Looking for some opinions on S-61's
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Looking for some opinions on S-61's
I would appreciate any input that you may have on these procedures.
1. Allowable TQ splits during all regimes of flight? Do we disregard TQ split and match T5, or Ng? why or why not? Does it put an unequal amount of stress on one input verses the other when TQ's are unmatched? I have always try to use the no more than 5% split.
2. Is it acceptable to abruptly release the rotor brake during rotor engagement? Is it harder on the input if we engage with only one engine started? I pull the brake out of the lock while still holding pressure and as ng accelerates 2% I gently release pressure off with the brake.
3. is it acceptable to land with the Tail wheel unlocked? engine failure on approach with the possibility of needing to run on or tail rotor failure. With he unpinned tail wheel wouldn't it add to the possibility of rolling the aircraft over on touchdown?
4. is it acceptable to ground taxi,sit loading pax and refueling with the AFCS engage? possible hard over on the ground and or loss of gyros on ground. Plus the AFCS will try to compensate for attitudes during taxi on uneven surfaces.
5. what is our minimum TQ (0%,10%, 20%)when descending to land? to reduce the chances freewheeling of the inputs and will descend with the collective bottomed out. Some guys say that it's okay for the inputs to freewheel as long as you reengage smoothly. Does it put any undue wear on the bearings when Freewheeling and is it okay when you hear the inputs whining?
1. Allowable TQ splits during all regimes of flight? Do we disregard TQ split and match T5, or Ng? why or why not? Does it put an unequal amount of stress on one input verses the other when TQ's are unmatched? I have always try to use the no more than 5% split.
2. Is it acceptable to abruptly release the rotor brake during rotor engagement? Is it harder on the input if we engage with only one engine started? I pull the brake out of the lock while still holding pressure and as ng accelerates 2% I gently release pressure off with the brake.
3. is it acceptable to land with the Tail wheel unlocked? engine failure on approach with the possibility of needing to run on or tail rotor failure. With he unpinned tail wheel wouldn't it add to the possibility of rolling the aircraft over on touchdown?
4. is it acceptable to ground taxi,sit loading pax and refueling with the AFCS engage? possible hard over on the ground and or loss of gyros on ground. Plus the AFCS will try to compensate for attitudes during taxi on uneven surfaces.
5. what is our minimum TQ (0%,10%, 20%)when descending to land? to reduce the chances freewheeling of the inputs and will descend with the collective bottomed out. Some guys say that it's okay for the inputs to freewheel as long as you reengage smoothly. Does it put any undue wear on the bearings when Freewheeling and is it okay when you hear the inputs whining?
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Stan,
I'll try and answer your questions as best I can,
1. Operating British Sea Kings in hot and high conditions we generally try and fly with Tqs matched. If the engines are poorly matched in terms of NG or PTIT (T5) we will match those so that we are getting the most out of the engines. If matching by something else generally accept no more than 20% Tq mismatch. (Westlands reckon you can go upto 30%) The only problem with this is when operating at the top end of Tq it becomes increasingly easy to inadvertently Overtorque. (Our limit is 111% Tq twin matched which becomes quite hard maths when you have up to a 30% Tq mismatch trying to get a heavy cab out of a dusty LS)
2. Taking off the Rotor brake should generally be a gentle movement. (Just being gentle to the moving parts), we pre torque the head to 70% NG and then release the brake. Single engine Flight Drive starts are reserved for last ditch attempts to get us out of holes that we would rather not spend the night. Don't forget though that effectively you are only single engine when in Accessory Drive even with both engines running, only one is providing a direct drive to the Gear Box.
3. You should avoid landing with the Tail Wheel lock disengaged as it can cause all sorts of grief particularly when trying to deal with other problems. It could lead to rolling if any pedal is left in during a running landing, crosswind or brakes jamming etc. Best not to tempt fate on that one. With emergencies such as Tail Rotor Failure the locked Tail Wheel helps straighten the aircraft as it touches down, if it was left unlocked you could end up in any odd position including upside down as the main gear touches down.
4. The AFCS should be out for all stages of ground taxiing and fueling. Occasionally when in a FOB we leave the AFCS engaged in case we need to get out in a hurry when loading/unloading pax. There have been instances of ASE packs that are approaching the end of their life causing the aircraft to spin on the spot when AFCS is left engaged and the pedals are left unguarded. Thankfully the fuel crew managed to get out of the way.
5. Your minimum Tq during descent should be 10%, the reason being: If you allow the gearbox to freewheel during the descent the engine failure will not be as obvious until you pull in the lever at the bottom (No matter how gently you do it that Tq just won't come back up). If you have at least 10% Tq on you will notice that you get a Tq split and know that you have a problem. If the inputs start whining it could be a sign that they are starting to wear out/vibrate dangerously.
Hope this answers your questions, some of the best flying I've had was in the Stan particularly during the summer months, if you're not sure how the King will fly you will certainly find out from May onwards.
I'll try and answer your questions as best I can,
1. Operating British Sea Kings in hot and high conditions we generally try and fly with Tqs matched. If the engines are poorly matched in terms of NG or PTIT (T5) we will match those so that we are getting the most out of the engines. If matching by something else generally accept no more than 20% Tq mismatch. (Westlands reckon you can go upto 30%) The only problem with this is when operating at the top end of Tq it becomes increasingly easy to inadvertently Overtorque. (Our limit is 111% Tq twin matched which becomes quite hard maths when you have up to a 30% Tq mismatch trying to get a heavy cab out of a dusty LS)
2. Taking off the Rotor brake should generally be a gentle movement. (Just being gentle to the moving parts), we pre torque the head to 70% NG and then release the brake. Single engine Flight Drive starts are reserved for last ditch attempts to get us out of holes that we would rather not spend the night. Don't forget though that effectively you are only single engine when in Accessory Drive even with both engines running, only one is providing a direct drive to the Gear Box.
3. You should avoid landing with the Tail Wheel lock disengaged as it can cause all sorts of grief particularly when trying to deal with other problems. It could lead to rolling if any pedal is left in during a running landing, crosswind or brakes jamming etc. Best not to tempt fate on that one. With emergencies such as Tail Rotor Failure the locked Tail Wheel helps straighten the aircraft as it touches down, if it was left unlocked you could end up in any odd position including upside down as the main gear touches down.
4. The AFCS should be out for all stages of ground taxiing and fueling. Occasionally when in a FOB we leave the AFCS engaged in case we need to get out in a hurry when loading/unloading pax. There have been instances of ASE packs that are approaching the end of their life causing the aircraft to spin on the spot when AFCS is left engaged and the pedals are left unguarded. Thankfully the fuel crew managed to get out of the way.
5. Your minimum Tq during descent should be 10%, the reason being: If you allow the gearbox to freewheel during the descent the engine failure will not be as obvious until you pull in the lever at the bottom (No matter how gently you do it that Tq just won't come back up). If you have at least 10% Tq on you will notice that you get a Tq split and know that you have a problem. If the inputs start whining it could be a sign that they are starting to wear out/vibrate dangerously.
Hope this answers your questions, some of the best flying I've had was in the Stan particularly during the summer months, if you're not sure how the King will fly you will certainly find out from May onwards.
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I think Matelo99 has answered all your questions although it referred to the Sea King. From my days on the S61N (a few years ago - OK a lot of years ago) everything Matelo99 has said is good for the S61N too.
If you pm Ant T, I know he is still flying the S61N in the Falklands so can give you good answers which my memory struggles for
Best wishes
TC
If you pm Ant T, I know he is still flying the S61N in the Falklands so can give you good answers which my memory struggles for
Best wishes
TC
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Hi Stan,
#1 people who come from other twins such as the 212 are always concerned about Tq split. This is not the same on the 61. You have to remember that max Tq for take-off is 206% not 103%. So as long as you do not exceed 206% combined then you are well within operating limits. Since the 61 is usually NG limited you most often will be matching NG ( T5 if that is the limiting factor) and don't worry about the Tq split.
#2 what you are doing sounds good.
#3 You are not saying if you are landing on a deck (pad) or a runway and intend to taxi after landing. If landing on a pad then of course the tail wheel should be locked. However, if you intend to ground taxi after landing then I preferred to land with it unlocked. We had more incidents with pilots breaking pins, inadvertent collective increases, etc landing with it in than ever had a problem with it out. If you read the RFM Sikorsky does not specifically say what to do, but they assume you will land with it out as they say "if during a running landing the tail wheel shimmies, lock it".
#4 Generally it should always be off when on the ground. If you are leaving it on at an FOB for the reasons you are stating then be very vigilant and be sure to keep your feet on the micro switches.
I remember once landing on an offshore deck to wait for another deck to become available and forgot to switch it off. I was sitting there with my feet on the floor and the next thing that I knew the tail wheel started skipping sideways across the deck. What happened? Sitting on a steel deck the flux valves were affected and thus affecting the C14, so with heading hold (feet off the pedals) the AFCS was inputting left pedal to try and stay on heading.
#5 Min Tq should be 10% (on each engine). Hard engagements are not the only way to damage the freewheel units. Don't mean to be critical, but you need to get into the books a bit as there are no traditional bearings in the high speed section of the S61. The babbit bearings could care less about freewheeling, they only care about oil. What you are damaging by freewheeling is the rollers and ramps inside the units. Have one of your mechanics explain how the freewheels work in a S61 and it will become clear why freewheeling is bad.
Good luck and enjoy the queen of the skies. She is a great machine and if you treat her right she will not let you down. My favorite helicopter of all time.
#1 people who come from other twins such as the 212 are always concerned about Tq split. This is not the same on the 61. You have to remember that max Tq for take-off is 206% not 103%. So as long as you do not exceed 206% combined then you are well within operating limits. Since the 61 is usually NG limited you most often will be matching NG ( T5 if that is the limiting factor) and don't worry about the Tq split.
#2 what you are doing sounds good.
#3 You are not saying if you are landing on a deck (pad) or a runway and intend to taxi after landing. If landing on a pad then of course the tail wheel should be locked. However, if you intend to ground taxi after landing then I preferred to land with it unlocked. We had more incidents with pilots breaking pins, inadvertent collective increases, etc landing with it in than ever had a problem with it out. If you read the RFM Sikorsky does not specifically say what to do, but they assume you will land with it out as they say "if during a running landing the tail wheel shimmies, lock it".
#4 Generally it should always be off when on the ground. If you are leaving it on at an FOB for the reasons you are stating then be very vigilant and be sure to keep your feet on the micro switches.
I remember once landing on an offshore deck to wait for another deck to become available and forgot to switch it off. I was sitting there with my feet on the floor and the next thing that I knew the tail wheel started skipping sideways across the deck. What happened? Sitting on a steel deck the flux valves were affected and thus affecting the C14, so with heading hold (feet off the pedals) the AFCS was inputting left pedal to try and stay on heading.
#5 Min Tq should be 10% (on each engine). Hard engagements are not the only way to damage the freewheel units. Don't mean to be critical, but you need to get into the books a bit as there are no traditional bearings in the high speed section of the S61. The babbit bearings could care less about freewheeling, they only care about oil. What you are damaging by freewheeling is the rollers and ramps inside the units. Have one of your mechanics explain how the freewheels work in a S61 and it will become clear why freewheeling is bad.
Good luck and enjoy the queen of the skies. She is a great machine and if you treat her right she will not let you down. My favorite helicopter of all time.
Stan,
Concur with all advice given, but don't be too confused by matelo99 as there are significant differences between the Westland Sea King and the Sikorsky S61 about which he may not be aware. Fuel control/engine matching and control is far improved on the Westland product, so tq matching is far more stable. Also the references to Flight Drive starts is peculiar to the blade fold accessory drive which isn't usually present in the S61!
Outwest has it nailed
Concur with all advice given, but don't be too confused by matelo99 as there are significant differences between the Westland Sea King and the Sikorsky S61 about which he may not be aware. Fuel control/engine matching and control is far improved on the Westland product, so tq matching is far more stable. Also the references to Flight Drive starts is peculiar to the blade fold accessory drive which isn't usually present in the S61!
Outwest has it nailed
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Thanks John
Stan,
I should have given a bit more advise on #2
If you have started both engines and now intend to engage the rotor this technique works well.
Pull both throttles out of the idle detent and move them forward slightly with your left hand. Now leading with one of them, look for your 2% rise and gently release the rotor brake as you described with your right hand. Now as the blades start to turn gently advance the other engine to keep load on both engines. This technique, when done properly, will be the smoothest engagement with the very least amount of time that the inputs are freewheeling.
Cheers
Stan,
I should have given a bit more advise on #2
If you have started both engines and now intend to engage the rotor this technique works well.
Pull both throttles out of the idle detent and move them forward slightly with your left hand. Now leading with one of them, look for your 2% rise and gently release the rotor brake as you described with your right hand. Now as the blades start to turn gently advance the other engine to keep load on both engines. This technique, when done properly, will be the smoothest engagement with the very least amount of time that the inputs are freewheeling.
Cheers
Last edited by Outwest; 20th Jan 2013 at 13:12.
4. is it acceptable to ground taxi,sit loading pax and refueling with the AFCS engaged
I flew S61's for Bristow years ago and they definitely didn't require AFCS disengaged on each landing, or while taxiing - it was one of the things I had to get used to doing when I converted onto the AS332. I now fly S61 for British International, and have just been through the books to make sure I had not missed something, and am sure that here we also are not required to routinely disengage AFCS while on the ground. The only exception is when we have landed on a moving deck. Other than that, ours goes on before first take-off and stays on till just before shutting down.
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61 stuff
I agree totally with everything Outwest said.
I would only add to your question regarding s/e engagments.
I have done this literally thousands of times. Start one engine (we used to alternate days), bring the Ng up 2% (if I recall correctly), smoothly release the rotor brake and Bob's your uncle. When the transmission is warm enough, bring the Nr up to 100%, then start and engage the 2nd engine. FYI, we NEVER had any unusual input wear doing this in many, many thousands of hours. Cheers, J.
I would only add to your question regarding s/e engagments.
I have done this literally thousands of times. Start one engine (we used to alternate days), bring the Ng up 2% (if I recall correctly), smoothly release the rotor brake and Bob's your uncle. When the transmission is warm enough, bring the Nr up to 100%, then start and engage the 2nd engine. FYI, we NEVER had any unusual input wear doing this in many, many thousands of hours. Cheers, J.
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Ant T,
you are correct, there is nothing in limitations that requires you to disengage the AFCS after landing.
However, from experience I can tell you that the a/c is far more stable on the ground with it off. I'm sure you have seen many pilots have the old girl do a "dance" immediately after touch down, this is the interaction of the AFCS. The next time you land, as soon as you have all 3 wheels on the ground (and there is no chance of lifting off) release the AFCS. You will see the a/c go stable.
When you are testing the AFCS on the ground and you have the monitor switch in Roll does the needle follow the stick or go opposite? Now when you are in flight and do the same thing what does the needle do? Why?
Also, taxiing with it on has a noticeable effect. I know, the micro switches should make it not matter, but just try it. Ground taxi with turns with it on and with it off and tell me which "feels" better.
The OP was asking for opinions and those are mine, not trying to tell anyone they are doing anything wrong or to change their ways.
you are correct, there is nothing in limitations that requires you to disengage the AFCS after landing.
However, from experience I can tell you that the a/c is far more stable on the ground with it off. I'm sure you have seen many pilots have the old girl do a "dance" immediately after touch down, this is the interaction of the AFCS. The next time you land, as soon as you have all 3 wheels on the ground (and there is no chance of lifting off) release the AFCS. You will see the a/c go stable.
When you are testing the AFCS on the ground and you have the monitor switch in Roll does the needle follow the stick or go opposite? Now when you are in flight and do the same thing what does the needle do? Why?
Also, taxiing with it on has a noticeable effect. I know, the micro switches should make it not matter, but just try it. Ground taxi with turns with it on and with it off and tell me which "feels" better.
The OP was asking for opinions and those are mine, not trying to tell anyone they are doing anything wrong or to change their ways.
ANt T: I know it's difficult not to follow company SOP's and the chief pilot should know better than to allow stab in on the ground. There is no reason whatsoever to leave it engaged on the gnd. If you did it on a moving deck, you could lose the a/c as did the RN in the 90's.
All the amps and motors have a will of their own and consequently cause problems whilst airborne (control malfunctions) let alone inviting those problems to manifest themselves on the ground through choice!!
It's all about husbandry and tidying up the cockpit. Stab out everytime on deck! (Moving or stationary).
PS: Doesn't the S61 from memory, droop its Nr as it climbs into the hover? Mechanical governor etc etc?
All the amps and motors have a will of their own and consequently cause problems whilst airborne (control malfunctions) let alone inviting those problems to manifest themselves on the ground through choice!!
It's all about husbandry and tidying up the cockpit. Stab out everytime on deck! (Moving or stationary).
PS: Doesn't the S61 from memory, droop its Nr as it climbs into the hover? Mechanical governor etc etc?
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That's why you set 106 NR, speed levers forward.
Ok all you experts, why advance SL on TO and Landing to 106 NR? Increase NR =. Least that's what you did 15 years ago.
Ok all you experts, why advance SL on TO and Landing to 106 NR? Increase NR =. Least that's what you did 15 years ago.
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Just looking at some of the back comments. So if the drills seemingly say that you can have the AFCS On when on a deck, what do they say about the compass and selections of MAG/DG.
Last edited by outhouse; 25th Jan 2013 at 20:15. Reason: Changed FMS for AFCS, too many reds before posting, must try harder.
OK - just to clarify......
Both at Bristow and British International it was/is standard to disengage AFCS on a moving deck.
However - it was NOT standard at Bristow (one of the largest operators of S61's in their day), and is not standard at BI (and presumably was not at their predecessors, Britsh Airways helicopters) to disengage it while taxiing or stationary on solid ground. So an awful lot of policy makers/training captains/line trainers (which I am not....) over the years must have found it acceptable. Also I can find no reference in the Flight manual suggesting or requiring it.
Both at Bristow and British International it was/is standard to disengage AFCS on a moving deck.
However - it was NOT standard at Bristow (one of the largest operators of S61's in their day), and is not standard at BI (and presumably was not at their predecessors, Britsh Airways helicopters) to disengage it while taxiing or stationary on solid ground. So an awful lot of policy makers/training captains/line trainers (which I am not....) over the years must have found it acceptable. Also I can find no reference in the Flight manual suggesting or requiring it.
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Ok, drifting back through 15 years then you may well be correct, I have just spent nealy an hour searching through crap in my barn for the S61 normal procedures documents, seems they are well hidden anyway, I must ask the question to any other S61 chaps, a, would you feel happy taxiing with the AFCS in, would you feel happy on a deck, possibly moving, ship or other, having the AFCS in, well if it was me the answer is NO.
JUST LOOKING AT MY AW139 checklist, AUTOPILOT OFF during taxi and on deck periods.
Outhouse.
JUST LOOKING AT MY AW139 checklist, AUTOPILOT OFF during taxi and on deck periods.
Outhouse.