EC135/A109 Force trim correct usage
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EC135/A109 Force trim correct usage
Hi ppruners,
I´ve been having a lot of discussion lately with colleagues as to what is the proper way of using the force trim in our machines. Several ways of doing it have arised, and it got me worried, since there are very different between themselves.
We operate A109 and EC135 hems machines. On the A109 seems that we all agree that we press the force trim every time we need to make large cyclic adjustments, i.e. on approach, as soon as we gain/lose translational lift, slope landings,platform landings etc. Only when on cruise and correctly trimmed we tend to use the cyclic electrical knob to make little adjustments.
In the other hand, when operating the EC-135 is a bit confusing. On the type rating taught me to use it pretty much as I did it with the Augusta. The company´s OM does not say anything about it, but some older-more experienced PIC I´ve flown with yelled at me in a sort of panic attack when I flew with the force trim pressed down. According to them it should b the other way around
, that only with the skids on the ground and collective half way down, the ***** switch should be used to control the mast-moment, or otherwise it could pose a very dangerous situation (because of somebody pushing against you when you are holding it and making the heli uncontrollable 
) . The rest of the time the electrical motor controlled by the mushroom? (is that the name in English') is to be used to fly the machine in every other situation.No more explanations...
As I´m only an inexperienced, useless, check list reader co-joe
, I would love to know what your never ending source of wisdom think about it, oh great commanders of PPrune 
.
Greetings from snowy Spain....
I´ve been having a lot of discussion lately with colleagues as to what is the proper way of using the force trim in our machines. Several ways of doing it have arised, and it got me worried, since there are very different between themselves.
We operate A109 and EC135 hems machines. On the A109 seems that we all agree that we press the force trim every time we need to make large cyclic adjustments, i.e. on approach, as soon as we gain/lose translational lift, slope landings,platform landings etc. Only when on cruise and correctly trimmed we tend to use the cyclic electrical knob to make little adjustments.
In the other hand, when operating the EC-135 is a bit confusing. On the type rating taught me to use it pretty much as I did it with the Augusta. The company´s OM does not say anything about it, but some older-more experienced PIC I´ve flown with yelled at me in a sort of panic attack when I flew with the force trim pressed down. According to them it should b the other way around
, that only with the skids on the ground and collective half way down, the ***** switch should be used to control the mast-moment, or otherwise it could pose a very dangerous situation (because of somebody pushing against you when you are holding it and making the heli uncontrollable ) . The rest of the time the electrical motor controlled by the mushroom? (is that the name in English') is to be used to fly the machine in every other situation.No more explanations...As I´m only an inexperienced, useless, check list reader co-joe
, I would love to know what your never ending source of wisdom think about it, oh great commanders of PPrune .Greetings from snowy Spain....
Hi Borjaracing
On the 135, it partially depends on whether you have a basic SAS equipped machine or an AFCS equipped one.
I’m not really familiar with the SAS only machine but can see no reason why you can’t fly it with or without the Force Trim Release being pressed during manoeuvres. All the trim is doing in this situation is giving you a datum position for the stick. Certainly when doing precision work, under-slinging or winching, I suspect most people would press the FTR but that does vary from person to person.
With AFCS, things are different, in this case the AFCS is working to maintain the attitude you have trimmed it to. It does this primarily by adjusting the SEMA’s, however if a SEMA runs towards the extreme of its authority the AFCS will allow it to re-centre by moving the force trim motors attached to the base of the cyclic. In so doing, the cyclic datum position will move. If you are flying with the FTR pressed, this cannot happen and you are essentially limiting the authority of the AFCS.
However, you will notice in the flight manual AFCS section that you should press the FTR button during T/O and Landing (or select the A Trim off I seem to remember but that seems far too complicated.) The reason for this ‘I believe’ is that as you are landing, the aircraft will touch down on the back of the skids first. As you continue to lower the collective, the nose of the helicopter will drop. However, the AFCS still wants to maintain the attitude that you last set and so tells the pitch SEMA to put in an aft input. This continues until the SEMA starts to run out of authority and then the AFCS instructs the Trim motor to move the cyclic.
You can see this effect if you trim the aircraft into a very steady hover on a calm day, then making sure you don’t put any input to the cyclic (other than necessary to prevent screwing up the landing!) lower the lever to land. You will be surprised how long the autopilot manages to hold the nose up and then by how far the cyclic moves aft and the MMI increases!
On sloping ground this is often the cause of a higher than expected MMI reading. Note: the Flight Manual also tells you to switch off the Autopilot for sloping ground landings. I’m not sure of the logic on that one I must confess.
Hope that is some help.
Regards
TeeS
On the 135, it partially depends on whether you have a basic SAS equipped machine or an AFCS equipped one.
I’m not really familiar with the SAS only machine but can see no reason why you can’t fly it with or without the Force Trim Release being pressed during manoeuvres. All the trim is doing in this situation is giving you a datum position for the stick. Certainly when doing precision work, under-slinging or winching, I suspect most people would press the FTR but that does vary from person to person.
With AFCS, things are different, in this case the AFCS is working to maintain the attitude you have trimmed it to. It does this primarily by adjusting the SEMA’s, however if a SEMA runs towards the extreme of its authority the AFCS will allow it to re-centre by moving the force trim motors attached to the base of the cyclic. In so doing, the cyclic datum position will move. If you are flying with the FTR pressed, this cannot happen and you are essentially limiting the authority of the AFCS.
However, you will notice in the flight manual AFCS section that you should press the FTR button during T/O and Landing (or select the A Trim off I seem to remember but that seems far too complicated.) The reason for this ‘I believe’ is that as you are landing, the aircraft will touch down on the back of the skids first. As you continue to lower the collective, the nose of the helicopter will drop. However, the AFCS still wants to maintain the attitude that you last set and so tells the pitch SEMA to put in an aft input. This continues until the SEMA starts to run out of authority and then the AFCS instructs the Trim motor to move the cyclic.
You can see this effect if you trim the aircraft into a very steady hover on a calm day, then making sure you don’t put any input to the cyclic (other than necessary to prevent screwing up the landing!) lower the lever to land. You will be surprised how long the autopilot manages to hold the nose up and then by how far the cyclic moves aft and the MMI increases!
On sloping ground this is often the cause of a higher than expected MMI reading. Note: the Flight Manual also tells you to switch off the Autopilot for sloping ground landings. I’m not sure of the logic on that one I must confess.
Hope that is some help.
Regards
TeeS
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Hi TeeS, thanks a lot for your answer. It has clarified me a couple of matters. Never thought of it, but probably you had the key on the SAS, AFCS subject. Thing is we fly the A109 based on Auto-pilot most of the time switching the Auto-Trim off when we land manually (we are still reluctant to let the computer land her, scares the s**t out of me 
), whereas the 135 does not have an AFCS, and has the SAS. Anyhow I will try what you say when we receive the T2+, which is due next month.
Let me take advantage of your knowledge a bit further. You mentioned "precision work" and its really interesting. After I had what I thought it to be a "bad habit" of using the FTR button on landing, and having been yelled a couple of times, I´ve tried to get rid of that habit, but, as we always land at base in one of those thight wheeled platforms, it has felt really awkward and hard work trying to land it with only the electric knob, without pressing the FTR. Somehow I feel as I had less control over the machine. I even think that is more dangerous this way, particulary in a cross-wind near buildings, as it is often the case. Interestingly enough those pilots that tell me not to use the FTR struggle even more than myself to put her down to the platform. Wouldn´t you say that this type of landing is kind of "precision work"?.
Once again thanks for your feedback, have a beer on me
), whereas the 135 does not have an AFCS, and has the SAS. Anyhow I will try what you say when we receive the T2+, which is due next month. Let me take advantage of your knowledge a bit further. You mentioned "precision work" and its really interesting. After I had what I thought it to be a "bad habit" of using the FTR button on landing, and having been yelled a couple of times, I´ve tried to get rid of that habit, but, as we always land at base in one of those thight wheeled platforms, it has felt really awkward and hard work trying to land it with only the electric knob, without pressing the FTR. Somehow I feel as I had less control over the machine. I even think that is more dangerous this way, particulary in a cross-wind near buildings, as it is often the case. Interestingly enough those pilots that tell me not to use the FTR struggle even more than myself to put her down to the platform. Wouldn´t you say that this type of landing is kind of "precision work"?.
Once again thanks for your feedback, have a beer on me
Hi Borjaracing
On the 135, it partially depends on whether you have a basic SAS equipped machine or an AFCS equipped one.
I’m not really familiar with the SAS only machine but can see no reason why you can’t fly it with or without the Force Trim Release being pressed during manoeuvres. All the trim is doing in this situation is giving you a datum position for the stick. Certainly when doing precision work, under-slinging or winching, I suspect most people would press the FTR but that does vary from person to person.
With AFCS, things are different, in this case the AFCS is working to maintain the attitude you have trimmed it to. It does this primarily by adjusting the SEMA’s, however if a SEMA runs towards the extreme of its authority the AFCS will allow it to re-centre by moving the force trim motors attached to the base of the cyclic. In so doing, the cyclic datum position will move. If you are flying with the FTR pressed, this cannot happen and you are essentially limiting the authority of the AFCS.
However, you will notice in the flight manual AFCS section that you should press the FTR button during T/O and Landing (or select the A Trim off I seem to remember but that seems far too complicated.) The reason for this ‘I believe’ is that as you are landing, the aircraft will touch down on the back of the skids first. As you continue to lower the collective, the nose of the helicopter will drop. However, the AFCS still wants to maintain the attitude that you last set and so tells the pitch SEMA to put in an aft input. This continues until the SEMA starts to run out of authority and then the AFCS instructs the Trim motor to move the cyclic.
You can see this effect if you trim the aircraft into a very steady hover on a calm day, then making sure you don’t put any input to the cyclic (other than necessary to prevent screwing up the landing!) lower the lever to land. You will be surprised how long the autopilot manages to hold the nose up and then by how far the cyclic moves aft and the MMI increases!
On sloping ground this is often the cause of a higher than expected MMI reading. Note: the Flight Manual also tells you to switch off the Autopilot for sloping ground landings. I’m not sure of the logic on that one I must confess.
Hope that is some help.
Regards
TeeS
On the 135, it partially depends on whether you have a basic SAS equipped machine or an AFCS equipped one.
I’m not really familiar with the SAS only machine but can see no reason why you can’t fly it with or without the Force Trim Release being pressed during manoeuvres. All the trim is doing in this situation is giving you a datum position for the stick. Certainly when doing precision work, under-slinging or winching, I suspect most people would press the FTR but that does vary from person to person.
With AFCS, things are different, in this case the AFCS is working to maintain the attitude you have trimmed it to. It does this primarily by adjusting the SEMA’s, however if a SEMA runs towards the extreme of its authority the AFCS will allow it to re-centre by moving the force trim motors attached to the base of the cyclic. In so doing, the cyclic datum position will move. If you are flying with the FTR pressed, this cannot happen and you are essentially limiting the authority of the AFCS.
However, you will notice in the flight manual AFCS section that you should press the FTR button during T/O and Landing (or select the A Trim off I seem to remember but that seems far too complicated.) The reason for this ‘I believe’ is that as you are landing, the aircraft will touch down on the back of the skids first. As you continue to lower the collective, the nose of the helicopter will drop. However, the AFCS still wants to maintain the attitude that you last set and so tells the pitch SEMA to put in an aft input. This continues until the SEMA starts to run out of authority and then the AFCS instructs the Trim motor to move the cyclic.
You can see this effect if you trim the aircraft into a very steady hover on a calm day, then making sure you don’t put any input to the cyclic (other than necessary to prevent screwing up the landing!) lower the lever to land. You will be surprised how long the autopilot manages to hold the nose up and then by how far the cyclic moves aft and the MMI increases!
On sloping ground this is often the cause of a higher than expected MMI reading. Note: the Flight Manual also tells you to switch off the Autopilot for sloping ground landings. I’m not sure of the logic on that one I must confess.
Hope that is some help.
Regards
TeeS
I'm flying the EC 135 with basic SAS now for more than 10 years and almost never push the FTR switch in flight, all trimming is done with the cooliehat or during maneuvers I usually simply overide the SAS. Even landings on tight platforms or landingzones are no problem.
skadi
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From what I remember of my type rating,we are not taught to touch the trim release except if you can not get the aircraft settled using the coolie hat. The AFCS though will take care of everything below 40kts and only above 40kts you need to use the coolie hat. I hope that makes sense.
Mostly I fly the machine on the coolie hat or have the coolie hat follow the cyclic.
The Dauphin I used to fly we handled the cyclic and then used the trim release to set the cyclic in it's new position.
Mostly I fly the machine on the coolie hat or have the coolie hat follow the cyclic.
The Dauphin I used to fly we handled the cyclic and then used the trim release to set the cyclic in it's new position.
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I think being yelled at by any of the line captains is not ok.
Very often people who yell try to hide their own uncertainty by yelling at someone who is using a different technique than they are used to.
This question should be asked at the type training captain/ fleet captain, to ensure standardisation across the fleet is optimal.
I mainly fly with the FTR, and am aware of what it does. The Coolie Hat (what you called "mushroom" and I see where that came from) operates too slow to my liking in the machines that I (used to) fly and now it has become a habit to use the FTR. But when flying coupled pushing the FTR is not a good idea and that is when I use the Coolie Hat, when flying manually I use FTR.
Many roads lead to Rome, get familiar with as many techniques as possible, find what suits you best for the purpose you need and know the limitations of each technique. This extends to way beyond trim and trim release as helicopters are very versatile machines that can be operated with quite some leeway to get the job safely done.
Often some of the "old folk" tend to get set in their (our) ways and be less open to other techniques but it should never end in yelling unless limits are in danger of being exceeded. Knowing the limits is one of the challenges to master. Good CRM is another one.
Happy landings,
I'll PM you soon as well.
Very often people who yell try to hide their own uncertainty by yelling at someone who is using a different technique than they are used to.
This question should be asked at the type training captain/ fleet captain, to ensure standardisation across the fleet is optimal.
I mainly fly with the FTR, and am aware of what it does. The Coolie Hat (what you called "mushroom" and I see where that came from) operates too slow to my liking in the machines that I (used to) fly and now it has become a habit to use the FTR. But when flying coupled pushing the FTR is not a good idea and that is when I use the Coolie Hat, when flying manually I use FTR.
Many roads lead to Rome, get familiar with as many techniques as possible, find what suits you best for the purpose you need and know the limitations of each technique. This extends to way beyond trim and trim release as helicopters are very versatile machines that can be operated with quite some leeway to get the job safely done.
Often some of the "old folk" tend to get set in their (our) ways and be less open to other techniques but it should never end in yelling unless limits are in danger of being exceeded. Knowing the limits is one of the challenges to master. Good CRM is another one.
Happy landings,
I'll PM you soon as well.
