on the 1011 even on the coldest Kimpo mornings, but then I only have about 8K on type.

Neither did I see it on the 742/3 Classic we operated.

This must have been an engine that had been corked for quite a while.

411A
4th Oct 2010, 12:05
The 'smokers' were nearly always -22B engines, the -524 series hardly ever 'smoked' in my sixteen thousand hours on type.
I also would debate your claim that a wing engine, if started in isolation using only APU bleed air, will spool up quicker than No 2.


Debate aside, that has been my experience.
Normally, old time Flight Engineers have wanted to place a small wager on the point...I prevailed every time, using the clock.
Imagine that, they actually learned something from the Commander...:}

Old Fella
4th Oct 2010, 12:32
411A I have learnt much from Commanders over the years and am happy to admit it. Equally some Commanders have at times, they tell me, benefitted from my advice. I also stand by my assertion re time to stabilize No 2 engine v's a Wing Engine during starting using only APU bleed air. I would suspect that you have "suckered" in those against whom you wagered by using Engine x-bleed from an operating engine when starting a wing engine. Other than that I can see no reason why a wing mounted engine should start any quicker than No2 and I do believe that the proximity of No 2 engine to the APU does have an effect on available air to the starter.

barit1
4th Oct 2010, 13:23
To be clear, I have (almost) no experience on the type.

But an episode at Haneda 26 years ago is very vivid in my memory. I was to ride jump seat in a newly-delivered All Nippon 747SR, and was lounging in the upper deck waiting for a gaggle of NH techs to complete their cockpit orientation tour.

I heard a foghorn-like sound begin, which I thought was some hydraulic noise. I tried to deduce what the trainees were doing to make such a sound - until I happened to glance outside. 500m down the ramp a 1011 was emitting a fog from #2 - just like the Roswell video. It took at least 2 min. for the fog generator to cease, at which time the foghorn also stopped.

barit1
4th Oct 2010, 13:39
lomapaseo (re locked-rotor starting):

Perhaps there is a corralary somwhere in the turboprop world of starting vs the prop speed

The 2-spool turboprops/turboshafts I'm familiar with are all approved for locked-rotor starts. VH-3D Marine One is an example, with core engines running but the helo rotor braked to a halt when el presidente embarks/disembarks.

And the CT7 turboprop has an extra pad on the prop gearbox for mounting a disc brake - but I don't know if any customers have ordered this option.

411A
4th Oct 2010, 15:53
I would suspect that you have "suckered" in those against whom you wagered by using Engine x-bleed from an operating engine when starting a wing engine.

Oh come now, Old Fella this is quite likely impossible, as...the engine bleed controls are within reach of the Flight Engineer, and...if these same folks were actually paying attention (Yes I know, sometimes a stretch:E), I'm quite sure they would have noticed that another engine was operating...;)

It took at least 2 min. for the fog generator to cease, at which time the foghorn also stopped.

Yup, quite common at times, and yes, even from aircraft that have not been in storage, with engines 'preserved'.;)

bcgallacher
4th Oct 2010, 21:16
I have also operated RB211 in cold conditions and have seen the clouds of vapour and slow spool up described and agree with 411a (unusually!) as it appears to be 22B engines that suffer from this - never seen it on a 524.

411A
4th Oct 2010, 21:52
...slow spool up described and agree with 411a (unusually!) as it appears to be 22B engines that suffer from this - never seen it on a 524.

Yup, 'tis a fact.:E

Old Fella
5th Oct 2010, 05:14
Quote: "Flight Engineer, and....if these same folks were paying attention (Yes I know, sometimes a stretch :E)"

411A, I trust you do not really believe what you post regarding your experience of Flight Engineers. I guess I will just have to leave this topic where it is, agreeing to disagree. One thing we can agree on is that the L1011 would be regarded by most who flew it as being a truly capable aircraft with a great working environment.

rudderrudderrat
5th Oct 2010, 10:13
Hi Old Fella,
L1011 APU's were not particularly efficient at best.
We operated the original -1s and 50s, and the APU was so efficient that we ran an air conditioning pack at the same time as we started the engine (apparently to avoid a pressure surge when the starter motor cut off). I can't remember any significant differences in the starting times between any of the engines.

When using a ground pneumatic starting truck, we'd start the engine closest to the truck (due leaky pressure loss).

Ah - those were the days - I'm envious of 411A.

Swedish Steve
5th Oct 2010, 11:02
We operated the original -1s and 50s, and the APU was so efficient that we ran an air conditioning pack at the same time as we started the engine (apparently to avoid a pressure surge when the starter motor cut off).

Really depends on the OAT. The APU was OK in the cold, but not so good in the desert. With an older APU, and 40 deg C OAT I used to close the aft isolation valve, and turn off the B and C EDPs, and start nbr 2 first. Then, at about 40 pc N3, open the isolation valve and turn a pack on to stop the APU surging at starter cut out. You needed someone on the F/E panel who understood the aircraft.

Because of the design of the APU, it runs most efficiently in min mode with a pack on. Close the APU bleed valve and the APU surge valve opens and all the load compressor air is vented overboard and you can hear the APU struggling.