Bob Barbanes repost 5: " Neophyte questions "

Repost of a *thread* from 5/2002 this time - it's long; I have concatenated the
thread posts into this single repost. Some content is by "Badwater Bill" and
other authors.

cheers,

Dave Blevins



Ryan asked:

1) Why is the helicopter more susceptible to carb ice than a fixed-wing
aircraft?

Before making a statement like this, I would ask if it is in fact true?

Ryan, you fly airplanes, right? When you push the throttle forward, your hand
can make sure that the mixture and carb heat controls also go to the proper
position for high-power. In a helicopter, adjusting the carb heat and mixture
would require that you remove one of your flying hands from the controls. So
unlike airplanes, in piston helicopters we don't wait until there are signs of
carb ice - we use a more pro-active approach to make sure it doesn't form in
the first place.

This is not to say that helicopters are more prone to carb ice than airplanes.
I've just never heard it stated as fact before. I can think of at least one
reason why a helicopter engine might be more susceptible to it, but I'll leave
that for the piston engine experts to address.


2) Is it considered absolutely unsafe, reckless, etc. to fly in the
shaded area of the H/V diagram? I am wondering if it's just considered
really bad form to hover at 100 ft. AGL and is never done unless
absolutely necessary. I can clearly see the reasons for why you are
vulnerable when flying in that part of the envelope.

Well, if you can "clearly see" the reasons to not fly in the shaded area of the
H-V chart, then why ask the question?

YES, it is considered absolutely unsafe, reckless, etc to fly in the
shaded-area if you don't have to. Sure, you imight/i be able to pull an
amazing auto out of your ass and get the ship down without damaging it or
hurting anyone. But too many factors would have to be just PERFECT. Most
likely, if you're hovering at 100' agl and it quits, you are GOING to bend it
and probably hurt yourself, your pax, and whoever you land on on the ground.
If you are flying in such a way that you cannot perform a safe autorotation at
all, or at least without super-human efforts, then you are being absolutely
unsafe and reckless. End of story.

3) Should downwind air-taxiing in moderate to strong winds be avoided at
all costs, or is it something that can be done safely under the right
conditions? Seems to me that it'd be safer to hover taxi when heading
downwind.

Yes, hover-taxiing is safer than air-taxiing downwind. Would you ever want to
do a downwind auto?

The "right condition" for air-taxiing is INTO THE WIND! See, "air-taxiing"
downwind puts you in a very precarious position, doesn't it? The laws of
physics do not get repealed simply because you want to air-taxi someplace. If
you air-taxi fast enough to stay out of the H-V curve at that altitude, you'll
be really hauling ass across the ground. If the engine quits, then you'll be
faced with doing a downwind auto with a GUARANTEED run-on landing. Me, I'd
rather do a hovering auto than a "real" auto any day of the week.

....Not to mention the possibility of getting into SWP when you try to
decellerate from the downwind air-taxiing condition to a hover. Or whacking
the tail rotor on the ground as you haul back on the cyclic trying to get it
stopped. Ugh.

I've never been a big fan of air-taxiing. But then, in my twenty years of
flying, I've RARELY had opportunities come up where it would be even be useful.
If the distance you have to go is that far, then just take-off, do a traffic
pattern and land at the other site. If it's not far enough to do
closed-traffic, then just hover-taxi. Yeah, yeah, our downwash has to be
considered, so that would come into play in my decision whether to hover-taxi
or just take-off and do closed-traffic.

I have been flying with some very low-time helicopter pilots lately. And while
I am not a CFI (...or isince/i I am not a CFI), I have only two rules:
1) We will *NOT* fly low, slow, downwind or any combination thereof; and
2) We will make EVERY landing into the wind and terminate to a three-foot
hover.

If the pilots want to do anything else, they are welcome to! ...Just not with
me in the ship.

Have fun with your r/w training. Hope you have a good instructor. And of
course, for a different perspective, make sure you ask HIM these questions too.

Bob -older, wiser- Barbanes


"The dignity of the craft is that it creates a fellowship."
Antoine de St. Exupery


---

Ryan wrote:

Because I occasionally see helicopters operating in this area, specifically
hovering below 450 ft. Others do it as a matter of course for their
operations.

Ryan, you are obviously an experienced pilot, as one look at your cool website
www.fergworld.com (how's that for a plug?) will tell. But here's the thing.
We ALL see pilots doing stuff that we *know* is "wrong." Whenever I see a
pilot in a single-engine helicopter hovering below 500 feet, I see a guy who is
"getting away" with something for the time being. Because if the engine so
much as burps, or of the tail rotor fails, he's gonna be one busy mutha*****.
And hopefully, a lucky one too.

Then again, in my own career I have done things that I'm sure would cause
knowledgeable onlookers to say, "That idiot is really hanging it out!" I had
to drop a guy off onto the top of a water tower once. What *should* have been
a simple job turned complicated when I saw the ten-foot tall mast (a vent or
antenna or something) sticking up from the very center of the tank that we
didn't know was there. Yikes. The end result was a scary piece of flying -
one that I'm not particularly proud of. Good thing inothing/i went wrong
or people would've died (me being one of them). Precision hovering a JetRanger
at 200 feet while looking over your left shoulder and your ionly/i hover
reference is a vertical pole that rises to within a couple of feet of your
rotor blades is not something you want to do even once. It was a tense,
stomach-tightening experience that called up every molecule of talent and skill
I had at my disposal, and then some. It all worked out, but I'm glad nobody
but God was watching.

The key is that you do not want to iregularly/i or iroutinely/i operate
in such a way that is unduly hazardous or dangerous. And when you "must" be in
such situations, be on your toes! Be Yeager.

And don't mimick things that other pilots do. Even supposedly good or
high-time pilots do really dumb-**** things - and some of them get away with it
for years! We're not re-inventing the Basic Helicopter Handbook here. You
KNOW what's "safe" and what's not. A bazillion hours does not guarantee that
you're a safe pilot.

I was ferrying a ship with a very low-time pilot recently. Prior to us flying
together, I made a few things clear about the way we were to operate when I was
in the ship. One of the things that I harp on...that I'm absolutely anal about
is proper landing technique. Unless there is a damn good reason to do
otherwise, I still make my approaches into the wind, to a particular SPOT, and
I terminate to a three-foot hover. THEN I hover-taxi to parking. I'm just not
good enough to do otherwise.

Arriving at our destination airport, the pilot shot his approach directly into
the wind toward a grassy area about 300 feet beyond where he was supposed to
park. "So far, so good," I thought; things were going fine. But as we got
down to about 50 feet (and below ETL) with the parking spot at our six-thirty
to seven o'clock position, he began a banked hover turn to the left, to kind of
"slide over" to the parking area. This would have put us up high, almost
directly downwind, with no airspeed, high power and in a descent. Can YOU say
"settling with power?" I became unglued and immediately jumped on the
intercom, telling him in no uncertain terms to terminate this f***ing approach
to a three-foot hover into the wind, RIGHT NOW! Damn, I hate when other pilots
put me in situations like that.

Afterward, the pilot's weak explanation was that there was an S-58T based there
too, and he had seen the Sikorsky pilots repeatedly do just the same (sloppy)
thing he was going to do. Nevermind that an empty S-58 does fantastic autos
with yards of available pitch to pull...nevermind that the S-58 pilots have
tons more time than he and tons of make/model time...nevermind that the S-58
has WHEELS that permit safe run-on landings...nevermind that the S-58 was
designed for aircraft carrier use and has oleo strut landing gear with twelve
inches of stroke and big balloon tires to absorb a heavy touchdown... No, we
were going to try the same maneuver in a heavily loaded single-engine
helicopter on skids. Oh yeah! bNot!/b

As you noted, fixed-wing pilots sometimes put their ships in risky or hazardous
situations, sometimes very intentionally. Ryan, you say that you occasionally
do aerobatics below 1200 feet? Well, if you crash and die during such a
display, is ianybody/i going to be surprised? Not me. You're hanging it
out, you feel that it is justified, you believe that you have the necessary
skills to do it, and you believe that you are adequately managing the risks.

I've watched Sean Tucker do that hovering-tail-slide down to a heart-stoppingly
low altitude, but I also know that it's not a safe thing for mere mortal pilots
to do...even if they could. Same with helicopters.

Happy helicopter flying!

Bob -ain't gonna die in a helicopter- Barbanes


"The dignity of the craft is that it creates a fellowship."
Antoine de St. Exupery

---

On Tue, 21 May 2002 21:26:41 GMT, "John"
wrote:

Hi Ryan, Hello Bob,

Thanks for letting all of us follow that dialogue - Bob, I've seen your
postings for quite a while on the Just Helicopters board (I post as JohnL).
Anyway, to throw in my 2c - I heard someone say that if you spend 20% of
your time in the "dead man's curve", and there's a 5% odds your helicopter
will break, then you have a 1 out of 100 chance of dying on every flight.
Reduce the time in the shaded area to 5%, your odds improve to 1 in 400, and
so on.
I too am in the early stages of training in the Schweizer 300CB - a hardy
and willing little hover-truck! I figure that I am inadvertantly in the H/V
curve way too much as it is (just watch me trying to do a pedal turn in a
strong wind...). Even though I am totally confident in the maintenance and
in my preflight, the fact is that those Lycomings do lose power on occasion,
and the drive systems have thrown a belt or two.
Hope all goes well for you Ryan, and thanks for sharing your experience,
Bob!

John Lancaster

Well, I fly a bit differently than this. I am never in the gray area
of the HV curve. There's no reason to ever operated there unless you
have to and you know you are sticking it out like Bob did while
landing on that water tower. Even high performance tko's put you in
that curve. I never do that unless I have to. My standard tko is to
get the airspeed up above 40 mph then pop up about 10 feet just enough
that I could do an auto straight ahead into the wind if she quit.
Even then you're going to have to do a run on landing in all
probability. No biggie, you just have to know to expect it and have a
clear area straight ahead INTO THE WIND.

On carb ice. Frank Robinson has the best explanation for this that
I've ever heard. He says that we airplane pilots get it all the time
on our glides to landing but the prop keeps the engine going. When we
come in on the power a bit, the vacuum the engine produces sucks in
warmer air and melts it, then ingests it. So, we may have multiple
engine failures during a glide to landing and not even know it. In
the helicopter you don't have that big fly-wheel (prop) wind milling
out there to keep your engine turning. When your engine gets starved
for gas and air, it quits and it stops because of the overrunning
clutch...then you have to enter an auto.

I wanted to say something about that move your student did with you
the other day where he had watched the higher timers do a sidestep in
the HV curve. I see a lot of that among the higher time kids who fly
here. The CFI's that have a 1000 hours or so can really make a
helicopter perform. They are crack because they are kids and have
perfect reflexes, vision and good training. The problem with that is
that they are so good they get bold. I was like that when I was a
young pilot too. I remember it real well. I had 2000 hours when I
was 23 and half of it was in helicopters. For fun I'd go out and
hover with a skid on the tip of an orange road-cone and I could do
that without looking up. In fact I used to take the doors off the
Huey and hover it by sticking my head out the right side and looking
at the tail...just to prove I could do it.

All this is fine if you do it below the HV curve and into the wind.
Why complicate things by doing it any other way? It's safe if you
just follow the laws of physics. If you don't, you hang your ass out.
And, yes, as a kid, you hang your ass out all the time. What I find
these helicopter pilots doing is cutting the margin on things as they
build time. Where they start out safe, they end up dangerous because
they cut the margins on things until there are none. They do this to
get the same kick out of flying that they did early on.

I used to fly in the Grand Canyon when I was a kid. I flew
Cessna-206's down between the walls of the canyon on a 135 operation.
When I started doing this I'd fly from Vegas to a point about 100 mile
into the east end of the canyon and turn around, drop down 1000 feet
below the walls and head back. About 30 miles later I'd drop down
another 1000 feet and fly along for about 50 more miles, then drop
down on the deck for the last 20-30 miles of the flight. As I flew
this run hundreds of times I was doing something that I didn't know I
was doing. I was cutting the margin of airspace I had between my wing
tips and the vertical walls from what started out to be about 100
feet. I took a buddy on that ride early on, then again five years
later. He was scarred on the second run. He told me what I'd done. I
was running my wing tips about 5 feet off the walls and didn't even
realize it because it was gobbs of room for me at that stage. He
pointed out that the pax enjoyed it just as much if I were 100 off the
walls and what I had been doing is cutting my own personal margin to
produce the same hype and adrenaline that I'd had initially.

I see this behavior all the time with the younger helicopter pilots.
They can do it but they don't have ANY room for any error.

I enjoyed reading Bob Barbanes take on air-taxi vs. hover taxi. I
thought I was sort of a pussy until I read how a real pro does it. I
do it the same way. I just take my time. That's the key. Taxing is
not a timed event. Take your time, stay low and go slow. You'll most
likely live longer. I've had situations where I've had to taxi
downwind from my landing spot (the end of my planned approach). If
the wind is too strong to turn downwind and you can't really see
behind you to back up...or it's too far, I just take off again, do
another complete circuit and land downwind of my final destination.
Then it's a simple matter to just taxi into the wind in a hover to get
there.

As Bob said above, planning is really the key. On my commercial check
ride, I had a fever of about 101 and I flew poorly. But I was safe.
When I was doing my pinnacle approach and landing I was talking to the
examiner all the time, telling him what I was thinking. I had an
escape route, I knew exactly where the wind was coming from and it was
blowing 25 knots too. I did a high and a low recon, talking all the
time about what I was looking for and I knew where I'd hit the trashed
air and I explained it to him. Like Bob says above, you can be a bit
off in your accuracy during your flying, but you can't ever stop using
your head. The planning and the execution have to be safe and sane.
Your flying accuracy can be a bit sloppy and you can still be fine.
Everybody has off days. Just don't let that make your mental
activities put you in jeopardy.

Helicopters are fun because they are dangerous and require a lot of
skill to fly. THat's the kick I get out of them. I love button hook
approaches to a confined area and you make it all work out fine.
Sometimes I can't believe that the human brain can calculate all this
stuff so well and seemingly automatic.

Don't fly in the HV gray area. Don't air-taxi if you are not into the
wind. Don't rush your set downs. Take your time...take your
time...take your time. Go around if you need to relocate a long way
downwind of your present position. None of this is a timed event as
long as you have enough gas to keep running. When you get into a
situation where you rush things is when it can bite you. Hell, it can
bite you anyway. Don't push your luck by putting yourself in any
situation where the energy momentum equations of physics are going to
be against you.

Bill

---

John L wrote:

Even though I am totally confident in the maintenance and in my preflight,
the fact is that those Lycomings do lose power on occasion,
and the drive systems have thrown a belt or two.

Well, if you lose a belt or two in a 269, at least you'll have six more to keep
you out of the autorotation zone.

Speaking of autorotations, PHI has a rather cavalier attitude about the H-V
curve. I guess it's because their pilots have to spend so much time inside it.
PHI instructors say that it only applies on take-off, but curiously the chart
in the Bell AFM does not make this distinction.

So then Helipilot wrote:

A couple of years ago I had the opportunity to go to PHI just for 206
training, I learned how to do autos (all the way down) from
practically every height (100,200, 300 FT etc.) in the shaded area
with zero airspeed in a fixed float 206 Jet Ranger, Alejandro Garcia
my instructor demostrated to me that this absolutely possible at least
in the 206, this gave me a lot of confidence to fly in this area

False confidence.

Not to be preachy, but here's why. The Allison 250 C-20 engine that is
installed in a Bell 206B has a ischeduled decelleration/I that specifies a
*minimum* time of two seconds from full throttle to idle. Most C-20 engines go
more than two seconds. What does this mean? You think it doesn't matter?
Well, in a B-model, the power comes off "softly." Everyone who's ever done a
hovering auto knows this. Pilots who've had "for real" engine failures in
206's report the surprise they felt at the suddeness of the torque removal.
One high-time pilot told me that when his engine quit in a hover, he initially
thought he'd had a tail rotor failure due to the fact that it yaw-snapped so
abruptly (the wrong way, unfortunately).

Also, we all know (or at least ishould/i know) that turbines don't
completely disengage when you roll the throttle off if the N2 and NR needles
don't split, and they generally do NOT split in a B-model. So even at "Idle"
they produce a small but noticeable amount of horsepower that helps not only in
the glide but in the flare...or more correctly, the cushion at the bottom.

So doing a PRACTICE hovering auto from even 100 feet into the wind and into the
water in a lightly loaded 206 on bags is a no-brainer, especially when you're
ready for it. There are crashed 206 airframes all over the world attesting to
the fact that no matter how forgiving the ship is, pilots can still **** it up
in a REAL engine failure.

Pilots who deliberately fly inside the H-V curve do it at their own peril,
whether they think it's dangerous or not. Won't be me proving it.

Bob -you're braver than I am- Barbanes


"The dignity of the craft is that it creates a fellowship."
Antoine de St. Exupery


---



False confidence.

Not to be preachy, but here's why. The Allison 250 C-20 engine that is
installed in a Bell 206B has a ischeduled decelleration/I that specifies a
*minimum* time of two seconds from full throttle to idle. Most C-20 engines go
more than two seconds. What does this mean? You think it doesn't matter?
Well, in a B-model, the power comes off "softly." Everyone who's ever done a
hovering auto knows this. Pilots who've had "for real" engine failures in
206's report the surprise they felt at the suddeness of the torque removal.
One high-time pilot told me that when his engine quit in a hover, he initially
thought he'd had a tail rotor failure due to the fact that it yaw-snapped so
abruptly (the wrong way, unfortunately).

Also, we all know (or at least ishould/i know) that turbines don't
completely disengage when you roll the throttle off if the N2 and NR needles
don't split, and they generally do NOT split in a B-model. So even at "Idle"
they produce a small but noticeable amount of horsepower that helps not only in
the glide but in the flare...or more correctly, the cushion at the bottom.

So doing a PRACTICE hovering auto from even 100 feet into the wind and into the
water in a lightly loaded 206 on bags is a no-brainer, especially when you're
ready for it. There are crashed 206 airframes all over the world attesting to
the fact that no matter how forgiving the ship is, pilots can still **** it up
in a REAL engine failure.

Pilots who deliberately fly inside the H-V curve do it at their own peril,
whether they think it's dangerous or not. Won't be me proving it.

Bob -you're braver than I am- Barbanes

God, is that ever interesting. I'd not seen or heard that all put
together like that but you are right. I've autoed the 206B many times
and it's a piece of cake. However, I have a buddy who balled one up
over at Bryce Canyon last fall tell a different story. He said
exactly what you just said Bob. He said that the reality of the
engine failure is that it just stopped, instantly. There was no
cushion in the timing like a practice auto. It really got his
attention...and now, thanks to you I can see why. When I roll the
power off in a hovering auto it's a second or so before she even
starts to settle. You wait for the settling, then sort of "pop" up
the collective a bit at about one foot and wait again. When she
starts settling this time you can do the gentle pull all the way up as
you land. I can feel what you are talking about in that there is
still some residual power in there at the time of the rolloff. I
thought it was because of the high inertia rotorsystem on the thing.
I guess it's not.

Interesting.

Bill
---

BWB wrote:

(snip)
I have a buddy who balled one up
over at Bryce Canyon last fall tell a different story. He said
exactly what you just said Bob. He said that the reality of the
engine failure is that it just stopped, instantly. There was no
cushion in the timing like a practice auto. It really got his
attention...and now, thanks to you I can see why. (snip)

Exactly! The 206 lulls pilots into a false sense of security and complacency.
(Actually, all ships equipped with the Allison 250 C-18/20 engines do,
including the FH-1100 that I now fly.)

Evidently, a LOT of pilots do not understand how a free turbine works. In
fact, the other day I was reading a fatal accident report of an FH-1100
(http://www.ntsb.gov/ntsb/brief.asp?e...08X08867&key=1) in which the
pilots were so concerned about not getting a needle-split when they rolled the
throttle off that they ended up crashing the ship! Hey guys, FLY THE AIRCRAFT?
Free turbines do not always show an N2 needle-split during autorotation.
(Fixed-shaft turbines are different - more like recips.) And if the needles
are not split, the freewheeling unit IS engaged.

During a recent make/model checkout, the pilot I was flying with had NO turbine
time. During our power-recovery autos he was doing pretty well. But in what
ended up being the last one, he did not make sure that the throttle was up at
"full" and we went all the way to the ground. Point being, it is VERY hard to
tell by glancing at the gauges whether the throttle is at "idle or "full."
Only clue would be the N1 sitting right on 60% (or whatever your idle was set
at) but the N1 is a tiny gauge and will be very low anyway on a flat pitch
approach at full throttle. And in an auto, you don't have that much time to
devote to studying it.

Doing practice autos to nice, big, flat, unobstructed areas is nice, and the
difference between engine-at-idle and engine-off is probably inconsequential -
although I'd like to experience it. But if you had to put the ship into a
tight spot, it could mean the difference between a no-damage landing and a
wreck. Just one MORE thing to be aware of as you fly...


Then Bart wrote:

Not arguing here, but many of the folks at the Bell factory
training center go out of their way to verbally state that
the HV only applies to takeoff.

Granted, takeoffs are your "worst case scenario" when it comes to transitioning
from powered flight into autorotation. But I don't care if Bell swore on a
stack of bibles that the H-V only applies on takeoff. I notice that I haven't
seen any iother/i height-velocity diagram in any other manufacturer's
aircraft state "this chart only applies on take-off." Maybe the boss will let
me take one of the FH-1100's out and experiment. Uhh...on second thought maybe
I'll find a younger/dumber pilot to actually do the flying while I just watch
from the ground, heh-heh-heh.

Bob Barbanes


"The dignity of the craft is that it creates a fellowship."
Antoine de St. Exupery

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*end*