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Post by okami on Apr 7, 2010 7:24:12 GMT -5
Hi all,
Yesterday I completed a leg with the Lockheed Starliner (v2.2 version), but I encountered a bit of a problem during my final approach.
While on an ILS approach into Robertsfield (GLRB Monrovia/Liberia), I increased my RPM to 2400 RPM and reduced power to obtain 130 KIAS, as the checklists state. With my flaps at 80% I extended my landing gear, when I suddenly noticed engine 3 was beginning to surge: while the other three engines remained steady at 2400 RPM, my number 3 was fluctuating between 2200 and 2600 RPM, so much so that as a precautionary measure I decided to shut it down and perform a 3-engined landing (first time that happened on my world tour, by the way).
Now my question is, of course: what happened, did I do the right thing, and how can I avoid this a next time? As far as I know I followed all the approach and landing procedures, and I've never encountered this problem before with any of the other Constellations (the L-749s and L-1049s, as well as the old L-049). Or is it just a case the R-3350 acting up as it was known to do?
Many thanks in advance,
Nikko.
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Post by ashaman on Apr 7, 2010 8:34:25 GMT -5
Sometimes engines do surge to me too, it I use the prop sync the way it " should" be used, so I... cheat.  The prop sync in the engine panel wants for you to select either engine 1 or 2 as a baseline for synchronization and THEN activate the synchronization for the other engines. This though doesn't really work all that much, at least in my case, and one time, going through the official operations resulted with me having THREE engines surging at the same time.  Solution? Disengage the prop sync and simply forget about it or leave the engines selector in the middle, with no engine selected and THEN activate the prop sync... and MAGICALLY, everything works perfectly, the props sync without a problem and never have any surge. Notice that this happens to me with the other Connies as well, if more rarely. It is not a misbehaving of the Starliner alone.  Never really thought to signal it because mainly I have found a way around it and... well, I thought it was a " known issue" or something like that.  |
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Post by volkerboehme on Apr 7, 2010 13:11:22 GMT -5
Hi,
I can't really contribute to that, because I don't know details of the Starliner system too well. While the different Connie versions are all based on the VN panel system, they do handle some details differently, so you can't completely rely on similarity.
If it is no persistent problem, then just take it as a lucky stroke of realism. Somethng like that happens in real life as well. And it seems like you were able to cope with it adequately.
Best regards,
Volker
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Post by ashaman on Apr 7, 2010 14:09:45 GMT -5
If it is no persistent problem, then just take it as a lucky stroke of realism. Somethng like that happens in real life as well. And it seems like you were able to cope with it adequately. No problems on my side, having found a home solution. As for the realism of it... maybe when one engine begins fluctuating it's all right... but three? Happened only one time, all right, but was FREAKY. ;D When a thing like that happen, to follow realism, I'd suggest disengaging the prop sync and treat it as a faulty system, to repair as soon as you land.  Different problem might be if the surging engine happens at prop sync disengaged or if the surge continues after the sync system having been disengaged ( never happened to me, but supposedly...). There the solution is to feather the engine and rely not on it. |
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Post by volkerboehme on Apr 7, 2010 15:17:30 GMT -5
Hi,
I understand that engine #3 (starboard inner) was surging, while the remaining 3 were working perfectly fine.
Best regards,
Volker
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Post by okami on Apr 7, 2010 15:31:08 GMT -5
Hi, I can't really contribute to that, because I don't know details of the Starliner system too well. While the different Connie versions are all based on the VN panel system, they do handle some details differently, so you can't completely rely on similarity. If it is no persistent problem, then just take it as a lucky stroke of realism. Somethng like that happens in real life as well. And it seems like you were able to cope with it adequately. Best regards, Volker Thanks, but I wasn't really satisfied with how I handled it. I mean, I managed to shut down my engine, but I only partially managed to feather the prop as the incident happened little over a minute before touchdown, so it was still windmilling as I was landing. Not exactly ideal, but luckily without any ill effects in this case. I have to add, though: earlier on during the same flight, as I was climbing out of Dakar, just after I had put the blowers in high (with the engines at 2500RPM and throttle set to 40") all four engines started fluttering, but only slightly. It was only something like 25-50 RPM, and whatever the problem was, it seemed to have solved itself after a about a quarter of a minute. I probably only noticed it as the RPM-indicators were fluctuating out of sync. Now that I know this can happen, though, I'll probably follow Ashaman's advise if it ever occurs again, before resorting to engine shutdowns. One thing I learnt out of it, though, is that it's true what they say: the Connie's great to fly, even on 3 engines... ;D PS: just read your later post after I posted this one: you are correct, Volker. No. 3 was surging between 2200-2600 RPM; Nos. 1, 2 & 4 were steady at 2400 RPM. |
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Post by volkerboehme on Apr 8, 2010 0:10:06 GMT -5
Hi Nikko,
I noticed that the engines aren't acting perfectly in sync, anyway. If I throttle up for takeoff, there's a slight difference in MAP between engines #1 and #2, for example. Prop settings are usually a bit different between engines when I look at the status gauge. This is unlike the effect I see in other planes but it might be actually closer to life than perfectly syncronized engines. I assume that this is intentionally coded.
I'm afraid that Hans-Joer Naegele would be the one who could shed some light on it here, I'm not really up to it.
Engine shutdown 1 minute before landing is always difficult. In the checklist, I tried to move all FE panel actions out of the checklist sections for takeoff and landing - you'll notice that the plane is set up for landing by the time you approach the IAF and all the other items are done in the front row. Some things of the real-life checklist have been omitted or moved to another place on the list to make handling practicable.
In real-life, shutting down the engine would have been performed by all 3 persons in the cockpit, so there'd be less risk of smashing into a hillside while the PIC has his view obscured by the FE panel. But on the other hand, sometimes you'd have to just make your choice which things to handle first. For example, when an engine bursts into fire on landing, the EC-121 manual explicitly states to reverse engines first, using possible braking power from the burning engine, and only then shut down the burning engine.
Best regards,
Volker
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Post by sunny9850 on Apr 8, 2010 0:52:31 GMT -5
Volker is correct that a slight difference in engine performance was intentionally put in to the FDE. After all you are working 4 very complex pieces of machinery here in unison. They will be close but never as 100% perfect as the sim could make it.
That close to landing the windmilling prop is not going to cause a huge problem. KIAS is fairly slow so the created drag is relatively low. The engine may or may not take further damage by turning without proper lubrication....but you will be on the ground soon with plenty of time to sort that out.
In close proximity to the ground you don't have a lot of time and room to fiddle about with levers trying to create a "perfect" failed situation. Focus on flying the airplane, compensating for what ever negative effect might be caused by the less than ideal #3 engine.
That is much better than crashing short of the landing runway because you were attempting to secure a bad but harmless engine.
On a recent Bi-Annual Flight Review my CFI failed "Sara's" one and only engine at about 1500ft AGL. Knowing my airplane I simply pointed her towards a best off-field landing site and then went through the steps to secure the engine (simulated of course).
He asked me afterwards why I had not gone through a restart and I told him that this low and already slowed for circuit entry it doesn't make sense. She would not be very likely to restart hot anyways and her glide ratio with 450+lbs of fuel is close to that of a rock. Much better to focus on setting up for the best possible landing off-airport without loosing control of the airplane.
The accident statistics are full of pilots who forgot to fly the airplane first.
As for the Prop control in the L-1649A I must admit it has been a while since I have flown that one. But I always use prop synch on engine 1 or 2 and did not have any trouble with it as long as my hardware levers did not try to play little tricks on me. Then of course you do get a bit of a fight between the software and the hardware and who wins is never certain.
As for the system not working at all like Ashaman claims that is not my experience on this or any of our other Connies. Not sure on the L-049 that is a different airplane all together.
Stefan
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Post by thunder100 on Apr 8, 2010 3:43:31 GMT -5
As i am probably the one(apart Hansi) which know the Starliner systems and FDE best,pls tell me Nikko,wether by chnace you can recall the engine status(white coloured rpm in Status panel,or yellow or red)
Usually the fluctuation starts just ahead of the engine getting into red.
Next time it happens make me a screenshot of the Status panel and send me a PM
Roland
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Post by okami on Apr 8, 2010 4:45:44 GMT -5
Well, to be honest with you, Roland, I didn't pay attention to that, being too busy at the time trying to shut down the engine while performing the landing. I do know, though, that at no point after the take-off I let the RPM go into the red.
Many thanks for the feedback, by the way. Now I know I probably didn't do the right thing by trying to shut the engine down, right before the landing. I've also read too many AAIB-reports of pilots forgetting to fly their plane... :/
Not sure when I get to fly the Starliner the next time, though. It's not featured in the rest of my journey, but it probably will be featured more prominently in a next edition.
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Post by ashaman on Apr 8, 2010 7:22:25 GMT -5
As for the system not working at all like Ashaman claims that is not my experience on this or any of our other Connies. Not sure on the L-049 that is a different airplane all together. Not to pour gasoline on the fire, but the only time I had three insurgences of multi-engine fluctuation, I was in the middle of a descent towards the landing airport ( RPM 2200, MAP... can't remember). Every time a fluctuation starts, as much I understand it, basing my hypothesis on my experiences with this phenomena, is when throttle is reduced ( never happened to me in any other part of the flight). Of course, when you see that one or more of the needles begin dancing, it's way too late to add power hoping for everything to re-stabilize, as even giving throttle by then is too little too late to stop the surging. I agree on a general basis that if ONE engine starts going on the fritz like that the most realistic thing to do is consider to shut it down and feather it, but I really don't want to even begin to start making hypothesis about the chances of landing a Starliner ( or any other Connie) on a single working engine, having to shut down the other three... if simply shutting off the prop sync stops the surging dead. Best realistic course of action, should a thing like that happen is, as much I can suggest, is to off the prop sync first and see if the situation stabilize. If not, shut down and feather the offending engine ( hoping it's only one). The... cheat I use leaving the engines selector in the middle, is just that, a cheat, and as such I cannot suggest to use it ( but you know how it is... ;D). It works a lot better and syncs all engines perfectly, while instead if I select one of the engines takes a long time to sync, and sometimes doesn't sync them at all too. |
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Post by Tom/CalClassic on Apr 8, 2010 9:33:24 GMT -5
Typically prop sync is used only during climb, cruise, and descent. It's not used during takeoff or landing. So turning it off is probably just fine. Hope this helps, |
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Post by thomas on Apr 8, 2010 16:29:25 GMT -5
You probably got a batch of bad Avgas in Dakar... Thanks, but I wasn't really satisfied with how I handled it. I mean, I managed to shut down my engine, but I only partially managed to feather the prop as the incident happened little over a minute before touchdown, so it was still windmilling as I was landing. Not exactly ideal, but luckily without any ill effects in this case. I have to add, though: earlier on during the same flight, as I was climbing out of Dakar, just after I had put the blowers in high (with the engines at 2500RPM and throttle set to 40") all four engines started fluttering, but only slightly. It was only something like 25-50 RPM, and whatever the problem was, it seemed to have solved itself after a about a quarter of a minute. I probably only noticed it as the RPM-indicators were fluctuating out of sync. Now that I know this can happen, though, I'll probably follow Ashaman's advise if it ever occurs again, before resorting to engine shutdowns. One thing I learnt out of it, though, is that it's true what they say: the Connie's great to fly, even on 3 engines... ;D PS: just read your later post after I posted this one: you are correct, Volker. No. 3 was surging between 2200-2600 RPM; Nos. 1, 2 & 4 were steady at 2400 RPM. |
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Post by okami on Apr 8, 2010 16:46:34 GMT -5
You probably got a batch of bad Avgas in Dakar... Quite unlikely, it's an Air France hub. Plus, with the Starliner's tankage, it's probable I was still carrying the required fuel for my second leg from my trip over from Paris. No, the way I see things now (I've been trying to reconstruct what I exactly did in those last five minutes - about as frustrating as an air crash investigation without Black Boxes to resort to), I probably either throttled back too quick during the final descent phase of my approach, or more likely, increased my throttle too fast when I noticed my airspeed was slipping toward 110 KIAS, rather than the 130 KIAS I should have been at in that stage of the approach. My investigation led me to two recommendations (to myself, that is): - For Starliner operations: 1) Disengage prop sync during approach phase; 2) Avoid rough handling of throttle during approach phase; With an additional notice: 3) If encountering engine failure or suspected engine failure after GS intercept, do not feather or shutdown engine. |
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Post by sunny9850 on Apr 8, 2010 17:46:29 GMT -5
Just for testing purposes you might want to eliminate the prop axis you have assigned and use only the VC lever or the P icon.
The most common source of problems with the entire Connie series are rooted in controller fluctuation or flutter.
Stefan
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