Power limits on R22
Peter Seddon
last.
I have always kept a very cerful eye on the manifold pressure as I was
taught not to exceed the red line limits. However yesterday I landed in a
very enclosed space at a Hotel and on lifting out I exceeded the red line
limit. This set me wondering about the implications of such action in terms
of danger to me or the heli.
Advice please ?
Regards Peter
Charles Peterson
the ground). "Okay, put your left hand on the collective. Now make your left
hand into a play gun. Raise the collective. Keep raising your hand off the
collective (Gun points at head). Any Questions?"
You can avoid pulling too much pitch by "feeling" your left arm against your
left side, then cross-checking the MP gage as needed.
The answer you'd like to hear is "don't worry about it", but the only answer
my lawyer will let me give you is "don't do it again".
There will be inspection requirements in the maintenence manuals for your
bird listed for various overlimit conditions. Read them. And when you go over a
limit, confess to a mechanic. He will like you, for feeding his family. Your
family will like you, for coming home.
PS- has that Lycoming had its SB-388B valve guide inspection done??
-=Charles Peterson, Advanced Ground Instructor, Aviak Helicopters Inc.=-
Palo Alto Airport, California
http://hometown.aol.com/cpeter7/index.htm
David Enson
course. It always brought a laugh from the test pilots. According to the
experts, the red line is there to protect the engine TBO, there is no
inspection requirement and that while not encouraged on a regular basis, you
shouldn't worry about the occasional excursions above the red.
Pat
"There will be inspection requirements in the maintenance manuals for your
bird listed for various overlimit conditions. Read them. And when you go
over a
limit, confess to a mechanic. He will like you, for feeding his family. Your
family will like you, for coming home."
True enough.
FYI, there is presently no inspection requirement for over-limit MAP
operation in either the R22 or R44 maintenance manuals. But don't make a
habit of it since it will probably require at least premature replacement of
MR hub bearings and engine cylinders.
Fly safely!
P. Cox
Charles Peterson
engine might not mind too much as its derated and all, but- what happens when
you're pitched to the max and it quits for whatever reason? Don't laugh, it
happens (not just to Robbies in particular), I know some dead guys to prove
it. What if you make it a habit down at sea level, and then go to high density
altitude with bad habits? Fly conservatively, whenever you can. Don't be
scared, but don't ever trust any engine in any aircraft completely all the time
every day. Or it will bite you.
Peter Seddon
Regards Peter
David Enson <da...@enson.com> wrote in message
news:396E94EF...@enson.com...
nla...@bellsouth.nospam.net
>I am a realtive new comer to flying having gained my licence in October
>last.
>
>I have always kept a very cerful eye on the manifold pressure as I was
>taught not to exceed the red line limits. However yesterday I landed in a
>very enclosed space at a Hotel and on lifting out I exceeded the red line
>limit. This set me wondering about the implications of such action in terms
>of danger to me or the heli.
>
>Advice please ?
>
>Regards Peter
>
>
Peter,
Power limits are set by several possible incipient problems, sometimes not so
very appearant:
1) Engine Life - The mainfold pressure red line is an engine limit, based on
the fatigue life of the engine, usually based on crankshaft torque. If the
red line is often exceeded, then reliability will be reduced, and the
potential for a pre-mature catastrophic failure is increased. If the power is
often abused, engine power might degrade more quickly, due to increased wear
of the rings or overheating of the valves.
The penalty for manifold pressure abuse is gradually applied, so some pilots
"learn" that it is not a first class problem, and get in the habit of
squeezing extra. This makes them more likely to overpitch, especially at
altitude, and face the consequences of lost rpm and a hard landing.
2) Tail Rotor margins - The power you pull is a direct measure of the tail
rotor thrust you need to balance it, so pulling too much manifold pressure can
result in having too little yaw control margin. LTE is often caused (in
aircraft with small yaw margins) by abuse of the collective pitch/power
especially at the bottom of approaches, where an agressive cyclic flare can
make you need a bunch of collective to stop the descent.
3) Excessive gross weight - Needing extra power is a symptom of too much gross
weight, with all the other problems that extra weight causes, including wear
on the rotor components, reduced main rotor stall margin, and inability to
survive a power failure, even if respecting the Height-Velocity curve.
Nick
Bob Barbanes
pressure limit applied to help IT get to TBO. Non turbocharged piston engines
like the Lycoming in the R-22 can take full throttle without worry. Remember,
without a turbo or supercharger, a piston engine can ONLY pull barometric
pressure (around 30 inches) or slightly less.
Like the old Bell 47J-2A however, manifold pressure limits are sometimes
applied to the engine to help the TRANSMISSION life, which might not be able to
take full rated power at sea level for very long. Or drivetrain (clutch, etc).
Or, as Nick correctly pointed out, tail rotor authority limits. The O-320 in
my airplane beats its little heart out at 2700 rpm and full throttle routinely
without complaint.
Pat
like the Lycoming in the R-22 can take full throttle without worry."
Yes and no. The engine can certainly develop full-rated power but there is
not enough cooling in this particular application. More hp= more Btu(heat).
You are also right about derating due to the drivetrain.
Both the R22 & R44 are known for ample tail rotor authority, as Frank
Robinson is an expert in that area.
Bob also wrote: <snip> "The O-320 in my airplane beats its little heart out
at 2700 rpm and full throttle routinely without complaint." I remember from
another post that you had a American Yankee. I presume you changed the
engine from an Lycoming O-235 to an O-320? Must climb like a homesick
angel. What is your cruise speed? FYI: the first R22 flew with an O-235,
but production aircraft use O-320 or O-360 engines.
Fly safely!
P. Cox
Bob Barbanes
>I remember from
>another post that you had a American Yankee. I presume you changed the
>engine from an Lycoming O-235 to an O-320?
A former owner did the mod, swapping the anemic O-235 for the adequate O-320.
And yes, it does climb like a proverbial bat out of Hades, even at max gross.
I run it hard, 2700 rpm in cruise, leaned as far back as I dare. At that
power-setting, I see an honest 120 knots at 9 g.p.h.. Trouble is, 24 gallons
of gas does not go far (literally). I'm not comfortable running it more than
two hours. And I'm too much of a speed-freak to pull the throttle back.
Back to the R-22 engine installation- Isn't it fan-cooled? I would imagine
that as long as the CHT's were within limits, a short-term max-power climb
wouldn't have any negative effects.
Bob -needs a Mooney- Barbanes
"The dignity of the craft is that it creates a fellowship."
Antoine de St. Exupery
Marc Whisman
> Back to the R-22 engine installation- Isn't it fan-cooled? I would imagine
> that as long as the CHT's were within limits, a short-term max-power climb
> wouldn't have any negative effects.
I've never tried it but if you just pull up on the collective you'll
probably over pitch the rotor and get the low Rotor rpm horn. The only
alternative would be to twist the throttle and override the governor to
send the engine RPM into the de-rated red zone.
Funny about that de-rated marking - it still looks ominous to over-speed
the engine even when you KNOW the red line has been moved down. I guess
that's because of all our training, and the fact that we never know how
far we can over-speed without doing damage.
regards
-Marc
Bob Barbanes
>I've never tried it but if you just pull up on the collective you'll
>probably over pitch the rotor and get the low Rotor rpm horn. The only
>alternative would be to twist the throttle and override the governor to
>send the engine RPM into the de-rated red zone.
Uhh...you wouldn't want to exceed the engine's (and rotor's) upper rpm limits.
Rolling on more throttle wouldn't necessarily increase the engine rpm
(especially at high collective pitch settings), but it definitely would
increase the manifold pressure to a value above some arbitrarily lower limit.
Does the R-22 have a wide rpm operating range, or is it fairly narrow like
every other piston ship?
Dave Venman
maximum, primarily for engine life and secondarily for transmission
life.
The red line is the maximum power you can pull in the optimum
conditions. Part of my prestart checklist is "Check max MAP" -
involves a little graph of power against pressure altitude with lines
for OAT ( that should be in all Robbies ). Yesterday's max was 24.5",
but the red line is above 25".
To some extent, my view is that if there's a limit there, then for the
most part it's designed in to keep me in one piece. Also, how would
insurance companies view a pilot's claim after a prang if red line has
been exceeded ?
>
> Funny about that de-rated marking - it still looks ominous to over-
speed
> the engine even when you KNOW the red line has been moved down. I
guess
> that's because of all our training, and the fact that we never know
how
> far we can over-speed without doing damage.
>
Sent via Deja.com http://www.deja.com/
Before you buy.
Marc Whisman
> Uhh...you wouldn't want to exceed the engine's (and rotor's) upper rpm limits.
Then the only choice is to raise the collective which increases MP and
then you exceed the MP red line. We know that the red line has been
moved down as that's how they "de-rate" the engine to 131 from the 160
that it can put out.
I was taught that you can call on the reserves by temporarily going into
the red at high altitudes when you NEED the extra power, but at some
point you will start to overpitch the rotor and you have to back off.
> Does the R-22 have a wide rpm operating range, or is it fairly narrow like
> every other piston ship?
It's pretty narrow. The R-22 RPM gage shows the percent of 2550 engine
rpm or 510 main rotor rpm. The rotor limits are 97% (459 rpm) to 104%
(530) The engine goes from 104 to 110% in the upper red arc, and 97
(2474 rpm) to 104% (2652) in the green arc.
I can assure you that I have (inadvertantly) exceeded ALL these limits
during my training. That alone is probably a good reason to de-rate the
power in a ship used for a lot of primary training.
regards
-Marc
Steve Waltner
<mar...@sprintmail.com> wrote:
> > Does the R-22 have a wide rpm operating range, or is it fairly narrow like
> > every other piston ship?
>
> It's pretty narrow. The R-22 RPM gage shows the percent of 2550 engine
> rpm or 510 main rotor rpm. The rotor limits are 97% (459 rpm) to 104%
> (530) The engine goes from 104 to 110% in the upper red arc, and 97
> (2474 rpm) to 104% (2652) in the green arc.
>
> I can assure you that I have (inadvertantly) exceeded ALL these limits
> during my training. That alone is probably a good reason to de-rate the
> power in a ship used for a lot of primary training.
>
> regards
>
> -Marc
The R-22 Beta II has an even narrower green band for rotor RPM. I don't
have an updated POH at home, but I believe it's only 4% (100%-104%) with
the newer engine and possibly governor. The low RPM horn/light still
activates at 97% on the Beta II.
--
Steve Waltner
swal...@kscable.com
Christophe Olivier
news:8kufpo$aaf$1...@nnrp1.deja.com...
> My understanding is that the engine in ALL R22's is derated from its
> maximum, primarily for engine life and secondarily for transmission
> life.
>
> The red line is the maximum power you can pull in the optimum
> conditions. Part of my prestart checklist is "Check max MAP" -
> involves a little graph of power against pressure altitude with lines
> for OAT ( that should be in all Robbies ). Yesterday's max was 24.5",
> but the red line is above 25".
Absolutely correct, I have the same understanding of managing Manifold
Pressure
than you.
Christophe
Paul R
In all the varied & experienced replies to your post, it all adds up to the
same thing:-
LIFE - yours, or the Helicopters!
If you HAVE to pull over the line to save yours, then do it. As you get more
experienced, you'll learn how to avoid having to do that anyway. In the
early days of piloting, it's really easy to get the R22 to the red line and
wonder where your extra lift you need is going to come from. (Been there,
done that!) Learn from the experience. Think about the situation you were
in, and consider if you could have made a different manoeuver, carried less
fuel, just put it back on the deck etc. etc.
As far as reducing the helicopter's life is concerned, just keep in mind
that one day you might just find yourself flying that same ship when it's
approaching it's overhaul time. Think then about all the pilots who might
have crossed that red line. Including you!
"Christophe Olivier" <christoph...@srg-ssr-idee-suisse.ch> wrote in
message news:8l6da8$gh5$1...@pollux.ip-plus.net...
John Bicker
1:52:
> Bob Barbanes wrote: <snip> " Non turbocharged piston engines
> like the Lycoming in the R-22 can take full throttle without worry."
>
><snip>
>
> Both the R22 & R44 are known for ample tail rotor authority, as Frank
> Robinson is an expert in that area.
>
> Bob also wrote: <snip> "The O-320 in my airplane beats its little heart out
> < snip>
>
> P. Cox
>
>
--
Is this this why Frank also put a tail rotor where a main rotor should be?