Super Puma quandary.
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Super Puma quandary.
We need a N. Lappos of the Eurocopter world for this one.
Flight manual limits for hovering the AS332 are:
Above 18410 lbs: 17 kts crosswind or tailwind.
At or below 18410 lbs: 35 kts crosswind or downwind.
Now assume you are ready to go at a max wt of 18960 lbs on an East/West choice of runway with the wind at 180/30 kts.
We have performance graphs that show us that a single engine reject or continued take off profile can be performed to satisfy the Authority and that we are also using a take off area that is clear of non-frangible objects etc. etc.(ie. one of the East/West runways).
Can you go? There is definately a split between the old school and the more court room case scenario pilots.
I personally find it hard to believe that you could lift to the hover into wind and then crab sideways down the runway, and then the one time in 100,000 everything went wrong and you damaged the aircraft,or even worse, damaged someone, that the lawyer wouldn't say "you exceeded the crosswind limits".
You could take it to the extreme; you can depart in over 70kts, and then I'm sure you would not take off crosswind.
To protect our butts from lawyers, should we forget that helicopters can do it, when carrying normal passengers, and perhaps limit ourselves to the flight manual hover limits.
It would be interesting to hear from anyone who's involved in the performance side of things.
I also have a theory. When the engine fails you droop the rotors to 245 rpm, which also slows the tail rotor down, and perhaps with a crosswind that exceeds the current limitations you would not guarantee tail rotor control. Basic, but sound enough for me to be wary.Can you go?
Flight manual limits for hovering the AS332 are:
Above 18410 lbs: 17 kts crosswind or tailwind.
At or below 18410 lbs: 35 kts crosswind or downwind.
Now assume you are ready to go at a max wt of 18960 lbs on an East/West choice of runway with the wind at 180/30 kts.
We have performance graphs that show us that a single engine reject or continued take off profile can be performed to satisfy the Authority and that we are also using a take off area that is clear of non-frangible objects etc. etc.(ie. one of the East/West runways).
Can you go? There is definately a split between the old school and the more court room case scenario pilots.
I personally find it hard to believe that you could lift to the hover into wind and then crab sideways down the runway, and then the one time in 100,000 everything went wrong and you damaged the aircraft,or even worse, damaged someone, that the lawyer wouldn't say "you exceeded the crosswind limits".
You could take it to the extreme; you can depart in over 70kts, and then I'm sure you would not take off crosswind.
To protect our butts from lawyers, should we forget that helicopters can do it, when carrying normal passengers, and perhaps limit ourselves to the flight manual hover limits.
It would be interesting to hear from anyone who's involved in the performance side of things.
I also have a theory. When the engine fails you droop the rotors to 245 rpm, which also slows the tail rotor down, and perhaps with a crosswind that exceeds the current limitations you would not guarantee tail rotor control. Basic, but sound enough for me to be wary.Can you go?
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Yes, the a/c can do it.
No, SOP's won't allow it.
Simple.You follow the rules or you don't.
As they say, there are only four ways to fly:
The right way, the wrong way, the flight manual way and the captain's way. Only one counts.
No, SOP's won't allow it.
Simple.You follow the rules or you don't.
As they say, there are only four ways to fly:
The right way, the wrong way, the flight manual way and the captain's way. Only one counts.
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I would think that the key descriptive phrase in use here would be flight manual hovering limits.
Are we going to go hover around the airfield or are we taking off?
Line up with 27, takeoff and when above ETL turn into the wind.
In this case ask if you can , at any point , bring the aircraft back safely on one engine. Yes means go, no means stay.
I think
Are we going to go hover around the airfield or are we taking off?
Line up with 27, takeoff and when above ETL turn into the wind.
In this case ask if you can , at any point , bring the aircraft back safely on one engine. Yes means go, no means stay.
I think
True. Further to that, with respect to hovering, whether or not the aircraft can 'do' it should not enter the equation. From a certification standpoint, the cross/downwind limits are dictated by either yaw axis controllability, loads or thermal issues, or all of the above depending on the aircraft.
How these limits find their way into the Flight Manual depends on how much the manufacturer wants to spend in flight test, and how hard the marketing types push for every ounce of performance.
Some aircraft will have a simple limitation, others will have separate charts, or an 'Area B' on the performance charts to take advantage of a headwind component or penalize for an out of wind condition.
The main thing to remember about your question is.... if it's in the 'Limitations' section in the flight manual, you are legally bound to comply. Period. Many operators will modify Normal Procedures or Emergency sections of the RFM in their approved SOPs, but Limitations can't be exceeded.
Did I just answer anything, or was that a rant......?
[ 25 October 2001: Message edited by: CTD ]
How these limits find their way into the Flight Manual depends on how much the manufacturer wants to spend in flight test, and how hard the marketing types push for every ounce of performance.
Some aircraft will have a simple limitation, others will have separate charts, or an 'Area B' on the performance charts to take advantage of a headwind component or penalize for an out of wind condition.
The main thing to remember about your question is.... if it's in the 'Limitations' section in the flight manual, you are legally bound to comply. Period. Many operators will modify Normal Procedures or Emergency sections of the RFM in their approved SOPs, but Limitations can't be exceeded.
Did I just answer anything, or was that a rant......?
[ 25 October 2001: Message edited by: CTD ]
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Can't help but agree with Pat on this one. It happened to me once in Scatsta, we were at 18960 and had a 35kt crosswind. I elected to dump payload to get below 18410 so that I could go legally, cause a minor bit of irratation, but at least we were all safe in the event of a failure.
So, if you really think that you can lift of in to wind, start a very slow banana departure eventually ending up along the runway, before your CDT, then great, but if you suffer an engine failure before CDT, you then have to banana your reject to end up in to wind at a very slow run on speed, exceedingly heavy! In the words of our chief technical training captain, "if you are that good go ahead, I'm not!"
Are You?
So, if you really think that you can lift of in to wind, start a very slow banana departure eventually ending up along the runway, before your CDT, then great, but if you suffer an engine failure before CDT, you then have to banana your reject to end up in to wind at a very slow run on speed, exceedingly heavy! In the words of our chief technical training captain, "if you are that good go ahead, I'm not!"
Are You?
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I'm so relieved that the majority (ie 100%) seem to agree that basically there is a problem with the Super Puma's laid down legislation of only a 17 kts crosswind limit above 18410, and legally you can't ignore it.
I believe originally the Super Puma came out at 18410 lbs, but then was increased to 18960, obviously with limitations to operate at a reduced crosswind. I guess nobody put the money in to get the increased crosswind certification, or maybe it can't do it.
It's a lovely machine and I'm sure you would operate it to it's max, if not outside, in a place in the middle of Africa, but we have to be safe here in St Kilda, and I'm sure it's the same in the North Sea with all benchmarking with narrow body jet pay and safety implications that you're all tied to.
I believe originally the Super Puma came out at 18410 lbs, but then was increased to 18960, obviously with limitations to operate at a reduced crosswind. I guess nobody put the money in to get the increased crosswind certification, or maybe it can't do it.
It's a lovely machine and I'm sure you would operate it to it's max, if not outside, in a place in the middle of Africa, but we have to be safe here in St Kilda, and I'm sure it's the same in the North Sea with all benchmarking with narrow body jet pay and safety implications that you're all tied to.
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Bintang,
just a few points,
1. What is the M1 weight of the AS332 in 30kts of wind. Can a Cat A departure be made. What about a roll take off at whatever speed you like.
2. Even if a company amends its SOPs to get the best from an aircraft the Flight Manual is god.
3. The limit as stated is a hover limit and therefore is applicable at all times and not just after an engine failure.
4. It is possible that the full certification was made at the lower weight and when the increased weight came up Eurocopter never recertified as the aerodynamic model would be much the same. Maybe they were saving their money to spend it on important stuff like customer support. EUROCOPTER!!!!! CUSTOMER SUPPORT!!!!! I must be of my rocker.
FOTH
just a few points,
1. What is the M1 weight of the AS332 in 30kts of wind. Can a Cat A departure be made. What about a roll take off at whatever speed you like.
2. Even if a company amends its SOPs to get the best from an aircraft the Flight Manual is god.
3. The limit as stated is a hover limit and therefore is applicable at all times and not just after an engine failure.
4. It is possible that the full certification was made at the lower weight and when the increased weight came up Eurocopter never recertified as the aerodynamic model would be much the same. Maybe they were saving their money to spend it on important stuff like customer support. EUROCOPTER!!!!! CUSTOMER SUPPORT!!!!! I must be of my rocker.
FOTH
Eurocopter, I take it, do not try and get out of the argument by saying that it is the maximum demonstrated weight to operate crosswind/downwind do they?. Sikorsky say that the maximum demonstrated crosswind/downwind is 35kts upto 6900ft pa, and 17kts above this. But does maximum demonstrated imply a strict limit. I think not! What do you think?
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Can anyone in Aereospatiale (or new Eurocpter) explain the 17 kts crosswind limit.
I love the Sikorsky method (and Bell) where they actually state that tests were not conductded beyond that for certification.
I love the Sikorsky method (and Bell) where they actually state that tests were not conductded beyond that for certification.
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The answer is quite simple, actually. You are seeing a cross over of two different limits, set by two very different technical factors. You must observe the lower of the two limits, and you cannot perform the operation.
The weight limit for crosswind is set by the amount of anti-torque available from the tail rotor. As weight increases, the main rotor torque to hover in still air increases, and the tail rotor torque to trim the main rotor increases proportionately. This leaves less tail rotor torque for yaw maneuvering, so at some point, the crosswind capability drops below acceptable limits.
In the case in hand, regardless of the single engine performance margin (which sets the Cat A weight), the takeoff might look like this:
Pilot picks aircraft up with 30 knot cross wind. Pedals are within a few percent of the stops, but pilot doesn't notice (pedals would have about 10% margin at 17 knots). Pilot increases torque to initiate takeoff, and pedal goes to the stop but nose continues to rotate into the wind, passes through the wind and aircraft spins around in an "LTE" event. Pilot increases collective pitch instinctively to avoid ground, and spin rate increases (because anti-torque deficit is now much greater). Pilot loses cyclic orientation, brushes tail against ground, aircraft rolls over and flogs itself to pieces.
Any AH-1 pilots out there can testify to what these events look like, the Cobra is notorious for its lack of tail rotor power, especially in left quartering downwinds. The Snake has a chart that shows how poor the wind limits are with altitude and weight, down to less than 9 knots capability in some cases. The left pedal stop was my nemisis in 1000 hours of AH-1G flying in Vietnam.
Many helicopters have weight limits set by yaw margins instead of by engine power. The entire Bell line has tail rotors that are sized for sea level, and often become the limit with higher density altitudes. Note the performance charts for the 212 and 412 that mysteriously limit you to "wind within 45 degrees of the nose" while hovering.
The weight limit for crosswind is set by the amount of anti-torque available from the tail rotor. As weight increases, the main rotor torque to hover in still air increases, and the tail rotor torque to trim the main rotor increases proportionately. This leaves less tail rotor torque for yaw maneuvering, so at some point, the crosswind capability drops below acceptable limits.
In the case in hand, regardless of the single engine performance margin (which sets the Cat A weight), the takeoff might look like this:
Pilot picks aircraft up with 30 knot cross wind. Pedals are within a few percent of the stops, but pilot doesn't notice (pedals would have about 10% margin at 17 knots). Pilot increases torque to initiate takeoff, and pedal goes to the stop but nose continues to rotate into the wind, passes through the wind and aircraft spins around in an "LTE" event. Pilot increases collective pitch instinctively to avoid ground, and spin rate increases (because anti-torque deficit is now much greater). Pilot loses cyclic orientation, brushes tail against ground, aircraft rolls over and flogs itself to pieces.
Any AH-1 pilots out there can testify to what these events look like, the Cobra is notorious for its lack of tail rotor power, especially in left quartering downwinds. The Snake has a chart that shows how poor the wind limits are with altitude and weight, down to less than 9 knots capability in some cases. The left pedal stop was my nemisis in 1000 hours of AH-1G flying in Vietnam.
Many helicopters have weight limits set by yaw margins instead of by engine power. The entire Bell line has tail rotors that are sized for sea level, and often become the limit with higher density altitudes. Note the performance charts for the 212 and 412 that mysteriously limit you to "wind within 45 degrees of the nose" while hovering.
What charts are those Nick? The ones I have make no mention of that....
212 publishes a Critical Wind Azimuth of 40º to 135º, and says the charts are valid with relative winds up to 20 kts from any direction, with more favorable t/r control margins realized if operated outside the CW Azimuth.
The 412EP has IGE and OGE Critical Wind Azimuths, and offers IGE performance up to 35 kts in all relative wind angles up to 3K Hd, with additional control margins if operated outside the two zones.
The OGE charts have Areas A and B, the latter providing a performance benefit if operated outside the Critical Wind Azimuth areas.
Seems logical enough to me.
Just for the record, the 407 is the ship which has the 45º Area B, and the reason for it is because of the limits imposed by the conditions available during the high altitude flight testing. Additionally, Area B only comes into play in certain lateral C/G conditions above 17 kts.
[ 26 October 2001: Message edited by: CTD ]
212 publishes a Critical Wind Azimuth of 40º to 135º, and says the charts are valid with relative winds up to 20 kts from any direction, with more favorable t/r control margins realized if operated outside the CW Azimuth.
The 412EP has IGE and OGE Critical Wind Azimuths, and offers IGE performance up to 35 kts in all relative wind angles up to 3K Hd, with additional control margins if operated outside the two zones.
The OGE charts have Areas A and B, the latter providing a performance benefit if operated outside the Critical Wind Azimuth areas.
Seems logical enough to me.
Just for the record, the 407 is the ship which has the 45º Area B, and the reason for it is because of the limits imposed by the conditions available during the high altitude flight testing. Additionally, Area B only comes into play in certain lateral C/G conditions above 17 kts.
[ 26 October 2001: Message edited by: CTD ]
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CTD asks what charts I referred to with the Bell line that publish hover capability with and without adequate crosswind capability.
I have seen copies of these charts for the Bell 212, 412, and 430. Specifically, they are the family of hover charts for hover (IGE and OGE) weight vs altitude/temperature that are titled "wind from any direction" and "wind within 45 degrees of the nose". The no-crosswind (wind from the nose) charts are also labeled (at the bottom, in small print) "Catagory B, 9 passengers or less". For the IGE and OGE cases, with the two wind cases, there are a total of four charts for each model helicopter.
This capability was brought about to allow operations at higher weights and powers with scant tail rotor capability as long as the pilot could operate with no cross wind (and with high hopes that there would be no need to raise the collective very much while hovering).
The charts are specifically for Cat B, 9 passengers or less operations, and should be available as flight manual supplements if you ask.
Bell used to have PDF files at their web site that had these charts, but they are not posted there now.
[ 26 October 2001: Message edited by: Nick Lappos ]
I have seen copies of these charts for the Bell 212, 412, and 430. Specifically, they are the family of hover charts for hover (IGE and OGE) weight vs altitude/temperature that are titled "wind from any direction" and "wind within 45 degrees of the nose". The no-crosswind (wind from the nose) charts are also labeled (at the bottom, in small print) "Catagory B, 9 passengers or less". For the IGE and OGE cases, with the two wind cases, there are a total of four charts for each model helicopter.
This capability was brought about to allow operations at higher weights and powers with scant tail rotor capability as long as the pilot could operate with no cross wind (and with high hopes that there would be no need to raise the collective very much while hovering).
The charts are specifically for Cat B, 9 passengers or less operations, and should be available as flight manual supplements if you ask.
Bell used to have PDF files at their web site that had these charts, but they are not posted there now.
[ 26 October 2001: Message edited by: Nick Lappos ]
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Glad to hear that my tail rotor theory has some credence!
Now! I'm a pretty demanding operator, and so I ask my chaps to do running take offs up to the max speed of 45 kts to bring the wind vector around to within the crosswind limits.
Hard task master, but unfortunately I think that will allow you to comply with the flight manual.
By the way, if I had $12,000,000 to spend on a helicopter, I'd make bloody sure it could carry everyone I wanted with an 18 kts breeze off the port bow.
[ 26 October 2001: Message edited by: bintanglagi ]
Now! I'm a pretty demanding operator, and so I ask my chaps to do running take offs up to the max speed of 45 kts to bring the wind vector around to within the crosswind limits.
Hard task master, but unfortunately I think that will allow you to comply with the flight manual.
By the way, if I had $12,000,000 to spend on a helicopter, I'd make bloody sure it could carry everyone I wanted with an 18 kts breeze off the port bow.
[ 26 October 2001: Message edited by: bintanglagi ]
Nick,
None of what you mention is current today.....if you want to talk fantasy, then we have nothing to discuss. I would have expected more from you.
BTW for the record, I expect to be departing company from the Bell mothership very soon, but I still don't like to see misinformation out there, no more than you want to see crap about Igor.
None of what you mention is current today.....if you want to talk fantasy, then we have nothing to discuss. I would have expected more from you.
BTW for the record, I expect to be departing company from the Bell mothership very soon, but I still don't like to see misinformation out there, no more than you want to see crap about Igor.
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CTD,
Let's bet a steak dinner right now, before you start checking. Please talk to your pilots, or call Jim Arnold of the FAA Rotorcraft Directorate at Fort Worth.
I first saw those charts in the hands of a Saudi Colonel who was planning a mountain rescue mission, using the Bell 412 "wind from within 45 degrees of the nose" chart. This is not a hangar flying story. I couldn't believe it, so I called the head of the Rotorcraft Directorate directly to discuss it. I attached a copy of the Bell 430 chart to a letter I wrote to a North Carolina legislator when Bell proposed to fly their Governor at the no-yaw-control weights. That Governor flys in an S-76C+ now.
I note you say these charts are "not current today". Do you have knowledge that these charts were withdrawn? From all models?
[ 27 October 2001: Message edited by: Nick Lappos ]
Let's bet a steak dinner right now, before you start checking. Please talk to your pilots, or call Jim Arnold of the FAA Rotorcraft Directorate at Fort Worth.
I first saw those charts in the hands of a Saudi Colonel who was planning a mountain rescue mission, using the Bell 412 "wind from within 45 degrees of the nose" chart. This is not a hangar flying story. I couldn't believe it, so I called the head of the Rotorcraft Directorate directly to discuss it. I attached a copy of the Bell 430 chart to a letter I wrote to a North Carolina legislator when Bell proposed to fly their Governor at the no-yaw-control weights. That Governor flys in an S-76C+ now.
I note you say these charts are "not current today". Do you have knowledge that these charts were withdrawn? From all models?
[ 27 October 2001: Message edited by: Nick Lappos ]
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getting back to the original question:
I've heard a training captain repeatedly state that in such an example as presented if you line up into wind, lift to the hover, commence transition and then turn down the runway the hover limit ceases to be a factor; as soon as the cyclic is pushed forward any hover limits cease to apply as you are no longer hovering.
I've heard a training captain repeatedly state that in such an example as presented if you line up into wind, lift to the hover, commence transition and then turn down the runway the hover limit ceases to be a factor; as soon as the cyclic is pushed forward any hover limits cease to apply as you are no longer hovering.
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Terrier said:
I've heard a training captain repeatedly state that in such an example as presented if you line up into wind, lift to the hover, commence transition and then turn down the runway the hover limit ceases to be a factor; as soon as the cyclic is pushed forward any hover limits cease to apply as you are no longer hovering.
Nick sez:
Having written a fair share of helicopter takeoff and emergency procedures, I am disappointed at that training captain's viewpoint. It's a bit like a legal rather than technical read on the issue. The idea that procedures are invoked and revoked by such clever word games is worrisome. Procedures aren't rules to be cleverly circumvented, they are technically based ways to get machines to behave predictably and safely. Treat them like lawyers treat laws, and you will need a lawyer after the trucks pull back from the wreckage.
The training captain may think that tricks will work to circumvent the manufacturer's recommended limits, but they do not. If you try to land back in the crosswind after pulling that trick, and you prang it, you will look pretty foolish, and your passengers will be more than disappointed. Simply said, the aircraft at that higher weight should not be operated in cross wind above 17 knots.
There is a point in the training captain's comments, though. If you can keep the crosswind component down by getting more or less into the wind, all can be quite nicely done, legally and technically. The whole operation should be done within the recommended crosswind component, however.
I've heard a training captain repeatedly state that in such an example as presented if you line up into wind, lift to the hover, commence transition and then turn down the runway the hover limit ceases to be a factor; as soon as the cyclic is pushed forward any hover limits cease to apply as you are no longer hovering.
Nick sez:
Having written a fair share of helicopter takeoff and emergency procedures, I am disappointed at that training captain's viewpoint. It's a bit like a legal rather than technical read on the issue. The idea that procedures are invoked and revoked by such clever word games is worrisome. Procedures aren't rules to be cleverly circumvented, they are technically based ways to get machines to behave predictably and safely. Treat them like lawyers treat laws, and you will need a lawyer after the trucks pull back from the wreckage.
The training captain may think that tricks will work to circumvent the manufacturer's recommended limits, but they do not. If you try to land back in the crosswind after pulling that trick, and you prang it, you will look pretty foolish, and your passengers will be more than disappointed. Simply said, the aircraft at that higher weight should not be operated in cross wind above 17 knots.
There is a point in the training captain's comments, though. If you can keep the crosswind component down by getting more or less into the wind, all can be quite nicely done, legally and technically. The whole operation should be done within the recommended crosswind component, however.
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I am new to this.
I have read the above with great interest and I am amazed that this has suddenly created so much interest and feeling. The Superpuma is hardly a new aircraft and this whole debate was precipitated as a result of an incident (or in fact, lack of one!) very recently. I don't believe that there has ever been any such crisis in the four years previously (perhaps with one noteable exception!) at the airfield to which the majority of the above refers.
I have read the above with great interest and I am amazed that this has suddenly created so much interest and feeling. The Superpuma is hardly a new aircraft and this whole debate was precipitated as a result of an incident (or in fact, lack of one!) very recently. I don't believe that there has ever been any such crisis in the four years previously (perhaps with one noteable exception!) at the airfield to which the majority of the above refers.
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To answer CTD's comments about the "fantasy" Bell charts where yaw control is traded off against gross weight to hover. On request, I can email to any interested party a sample of the charts for the 430 to illustrate the point.
How about that steak dinner, CTD!
How about that steak dinner, CTD!