AS 350 Negative "G"
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AS 350 Negative "G"
To all Squirrel polers out there,
How much negative "G" can one get out of a B2? With a little amount there is the MGB P light that comes on, and with a little more the Eng P light illuminates aswell. Both these lights comes on just for a split second, and I pressume its because of the sudden fluctuation of the oil levels.
Is this pushing the heli too far?
Please advise,
thanx
How much negative "G" can one get out of a B2? With a little amount there is the MGB P light that comes on, and with a little more the Eng P light illuminates aswell. Both these lights comes on just for a split second, and I pressume its because of the sudden fluctuation of the oil levels.
Is this pushing the heli too far?
Please advise,
thanx
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A pilot in a company I used to work for, had an incident where he lost control of the cyclic stick in his B2, (think the report stated that he was busy folding charts..) which ended up going forward, as a result he found him self upside down wings level, with enough negative g's in the manouver to pull the Garmin 120 out of it's socket, and that takes quite a lot i think.. when he landed, there was oil all over the aircraft of course.. Eurocopter had someone to look it over, found nothing wrong, after a while it was back on line.
Last edited by northseaspray; 15th Oct 2007 at 20:02.
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If I knew, I would not have asked the question!!!
I can also add that there are no pax and it is operational flying contour lines, and that I felt that I am well in the machines flying capabilities.
I can also add that there are no pax and it is operational flying contour lines, and that I felt that I am well in the machines flying capabilities.
"Just a pilot"
I don't know how much or if I've ever had negative G. Slammed about in some weather that flickered the XMSN caution panel segment- pitch, roll, yaw, vertical- could have been oil slosh instead of negative, although the engine kept running.
I would never try anything aerobatic in one of these. Jack-stall is unpredictable and at the wrong time, in a critical situation, I think it could provide more excitement than I want. Other than that, they're a treat to fly and strong.
I would never try anything aerobatic in one of these. Jack-stall is unpredictable and at the wrong time, in a critical situation, I think it could provide more excitement than I want. Other than that, they're a treat to fly and strong.
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I also want to add that there are nothing in the Limitations section of the flight manual. This question is here to get advice, to fly as safe as possible, not to see how far I can push the helicopter.
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It's a good question, I was wondering that myself the other day.
There is nowhere that I have seen to say you cant do -G maneuvers, no acrobatics maybe, so?
I don't know about worrying about "jack stall", as the disk is unloaded rather than over loaded?
Hope you get a 'good' answer!
There is nowhere that I have seen to say you cant do -G maneuvers, no acrobatics maybe, so?
I don't know about worrying about "jack stall", as the disk is unloaded rather than over loaded?
Hope you get a 'good' answer!
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I've used gentle pushovers when low level to keep the tail away from trees etc, can't say I've had any lights on but I'm carefull not to be to aggresive. Saying that I have seen them done pretty aggressively by others with no probs encountered,heard reports of pressure lights flickering during severe turbulence though.
Small cracks in the star my arse.
It leads to cracks that right off the star at several thousand pounds a pop.
We had a series of unexplained star failures on a hoist equipped Dauphin.
In an unguarded conversation one of the hoist operators told us about a certain captains
party piece. He would place a pen on the console induce negative g and watch the pencil rise to the amusement of the crew.
The captain had his arse well kicked and the series of star failures stopped surprise surprise.
It leads to cracks that right off the star at several thousand pounds a pop.
We had a series of unexplained star failures on a hoist equipped Dauphin.
In an unguarded conversation one of the hoist operators told us about a certain captains
party piece. He would place a pen on the console induce negative g and watch the pencil rise to the amusement of the crew.
The captain had his arse well kicked and the series of star failures stopped surprise surprise.
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Just for the record, the limitations in the AS 350 JAA Type Certificate listed +2.67g and -1g. The JAA version has since been superseded by the EASA version it doesn't include that information, nor does the FAA version.
I don't think I want to experiment with this though, as I could picture the engine quitting real quick when the fuel pump inlet became uncovered and sucked air.
I don't think I want to experiment with this though, as I could picture the engine quitting real quick when the fuel pump inlet became uncovered and sucked air.
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If you contour fly using the collective ( I think thats what its there for) and bleeding off airspeed to go up and down steep bits you won't have to worry about negative G
SL
SL
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If I knew, I would not have asked the question!!!
By the way - there isn't one to tell you to start when to start reciting the Lord's Prayer...
There's been some good advice offered here - take it. (But not mine).
Good luck.
>
…I felt that I am well in the machines flying capabilities.
<
Flying by feel? Isn't that how a blind man reads?
The minimum load factor boundary of the maneuver envelope for a helicopter is more restrictive than that of the fixed wing aircraft. The primary reason for this is that control is directly related to the load factor. At zero G, the pilot of the teetering-rotor helicopter has no cyclic control effectiveness, while loss of cyclic control effectiveness occurs at some negative G value for helicopters with flapping-hinge offset. To avoid loss of control the Nz envelope is established at some margin above the value where loss of control would occur. Approximate values for the lower load factor limit for a helicopter is somewhere between -1 and +0.5.
Further minimum load factor limits can arise from aircraft systems (i.e., oil system, fuel system, gps mounts, etc.) which are not designed for negative load factor.
I believe the AS-350B2 TC is based upon the original type certificate, so a little digging uncovers the (US) FAR at the time--
"The rotorcraft must be designed for--
(a) A positive limit maneuvering load factor of 3.5 and a negative limit maneuvering load factor of 1.0; or
(b) Any lesser positive limit maneuvering load factor not less than 2.0, and lesser negative limit maneuvering load factor not less than 0.5, whose probability of being exceeded is shown by analysis and flight test to be extremely remote."
not sure what the corresponding icao reg stated back then...
…I felt that I am well in the machines flying capabilities.
<
Flying by feel? Isn't that how a blind man reads?
The minimum load factor boundary of the maneuver envelope for a helicopter is more restrictive than that of the fixed wing aircraft. The primary reason for this is that control is directly related to the load factor. At zero G, the pilot of the teetering-rotor helicopter has no cyclic control effectiveness, while loss of cyclic control effectiveness occurs at some negative G value for helicopters with flapping-hinge offset. To avoid loss of control the Nz envelope is established at some margin above the value where loss of control would occur. Approximate values for the lower load factor limit for a helicopter is somewhere between -1 and +0.5.
Further minimum load factor limits can arise from aircraft systems (i.e., oil system, fuel system, gps mounts, etc.) which are not designed for negative load factor.
I believe the AS-350B2 TC is based upon the original type certificate, so a little digging uncovers the (US) FAR at the time--
"The rotorcraft must be designed for--
(a) A positive limit maneuvering load factor of 3.5 and a negative limit maneuvering load factor of 1.0; or
(b) Any lesser positive limit maneuvering load factor not less than 2.0, and lesser negative limit maneuvering load factor not less than 0.5, whose probability of being exceeded is shown by analysis and flight test to be extremely remote."
not sure what the corresponding icao reg stated back then...
To sum up JimEli's response: DON'T TRY IT!
An inadvertant transient excursion into less than 1.0 g, due, for example, to turbulence, may be OK, but most helicopters were not designed for less than 1.0 g.
If you think you have a genuine need (?) to be in this flight regime, then ask the Design Authority /OEM for advice and clarification of the flight envelope. Designers and test pilots do their best to give you the widest possible operating envelope: if what you want ain't there, we probably thought there was a good reason.
An inadvertant transient excursion into less than 1.0 g, due, for example, to turbulence, may be OK, but most helicopters were not designed for less than 1.0 g.
If you think you have a genuine need (?) to be in this flight regime, then ask the Design Authority /OEM for advice and clarification of the flight envelope. Designers and test pilots do their best to give you the widest possible operating envelope: if what you want ain't there, we probably thought there was a good reason.
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The only part of most modern helicopters that MAY handle stresses associated with extremes of flight (including those imposed during "aerobatics") is the main rotor system. The rest, ie the fuselage structure, engine/gearbox oil systems, fuel systems, hydraulic systems etc, are not. Leave exploration of the edges of the flight envelope to test pilots!
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Pushing the envelope as far as G's go has a drawback in the hydraulic system. Extreme manuevers tend to result in 'stiffness' of cyclic control, and the last thing you need while in a extreme manuever, is a lack of control.
I'm sure we've all wanted to 'see what this baby can do', but with experience you learn there are ways of tweaking manuevers to not test the limits.
I'm sure we've all wanted to 'see what this baby can do', but with experience you learn there are ways of tweaking manuevers to not test the limits.
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Light flicker
I used to get the transmission light flicker when I was in Alaksa flying round the mountains. The turbulence there could get quite hairy! 
time to tighten that seatbelt again!! MUMMY!! 
time to tighten that seatbelt again!! MUMMY!!