Twisting By The Pool - Fiji Style
John R81: Can't apply rear cyclic - risk = chop the tail - so "wait it out".
Is it normal that at zero pitch & flight idle, full aft cyclic will trash the tail?
There is that US Army video of old instructing about mast bumping. Initially they demostrate how the rotordisk of a Huey (on the ground) will nicely tilt according to cyclic input. I was amazed at the angle that rotordisk can move.
Then there were accident reports of Robbos cutting off their tails inflight.
Okay, both are of semi-ridig see-saw type.
But now you were implying that "emergency strength" rear cyclic on an AS350 rotorhead would chop the tail.
So would I trash my S300-C tail when applying full aft cyclic at flight idle (e.g. no pitch -> no upward coning)
Nobody warns me about that, the AFM has no restricting as well.
Last edited by Reely340; 29th Dec 2015 at 11:25.
No, Reely, you should be able to pull full aft cyclic in most running helicopters, even on the ground at flat pitch. Really, Reely. In fact, the procedure for bleeding the hydraulic system of the FH1100 called for repeated *FULL* fore and aft excursions with the cyclic while at 100% NR flat pitch on the ground. Even though I knew it wouldn't hit...it was pretty nerve-wracking, let me tell you. Same with the Bell 206 - it won't hit. And I wonder if there are any helicopters certified in which full aft cyclic would cause the blades to hit the tail under normal circumstances? Would that even be allowed?
But here's the problem: If your tailboom is coming *up* (like due to a gust of wind) while your main rotor blades are tilting *down* back there (due to your aggressive over-reaction)...well, could be trouble! Things can get quite dynamic back there.
But here's the problem: If your tailboom is coming *up* (like due to a gust of wind) while your main rotor blades are tilting *down* back there (due to your aggressive over-reaction)...well, could be trouble! Things can get quite dynamic back there.
Wind not a factor, there was no gust. Pilot had good smooth control of the aircraft and was within an inch of setting it down nicely. Pad size was reasonable for the operation.
I'm with Peter3127, somebody else pulled collective.
I'm with Peter3127, somebody else pulled collective.
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The facebook video was for sure due to overcontrol when the pilot was surprised by the slope gradient. I also don't think a gust can ever be the sole cause of the results we've seen on the Fiji video.
Agreed jymil - the FB video clearly shows that an inappropriate cyclic movement can rapidly change the attitude of the helo - it is a natural pilot reaction if you feel the tail going down to push forward with the cyclic - if you panic and shove it forward while you still have some collective applied then the videos amply demonstrate what happens.
JohnR81 - the rearwards flight demo has been a standard one in the military for many years. The idea is to make pilots aware that the combination of groundspeed and windspeed must be considered when manoeuvring. In particular, the demo should highlight that, when trying to arrest rearward movement, care must be taken with forward cyclic to avoid a rapid nose down pitch and, if it is experienced, the recovery should be led with collective.
JohnR81 - the rearwards flight demo has been a standard one in the military for many years. The idea is to make pilots aware that the combination of groundspeed and windspeed must be considered when manoeuvring. In particular, the demo should highlight that, when trying to arrest rearward movement, care must be taken with forward cyclic to avoid a rapid nose down pitch and, if it is experienced, the recovery should be led with collective.
Fiji video,
By the way the helicopter touches down nose low, suggest that it is having a CG far in front (not uncommon in the 350, and especially if it is fitted with the bench). In a normal downwind landing (with CG within limits) you will sit with more aft cyclic than if you do the same landing into wind. This chap is landing on an edge of a wall up to the helipad, and I will not be surprised if he get some ''lift'' that lifts his tail more than he expects. It appears also that the helicopter is rocking/ touching aft a bit hard, so the pilot may have pulled collective to soften the landing, but with the combination of tailwind and collective-intput finds himself airborne. Now, if you have a foreward CG in this scenario, you'll run into the aft stop of the cyclic and you will accelerate forward if you don't floor the collective. You pull pitch and the nose will come up, but if there is palm trees in your way of escape, you'll end up on youtube....
Facebook video,
The guy don't misjudge the slope gradient...... he misses the pad (marked by 4 dark point, lights?!), by landing too far back and over controlling in the recovery. Similar to the B3 trying to land on the dolly in CA, but with a much happier outcome.
From the 2 videos, I find the general handling of these pilots to be fair to poor and suspect that these pilots don't have much experience.
By the way the helicopter touches down nose low, suggest that it is having a CG far in front (not uncommon in the 350, and especially if it is fitted with the bench). In a normal downwind landing (with CG within limits) you will sit with more aft cyclic than if you do the same landing into wind. This chap is landing on an edge of a wall up to the helipad, and I will not be surprised if he get some ''lift'' that lifts his tail more than he expects. It appears also that the helicopter is rocking/ touching aft a bit hard, so the pilot may have pulled collective to soften the landing, but with the combination of tailwind and collective-intput finds himself airborne. Now, if you have a foreward CG in this scenario, you'll run into the aft stop of the cyclic and you will accelerate forward if you don't floor the collective. You pull pitch and the nose will come up, but if there is palm trees in your way of escape, you'll end up on youtube....
Facebook video,
The guy don't misjudge the slope gradient...... he misses the pad (marked by 4 dark point, lights?!), by landing too far back and over controlling in the recovery. Similar to the B3 trying to land on the dolly in CA, but with a much happier outcome.
From the 2 videos, I find the general handling of these pilots to be fair to poor and suspect that these pilots don't have much experience.
Last edited by Nubian; 3rd Jan 2016 at 09:54.
It seems v ery unlikely to me that anyone other than the pilot could have pulled the collective. Those Island Hopper ships are all single control and the pilot would have had his hand controlling the lever.
FH100: But here's the problem: If your tailboom is coming *up* (like due to a gust of wind) while your main rotor blades are tilting *down* back there (due to your aggressive over-reaction)...well, could be trouble! Things can get quite dynamic back there.
However, you're saying, that a rotodisk spinning at 100% Nr might be caught by the tail being pushed up (by external forces, further than aft cyclic is able to tilt back the disk).
I can easily see that happen with them semi rigid seesaw two bladed rotors, a gust whacking the tail into the rotordisk. (Robo et.al.)
I can picture a fully articulated rotorhead to be flexible enough (flapping hinge) to leave the rotordisk (inertia!) unaffected when the fuselage bucks its tail.
But can that happen on rigid BO105/BK117/EC135 rotors or bearingless AS350s as well?
I'd have guessed that all ac with mast moment indicators (and limits) won't allow the bladetipspath to deviate significantly from being in an plane perpendicular to the mast, w/o breaking it, of course.
( Then again, maybe I wrongly count bearingless rotorheads as similar to rigid ones. Does an AS350 have mast moment limits?)
