Bell 412
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I can't believe Bell got that fuel transfer light thing certified. At 2AM, on short final or just clearing the deck on takeoff, it is brighter than the sun. Even if you know it's going to come on, it causes a very sudden increase in heartrate, and distracts both pilots at a critical phase of flight, because you have to verify what the master caution light was. I've cursed the 
idiot(s) who designed the 412 fuel system more times than I can count. Rube Goldberg had nothing on them, and it's all caused by the simple failure to put the fuel underneath the mast, and thus the problem of CG movement when fuel is burned. The entire machine is one huge kludge, cobbled together without any apparent forethought.
idiot(s) who designed the 412 fuel system more times than I can count. Rube Goldberg had nothing on them, and it's all caused by the simple failure to put the fuel underneath the mast, and thus the problem of CG movement when fuel is burned. The entire machine is one huge kludge, cobbled together without any apparent forethought.
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heavy 412s
When slinging heavy loads with the HP or EP, you really need to pull up to near 94 or 95% mast torque. Now with the way the torque needle swings between various helicopters you need to be careful around 94 to 100%.
If the load is starting to move while holding this power, wait, it will come away gently without much need for addition to collective.( As the disc settles and becomes more efficient)
3 items will cause her to overtorque, 1, addition of collective obviously, 2, using your feet ( so be very stable on those pedals) and 3, addition of forward cyclic. Now, you may think well thats a load of good because I need to fly the load away right? Once you get lift on the load near 95% MTq, very gently add the forward cyclic, the 5 -6% up your sleeve will normally be enough to allow the torque needle to spike up to the 100% limit. What it is doing is measuring the added aerodynamic force to the rotor system by your forward cyclic input.
Now add turbulence to the equation and you will need to allow for this as well, however generally if your load is not moving at 94 to 95% Mtq it may well be a little heavy for you to carry out successfully without setting off the overtorque light.
Hope this is of help
If the load is starting to move while holding this power, wait, it will come away gently without much need for addition to collective.( As the disc settles and becomes more efficient)
3 items will cause her to overtorque, 1, addition of collective obviously, 2, using your feet ( so be very stable on those pedals) and 3, addition of forward cyclic. Now, you may think well thats a load of good because I need to fly the load away right? Once you get lift on the load near 95% MTq, very gently add the forward cyclic, the 5 -6% up your sleeve will normally be enough to allow the torque needle to spike up to the 100% limit. What it is doing is measuring the added aerodynamic force to the rotor system by your forward cyclic input.
Now add turbulence to the equation and you will need to allow for this as well, however generally if your load is not moving at 94 to 95% Mtq it may well be a little heavy for you to carry out successfully without setting off the overtorque light.
Hope this is of help
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Slinging in the 412
Hi Guys,
Further to Tribals excellent advice, I would also warn you that most 412 HP/EP aircraft with DF engines have very twitchy FCU's - so once you do get above that steady 95% Mast Tq on lift, you are into the 'twitch range' and need to pull in your remaining 5% power very gently to avoid an overtorque (which does you no good whatsoever in this aircraft anyway - except result in nasty interviews with the Boss!). The co-pilot's overtorque light tends to be the first one to illiminate - usually as the P1's is oscillating gently about 98-99% - so even though your TQ Meter says you've got something left in hand, you haven't! Use the co to call the Torques as his will normally be the slightly higher reading of the two! Also if you have slightly different speed FCU's this in the range within which the engine torques might split - so you will have to trim your N2 lateral beeps (DF engined aircraft only) or even carefully tweak a throttle slightly to ensure the needles stay together through to 100%. Sometimes the naughty ones oscillate in this range also! What fun!
Tribal is spot on with the pedal input/torque demand problems too. If you have good vertical motion with the load (which you must aim to lift from the deck at or below about 85% Mast Tq to have the required power in hand for a safe transition with low wind/90% with a higher wind)) you will need to start your rotation (into wind, or preferably with the wind from Red 30 to Green 10) before you lose vertical motion, - in order to get the requisite nose-down for a safe transition. In normal pax operations, modern proposed JAR Perf E recommendations now point to using 95% to max available Mast TQ (carefully!) and then using a whole 15 to 20 degrees nose-down for the transition to Vy/VBROC (70KIAS, not 60 as some people insist on thinking!) within the 9 seconds of the 'Exposure Profile' ('Rotation' to 'Vy' time - not TDP or Vtoss off a helideck!). For Underslung Loads, - particularly long-lines from a deck (or land surface) your will only be able to put in a gentle nose-forward pitch at the rotation point of about 5 to 10/15 degrees. Unlike the 205/212/214B, the four-bladed messy 412 monster hasn't the inertia in the head to allow you to happily 'pull to the bells' and chuck in a huge nose down attitude on departure to 'pendulum' the load off the ground and then accelerate through Translational Lift speed using the 'sling-shot' effect of that 'pendulum-effect' departure. Ah! - Such halcyon days of Yore!
Le Slug 412 however, will fall out of the sky doing this - due to its 'LO (i.e. NO) -Inertia Head! Remember that the 412 likes to have at least 8 knots of wind to attain MTOW graph performance -especially with OATs above 25 degrees. Winds above that -no worries - except that the flight deck turbulence will require you to shuffle at very low skid height about the deck to get into wind before departure with pax/internal cargo. No 10-foot hovers in this beast at MAUW! Best not to turn off the wind at all for deck landings in wind speeds above 20 knots or in the Classic or older SP/HPs you won't have the torque on lift to turn back into wind as the tail rotor input will overtorque you quite quickly and alarmingly! Remember your TR charts in the PFM - the 412 hates winds from abaft the beam and likes to fall out of the sky at that point, leaving you pedaling like you're in a kids go-cart!
As the fixed USL mirrors are crap for long-line work - particularly to offshore platforms/decks, I would recommend that you take a suitably competent and well-briefed co-pilot in the LHS, then on the run-in for the deck with the load, <45 KIAS (and also during the initial take-off to position over the load) he loosens his lap-strap about 12 inches, which allows him to turn slightly in the seat, grip the leather door strap firmly with his right hand, while opening (and firmly gripping!) his lower door handle with his left hand - and between those two 'geometrically locked' hands he can firmly hold the door partially open and at the same time look out and talk you down with the load to the desired landing point giving the usual con 'patter' with reference to height and speed for the load (Word-Picture-Information as my old mate Robbo used to say!). He can also confirm proper subsequent release/unhooking of the load and or strop without any nasty lateral/fore/aft drift over the load. This is particularly effective for changing out flare heads on offshore platforms, where very accurate positioning is required for safe installation. Of course if you have a proper 'bubble' load door in the LHS with instrumentation included, then just fly the load from the LHS like a 212! What joy! Just remember that if you are flying a 412 Classic or an SP (or HP with BF engines) you won't have the same engine/torque response/pulling power for the same amount of lever movement that you would have had in a DF-engined aircraft, nor will you have the same level of power margin under any set circumstances. As the Older Classic and SP aircraft - in particular - age, the machine will not normally perform to graph expectations (especially in low wind conditions) and you will, by necessity, have to work at minimal fuel loads or with reduced MAUWs (usually by reducing the published weight by about 600 to 800 lbs depending on the ambient wind conditions). The older (212-type) torquemeter instruments are much steadier but have no overtorque warning lights and will - effectively - give you much less raw 'grunt' or 'pulling power' than the more reactive (and excitable) DF-equipped HP and EP split-type Mast Torquemeters.
Happy humping! Any more questions - fire away!
Further to Tribals excellent advice, I would also warn you that most 412 HP/EP aircraft with DF engines have very twitchy FCU's - so once you do get above that steady 95% Mast Tq on lift, you are into the 'twitch range' and need to pull in your remaining 5% power very gently to avoid an overtorque (which does you no good whatsoever in this aircraft anyway - except result in nasty interviews with the Boss!). The co-pilot's overtorque light tends to be the first one to illiminate - usually as the P1's is oscillating gently about 98-99% - so even though your TQ Meter says you've got something left in hand, you haven't! Use the co to call the Torques as his will normally be the slightly higher reading of the two! Also if you have slightly different speed FCU's this in the range within which the engine torques might split - so you will have to trim your N2 lateral beeps (DF engined aircraft only) or even carefully tweak a throttle slightly to ensure the needles stay together through to 100%. Sometimes the naughty ones oscillate in this range also! What fun!
Tribal is spot on with the pedal input/torque demand problems too. If you have good vertical motion with the load (which you must aim to lift from the deck at or below about 85% Mast Tq to have the required power in hand for a safe transition with low wind/90% with a higher wind)) you will need to start your rotation (into wind, or preferably with the wind from Red 30 to Green 10) before you lose vertical motion, - in order to get the requisite nose-down for a safe transition. In normal pax operations, modern proposed JAR Perf E recommendations now point to using 95% to max available Mast TQ (carefully!) and then using a whole 15 to 20 degrees nose-down for the transition to Vy/VBROC (70KIAS, not 60 as some people insist on thinking!) within the 9 seconds of the 'Exposure Profile' ('Rotation' to 'Vy' time - not TDP or Vtoss off a helideck!). For Underslung Loads, - particularly long-lines from a deck (or land surface) your will only be able to put in a gentle nose-forward pitch at the rotation point of about 5 to 10/15 degrees. Unlike the 205/212/214B, the four-bladed messy 412 monster hasn't the inertia in the head to allow you to happily 'pull to the bells' and chuck in a huge nose down attitude on departure to 'pendulum' the load off the ground and then accelerate through Translational Lift speed using the 'sling-shot' effect of that 'pendulum-effect' departure. Ah! - Such halcyon days of Yore!
Le Slug 412 however, will fall out of the sky doing this - due to its 'LO (i.e. NO) -Inertia Head! Remember that the 412 likes to have at least 8 knots of wind to attain MTOW graph performance -especially with OATs above 25 degrees. Winds above that -no worries - except that the flight deck turbulence will require you to shuffle at very low skid height about the deck to get into wind before departure with pax/internal cargo. No 10-foot hovers in this beast at MAUW! Best not to turn off the wind at all for deck landings in wind speeds above 20 knots or in the Classic or older SP/HPs you won't have the torque on lift to turn back into wind as the tail rotor input will overtorque you quite quickly and alarmingly! Remember your TR charts in the PFM - the 412 hates winds from abaft the beam and likes to fall out of the sky at that point, leaving you pedaling like you're in a kids go-cart!
As the fixed USL mirrors are crap for long-line work - particularly to offshore platforms/decks, I would recommend that you take a suitably competent and well-briefed co-pilot in the LHS, then on the run-in for the deck with the load, <45 KIAS (and also during the initial take-off to position over the load) he loosens his lap-strap about 12 inches, which allows him to turn slightly in the seat, grip the leather door strap firmly with his right hand, while opening (and firmly gripping!) his lower door handle with his left hand - and between those two 'geometrically locked' hands he can firmly hold the door partially open and at the same time look out and talk you down with the load to the desired landing point giving the usual con 'patter' with reference to height and speed for the load (Word-Picture-Information as my old mate Robbo used to say!). He can also confirm proper subsequent release/unhooking of the load and or strop without any nasty lateral/fore/aft drift over the load. This is particularly effective for changing out flare heads on offshore platforms, where very accurate positioning is required for safe installation. Of course if you have a proper 'bubble' load door in the LHS with instrumentation included, then just fly the load from the LHS like a 212! What joy! Just remember that if you are flying a 412 Classic or an SP (or HP with BF engines) you won't have the same engine/torque response/pulling power for the same amount of lever movement that you would have had in a DF-engined aircraft, nor will you have the same level of power margin under any set circumstances. As the Older Classic and SP aircraft - in particular - age, the machine will not normally perform to graph expectations (especially in low wind conditions) and you will, by necessity, have to work at minimal fuel loads or with reduced MAUWs (usually by reducing the published weight by about 600 to 800 lbs depending on the ambient wind conditions). The older (212-type) torquemeter instruments are much steadier but have no overtorque warning lights and will - effectively - give you much less raw 'grunt' or 'pulling power' than the more reactive (and excitable) DF-equipped HP and EP split-type Mast Torquemeters.
Happy humping! Any more questions - fire away!
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Interestingly enough, I have found that when working the 412 EP / HP very heavy and in light winds ( not underslung) it is possible to fly the aircraft away with a right quartering tail wind, at a considerably reduced Mast torque. You do need a drop down height available, to gain airspeed, so I am talking platforms and the like. I call it putting the wind in your back right pocket.
Others I know have used the technique with success, but as we are mere drivers none of us have an idea as to WHY it works.
I know there is added exposure of risk in using drop down for airspeed, being near downwind, so this requires judgement, however it will get you away when very heavy and hot. ( Im not after a slagging from so called experts here on the technique, but does anyone actually know why it works?)
Others I know have used the technique with success, but as we are mere drivers none of us have an idea as to WHY it works.
I know there is added exposure of risk in using drop down for airspeed, being near downwind, so this requires judgement, however it will get you away when very heavy and hot. ( Im not after a slagging from so called experts here on the technique, but does anyone actually know why it works?)
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Downwind 412 departures?
Yes, well........... what a brave chap you are! Of course if your TOW is low and your tail wind is below 5to 8 knots, then this is certainly possible, but I wouldn't recommend it as a regular occurrence and certainly never with an Underslung Load - which is what I was primarily talking about above. The 'drop-down’ use for trading height to speed during departure is great with pax/internal cargo - (when you actually have a decent deck height to give you the drop-down option) - but the aim of the act of rotation is to get the tail clear of the deck in the event of a critical engine failure after the nose-down rotation has been input. During a downwind deck departure (pax/frt) this would be pretty-well guaranteed, because of your exaggerated tail-up, nose down attitude from the downwind departure (just about where you feel your butt-puckering rate increasing quickly!) will ensure this, however you are still downwind and therefore will sink more rapidly after an actual EFATO and your subsequent ability to fly away safely from an engine failure after rotation will therefore not be quite so cozy. It will take you longer to carry out your fly away, and if you were (horrors!) at MAUW it is highly likely that you would not make your 70 KIAS VBROC/Vy at Max SE Torque before you impacted the water, in which case, you would then be faced with converting to a down-wind run-on into de briny blue (whilst maintaining translational lift iaw with the PFM!) In a 412? No thanks mate!
Purely as a guide to pilots new to these 412 helideck operations and especially Underslinging to/from offshore platforms, I would say NEVER do a downwind departure in a 412 unless you are light and the winds are below 5 Knots. As for the pedal input - yes, you can do this during any deck departure, - downwind or otherwise, but from vast experience teaching new guys offshore, it is far less stressful for them (and for me) to depart on a steady chosen heading (especially at night) into wind or within the 'nice' relative wind arc for the 412 (Red 30 to Green 10) without making pedal inputs during this departure. Such inputs tend - until they have frightened themselves sufficiently in a 412 offshore - to be excessively applied and the cause of quite alarming and wholly unexpected Torque 'spikes'/overtorques after rotation which they are usually wholly unprepared for! Sorry, - but the machine flies like a dog compared with its illustrious predecessors and therefore needs to be mollycoddled off the deck in the smoothest, gentlest way possible. We helicopter Gods are meant to be smooth, of course! Downwind departures with excessive rates of pedal input on departure are liable to end up with passengers submitting complaints after flight - so lily-livered and chicken-hearted, those oilies!
The gentle, expert use of pedal by an experienced pilot is another matter entirely, of course - and one which shows the devastating skill and experience of the 412 operator involved!
When you do have sufficient experience offshore to be skilled at, and be comfortable with, doing downwind departures off decks, then you will know exactly where that very fine dividing line is. However, within a company employing over 15 different nationalities, I personally find that the safest standard to set is usually the most straight-forward and sensible one. - K.I.S.S. (Keep-It-Simple-Stupid) - it works well for new guys, especially when one only has one pair of instructional brown-corduroy trousers supplied by the company!
In the end - operating the Bell 412 (especially above 44 degrees C) is all about getting enough hands-on experience on the type, - in all winds and weathers, without going swimming or bending the machine, and then using that expertise to try always to operate the aircraft with the most suitable (fine) margin of power/weight and fuel 'insurance' in-hand to provide for the wife and kids!
Fond regards,
O
Purely as a guide to pilots new to these 412 helideck operations and especially Underslinging to/from offshore platforms, I would say NEVER do a downwind departure in a 412 unless you are light and the winds are below 5 Knots. As for the pedal input - yes, you can do this during any deck departure, - downwind or otherwise, but from vast experience teaching new guys offshore, it is far less stressful for them (and for me) to depart on a steady chosen heading (especially at night) into wind or within the 'nice' relative wind arc for the 412 (Red 30 to Green 10) without making pedal inputs during this departure. Such inputs tend - until they have frightened themselves sufficiently in a 412 offshore - to be excessively applied and the cause of quite alarming and wholly unexpected Torque 'spikes'/overtorques after rotation which they are usually wholly unprepared for! Sorry, - but the machine flies like a dog compared with its illustrious predecessors and therefore needs to be mollycoddled off the deck in the smoothest, gentlest way possible. We helicopter Gods are meant to be smooth, of course! Downwind departures with excessive rates of pedal input on departure are liable to end up with passengers submitting complaints after flight - so lily-livered and chicken-hearted, those oilies!
The gentle, expert use of pedal by an experienced pilot is another matter entirely, of course - and one which shows the devastating skill and experience of the 412 operator involved!
When you do have sufficient experience offshore to be skilled at, and be comfortable with, doing downwind departures off decks, then you will know exactly where that very fine dividing line is. However, within a company employing over 15 different nationalities, I personally find that the safest standard to set is usually the most straight-forward and sensible one. - K.I.S.S. (Keep-It-Simple-Stupid) - it works well for new guys, especially when one only has one pair of instructional brown-corduroy trousers supplied by the company!
In the end - operating the Bell 412 (especially above 44 degrees C) is all about getting enough hands-on experience on the type, - in all winds and weathers, without going swimming or bending the machine, and then using that expertise to try always to operate the aircraft with the most suitable (fine) margin of power/weight and fuel 'insurance' in-hand to provide for the wife and kids!
Fond regards,
O
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Oracle, I think you and I have a very similar job, and you add a wealth of knowledge in your threads.
Now let me be more specific with the right quartering tailwind takeoff. Ok as I said earlier, No underslung loads, Im talking 11,900 pounds, Internal load,temps 30+.
I have found at offshore facilities, where due to obstructions nearby or in the takeoff flight path, that an into wind takeoff is either precluded or not the best option. Now I know your thinking, drop the weight, however its not necessary in every case. By turning the aircraft, (to the left, ideally for tail rotor effectiveness) and placing the wind in your back right pocket, hover power (MTq) will considerably reduce, 5 - 10%.
Try this without effecting the takeoff and you will see that it is true.
To carry out the takeoff, this allows you to clear the deck edge gaining more height over airspeed in that critical phase....ie without fear of overtorque , and allowing safe passage for the tail. Now it is true that once the deck is cleared you will need to make a transition to gaining airspeed, so to nullify the effect of a larger forward cyclic adding to torque required, you may check collective down a touch ( Now I mean, check it , not drop it, Im talking 1/4 of an inch) You will get more dropdown height for sure, you can re-evaluate your takeoff decision point, depending on height available, and airspeed. Or more correctly your judged ditch/fly away point. To my way of thinking getting off the deck at maximum power is the worst part of exposure in the event of failure.
The point was, why does the aircraft use a lot less Mast torque in a right quartering downwind while heavy in the hover? I will add that although I know 3 pilots who also use this technique occasionally, I do not teach the technique to those new to the 412, but have added it here so for those of you who have a lot of time on this aircraft to look at it as an option and see for yourselves. I dont know why aerodynamically it works.
Thanks for your input fellow drivers, it makes interesting and valuable reading.
Now let me be more specific with the right quartering tailwind takeoff. Ok as I said earlier, No underslung loads, Im talking 11,900 pounds, Internal load,temps 30+.
I have found at offshore facilities, where due to obstructions nearby or in the takeoff flight path, that an into wind takeoff is either precluded or not the best option. Now I know your thinking, drop the weight, however its not necessary in every case. By turning the aircraft, (to the left, ideally for tail rotor effectiveness) and placing the wind in your back right pocket, hover power (MTq) will considerably reduce, 5 - 10%.
Try this without effecting the takeoff and you will see that it is true.
To carry out the takeoff, this allows you to clear the deck edge gaining more height over airspeed in that critical phase....ie without fear of overtorque , and allowing safe passage for the tail. Now it is true that once the deck is cleared you will need to make a transition to gaining airspeed, so to nullify the effect of a larger forward cyclic adding to torque required, you may check collective down a touch ( Now I mean, check it , not drop it, Im talking 1/4 of an inch) You will get more dropdown height for sure, you can re-evaluate your takeoff decision point, depending on height available, and airspeed. Or more correctly your judged ditch/fly away point. To my way of thinking getting off the deck at maximum power is the worst part of exposure in the event of failure.
The point was, why does the aircraft use a lot less Mast torque in a right quartering downwind while heavy in the hover? I will add that although I know 3 pilots who also use this technique occasionally, I do not teach the technique to those new to the 412, but have added it here so for those of you who have a lot of time on this aircraft to look at it as an option and see for yourselves. I dont know why aerodynamically it works.
Thanks for your input fellow drivers, it makes interesting and valuable reading.
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The 412 really hates crosswinds. I've lifted up off tankers where there was no way to turn the tail until at a very high hover, and it took gobs of power to get up there, but a simple pedal turn resulted in a rather exciting rate of climb, immediately. The rotor system doesn't know where the wind is, but the fuselage does. Either a headwind or a tailwind requires less power than a direct crosswind, IME.
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Tribal,
What is a typical location of your cg when you do this? The helicopter attitude may become more level with the aft right wind, which may show a slight decrease in required mast torque. However, I doubt the magnitude of this effect will be as large as what you're finding.
I think the most likely area for the savings is the power requirement of the tail rotor. The aft right wind may direct the tail rotor wash away from the vertical stab, or even around it in such a way that favourable yaw forces are generated. Again 5-10% seems high, since I would have thought that would represent the total power requirement of the tail rotor.
One caution, everything you're saying suggests you only get this excess power with a tail wind. As you translate forward, you're necessarily eliminating that excess, and arriving at a minimum wind condition (also max power required) with a rate of descent established. You'd be better off starting at that max power condition being level or with a rate of climb.
Just my thoughts,
Matthew.
What is a typical location of your cg when you do this? The helicopter attitude may become more level with the aft right wind, which may show a slight decrease in required mast torque. However, I doubt the magnitude of this effect will be as large as what you're finding.
I think the most likely area for the savings is the power requirement of the tail rotor. The aft right wind may direct the tail rotor wash away from the vertical stab, or even around it in such a way that favourable yaw forces are generated. Again 5-10% seems high, since I would have thought that would represent the total power requirement of the tail rotor.
One caution, everything you're saying suggests you only get this excess power with a tail wind. As you translate forward, you're necessarily eliminating that excess, and arriving at a minimum wind condition (also max power required) with a rate of descent established. You'd be better off starting at that max power condition being level or with a rate of climb.
Just my thoughts,
Matthew.
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I appreciate all comments and ideas in this thread. It gives me a lot to sift through and many questions to cause beads of sweat on the forehead of the instructor when I go to Flight Safety soon.
We all have to earn our money.
8,000+ hrs on the 212, 2,000+ on the 412 Classic, and learning a lot from this thread.
Please keep going, I don't have many years left to experience all the mistakes myself.
Chas A
We all have to earn our money.
8,000+ hrs on the 212, 2,000+ on the 412 Classic, and learning a lot from this thread.
Please keep going, I don't have many years left to experience all the mistakes myself.
Chas A
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Matthew, Thanks for your thoughts.
As far as translating forward is concerned, like I said you need drop down height, and with smooth controlling it doesnt present a great deal of problem, provided you are aware of your actions prior to and after your selected fly away point, to ditch or to fly in the event of a failure. Thats the second part of the equation.
However like most things mechanical, they have a tendancy to fail at the time of most stress, under the highest power requirement, and to me on the edge of the deck or on the way over the edge, is probably worse than in flight clear of the deck.
Now I didnt say that this excess power was available only with the wind on the right tail quarter. I do agree a headwind is always the best option, IF it is available ( obstructions etc...). I have noted that wind within a 360 arc around the aircraft that from the angle I suggest you will note a considerably less torque requirement. Try it without effecting your takeoff and you may become a believer.
As far as CG is concerned, I can only say within limits, because with this operation we effect up to 70 takeoffs and landings per day at offshore facilities with many varying numbers of pax and freight. To work out CG closely to figures becomes impractical.
Having said that, with the extremely high numbers of t/o's and landings, we do find many situations in which one can find little nuances such as this one Ive passed to this forum.
The thoughts on the tail rotor wash may be the answer as to why this works. Appreciate the input. Thanks
As far as translating forward is concerned, like I said you need drop down height, and with smooth controlling it doesnt present a great deal of problem, provided you are aware of your actions prior to and after your selected fly away point, to ditch or to fly in the event of a failure. Thats the second part of the equation.
However like most things mechanical, they have a tendancy to fail at the time of most stress, under the highest power requirement, and to me on the edge of the deck or on the way over the edge, is probably worse than in flight clear of the deck.
Now I didnt say that this excess power was available only with the wind on the right tail quarter. I do agree a headwind is always the best option, IF it is available ( obstructions etc...). I have noted that wind within a 360 arc around the aircraft that from the angle I suggest you will note a considerably less torque requirement. Try it without effecting your takeoff and you may become a believer.
As far as CG is concerned, I can only say within limits, because with this operation we effect up to 70 takeoffs and landings per day at offshore facilities with many varying numbers of pax and freight. To work out CG closely to figures becomes impractical.
Having said that, with the extremely high numbers of t/o's and landings, we do find many situations in which one can find little nuances such as this one Ive passed to this forum.
The thoughts on the tail rotor wash may be the answer as to why this works. Appreciate the input. Thanks
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I thought I was in meetings today. Show up at work and discover I'm doing low speed performance work-ups in the 412. It was done just for technique so the data gathering was far from rigorous, but I saw the numbers you mentioned.
We flew cardinals and subcardinals at 10 and 20 knots relative wind. Unfortunately, I thought the FTE was recording perf...he wasn't. So I only had the green and red 135° and the 180° data, at 20 knots. With those three data points the effect was seen, about 7% less mast torque at the green 135° than at the red 135.
We flew cardinals and subcardinals at 10 and 20 knots relative wind. Unfortunately, I thought the FTE was recording perf...he wasn't. So I only had the green and red 135° and the 180° data, at 20 knots. With those three data points the effect was seen, about 7% less mast torque at the green 135° than at the red 135.
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A slightly different subject related to the 412. Does anyone have problems with the gimbal ring and related swashplate parts starting to fail at 300-500 hours?
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Yer bits dropping off?
Shawn,
Just a consideration.
Some years back many (ex-212) 412 operators were beeping down to 97% NR for cruise flight (which really does nothing for you with 4 blades except get very exciting trim actuator-induced TQ spikes in the >105KIAS mast torque limitation range!). When the EP came along, the same cruise reduction started causing noticeably increased wear on the rotating components of the head, some of which were being damaged quite markedly within very low flight times.
Bell then advised that the probable cause was pilots climbing the aircraft regularly (and at varying ROC!) at less than 100%NR, which was damaging said components in very short order. Subsequently, Bell advised 412 operators not to beep down at all for cruise flight in any 412 variant and to maintain 100% throughout the normal twin-engine flight envelope. My own company and many others subsequently withdrew any reduced-NR cruise operations. No further occurrences of such increased wear in rotating components were subsequently encountered. The climb at 97%NR in the EP model was the particular hard-wearing activity. (Of course, any prolongued operation of a 412 with poor tracking/rotor balance will also speed such wear.)
FYI
Just a consideration.
Some years back many (ex-212) 412 operators were beeping down to 97% NR for cruise flight (which really does nothing for you with 4 blades except get very exciting trim actuator-induced TQ spikes in the >105KIAS mast torque limitation range!). When the EP came along, the same cruise reduction started causing noticeably increased wear on the rotating components of the head, some of which were being damaged quite markedly within very low flight times.
Bell then advised that the probable cause was pilots climbing the aircraft regularly (and at varying ROC!) at less than 100%NR, which was damaging said components in very short order. Subsequently, Bell advised 412 operators not to beep down at all for cruise flight in any 412 variant and to maintain 100% throughout the normal twin-engine flight envelope. My own company and many others subsequently withdrew any reduced-NR cruise operations. No further occurrences of such increased wear in rotating components were subsequently encountered. The climb at 97%NR in the EP model was the particular hard-wearing activity. (Of course, any prolongued operation of a 412 with poor tracking/rotor balance will also speed such wear.)
FYI
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Oracle,
Do you have a reference for that advisory? We still have 97% cruise in our books.
Subsequently, Bell advised 412 operators not to beep down at all for cruise flight in any 412 variant and to maintain 100% throughout the normal twin-engine flight envelope.
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To beep down or not to beep down, that is the question!
The "EP" RFM says for;
"In-Flight Operations"; ENG - 97 to 100% RPM (N11).
"ROTOR RPM - POWER ON"; Continuous operation 97 to 100%
"FUEL FLOW VS. AIRSPEED" graphs; ENGINE RPM = 97%
Now that all said and done, I do prefer to only beep down when I am cruising at a sufficient cruise altitude to have time to beep back up if something happens.
800
"In-Flight Operations"; ENG - 97 to 100% RPM (N11).
"ROTOR RPM - POWER ON"; Continuous operation 97 to 100%
"FUEL FLOW VS. AIRSPEED" graphs; ENGINE RPM = 97%
Now that all said and done, I do prefer to only beep down when I am cruising at a sufficient cruise altitude to have time to beep back up if something happens.
800
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Not beeping down to 97% for cruise in the 412
Hi Guys,
- Amazed to find so many people still beeping down in the 412! Old habits (like helicopter pilots) die hard!
I will indeed attempt to find the communication from Bell about this although it was some three years ago!
However, at that time we did approach Bell directly with regards to over-fast wear/way-short life expectancy experienced on the rotating head components' of our new 412 EPs at that time and they came back with the very definite advice and recommendations that they considered it unwise and quite uneccesary to beep down to less than 100% NR for cruise flight in any model 412, and particularly in the EP Variant, which would definitiely sustain excessive wear - particularly during sustained climbs at less than 100%NR.
Meanwhile, I must say that removing such cruise reductions from our company checklists and SOPs has made the whole excessive wear issue go away and also made for much easier day-to-day operations, particularly as this outfit doesn't rate-time their N2 beep actuators (as we used to do in my old 205 and 212 Fleet).
I am sure that some of you will already have been shocked at the 2-nanosecond min-to-max beep rates on some new actuator units! I have actually had one so bad after instalation that it turned the aircraft on its skids on the ground in less than 2 seconds! By removing the beeping up and down during each flight, my heart-attack rate has subsequently been reduced - as newbies seem to insist on holding the beep-up button (rather than tapping at it gently) whilst tooling along at 79% Mast Torque at full chat, thereby exceeding the 'top of the green' Mast Torque Limitation above 105 KIAS. Such exceedences were commonplace before we lost the 97% NR cruise, and we are therefore saving ourselves wear an tear from that angle as well as from the obvious transient torque-spike transmission wear during 'savage' beep actuator operations. Life is FAR more sedate and comfortable now, - and the fuel saving was never really noticeable over a 200 mile sector in the 412 anyhow!
One thing I should add though (as my single random 'duty brain cell' suddenly kicks in) is that part of our change to continuous 100% NR operations (twin-engine) in our 412 fleet was that we had to change our engineering practices and air test schedules to reflect the fact that our FRAM Dampers would now be re-tuned to 100% so that RADS workups and in-flight-tracking would reflect our cruise speed requirements (although we do still check the RADS at 97% to ensure there are no naughty vibes in the OEI range!). All of our 412s subsequently display red cockpit decals on either side showing 'FRAM DAMPER TUNED TO 100%NR'.
I'll see if I can dig out the original response from Bell from way back and get back to thee if I am successful!
Happy Beeping meanwhile!
Cheers,
'O'
- Amazed to find so many people still beeping down in the 412! Old habits (like helicopter pilots) die hard!
I will indeed attempt to find the communication from Bell about this although it was some three years ago!
However, at that time we did approach Bell directly with regards to over-fast wear/way-short life expectancy experienced on the rotating head components' of our new 412 EPs at that time and they came back with the very definite advice and recommendations that they considered it unwise and quite uneccesary to beep down to less than 100% NR for cruise flight in any model 412, and particularly in the EP Variant, which would definitiely sustain excessive wear - particularly during sustained climbs at less than 100%NR.
Meanwhile, I must say that removing such cruise reductions from our company checklists and SOPs has made the whole excessive wear issue go away and also made for much easier day-to-day operations, particularly as this outfit doesn't rate-time their N2 beep actuators (as we used to do in my old 205 and 212 Fleet).
I am sure that some of you will already have been shocked at the 2-nanosecond min-to-max beep rates on some new actuator units! I have actually had one so bad after instalation that it turned the aircraft on its skids on the ground in less than 2 seconds! By removing the beeping up and down during each flight, my heart-attack rate has subsequently been reduced - as newbies seem to insist on holding the beep-up button (rather than tapping at it gently) whilst tooling along at 79% Mast Torque at full chat, thereby exceeding the 'top of the green' Mast Torque Limitation above 105 KIAS. Such exceedences were commonplace before we lost the 97% NR cruise, and we are therefore saving ourselves wear an tear from that angle as well as from the obvious transient torque-spike transmission wear during 'savage' beep actuator operations. Life is FAR more sedate and comfortable now, - and the fuel saving was never really noticeable over a 200 mile sector in the 412 anyhow!
One thing I should add though (as my single random 'duty brain cell' suddenly kicks in) is that part of our change to continuous 100% NR operations (twin-engine) in our 412 fleet was that we had to change our engineering practices and air test schedules to reflect the fact that our FRAM Dampers would now be re-tuned to 100% so that RADS workups and in-flight-tracking would reflect our cruise speed requirements (although we do still check the RADS at 97% to ensure there are no naughty vibes in the OEI range!). All of our 412s subsequently display red cockpit decals on either side showing 'FRAM DAMPER TUNED TO 100%NR'.
I'll see if I can dig out the original response from Bell from way back and get back to thee if I am successful!
Happy Beeping meanwhile!
Cheers,
'O'