Originally Posted by
DOUBLE BOGEY
HC - firstly we are more aligned than you think. Secondly they are not "My" modes. It's the way the system is set up.
I do not disagree with you BUT a pilot who finds it necessary to "Fly Through" the upper modes by pressing the trim release is simply defeating the object of engaging them in the first place. I absolutley agree that if the flight path becomes unsafe, coupled, one quick method to correct is to trim release, but I personally prefer to correct the origin of such errors by ensuring the pilot understands the behaviour of the upper modes in first place.
It is a nonsense to engage upper modes and then disable the autopilot by pressing the trim release. This is not in any manual not recommended by the OEM.
Stick and Trim I agree completely and in fact never use this myself but I show pilots it is there and add my views as to its relevance. Nevertheless it is a recognised method of attitude modulation.
HC - the bit I struggle to understand is why you believe holding the cyclic trim depressed is a stable condition, especially if IMC. It has a role VMC but in IMC it effectively sacks four digital lanes of ATT feeding off two AHRS in favour of the pilot and his skills. Surely we have by now accepted how limited those skills are if we explore the sticky bits of the flight envelope.
This should not be a debate about what can be done or indeed how we all do it. It should be a debate on the " Optimum" use of the AP. with the Trim pressed only SAS remains and that can never be regarded as optimum. The training mission is to develop CONSISTANT behaviours that will serve us well when we are tired, in the dark and maybe a little distracted. Maximum use of ATT and coupled modes. Planned and executed correctly there should be no requirement to interfere with the AP as it delivers the commanded flight path.
One more point. This OEM does have the expertise in Offshore Operations. There are four of us at least with a combined total of 80 years offshore experience amongst other environments. We certainly do not have all the answers but we are determined to provide the best information and guidance we can on the optimum use of the products.
"My modes" - only your modes in the sense of the numbering you assigned to them.
"Flying through" - I still think you don't quite get the point of having an underlying mode during manual flying. You are used to having an underlying mode of attitude retention, you might be used to having an underlying HOV mode if you flew SAR, you would be used to having an underlying GTC mode if you flew the 175 and updated 225. Thus GA is just another such underlying mode appropriate for departure.
Whilst flying manually none of the above-mentioned modes do anything, but when you let go they each provide some sort of flight attitude or path control. I can't see any reason for not choosing one that fits the flight phase.
"Holding trim release down" - I can't remember if you flew the 225 when you worked offshore, but if you did you will surely have found that when operating against the trim, the aircraft is very unsteady. For example if you want to hold a steady bank angle against the trim, it is quite difficult. If you want to hold a steady bank angle with the trim release pressed, it is a doddle. Ditto for a nose down attitude eg for a rig takeoff. Surely this is an easy thing to prove, not to me, but to yourself by trying the two ways in the aircraft. I commend you to try it. Quite why the software is less stable when against the springs than with trim released pressed I don't know, you would have to ask AH's autopilot folks.
I suppose possibly there is no difference in the software (though I still think there is) and the difference is due to the ergonomics of having to hold a steady but light force on the cyclic (FTR not pressed) vs being able to relax completely with FTR pressed (or of course release the button at the desired bank angle). Such a difference does, after all, make a fundamental difference to the propensity for biometric oscillations on the collective on ground, as we know to our cost!
Your comment about "only SAS remains" is valid whether or not you press the trim release - although as mentioned, the flavour of SAS when against the springs is less stable than with FTR pressed (for one reason or another). In the former case, when you let go the stick jumps back to some previous position which might or might not reflect a desirable attitude, in the latter the current attitude is held.
All the above is despite the fact that in general (as I think we both agree) the best way to fly it is to select the appropriate upper modes and let it get on with it!
As to the OEM's experience, sorry, I was discounting ECUK (or is it AHUK yet?). I don't know how much "input" you get to the factory but certainly as recently as a year ago, it didn't seem to be much. Yes I am told AH France now has a real live offshore pilot on its payroll, but I have no idea of whether he is of sound judgement, what his background is and how much influence he might have - one voice amongst 9000 (?) employees doesn't seem a lot. I have said it before many times (to EC/AH) but it would be a very good idea if the AH experimental test pilots were seconded to the N Sea for a few months. Flight Test engineers too if they could be allowed to sit in the Jump Seat (after all, it is the FTE's who are the real bosses under the French system!). It would transform thinking at the factory! Just the one non-rev night offshore flight I had with Herve made a difference I think.
You only have to look at the standard offerings of centre console layouts to see that AH don't understand the 2 crew concept - eg they have the "pilot radio" and the "copilot radio". They don't get the simple concept of the PM being the one to work both radios! Each time we had a new batch of helicopters, they wanted to revert to radios at the LH and RH of the console, and I had to get them put back in the middle where both pilots could easily reach both radios. Latterly and amusingly, I had to get this change approved by an EC experimental test pilot - who of course routinely flew single pilot!
Edit: just re-reading your post, I am not advocating pressing the FTR in IMC. There is only one standard way (ie malfunctions excepted) to operate in IMC and that is by use of the upper modes. To fly it manually is to degrade safety and that seems inexcusable when pax are carried. It is not a feasible malfunction to have ATT mode working but other modes such as ALT, HDG, IAS not working so there is absolutely no point in wasting training time for it either.