Sikorsky S-92: From Design to Operations
Sultan,
At least the 92 can "autorotate" to a landing....something your favorite bird cannot do at all. Your favorite machine cannot survive dual engine failure....or loss of the last engine when in the helicopter mode below 1600 feet AGL.....or AVRS below that same approximate altitude. Bell admits to those problems.
Perhaps you might spend some time worrying about that rather than wasting our time suggesting the Sikorsky Products cannot survive a tail rotor failure which you do without any corroborating source material.
At least the 92 can "autorotate" to a landing....something your favorite bird cannot do at all. Your favorite machine cannot survive dual engine failure....or loss of the last engine when in the helicopter mode below 1600 feet AGL.....or AVRS below that same approximate altitude. Bell admits to those problems.
Perhaps you might spend some time worrying about that rather than wasting our time suggesting the Sikorsky Products cannot survive a tail rotor failure which you do without any corroborating source material.
SAS
My favorite helicopters are the Bell 47, 206's, 214B and the 412. All autorotate to touchdown so easily that they are not just demonstrated once, but practiced all the time. After a while it was actually kind of boring to sit through all the ones I participated in, except for the 214B which allowed you to do a point touchdown, lift off and move 20 feet or so to the final spot only using the rotor inertia. That was a hell of machine.
The Sutlan
My favorite helicopters are the Bell 47, 206's, 214B and the 412. All autorotate to touchdown so easily that they are not just demonstrated once, but practiced all the time. After a while it was actually kind of boring to sit through all the ones I participated in, except for the 214B which allowed you to do a point touchdown, lift off and move 20 feet or so to the final spot only using the rotor inertia. That was a hell of machine.
The Sutlan
After a while it was actually kind of boring to sit through all the ones I participated in
Crab,
In the aforementioned aircaft any competent pilot can accomplish the task hour after hour, day after day. So there was never a need.
Note: I have also not driven a bus, I leave that to bus drivers.
The S-92 is ranking 0-2 (Counting Korea).
The Sultan
In the aforementioned aircaft any competent pilot can accomplish the task hour after hour, day after day. So there was never a need.
Note: I have also not driven a bus, I leave that to bus drivers.
The S-92 is ranking 0-2 (Counting Korea).
The Sultan
Sultan - but you still feel the need to tell the bus driver how to drive buses
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While there is a momentary pause in the action here, I have a quick question regarding the DG/Slave mode on the S92. Do all operators select to DG prior to landing on a rig? When I flew the 76C+, and C++, didn't have to. I tough that the S92 was smart enough to know that the AHRS was giving it erroneous info and would allow the rigs magnetism to slave the system. I had heard that there was some programming involved within one of the "boxes" (FCC, AHRS?) that corrected for this. Once airborne, it would do a self align. Can anyone shed some light? Thanks
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I have found that AHRS problems in the 76 and 92 seem to be more aircraft specific than a general problem. I've had a few 76's whose AHRS just didn't like certain metal decks. I've also noted that some 92's seem to be more sensitive to certain decks than others. In general the 92's AHRS are more susceptable to magnetic interference than the 76. It's easier to just put the compasses in DG before landing than have to mess with the AHRS going catywhompas on the deck.
We don't 'free' them, and have had no problems doing so, but then we tend to have shorter deck times than some areas, and slightly smaller platforms. Re-slaving them after take-off requires simultaneous LHS/RHS switch operation to avoid AFCS DEGRADE.
An AHRS will self-align once airborne (on any type) - it will just take time and give erroneous heading info whilst it does. If you are following the FMS/GPS course you will get large apparent drift angles and computed wind speeds whilst it sorts itself out.
Once airborne, it would do a self align. Can anyone shed some light?
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DG
Like any A/C landing on a large metal island, It is recommended that the Heading bug is centered then compass is set to DG (this is done after landing checks, last thing you want to do on an ARA is switch to DG)all while watching the bug to see if it moves.
Other A/C usually switch from DG during the after takeoff checks, however with the 92 it seems prudent to allow the A/C some extra time to sort itself out and switch in the level off checks.
Why this would not be done eludes me!
What reason is there for not doing it they way I have described?
Other A/C usually switch from DG during the after takeoff checks, however with the 92 it seems prudent to allow the A/C some extra time to sort itself out and switch in the level off checks.
Why this would not be done eludes me!
What reason is there for not doing it they way I have described?
Why this would not be done eludes me!
What reason is there for not doing it they way I have described?
What reason is there for not doing it they way I have described?
HVHmt
Well you haven't really given us a reason TO do it. Recommended by whom, BTW?
However I can tell you that experience has shown that with the S92 it isn't necessary. Have you TRIED not doing it in the S92?
It is recommended that the Heading bug is centered then compass is set to DG.
What reason is there for not doing it they way I have described?
What reason is there for not doing it they way I have described?
However I can tell you that experience has shown that with the S92 it isn't necessary. Have you TRIED not doing it in the S92?
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I don't believe its officially recommended by anyone. For example, its not on our checklist. Its one of those things that we experience and adapt to. I've landed without putting the compass's in DG and had no problems at all. Other times, on landing in magnetic you find a simple miscompare in the HSI's. I just figure which one is off, manually slave it, then switch to DG until after takeoff. I've also had the AHRS drop offline and take the auto pilots with them. Now you've got a mess. Like I said above, I just find it easier to switch to DG before landing and not have to mess with it.
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4.6 landings per hour
212 Man,
Yes, I too occasionally do .6 of a landing, but I try not to do one evry hour.
Seriously, though, the solution we use is to leave the compasses in D.G. throughout the shuttle. After an hour and six decks, they are usually within about 3 degrees.
TD
Yes, I too occasionally do .6 of a landing, but I try not to do one evry hour.
Seriously, though, the solution we use is to leave the compasses in D.G. throughout the shuttle. After an hour and six decks, they are usually within about 3 degrees.
TD
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Variable load and js0987,
I have worked with the 92 at a few companies, one place we always bugged and switched. The other company didn't, which is why you are involved in this topic.
The bug is set on the DG for reference, (very good idea for a floating rig or any for that matter) then you watch it to see if it moves off when you switch to DG.
It is recomended by many flight depts. and A/C manufactures. To avoid any magnetic variations from large metal obstacles.
Have you not seen this before?
Though by all means do as you like, feel free never to question the merits of a checklist.... its all up to you.
I have worked with the 92 at a few companies, one place we always bugged and switched. The other company didn't, which is why you are involved in this topic.
The bug is set on the DG for reference, (very good idea for a floating rig or any for that matter) then you watch it to see if it moves off when you switch to DG.
It is recomended by many flight depts. and A/C manufactures. To avoid any magnetic variations from large metal obstacles.
Have you not seen this before?
Though by all means do as you like, feel free never to question the merits of a checklist.... its all up to you.
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HVHmt said:
Okay, now I'm confused as to what is trying to be accomplished. As I understand it, when one is flying any aircraft, the magnetic detection unit (Flux valve, or whatever it is called) sends its information to the AHRS. The AHRS then uses this to give the pilot a magnetic compass. Computers with deviation and variation will further correct this for the pilot. When approaching a huge magnetic anomaly, like a rig/ship, then disconnecting the magnetic input to the system is what one would want. This means switching to DG before landing on the rig. When down, the heading bug is set to the lubber line at the top. This is done because the gyro will precess. Knowing how much is important so that the pilot can slave the DG to the heading that was closest to magnetic after T/ O (slaving heading bug to the lubber line). After T/O checks usually includes the compass. As far as I know, this is for the pilot to compare the HSI with the standby prior to selecting back to Slave mode. If there is errors with respect to the two compasses, then the standby compass deviation card should be looked at then corrected and this should be the right magnetic heading. The AHRS can now be slaved to that.
I didn't intend to go into a lengthy conversation or how different companies go about their approach to a rig, I just wanted to know if the AHRS or FCCs would ignore a large deviation error due to a rig. I guess the answer is no. I thank you all for your inputs and please correct me if I have made an error or omission in my understanding.
Blade
The bug is set on the DG for reference, (very good idea for a floating rig or any for that matter) then you watch it to see if it moves off when you switch to DG.
I didn't intend to go into a lengthy conversation or how different companies go about their approach to a rig, I just wanted to know if the AHRS or FCCs would ignore a large deviation error due to a rig. I guess the answer is no. I thank you all for your inputs and please correct me if I have made an error or omission in my understanding.
Blade
I didn't intend to go into a lengthy conversation or how different companies go about their approach to a rig, I just wanted to know if the AHRS or FCCs would ignore a large deviation error due to a rig. I guess the answer is no
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However, they still require accurate MSU input to give useable heading data.
That is it, bugging the heading is just a simple check as well if a FPSO or semi-sub deviates heading, well.... it just gives you a heads up.
That is it, bugging the heading is just a simple check as well if a FPSO or semi-sub deviates heading, well.... it just gives you a heads up.
