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Wisdom for low-level ops


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It's good to see some of the more experienced guys here also like to have plans, know where the wind is and the importance of keeping RRPM when task saturated.

 

Again, I did not share my instructor's experience level to brag but so that the OP knew that is was coming from a good source. It really is a shame this thread devolved into questioning people's experience, backgrounds or intentions. Good advice is good advice and stands on its own. Buyer beware the cost of free advice.

 

That said, as greenhorn nubile punk - I went from an underpowered Bell 47 D1 with the 200hp Franklin at sea level with a wet commercial to flying the G3B1 with the turbo normalized TVO-435 Lycoming 270hp and weighted tip blades in the "mountains" of the Black Hills regularly hitting DA of 8000. Now that's not like landing at Leadville mind you, which was a pretty cool experience on its own, but again as a nubile greenhorn punk taking off at max gross min fuel with swirling winds at the bottom of a valley it was a pretty challenging environment. I made it out alive, many close calls. I owe it to the training I given (which I was trying to relate, not to brag, but to illustrate the importance of) and sum total advice I tried to share.

 

So, yea - I most definitely have used right pedal many times to save the bacon in the G3B1 and the R44. Wind sock at the pad says this, on climbout 50' up it changes and another 50' it changes again. The helipad is where it is, the routes are the routes and winds are what they are. I've never "corkscrewed" but definitely have crabbed the sh*t out of it while trying to build some airspeed through shifting winds.

 

Even in Florida, the helipad for tour flights was 50' away from powerlines, had to right pedal crab out of there a few times as well. Humidity is severely under rated on its effect on performance. Simply lowering the collective isn't always an option or the answer. You need to have altitude and/or distance to have that option. The book performance says it can be done and the boss expects it to be done. Sure you can set your standards lower, say you can only take so much weight and play it safe - never had a boss that had a problem with that, have fun being a loader instead being a pilot. Happens every tour season, "I can only take this much" when someone else with more experience takes more - "they are unsafe" is what they say, when they get tired of loading instead of flying by mid season they are taking the same weights they said were unsafe.... :shrug:

 

So if sharing my experience makes me a bragger, F^@K it I'm a bragger. I'm not exaggerating or kidding when I say my instructor took me into a really tight spot. I've seen what people have called "tight" and its not close. The reason that spot was used was because it demonstrated the difference between keeping the RRPM at the top of the green and the bottom of the green. Its a natural tendency to want to pull pitch coming out of a hole like that. Bottom of the green you won't make it, top of the green you will. Sometimes it take a little right pedal crab to keep it at the top of the green. It took me a week to get all of the seat cushion out of my a$s.

 

OP - good luck, you have your license you know what to do, so do what you are supposed to do and you will be fine. Find an old gray haired guy to scare the $hit out of you if you feel the need to find your limits.

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Well as a pilot who has never felt the pressures to fly beyond my ship's limits, what have I learned from this thread?

 

If I ever find myself with a right yaw developing as I slow down (or am just hovering about mustering cattle or what not) and when I push in the left pedal the nose doesn't straighten out but is accompanied by rotor droop and the ship begining to settle, I will not jam in the right pedal to try and corkscrew my way out (sorry, not going to try something I merely heard about on the internet, I may though one day ask an old grey hair to show me that technique) I will however take out that left pedal I just tried to put in and ride it out to the right to recover,...and I won't panic if I begin to spin like that aircrane in the video (hopefully) might scream a bit though,...and that is one long ass run-on sentence, my 4th grade English teacher would be proud!

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Ruperts 'corkscrew' technique has already been discussed.

 

http://helicopterforum.verticalreference.com/topic/16907-myths-and-crosswinds-and-know-it-alls/page-2?hl=spin

 

As I mentioned in the last discussion, full torque pedal puts you at negative tail rotor pitch, which still eats up available power with the additional disadvantage of accelerating your rate of yaw. The technique that Rupert is describing requires a smooth reduction in anti-torque, but by no means should you apply full torque pedal.

 

Typically, full right pedal simply means no left pedal and maybe two degrees tail rotor blade pitch in the direction of right pedal. Hardly any nose right thrust at all. Mostly a discontinuance of nose left thrust.

 

Looks like you’re both finally in agreement, no full right pedal. Basically, we have a power required versus our lack of power available situation, therefore, our goal is to decrease the power required.

 

We could accomplish that by flat pitching the collective, but we can’t give up our altitude; however, we can flat pitch the tail rotor and give up a little right yaw rate. So we flat pitch the tail rotor, sounds good, between 0º and -2º, close enough for government work.

 

No need to push, to the stops, full right pedal…

 

Tail rotor pitch ranges:

R22 Beta; 19.5º left / -10.6º right

Bell 206L3; 19.5º left / -12.45º right

MD500; 27º left / -13º right

300C; 26º left / -12º right

Bell 412; 19.85º left / -10.15º right

BO 105CB; 20º left / -8º right

S76A; 14.5º left / -14.2º right

CH53E; 24º left / -10º right

Source: Helicopter Performance, Stability, and Control; Appendix B; R.W. Prouty

Edited by iChris
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Okay, jaybee, your cumulative advice for low level operations advice so far is: maintain your rotor RPM, know which way the wind is blowing, use some right pedal and have an "alternative plan". Check. Pretty much what every 200 hour CFI will tell you. Isn't this something any pilot past solo already knows? Do we not already do this at every altitude (besides using that right pedal to get them tourists over the wire)?

 

You are now entering into the same league as avbug with all the extraneous and irrelevant malarky (high gross weight! low fuel! task saturated!) Task saturated? All that's missing is the 747, but the "G3B1 with the turbo normalized TVO-435 Lycoming 270hp and weighted tip blades" is a good start.

 

If I go into a generously large confined area, can I forget about the all important rotor RPM? Why does maintaining high rotor RPM put the seat cushion in your ass?

Edited by helonorth
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Low level flight operations share a common requirement with all flight operations, regardless of the aircraft type; regardless of what else may be going on, fly the aircraft. This should go without saying, but it does not. Pilots and passengers die every year when pilots fail this most basic requirement. Whether it is maintaining a sufficient energy reserve, power reserve, control authority, or simply keeping the aircraft away from the operating edges of the envelope, it's always about flying the aircraft first and foremost. Do that.

 

With the safe assumption that flying the aircraft is most important, obstacle avoidance is the next paramount. Powerlines, trees, cliffs, ridgelines, hangars, buildings, other aircraft, towers, etc. All flights encounter the low level environment at least twice on every leg, but low level utility operations spend a disproportionate amount of time there, with a much higher exposure. Straight lines mean fences and powerlines. Guy wires extend far beyond towers; at least as far out as the tower is tall. Tensioned and supported lines (power, phone, etc) are often difficult to see or invisible. Pole tops.

 

I'm far less concerned with the direction of the wind with respect to the aircraft than I am the direction and velocity of the wind with respect to terrain and obstacles; it's the wind that determines where I'll have rising and sinking air, rotors (horizontally rotational air, as opposed to part of the airframe), wind shear, etc. Maintaining aircraft control is first; that includes an understanding of one's relationship to the wind with drift control, offset, line of flight, control authority, etc. Knowing what to expect and planning for increases and loss of lift on the windward vs. leeward side of a ridge, shears adjacent to a tree line, or the effects of drag close to the surface vs. free airstream and windshear above the surface boundary layer is crucial to operating not only safely, but effectively.

 

Wind has a crucial role in drift with ag and fire operations, as well as approaches to a spray or drop run, approaches to a pinnacle, runway, landing zone or site, etc. Know where it is, but know the terrain and it's effect on wind; local wind is often vastly different than the prevailing wind; quite possibly the opposite direction.

 

Low level operations should keep a high degree of awareness at all times of options in the event of a forced landing. This is a much greater requirement than when operating at higher altitudes where one has more options. It's also necessary to be blindfold-familiar with the aircraft and emergency procedures, abnormal stabilizing actions, etc.

 

As a close second to maintaining control of the aircraft, is judgement once in the air. A close first before maintaining control is the judgement to know when to take off, and when to stay on the ground.

 

The most critical skill one can possess is the ability to say "no," and to know when to say it. The ability to say "I can't do that, but I can do this" is a big plus. Learn to do that.

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In response to iChris-

 

I don't believe Rupert and I are in agreement. My interpretation of his comments is that he believes fully pushing the right pedal to the stop (full right pedal) only results in a few degrees of negative tail rotor pitch.

 

If this is not what you are saying Rupert, then please say so.

 

If that is your argument, then you are wrong. As iChris stated, helicopters are designed with a significant amount of negative tail rotor pitch (approximately 12 degrees). Which is a significant amount of thrust; you don't want to be in the negative range if trying to restore low rotor RPM. Anything past flat tail rotor pitch is detrimental.

 

Sorry to keep beating a dead horse, but I want it to be very clear for anyone reading this thread that using all available right pedal (torque pedal) is not an acceptable action for restoring low RPM, and can result in a loss of control.

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As an old timer with 50 plus years of flying ag and utility I have enjoyed reading this thread. It has been one of the better one's in quite awhile . I don't have much to add , it all boils down to situation awareness as has been pointed out by several posts. As to the spat with Rupert, he mentioned a Hiller 12B. For those of you that haven't had the opportunity to work a 178 or 200hp Franklin you have to understand that at times you had to pull a rabbit out of a hat to keep your butt out of the mud. I was fortunate to have been taught to fly by the pioneers of the industry who had to learn it on their own. What they passed on to me and flying those old first generation machines has kept me alive and kickin' all these years. My advise to the younger crowd is to keep your head out of the cockpit and on a swivel and fly the machine for what it is at all times.

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If iChris has his facts right, then I have mine wrong; at least regarding negative pitch in a tail rotor.

 

Hm. If on Double Jeopardy, I would have said two degrees. :)

 

I hope he'll provide a link to his sources. I like to learn.

 

=====

 

Wally and I have a remarkably similar resume. My apologies for negatively characterizing him.

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If iChris has his facts right, then I have mine wrong; at least regarding negative pitch in a tail rotor.

 

Hm. If on Double Jeopardy, I would have said two degrees. :)

 

I hope he'll provide a link to his sources. I like to learn.

 

=====

 

Wally and I have a remarkably similar resume. My apologies for negatively characterizing him.

Source: Helicopter Performance, Stability, and Control; Appendix B; R.W. Prouty

 

Here are a few from that appendix:

 

Scan-1%202_zpsqpedcwom.jpgScan-1%201_zpsjw1m2vzg.jpgScan-1_zps9cqb1wbb.jpg

Edited by iChris
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Again I am forced to piggyback on and iChris reply.

I have said it before, I consider iChris posts to be the gold standard.

It should come as no surprise when peak power output is being approached.

The closer you get to it, the more you can count on insufficient power pedal.

If you are already close to peak power at a (no wind) hover, your low level flying options are markedly diminished.

I can't say I have never heard of the screwing technique for reducing power required, but this is a first as a recovery technique.

I would consider it in a last ditch effort.

 

 

 

Great thread by the way.

edit:add

Edited by aeroscout
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