R22 Power Check

[ChopperJ]

Since confined area landings are now required for the private license I was wondering how CFIs out there are teaching the power check in an R22. I am familiar with the power check in a 300CB but with the manifold pressure limitation in the R22 how is this done? Is it just an OGE hover?

[Helibear]

500 ft AGL, 50 KIAS, carb heat set for landing.

Note MAP as base.

Estimate PA and temp at the Spot, check chart for max. MAP

If the difference is 5" or more - go for it

 

That´s how I learned it.

 

Rainer

[klasmartin]

The way they taught us is to fly at 53KIAS and check your MAP.

 

If the difference between your max takeoff MAP and the MAP noted while flying at 53KIAS is:

 

7" = vertical descent / climb out

6" = HOGE

5" = HIGE

4" = 0 speed landing

3" = run on landing

 

Check out this site, some good info on flying the 22:

 

http://www.r22helicopters.com/tech25.html

 

http://www.r22helicopters.com/tech.html

 

 

 

 

 

 

 

 

quote name='Helibear' date='May 26 2006, 10:37 ' post='29946']

500 ft AGL, 50 KIAS, carb heat set for landing.

Note MAP as base.

Estimate PA and temp at the Spot, check chart for max. MAP

If the difference is 5" or more - go for it

 

That´s how I learned it.

 

Rainer

[volition]

Wow!! I learned it very diffirent. 50 feet, 30knots, carb cold, vsi 500feet=go to go, 400feet........and so on.

[joker]

500 ft AGL, 50 KIAS, carb heat set for landing.

Note MAP as base.

Estimate PA and temp at the Spot, check chart for max. MAP

If the difference is 5" or more - go for it

 

These are nice figures, Helibear. But could you use this in a checkride? Same goes for those ones who say, IGE hover, then add 5" or 6" and that sort of thing.

 

Let me state first of all that I was also taught (and taught) these very good rules of thumb.

 

However, an FAA examiner (one of those pedantic types) asked my student during a checkride, "Where do you get your 'power check' data from. Show me the figures in any flight manual."

 

Of course my student couldn't answer with anything better than,"They are 'rules of thumb' that my instructor taught me." Well, not a fail, but certainly picked up during the debrief.

 

After the debrief, I followed up on this with the examiner. We got into a lengthy conversation about what is a power check. Which methods are arguable (not proven data) and which methods are infalliable.

 

Food for thought!

 

Joker

[Sebas]

Joker,

 

Can you tell us what the examiners method was?

 

These are nice figures, Helibear. But could you use this in a checkride? Same goes for those ones who say, IGE hover, then add 5" or 6" and that sort of thing.

 

Let me state first of all that I was also taught (and taught) these very good rules of thumb.

 

However, an FAA examiner (one of those pedantic types) asked my student during a checkride, "Where do you get your 'power check' data from. Show me the figures in any flight manual."

 

Of course my student couldn't answer with anything better than,"They are 'rules of thumb' that my instructor taught me." Well, not a fail, but certainly picked up during the debrief.

 

After the debrief, I followed up on this with the examiner. We got into a lengthy conversation about what is a power check. Which methods are arguable (not proven data) and which methods are infalliable.

 

Food for thought!

 

Joker

[flingwing206]

Joker,

 

Can you tell us what the examiners method was?

Not Joker, but...

 

The performance charts in the PFM are the only "approved" means of calculating (predicting) performance. When you go beyond piston trainers, the PFM also (usually) contains approved methods for determining the actual power available (so you know if your calculations are meaningful).

[joker]

Thanks Fling!

 

As usual, Fling is seeing where I'm going with this.

 

Just to answer the original question first...

 

I am familiar with the power check in a 300CB but with the manifold pressure limitation in the R22 how is this done?

You would do the same procedure as you would with the 300CB, but instead of rolling throttle all the way to the stop (to find max power) you use the chart figure as the max power.

 

As I said before, I don't want to alarm anyone who uses the +5" / +6" type of method! They are pretty well tried and tested and make good rules of thumb.

 

The point that the examiner was making was this.

 

The PFM has the only approved data for performance. Quoting 'Cylic & Collective' or your instructor isn't good enough! (Interestingly, note how little the Helicopter Flying Manual says about power checks!)

 

As Fling said, many turbine aircraft have performance charts detailed enough to calculate accurately the performance you'll have for different takeoff profiles, for different winds and for different situations. That is getting into the realms of Cat A/B Performance aircraft. For example, the for the Cat A vertical departure profile we do here, we have charts which tell us exactly how high to go and how much TQ or N1 to pull, how many degrees nose down we should use when rotating, and how much drop down we'd have if we had an engine failure at the critical decision point. That in turn tells us exactly the height of the obstacles we can have around us...etc..etc...

 

Anyway, all too often he would see people who were blurting out the +5s and +6s without really knowing much about them and more importantly their limitations..like I said - sometimes they were just numbers their instructors had told them to learn.

 

For example, a common one is for people to do a hover check before they depart. Well this is good (and should be done prior to every takeoff), but to use the 'data' you found during that check for a confined area might be very misleading.

 

Let's say you are just about to depart your local airfield. You turn into the wind (about 15kts) and you do your usual hover check and find that you are hovering with say 19". Can you spot the problem? In a confined area, you can't count on a wind (due to it being a confined area). At your departure hover check, you had some translational lift, which would give you a lower than normal MP. Another point is that your local field might not have the same density altitude (temperature and pressure) as your confined area.

 

So what about the '53kts, then max power - and check the difference method'. Well, if this is done closer to your confined area, say when just approaching before your high recon, it is a pretty accurate measurement for the conditions. I like this method and would use it myself (if I knew the aircraft well enough.) However, you still have a translational lift, which you wouldn't have in a hover. If you've ever flown aircraft with torque gauges, you'll notice how much difference translational lift makes a difference.

 

None of these checks take into account any 'recirculation' that might occur (which will increase induced flow). Nor do they take into account that you might have a crosswind (due to obstacles on your departure path) which would necessitate power to the tailrotor (if from the wrong side). Or there could even be swirling winds within the confined area which put you in a tailwind situation at the critically wrong moment!

 

Also, the R22 charts do not have any data for any takeoff profile other than the HV diagram which shows a standard departure with climbout at 50-55kts.

 

Lastly, there are some issues which of course must be considered, when departing from a confined area. Most of all, the issue of the engine failure, which in a single engine is pretty drastic! Having +7" might impress the women, but if your vertical climb is high, then you expose yourself to the HV curve for longer and strain the engine for longer. Maybe electing for a larger space where you can get some speed up sooner and / or have a reject area would be wiser.

 

So getting back to this 'pedantic' examiner. We discussed for ages, and eventually decided that the only way to know if you have sufficient power (assuming you'll need a vertical takeoff) is to do an OGE hover and check that MP against your chart (or max available).

 

The main point that came up was to ensure that students can not only apply the numbers +5/+6 etc..etc.., but also understand the limitations of these methods of checking power.

 

I hope this helps,...if only to get people thinking about the management of power during the confined areas and not just 'regurgitating' the numbers. (BTW, I'm not saying that anyone here was doing that! !)

 

Joker

 

P.S. Just a couple of other points to think about.

 

Wow!! I learned it very diffirent. 50 feet, 30knots, carb cold, vsi 500feet=go to go, 400feet........and so on.

Volition, can you explain this further? I'm not sure I understand.

 

Klas, those weblinks are great...a lot of excellent information. Thanks! When are we going to have a beer!

 

500 ft AGL, 50 KIAS, carb heat set for landing.

Why carb heat set for landing? If there was one landing where I'd definitely have the carb off, it would be a confined area one! Why 50kts?

 

HeloJVB, how were you taught to do it in the 300CB?

[West Coaster]

So getting back to this 'pedantic' examiner. We discussed for ages, and eventually decided that the only way to know if you have sufficient power (assuming you'll need a vertical takeoff) is to do an OGE hover and check that MP against your chart (or max available).

 

That's pretty much how I was taught it.

 

If the confined area was a fairly flat area we'd pull into an OGE hover maybe 30-50' above the trees, then compare what MP we were pulling compared to max for the conditions. If it was an area on a slope or a pinnacle, then we'd hover OGE downhill from the spot at roughly the same altitude ASL as our intended landing point, and again compare MPs.

 

If of course we found we couldn't hover OGE in either scenerio, we'd reevaluate the spot and ponder other depature profiles available for it.

 

Used to love getting into a confined area we could easily get out of, then the instructor would point to a lone 150' pine tree and tell me to clear that instead of the 50' ones surrounding the area. I'd kinda shudder at the thought, and then he'd say "By the way, let's assume you can only pull 23" MP today... have fun!"

[klasmartin]

Klas, those weblinks are great...a lot of excellent information. Thanks! When are we going to have a beer!

 

I found that website quite useful when I was doing my training and still reference it to brush up.

 

As for the beer, I'm in the states right now and won't be back until early July but we can try and hook up after that, maybe at the aviation club? I'm actually heading down to HAI Titusville to try and do some cross country training this weekend since I can't do it in Hong Kong.

 

Regards

[Goldy]

Someone asked about "why carb heat set for landing". this is a requirement in the Robbie22...due to the failure of their engineers to fully understand the effect of venturi's...it's required whenever you drop MP below 18 "..(just my politically incorrect opinion of course) !

[joker]

Thanks Goldy!

 

I was wondering if anyone would pick up on this? (Said with a mischeivous grin )

 

The original statement was:

 

"Carb Heat Set for Landing"

 

For some time during my training, I thought you had to land with Carb Heat on too. This was until someone (an instructor or examiner possibly) asked me exactly this same question...."why carb heat for landing?" At that moment, I realised that I had the 'rote' learning, but not the understanding. So I went away, gave it some thought and did some research.

 

After that, I changed my 'check call' to "Carb Heat Set As Required" rather than 'Carb Heat set for landing'.

 

Here's my thinking:

 

First of all, the use of Carb Heat is not in the limitations unless you get to the yellow arc of the CHT (and you suspect carb icing conditions!). Then you must avoid that range with carb heat. All other metion of the Carb Heat is in the 'Normal Procedures' section of the POH. In this 'Normal Procedures' section, the 'Approach and Landing' chapter (4-12) says nothing about Use of Carb Heat. In fact the use of the Carb Heat is contained in its own sections.

 

So actually, the Robinson POH doesn't make the use of carb heat a 'requirement' for landing, does it?

 

Secondly, ask yourself if 'Confined Area Ops' can actually be considered as a 'Normal Procedure'. I don't think so.

 

Thirdly, (and most pertinent) is this:

 

Here is the paragraph about the use of Carb Heat, typed out in full.

 

USE OF CARBURETOR HEAT

 

When conditions conducive to carburetor ice are known or suspected to exist , such as fog, rain, high humidity, or when operating near water, use carburetor heat as follows:

 

At power settings above 18 inches MAP, apply carburetor heat as required to keep CAT gage (sic) needle out of the yellow arc.

At power settings below 18 inches MAP, ignore gage and apply full carburetor heat (CAT gage does not indicate correct carburetor temperature below 18 inches MAP).

 

CAUTION

 

The pilot may be unaware of carburetor ice formation as the govenor will automatically increase throttle and maintain constant manifold pressure and RPM. Therefore, the pilot must apply carburetor heat as required whenever icing conditions are suspected.

 

So the first paragraph says it all. If you do not suspect icing conditions (see caution) are you advised / required to use carb heat? Nope. The first paragraph and the caution both suggest that this whole chapter relates to times only when you suspect icing conditions!

 

Now then...that is what the book says. Now onto what is wise!

 

We all know from our friend Boyle, that if we suddenly reduce the pressure of the air in the venturi (by closing the butterfly) then we do get a reduction in temperature. Also, the almost-closed throttle valve will cause a massive pressure differential on the back side, which would also cool the air. This, in some cases, could cause some icing. So yes, it would be wise to apply carb heat every major reduction of power. What does it matter anyway? You don't need that power then as you are descending! And it would be prudent to leave it on any time the venturi is 'almost closed' say 18 inches!

 

In some cases for the landing with carb heat may be advisable too, if you suspect carb icing conditions. Most of the time, landing with carb heat on is not a problem.

 

But we also know that as we make our descent, we also slow down. In fact, at 53kts we get on the other side of the power curve, and actually start applying throttle. Particularly so during a steep approach (such as those used to get into confined areas). So at this point, wouldn't it be acceptable to reduce the carb heat? (This is exactly what the 'Carb Heat Assist' does, of course.)

 

Remember we are talking about 'what is wise' now. When doing a confined area approach on a hot and sunny day, fully laden with pax and bags, power is going to be my number one concern, not carb icing.

 

The last thing I want is to find myself falling through, risking SWP or simply hard landing as I get below the tree line or lose ETL, simply because I don't have the power.

 

How does the carb heat factor into this? Well, I know that at the last part of the confined area approach, I am going to be almost at max power. The air will be at its densist and hottest there too. All of these reduce the likelihood of carb icing. If there weren't carb icing conditions high up in cruise, then there sure won't be down by the surface. So, the last thing I need is carb heat which will reduce the power of the engine. Especially since I had carb heat on for the entire descent, I don't 'suspect' carb icing at the end of my approach when bringing in power.

 

Another consideration is the possiblity of having to go around, which is more likely during a confined area. You might find that your 'high-recon' is was not so good, and during your approach you suddenly see that the confined area is full of furry little animals. In deciding to go around I need all the power I have.

 

Lastly, as Fling points out below, there are times when there isn't moisture in the air. No need for carb heat then!

 

So, the point of all this is....during most approaches (and especially confined area approaches), I will turn the carb heat off during the last part of my descent (about 200-300' AGL or decision height). I do not intend to land with the carb heat on. Hence the reason why I don't call, "CARB HEAT SET FOR LANDING" anymore!

 

Some people (instructors) may disagree with what I typed here, but I hope it makes sense. Any comments welcome!

 

Joker

 

P.S. A similar case is where a student will intend to make a cruise descent (without reducing power) and still apply carb heat! Is this showing rote or understanding?

 

P.P.S Here's an article I found from Rotor & Wing. Read the article, asking yourself how the use of carb heat at the wrong time may have worsened the situation. Read the conclusions at the end...particularly the 'Know Your Aircraft' paragraph. Rotor & Wing Article

 

Disclaimer: There have been horrific accidents in the past due to incorrect use of carburetor heat (in most cases the lack of carb heat and subsequent carb icing). The information I have typed here is my opinion only. Always trust the guidance of your instructor and the approved flight manual (including pertinent Safety Notices). Joker

[flingwing206]

Heck, I've had CFIs who insisted on applying carb heat in cruise on a clear blue and frozen Minnesota day "to keep the carb heat out of the yellow". Never mind the fact that there was almost no moisture in the air, and that the air was at -15C before it ever met the carb...

 

However, it is a relatively easy matter to adjust the carb heat on an R22 in the terminal part of an approach. Not so with a 300CB, especially if you are lucky enough to be flying a left-PIC version with a 6-year old kid in the middle seat and his dad in the right while doing rides on a showery, humid 90-degree day. Hmmm. Friction the collective at 50' AGL and reach across, or grip the cyclic between your knees while you do a ju-jitsu lightning strike for the carb heat lever.

 

Ahhh, these are the days!

[Helibear]

Hi guys,

 

I wrote

"Carb heat set for landing"

 

I didn´t said that I want to land with full carb heat, the discussion was about the power check.

Where I do my training we have mostly condition in which carb ice can be expected, so usually I would ably full carb heat when flying with 50 - 55 Knots because MAP would be below 18 ".

For the power check we don´t want to have full carb heat, because we don´t use full carb heat for landing.

 

But the POH tells us that the carb heat should be out of the yellow arc all the time. So, yes sometimes I do use a little carb heat even during the landing, depending on the hole situation.

 

I guess that´s the reason why our maneuver guide tells us "carb heat for landing"

Do the Power check with a carb heat setting you expect to use during the landing.

 

Hope this clears the thing up.

 

Rainer

[Worldcrime]

So after I lose power and crash on approach to a confined area because i did not have any carb heat on I'll be so thrilled that I had soooo much power on my approach before the engine quit. Hello. Use the performance charts in ref to power required. Keep copies on your kneeboard. Carb heat on below 18" MP, carb heat off at 75 feet on descent.

[joker]

So after I lose power and crash on approach to a confined area because i did not have any carb heat on I'll be so thrilled that I had soooo much power on my approach before the engine quit. Hello. Use the performance charts in ref to power required. Keep copies on your kneeboard. Carb heat on below 18" MP, carb heat off at 75 feet on descent.

 

 

Worldcrime, before you completely twist my meaning....

 

You talk as if carb icing occurs the moment the collective goes below 18"!

 

All that Robinson are saying is that the gague cannot be reliable below 18" and so IF THERE ARE CARB ICING CONDITIONS SUSPECTED you should have carb heat applied.

 

Use the performance charts in ref to power required.

100% Agreed. Infact if you look at my earlier post, you'll notice this is what I was saying all along, about the Power Check.

 

Keep copies on your kneeboard.

Good idea!

 

Carb heat on below 18" MP<>carb heat off at 75 feet on descent.

Well, which is it? What if you're below 18" AND below 75 feet? BTW, isn't this pretty much what I suggested?

 

Actually, if you read my post carefully, I have not suggested that anyone risk carb icing in order to gain extra power for the confined area. Hello! There bolded just in it wasn't obvious!

[Worldcrime]

Worldcrime, before you completely twist my meaning....

 

You talk as if carb icing occurs the moment the collective goes below 18"!

 

All that Robinson are saying is that the gague cannot be reliable below 18" and so IF THERE ARE CARB ICING CONDITIONS SUSPECTED you should have carb heat applied.

 

100% Agreed. Infact if you look at my earlier post, you'll notice this is what I was saying all along, about the Power Check.

 

Good idea!

 

Well, which is it? What if you're below 18" AND below 75 feet? BTW, isn't this pretty much what I suggested?

 

Actually, if you read my post carefully, I have not suggested that anyone risk carb icing in order to gain extra power for the confined area. Hello! There bolded just in it wasn't obvious!

 

Well said.

Point taken about icing the moment the collective goes down.

I was not piling on just makin a comment..

Fly safe.

[Goldy]

Hey Joker- I love that my 3 sentence response generated a 3 pager !

Yes, I stand corrected, below 18 inches only when conditions for carb ice exist. My real point was this....we can send men to the moon, but we cannot accurately measure temperature within a carb? Something is wrong with that. Gee, I think they invented fuel injection about 50 years ago ???

 

Goldy

[jimbo2181]

What about the real world way? Try it and if you don't like it, don't do it. Or if you know you shouldn't try it...don't. Getting too caught up in figures. I don't know any examiner that would fault you if you said A) the performance chart says we can't do it so we aren't going to or the performance chart says we CAN do it but I didn't like my available power on the approach so pick a new spot.

[Little Red 22]

Has anyone ever experienced a malfunctioning MAP gauge? My CFI thinks the MAP is reading on the "high" side, and that the gauge is getting old. This particular R22 is an old ship with just over 200+ hours after it's second rebuild. The gauge is original.

 

Susie

[Pohi]

If it is not the gauge, it might be the sensing line from the manifold that is leaking, where I have seen it most is the fitting right on the engine. Usually, however, in the situations where it started to leak significantly the manifold pressure gauge showed really high when power was applied.

 

It might be worth checking before you replace the gauge.

[Little Red 22]

Yes, the MP appears normal at cruise but is too high in the hover.

 

Thanks for the info.

[kodoz]

What's the MAP showing before start-up? Shouldn't it be close to what your altimeter setting is?

[joker]

Have a read of this document.

 

http://www.advancedpilot.com/downloads/prep.pdf

And here is a thread I was involved in a long time ago! Those were the days, when I could busy myself online for hours on end.

 

http://helicopterforum.verticalreference.com/topic/3786-general-knowledge-question-get-yer-brains-working/

[r22butters]

Yes, the MP appears normal at cruise but is too high in the hover.

 

Perhaps your CFI has gained a little weight and doesn't want to admit it?

 

On the last overhaul, did the engine get new cylinders, or were they just honed?