AS355 TwinStar
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AS355N MAUW Query
Can anybody tell me why the MAUW on some AS355Ns is listed as 2540kg, and on others as 2600kg?
Was there some sort of mid-life increase, and if so does it automatically apply to all 355Ns? Or was there a mechanical change maybe?
Was there some sort of mid-life increase, and if so does it automatically apply to all 355Ns? Or was there a mechanical change maybe?
Avoid imitations
Join Date: Nov 2000
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I think there was a general permission to increase MAUM to 2600kgs, isued about 3 yrs ago in UK.
The mod is available as an option; I think it's mod. no. 072157. It involves a few hardware changes [torque gauge, limit light logic, and I think collective anticipator]. The end result is that the MAUM is increased to 2600kg; helipad weight at ISA is 2550kg. There is no increase in the power limits though so for prolonged hovering it has only a slight advantage. For the corporate user however it's quite handy. No idea what the mod costs.
I also seem to recall that the French military have operated their 555Ns at 2700kg but that they -spookily- got through quite a few main transmissions.
email me if you want to discuss "N" stuff in detail.
I also seem to recall that the French military have operated their 555Ns at 2700kg but that they -spookily- got through quite a few main transmissions.
email me if you want to discuss "N" stuff in detail.
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We operate UK certified AS 355N;'s and these had the AFM Group A supplements changed about two years ago to reflect the increase to 2600kg. Ours were already at the required mod state (torquemeters & limit light changed to indicate take off rating of two times 80% torque vice two times 78%). The 355N previously already had a 2600kg max AUM clearance, but for underslung loads. We use the 2600kg regulalry for clear area sites which gives us an additional 30 mins endurance.
NB did you notice that the previous Helipad graphs all started at 2540kg at ISA SL and the new ones now start at 2550kg at ISA SL? We can only use 2600kg for Helipad ops at -1000ft pa (quite rare in UK!). In most conditions above about +28 deg C (Also rare in UK) and/or above + 1000ft pa, the limiting factor is now the required second segment OEI rate of climb requirement (1.5%), not Helipad or Clear Area WAT.
NB did you notice that the previous Helipad graphs all started at 2540kg at ISA SL and the new ones now start at 2550kg at ISA SL? We can only use 2600kg for Helipad ops at -1000ft pa (quite rare in UK!). In most conditions above about +28 deg C (Also rare in UK) and/or above + 1000ft pa, the limiting factor is now the required second segment OEI rate of climb requirement (1.5%), not Helipad or Clear Area WAT.
355 N Starting Sequence ?
Could any 'N' drivers describe the main differences in the starting sequence from the N to the Allison shod ones.Can't get my mittens on the manual until next week!
Avoid imitations
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The N is easier to start as it's almost completely automatic. The pilot still has to monitor the EGT though, there is no auto limiting during the start sequence so you are required to manually abort the start sequence if it gets too hot. Never seen it do that though, even after a shutdown and immediate restart, the Arrius is very good in that respect, far more stable than the Allison.
The engines can be started with the ECLs (read throttles) either at ground or fly if desired. BEWARE! If you do start them at fly (useful for scramble starts) you MUST ensure that the collective is locked down or you will find the aircraft getting airborne by itself, probably while you are pre-occupied starting the second engine and looking inside
Have fun flying it!
The engines can be started with the ECLs (read throttles) either at ground or fly if desired. BEWARE! If you do start them at fly (useful for scramble starts) you MUST ensure that the collective is locked down or you will find the aircraft getting airborne by itself, probably while you are pre-occupied starting the second engine and looking inside
Have fun flying it!
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Agree with Shytorque, make sure that the FADEC has got a grip of the T4 before you go on to do anything else. Occasionaly the FADEC will get a "Logic Lock" and not let you start an engine. The only answer is to shut everything down, switch off the batteries, count to 10 and have another go - usually cures it.
Enjoy
Enjoy
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Silly question - I've flown JetRangers for 35 minutes now and I thought the generator was the starter, and hence by definition it couldn't be online during the start. Please explain.
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The starter and generator are the same piece of kit. However, in the starter mode it is driving the engine but in the genny mode it is driven BY the engine, via the quill (= thin like a quill) shaft.
During the starting phase it will go off line completely once the self sustaining engine speed is reached, provided the generator switch is OFF.
If it goes straight from driving the engine to producing electrical power because the genny switch is left ON during engine start, the sudden load can cause the quill shaft to become over-torqued and fail (low engine speed = fewer volts = more Amps = more torque on the quill).
Hence the advice to leave the genny switch selected off during engine start. As I understand it, the Arrius engine has a thicker quill shaft so it's not likely to break.
Edited bit: [I should have mentioned that going from DRIVING the engine to being DRIVEN by the engine involves a reversal of the rotational torque load on the quill shaft; that's what can shear it
]
During the starting phase it will go off line completely once the self sustaining engine speed is reached, provided the generator switch is OFF.
If it goes straight from driving the engine to producing electrical power because the genny switch is left ON during engine start, the sudden load can cause the quill shaft to become over-torqued and fail (low engine speed = fewer volts = more Amps = more torque on the quill).
Hence the advice to leave the genny switch selected off during engine start. As I understand it, the Arrius engine has a thicker quill shaft so it's not likely to break.
Edited bit: [I should have mentioned that going from DRIVING the engine to being DRIVEN by the engine involves a reversal of the rotational torque load on the quill shaft; that's what can shear it
]
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The biggest differences are not with the start on the N - that's a piece of cake. The new bits are the ways of dealing with governor failures, engine failures and what to look at when an engine stops (for real or in training mode).
The most important benefit is that you can carry both a decent fuel load and pax/baggage and still use helipads. The AS355N is a great piece of kit for public transport - not enough of them around in the UK unfortunately.
The most important benefit is that you can carry both a decent fuel load and pax/baggage and still use helipads. The AS355N is a great piece of kit for public transport - not enough of them around in the UK unfortunately.
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Yes too true helinut
6 big fat aussies 33deg C aircon on off the peninsula no problems
No unsafe area up to 2250KG (empty 1600kg) 7000'
Our new one arrives in mid september
fly safe
6 big fat aussies 33deg C aircon on off the peninsula no problems
No unsafe area up to 2250KG (empty 1600kg) 7000'
Our new one arrives in mid september
fly safe
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The 355N is a very understated helicopter. It does a good job in a quiet and unhurried way. Good for Corporate work. Better fuel burn if you can achieve above 4000 feet. I agree with the previous comments on the starting.
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The F1 is started with the Gennies on line in Canada - at least that was what I was taught on the factory course. Doing it the 206 way only serves to confuse everything and the generators go offline a lot more.
The reason for waiting a minute before switching the genny on in a Jetbox is so that the battery can settle down - and the extra amperage required if you don't doesn't draw fuel from the FCU and slow the engine - I've had more than one engineer tell me that the theory about the shaft breaking is complete b*ll*cks
I agree with the comments on the N model - very nice machine. You will find the engines very responsive in flight
phil
The reason for waiting a minute before switching the genny on in a Jetbox is so that the battery can settle down - and the extra amperage required if you don't doesn't draw fuel from the FCU and slow the engine - I've had more than one engineer tell me that the theory about the shaft breaking is complete b*ll*cks
I agree with the comments on the N model - very nice machine. You will find the engines very responsive in flight
phil
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Even though most of the times you start up without problems, I strongly recommed to pay very close attention if you are going to start with a tail wind. It may be scary and I've abborted a few of them when T4 was raising real fast very near the limits.
I've flown with only one engine and it's quite good, I can even tell you that she flies with both engines in TRAINING position, but for training pourposes makes you deal with much worse conditions than with a real engine failure.
We use it for fire fighting and mountain rescue and are quite happy with it, mostly when you take a look to performance in one engine in case you are hoisting a rescuer at the mountains. The weakest point to me is the electronic staff that every once in a while gives you a hard time but still less than what I've heard about the FADEC in B 407 or EC 135.
Buen vuelo
I've flown with only one engine and it's quite good, I can even tell you that she flies with both engines in TRAINING position, but for training pourposes makes you deal with much worse conditions than with a real engine failure.
We use it for fire fighting and mountain rescue and are quite happy with it, mostly when you take a look to performance in one engine in case you are hoisting a rescuer at the mountains. The weakest point to me is the electronic staff that every once in a while gives you a hard time but still less than what I've heard about the FADEC in B 407 or EC 135.
Buen vuelo
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Variable decision point for AS355
PremiAir Aviation Services has obtained UK CAA approval of a Group A ops variable decision point for the AS355.
The variable decision point enables Group A ops to a helipad where surrounding obstacles would otherwise prevent its use - the original flight manual approved TDP for Group A was at 90 feet.
As I understand it, the new variable TDP is a point equal to the height of an obstacle 165 metres upwind of the takeoff point plus 90 feet but up to a maximum height of 190 feet.
Similar changes apply to the variable landing decision point.
The CAA requires a flight manual supplement to be incorporated in the specific helicopter’s flight manual before the 'variable decision point' can be used.
Looks as if the new profile will increase the number of Group A approved helipads for the AS355, especially the N series.
Any thoughts?
PremiAir or McAlpine pilots - please correct anything I've got wrong / tell us more about it.
The variable decision point enables Group A ops to a helipad where surrounding obstacles would otherwise prevent its use - the original flight manual approved TDP for Group A was at 90 feet.
As I understand it, the new variable TDP is a point equal to the height of an obstacle 165 metres upwind of the takeoff point plus 90 feet but up to a maximum height of 190 feet.
Similar changes apply to the variable landing decision point.
The CAA requires a flight manual supplement to be incorporated in the specific helicopter’s flight manual before the 'variable decision point' can be used.
Looks as if the new profile will increase the number of Group A approved helipads for the AS355, especially the N series.
Any thoughts?
PremiAir or McAlpine pilots - please correct anything I've got wrong / tell us more about it.
Haven't seen the supplement yet, but will be v. useful for the "N" and handy for the "F", though obviously only at 2200kg for the latter. Just a pity it's taken such a long time to appear, though I seem to remember they had a couple of extended TDP permissions for specific sites in the late 80's.