a little more detailed
 

Thank you all for your anwers!

I have to be more clear about the situation we had:

-carb heat wasn't applied (down)
-it was a cut grass surface
-we had already hovered 2min before we lost rpm
-the power we applied (when rpm dropped): 23 inches Manifold Pressure
-the rpm dropped very abrupt (lower than 97% in less than a 1sec)
-when the rpm dropped we had already stopped the turn
-weight was within limit with the RFM
-RFM says it's possible to hover IGE up to 10000ft (PA) with the weight we had

An other question:

-When full power is used (butterfly at approx. 45° open) what about the possibilty to risk carb icing?

Greetings.

Food for thought...
 

You can get carb icing if the degree difference between dew point and OAT is 20F/11C. Since you had a 15F/8C difference, it is likely that you experienced carb icing (it was already pretty cold that day).

As far as engine performance is concerned, the O-360-J2A (Lycoming engine for Beta II) was designed at 180 BHP; however, Lycoming only tested it at 145 BHP because they thinned-out the cylinder heads and used Aluminum pistons to save weight (and they wanted to cover their tail feathers). The engine is fully capable of producing 180 BHP, but the data plate says 145 BHP. So that's what we go by. If you stay within POH limits, you should not exceed 131 BHP. Why did RHC specify 131 BHP in their design?

In piston engines, you loose about 7 horsepower for every thousand feet (roughly). It's the pilot that derates the engine by staying within MP limits, which affects your angle of attack on the blades. There isn't really a mechanical device that "derates" the engine... just the pilot.

Therefore, at 7000' you have every bit of that 131 horsepower available to you...

180 HP
- 7 (thousand) x 7 HP = 49
--------------------------
131 HP

Schweizer's web site claims the 300 has a HIGE of 10,800 feet. This is a sneaky advertisment because this is at a weight of about 1400 pounds... one person and an hour of fuel. At gross weight, the Schweitzer can only handle 5,900 feet.

Piston helicopters that operate at their maximum horsepower at all times are not high altitude performers. Specifically, the performance power available to their engines is extremely limited when compared to the Beta II at the same altitude because you are subtracting from an available horsepower figure that was running at maximum at sea level! In other words, they don't have the same altitude "buffer" that the R22 Beta II does.

The Beta I and Beta II are almost the exact same aircraft. A few minor changes, but the biggest difference is the engine. So if you fly mostly at lower alititudes, you will NOT have ANY performance increase from a Beta II vs. Beta I. If you fly at higher altitudes, you will need the Beta II.

One more thing, most folks don't know how to properly use the chart that Johe02 posted earlier. You are probably already aware of this, so forgive me if I'm speaking in infant terms...

http://www.a2b-web.co.uk/pics/PGR22.gif

There is a reason why the MAP lines extend past the "full throttle" line. The extension is used to calculate your max continuous power. Example...

Assume 6000 MSL @ 0 C

To calculate your 5-minute MAP rating, you simply follow the chart. Go to 6 line at bottom and follow it up to the 0 C line to find your 5-minute MAP rating. In this case, you run into the "full throttle" line BEFORE reaching the 0 C line. Therefore, your 5-minute MAP rating is about 23.5 inches.

Now, the chart says, "for MCP subtract 1 inch MAP." Without putting much thought into it, that's exactly what most people do... and that's exactly the wrong thing to do. To calcualte your max continuous power rating, you subtract 1 inch MAP from the calculated 5-minute MAP rating!

Now, the reason for the extended MAP lines beyond the full throttle mark becomes clear. The calculated 5-minute MAP rating in this scenario is 24 inches (actual 5-minute MAP rating is 23.5 inches at full throttle). If you subtract 1 inch from the calculated 5-minute MAP rating, your max continuous power rating is 23 inches.

In summary the difference between your actual 5-minute MAP rating and your max continuous power rating is only 0.5 inches in this case (not the full 1 inch). If you use the "full throttle" line instead of the calculated 5-minute MAP rating, you will cheat yourself a little power.

Hope this helps.


(edited for grammar & spelling)

Mr Selfish,

I didn't have a Beta II chart handy. Just wanted to show that alpinehelicopter was hovering at or close to full throttle.
All those graphs and figures assume a perfect engine, (and correct weights!?). It only needs the timing or valve adjustment to be slightly out (even old oil) and you've got less power than expected.

Maybe the engine was hot from being over worked at that PA?
I still think he overpitched. Carb icing is for small throttle openings, where the pressure difference across the butterfly is great.

Either way I don't think he's gonna strip the engine. . . :hmm:

Alpinehelicopter
 

To answer your throttle question, yes, carb-ice is very possible at, or close to, full throttle in an R22. The reason, as you state and as others have pointed out above, is that the engine is derated and the butterfly is not wide open.

The information you add in your second post reinforces the likelihood of carb-ice. Hovering over grass can recirculate the moisture necessary to produce the ice. You state you had nil wind conditions. This just helps the recirculation process. And you'd been there for two minutes already. Perfect for ice!

I'd still get the machine checked over for all other possibles. Your 'hard' landing should be checked too if you suspect damage may have been done.

I am not a little disconcerted to read amongst the above that some of us here cannot see the likelihood of carb-ice in this case. Having done a lot of work on this subject I can assure you carb-ice in Robinsons is very possible under a surprisingly wide variety of conditions. Given that pulling out the carb-heat control costs nothing (well, almost nothing) to keep that temp needle out of the yellow arc, the rule here just has to be:::

"If in doubt, pull it out" :ok:

For RDRickster:
Just a question on your detailed response- didn't you mean the maximum MAP you could get is 22.5" - that's where the full throttle line crosses at 6,000'?
How can you get more MAP than full throttle?
Otherwise, an excellent post.

Ooops!
 

You're right... nice catch. I must have been seeing things. Anyway, the principle is the same... just make sure to read the right line!

Dantruck,

Full throttle is full throttle my friend, butterfly as open as it can be. Perhaps you mean at or close to max POWER that you can use according to the limit chart, that the butterfly is not wide open?

It is by adhering to the limit chart that the pilot "derates" the engine at lower altitudes, but as you climb you will eventually be running at full throttle and quite within the stated limits.

I still think carby icing is also possible at full throttle due to fuel and/or impact icing and not throttle icing. Can any of you icing guru's prove me right or wrong?

Alpinehelicopter,

There is also the possibility you had a stuck valve momentarily, although the engine will run very noticeably rough as it drops a cylinder. It may have only done it for a couple of strokes though. How "sudden" was your power loss?

With carb heat, always, always keep the inlet temperature out of the yellow. I always fly with +10.

And be aware that the "temperature assist" doesn't always do you favours. As you transition and reduce power, the carb heat knob actually drops. If you are doing training across the airfield, you'll more than likely be constantly starting and stopping exercises frequently. Make sure the knob is always up at least an inch.

I'm not a great fan of the temp assist mechanism - it never seems to assist when you need it and its reactions in no way reflect the actual inlet temperature.

Mayby your mixture was to rich..............!!! Was it leaned ?

rotordk:

There's nothing in the POH which recommends leaning the mixture in an R22, it's not taught (to my knowledge) and as far as I remember I've never done it nor spoken with anyone who has.

In my defence, if I'm wrong, I can't get to my copy of the POH cos it's packed away cos we're moving house next week!

They put it there for a reason, and we are allowed to think for ourself, even though it's not SOP ( Yeah, I know, but hey.......it could save your as* one day !!! ).

Ofcourse any leaning will be performed on the ground ( if I recall correctly, their lawyers don't recommend inflight mixture manipulation ). !!

Dropping a Robinson
 

Information wanted please. I am trying to to do some evaluation on skid setups, and would be interested on any information from anyone who has had engine failure or other problems which have necessitated dropping a Robinson from eight feet or less, from a hover. I refer to structural damage rather than the cause. Many thanks, Bug.

I'm assuming that you live somewhere that makes it inconvenient to attend the factory school - a pity, as it's a great school. Anyway, in the school they show you video tapes of their products being dropped (not hover auto - cut-the-string dropped) while they measure the skid distension.

I'd suggest you call RHC and ask to talk to Ken Martin or Pat Cox and see if they can get you some numbers.

As part of the certification testing of the R22, they did some drop tests. RHC have a video which, as has been mentioned, is shown on their course. Its quite impressive to see how much the skids deflect, and then return.

From experience doing instruction, the R22 skids are pretty good at resisting damage from "drops": much more so than many other apparently stronger helicopters. However, helicopters can be dropped in various ways. Sometimes, even when the drop is not large, it can be awkward. If the drop is not just straight down, but has a lateral element, you can get damage. Not necessarily the skids, but damage to the MR gearbox and/or its fairing.

If a Robbo is dropped or put down hard and nearly level at impact , this can be seen after the event in the cross member at the rear of the cabin will show varying stages of deformity IE it wont be straight the bigger the bend the harder the hit, after that it in the other things like the tail boom drooping and the rotor mast moving(deflecting) so much that it will deform the roof around where it pokes out from the main body!

Dropping an R22 may increase the bend in the beam that VFR mentions - however it is bent to some extent as it comes out the factory, so don't reject an R22 just because it is bent.

If I remember right, RHC specify a check of the height of the tail stinger above level ground as part of the check after a heavy landing - it will all be in the maintenance manual. Presumably it effectively checks that any deformation of the skids was elastic and that the skids system remains within limits.

I guess what I was trying to say earlier is that, in my experience you are more likely to get damage from drops, in practice, away from the skids.

Tail stinger height must be at least 3' high on the R22

R22 overspeed query
 

Hi - can anyone tell me why some sort of engine rpm limiter could not be incorporated into the design of an R22/R44?

It seems that a lot of low time pilots waste a fair amount of cash coughing up for accidental engine overspeeds and R22s remain grounded pending inspections when e.g. starting up with the throttle open or raising the collective without the governor on and not reacting quickly enough to reduce rpm.

Thanks

I don't need no stinking limits.
 

To: rba194

Some automotive engines have over speed limiters, which either cut off the fuel supply or cut the ignition. On an automotive engine when you stop ignition or fuel the rear/front wheels through the transmission are still back driving the engine.

On the Robbie or any other helicopter the internal combustion engine is isolated by the free wheeling unit and when any overspend device were actuated the engine would most likely stop.

To put some type of limiter on an existing engine it would require re certification or that an STC be issued which would require much less paperwork than a full re certification.

Many years ago the US Army took delivery of a brand new H-34. A new pilot was transitioning from H-13s to the H-34. He started the engine while twisting or untwisting the throttle trying to get fuel pumped into the engine. The throttle canceller switch was misrigged and the engine caught with the throttle wide open. The engine went to 2800 RPM and there was so much force in the hydromechanical clutch that it broke and the engine was connected to the driveline. It took only one second under those conditions to make that brand new H-34 a write-off and it was taken to the training school as a training aid.


:E :E

rba:

Point taken - I've been there :*

To my mind, if the pilot follows the checklist, they're safe, and it's incumbent on the school to teach well enough to avoid it - not only in the "this is what you do and don't do" but "this is the time you concentrate on one task" sort of stuff.

Adding technology probably means the aircraft will be grounded with a limiter fault more often anyway.

rba194,

how much are schools charging for overspeeds??:suspect:

i have never heard of that happening anywhere.

Most schools charge the insurance deductable/excess, frequently £1000. :(

The most likely time for an overspeed at this time of year is the first flight of the day, when checking the carb heat, now that it's done at 100% RPM again rather than 75%. Carb ice melts, and RRPM goes up...and up...and up. It can do it very quickly sometimes, and you have to be quick to catch it,. I'm surprised there aren't more overspeeds in that situation.

The R22 has reached the limit of it growth margins, adding any further weight to the aircraft would required a substantial redesign. Therefore, since virtually all developments will add weight to the aircraft they are ruled out as a matter of policy.

Anyway, adding an overspeed protection device is a small priority compared to the other things that big-R would change if it was worth doing....but of course it is not if you have a complete monopoly on the market (91%) last time I checked. The only customer migration big R has to worry about is customers moving from R22 to R44, hardly a big problem is it, having to take twice as much money off them...

I shouldn't expect too much more to happen to the R22 until R's had is forced...and even then it many not be worth his while, R44 accounts for over 80% of aircraft sales revenue and is in slightly less risky market [i.e. not a primary trainer].

Hope this helps
:ok:
CRAN

Whirly and anyone else, I have not yet received the POH ammendment to carry out the carb heat check on the R22 at "100%". Can you give me the date of the new page and I can chase it up? We usually get seamail updates to HKG...

I haven't received that update either, and my subscription service for their POH is current. I've always done it at 75 percent.

Dohhhhhhh!!! Here I am spreading rumours again. Oh well, this is a rumours forum. I haven't seen anything in writing either, as it happens. I got told we were back to doing it at 100%, and I just believed it. After nearly getting an overspeed, maybe I'll go back to 75% if no-one else knows of any change. Sorry for the confusion.

Overspeeds on the R22 can and do occurr when in flight also, a very well known FTO rented to me on SFH basis one of their R22's what they omitted to tell me was that it had suffered from an overspeed by one student pilot whilst with one Fi and it reached in excess of 115%, I was the lucky guy who next flew this by now heap of scrap, one problem with any helicopter is the walk round pre flight, you can look and touch and rock about and twist things around, do all you full and free and then you Ts&Ps on start up, what you cant see are the stretched and completly goosed rotor bearings that are in the teetering head, and as far as I know there really is no way these can be checked from the pre-flight.

But dear reader, once airborne and reaching the types of velocity to start flying this problem will show its self, I am only here today I think because I weigh 90Kgs and have previously wrastled big things on farms, the stick shake that was induced from about 38knts was so severe I couldnt raise my thumb to press the radio button to declare a problem, I was forced to carry on and kept to a minimum of 500ft whislt working out what I had to do, the tide was in I couldnt land on the beach so I had to fly a long gently looping arc to get back to the field, after locking off the collective and using that free hand to comm with the tower, I then concentrated on getting that giant vibrator back to the ground, whilst doing my best to fly over green field and to miss the housing and factories that abound around EGNH, the fact that I am here tells you I got down, with the help of the tower by keeping everyone well away from me until I had got back down to hover taxi speed, when at that point the giant vibrator stopped.

After I had landed and done my run down and after flight checks I still couldnt see anything wrong with the rotor, or head despite now knowing something had happened to it and was sadly wrong, but as I was very slowly walking in I was met by certain people who proffessed they had forgotten to red card the Heli.

What I wonder would have been said if I had gone in!! needless to say that crowd of cowboys has never since had any money from me.:mad:

But I still dont know how you would see overspeed damage on any preflight

Vfr

Overspeeds
 

Vfr,

Dont know if this is going to be of any help to you because you may already be awear of this, but one way of checking for an over-speed on either the R22 or the R44 is to have a look at the nut that holds the cooling fan in place. There should be a line of white 'torque seal' drawn from on one side of the fan, across the nut and back onto the other side on the fan. If this line on the nut doesnt match up with the two lines on the fan then this may be an indication of an overspeed, allbeit an engine overspeed.

As to checking for brindled bearings in the blades, I dont think there is any way of checking them in a pre-flight, only when the blades come off the A/C.

PA321

I has been taught to do always the carburetor heater check with my left hand in the throttle and the right in the "lever?" (stick between legs) , ALWAYS looking at the engine rpm , I can't see the problem with the ice and high rpm, you can always roll the throttle, but it's also true that I haven't flown in icing conditions... :O
I think that there is no need for a rpm limiter , but I'm just a low time student :rolleyes:

I think extacly the same...

A friend of mine , in the first hours almost had a overspeed but , as it should be he was with an instructor.

Regards.

PA321,

Yes, on my preflight the white line was Ok and not cracked. have been told since that the only way a Rotor Overspeed can become known about is by those responsible being HONEST, sadly sometime Honesty is a very rare commodity.

:ok:

Absolutely right Vfrpilotpb and with the schools charging the students or instructors for the overspeeds I'm almost sure this, in most cases, will make it even harder (more expensive) to be honest.

I used to teach in school with R22's and Schweizer 300's (about 20 aircraft in total) and the boss always encouraged honesty by never charging for damage to aircraft. On the other hand everybody knew an unreported overspeed would be the fastest way out of the school and rightly so.

In sweden a R22 goes for 4000 SEK which is $516 USD per hour, or 308 GBP per hour.

Does anyone have a higher rate?

hey kates,

is that dual training or self fly hire?

r22 rotor stall
 

I have a question that has been bugging me perhaps you guys can help.

In the R22 POH it states that “In the event of low RPM (indicated by horn and light I presume) the pilot must first roll on throttle and lower collective simultaneously to recover RPM before investigating problem”

I can not understand why the manual does not tell you to enter autorotation immediately as I thought that you only had 1 second to react to an engine failure. A low RPM horn and light could also indicate an engine failure. Why not enter auto and then investigate?

My question is

1 In flight how do decide whether to enter autorotation or roll throttle and lower collective given that you have one second to make your mind up?

2. How many of you have experienced the low RPM and light activating in flight? What were the conditions? How often have you experienced it?

Thanks

Raven2
:)

I'll pass on what I still remember Dick Sanford saying on the R22 Safety Course.

In the event of engine failure, you will get a violent yaw to the left. That is apparently the most obvious sign, so if you get that AND the horn, then enter auto-rotation immediately. But what Dick said was that there are other reasons for low rotor RPM. The most common one is over-riding the governor. He gave a likely scenario...you're on a cross country, the weather starts closing in, you're not sure where you are and perhaps a bit worried about your endurance. You start to worry and get tense, which means you grip the collective too hard and inadvertantly over-ride the governor. The next thing you know is the horn goes off. Already stressed, you enter auto-rotation...

He said there had been accidents from unsuccessful attempted forced landings in this sort of situation. So what he told us was: if the horn goes off, with no other indications, roll on throttle and flare. The flare will raise the RPM anyway, thereby giving you slightly longer to see if it works, or if you really do need to enter auto-rotation.

The only time I've experienced the horn and going off in flight is during governor-off training. You might say that doesn't count. However, it is also a good thing to practise (with an instructor, not allowed otherwise), just so that you don't immediately panic as soon as the horn goes off. Governor failure is of course another possible cause of low RRPM, and I gather is not unknown...if something can fail, then one day it will.

I hope that helps. And if you haven't been on a Robinson Safety Course, I'd highly recommend it; one of the best things I've ever done.

Raven,
The reason for your confusion is your predisposition to think that the rpm is low because the engine failed. Remember that rpm drops when the demand for power is more than the power you have.

The demand for power is determined by many things, but collective setting is primary. As written, the rpm recovery procedure is telling you to demand less power (lower collective) and be sure you are at high throttle (increase throttle).

This procedure has nothing to do with autorotaion, in other words. The British term for the condition is overpitching, a really good way to say you are asking for more power than the engine can deliver, and so you are dragging the rotor down.

In a hover, this is a nice way to start an LTE event (I do not like that term, but it is with us). This means you are likely to hit the pedal stops during an overpitch because you have now demanded max power (max main torque means max tail torque to counter it) and at the same time you have limited the tail rotor thrust because the rpm is reduced (and rotor thrust is reduced by the square of the rpm).

Helibiggles

Judging by a recent discussion in this forum about training in the UK, the R22 rental price you quote doesn't seem very different from prices in the UK.

Training in an R22 here costs about £210 pr/hr plus tax.
Fuel is very expensive because of our extremely high fuel tax, and FI costs are about £40 pr/hr even for a newly qualified QFI with nothing like the 17000 hours you mention.

£170 for an R22 + £40 for the FI plus tax @ 17.5% = £246.75 per hour. :eek:

Not surprisingly, if family/work commitments allow, many Brits train in America where fuel is much cheaper and FI hourly rates are less than half here.

4000 SEK is dual

Self hire is 3200 SEK, wich is 246 GBP or 449 USD. This however includes fuel and insurance.

doesnt sound too bad, the true cost of r22 rental in the western us would be about 220for dual instruction.

rb

Just for information:
R22 in Spain around 300€/h flight training with instructor