Robinson R44

[rotorfossil]

Robinson Tailboom chops

Years of teaching and examining in Robinsons convinces me that whereas tailboom strikes have undoubtedly occurred due to the low 'g' scenario, and in two cases, probably when the phenomenon was being demonstrated, this is not the main initiator. In my view the sequence is almost invariably- loss of power, "what the hell is that", lowering the collective far too late (if at all) and too slowly. Result - rotor stall, rotor blowback, chop tail off - die. I am further convinced that the main reason for the loss of power (and the lack of evidence) is almost always down to carb icing due to incorrect handling of the carb heat. Under pressure, this aspect of handling seems to be the item that is most neglected, exacerbated by over reliance on the carb heat assist, the governor masking the power loss and the fact that helicopter engines without the benefit of a prop, quit running more suddenly and with less warning. Answer - GET THE LEVER DOWN BLOODY QUICK if it all goes quiet. If you wait to say "O Christ", you can't lower it too quickly.

[killahertz]

44 options

hi,
a group of us are about to place an order for a rob 44 raven 2 very soon,its for private use only. any advice on what (if any) extra's to load the ship with? there are plenty to choose from on the options list.am sure there are many expierenced piots/operators that would have some CONSTRUCTIVE advice.

thanks,
kh

[float test]

go an order one from mike smith at heliair, he will tell you everything you will need to know

[blave]

Having just flown a Raven I across the US, I found the GNS530 to be a tremendous help. It's hard to consult a paper map all of the time while sticking a helo around, and just having the various types of airspace (military, restricted, etc.) represented on the screen was very handy.

The 530 *is* a bit of overkill since it's an IFR approach GPS, but (if you get the full IFR panel) then the ship could be used for GPS approach training.

I personally also think that a helicopter should have an attitude indicator, just in case things go pear-shaped wx-wize too quickly. The high-timers might disagree with this assertion, but if I'm ever fortunate enough to buy my own ship I'll be looking for one with an AI, or else put one in.

Dave Blevins

[helicopter-redeye]

Extras, Extras

Order the machine with a ten hole panel (these can be fitted to standard machines now) 'just in case' you want more holes later.

Garmin 430 (nav/ com) + a Bendix King KX165 with glideslope (just in case for later). This gives you two radios and two sets of nav boxes for NDB and VOR/LOC/ GS.

If you feel like spending money fit a Bendix King HSI for radio navigation use. If getting a VOR/LOC to go with the KX165 get a VOR/LOC/GS indicator instead (just in case)

As a backup and etc fit a Skymap IIIC Topo on the panel top.

Fit an ELT for overwater use out of Eire ...

.. and four point front belts for the harness.

.. and a spare eyeball (to spot jets) and monkey chow (sorry, dropped into Buzz Lightyear speak then, you have to know the film to appreciate the point) ...

h-r

[killahertz]

folks,
thanks for the help, lots there to consider but all very usefull.

thanks again.
kh

[Hairyplane]

CARB ICING

The onset of carb icing is likley to be masked initially by the governor compensating for power loss by automatically opening the throttle.

The flywheel effect achieved with a propeller bolted to the engine will give you plenty of warning of ice-induced power loss. The prop will also continue to turn the engine for you while you finally decide what has happened, pull the carb heat out, leave it out and hope that the think will pick up again.In the heli we dont have this comfort, it will likely quit without warning.

I enjoyed the R22 and found myself using more heat than necessary. However, I would rather suffer a slight power loss and excessive fuel consumption than risk engine failure through carb icing.

I have found the contributions here very useful indeed thank you and feel more confident as a result.

I hope to be flying my new Raven 2 within the next couple of weeks and plan to be very, very careful with it.

HP

[bladewashout]

With your nice R44 raven II, you have fuel injection and no carb icing to worry about (unless you are very unlucky and get inlet icing!)

I am lightweight, 135lbs and find that solo I am often pulling only about 19" MAP. I tend to keep the carb heat on most of the time unless I know I am going to be cruising fast.

I am also paranoid and am trying to keep ingrained a habit of reaching down to pull up more heat every time I am making speed or power changes downwards, or look at the gauge and see it at sub 20".

I did read once that excessive use of carb heat can cause detonation, but I'm not sure that it is a problem in UK temperatures.

BW

[muffin]

Most of my rotary flying has been in R22 Betas without carb heat assist. Since I got my Beta 2 a few months ago, I have found the heat assist to be a nuisance. I monitor the temp very closely and always keep it over 10 deg. However, I find that with the assist function I am always having to pull the heat out some more. I know that you can flick the catch over and lock it out but have not done so. Increased fuel consumption is a very small negative considering the amount of money we are all burning anyway.

Could some of the experts comment on the benefits/disadvantages of leaving the heat full on all the time?

I also have a small Rotax engined kitplane which has its cooling water ducted round a jacket on the carb throat, thus heating the carb body all the time. This works a treat. No hot water in an R22 unfortunately!

[Gaseous]

Hi Muff.

The detonation thing is a myth.
Probably put about by the ill informed thinking that hotter induction means hotter combustion.
Not so. According to Lycoming, hot air will push the mixture even richer than it normally is which will lower the combustion temperature, pushing the engine away from the detonation zone. Your Robbie runs a mile away from detonation anyway unless you run on mogas or mess with the mixture which I know you dont, dont worry about it. The only downside to too much carb heat is the lowering of maximum available power. According to Lycoming, 15% power loss using full carb heat is possible. This may be a problem in your R22 with a fat pax and lots of fuel.
Keep working that carb heat knob.
Incidently, I agree. The Carb heat assist is worse than useless.

Cheers,

Phil

Edit: Lycoming do warn about detonation when using carb heat on LEANED engines.

They also say that in the cruise using full carb heat and a suitably monitored engine, detonation was never detected in their flight tests.

[Hairyplane]

Carb heat/ mixture

I was very nervous of the carb heat assist on some of my training 22's and tended to pull more.

I can't imagine a problem with excessive carb heat other than coming into the hover at high weights/ Density Altitude and forgetting to push the heat back in.

I was taught to push it in at around 300ft but felt more comfortable doing so much later, for reasons that should seem obvious to any operator of normaly aspirated engines.

Constant hot air is nothing new - I have Gipsy powered vintage fixed wing machines that operate in hot air at all throttle settings other than fully open - never a carb ice problem or even consideration in normal use.

Mixture - I cant imagine anyone leaning the mixture on a heli and feeling happy about it.

To lean an engine properly requires the pilot to find the 'lean of peak' setting. Whilst this will cause an engine driving a propeller to just splutter and cough it will stop a Robbo engine dead.

Touching the mixture is therefore tempting fate?

Happy with my choice of injected Raven 2 (despite not really needing the extra performance and having to cough up an extra $50k over the Raven 1...)

Hairyplane.

[Gaseous]

Hi H,
I have written loads on mixture/leaning in the past.

Mixture adjustment is standard procedure on suitably equipped Enstroms and I always lean. Usually to 80-90 degrees lean of peak. Although this degree of leaning is outside the POH advisory limit, it it the best way to run a Lycoming. The injection system on my aircraft had to have a lot of work to get it to run smoothly at this mixture but it is now dead smooth to 100 degrees lean. If you go too far there is an increasing roughness and power loss way before the engine cuts dead - and yes I have done it.

On the contrary I don't feel happy running full rich. it wastes fuel, makes the engine run hot and clogs up the valve guides with crap. Cockpit carbon monoxide levels drop from 30 ppm to zero when lean. (I carry a digital detector) Fuel consumption drops from 14 to 10 usg/hour. A useful increase in range.

Running a carb Robbie lean is not possible as the mixture distribution is too poor. The injected Raven is ideal to run lean but unfortunately is not suitably equipped and you aren't going to get approval to modify it. You have no choice but to run full rich.

The risk with leaning is the brainstorm that makes you pull the knob when you want to go full rich. The silence is such a surprise and yes, I have done that as well, followed by an airborne restart.

Proper leaning and engine management of a piston heli is certainly possible but is not for the feint hearted or inexperienced.

Get it wrong and you will destroy your engine. Get it right and it turns the Lycoming into just about the most fuel efficient gasoline piston engine on the planet including modern automotive designs.

Quite a few Ppruners have flown with me and non have asked to get out when I do the lean bit.

[Hairyplane]

Leaning

Hi Gaseous,

Interesting stuff.

Without any reliable method to find 'lean of peak' I'll leave well alone and guess that most heli pilots will do the same.

The prospect of wrecking the engine ( at least) just to save a few quid doesn't gel with me. Also, whilst I accept that these engines run too rich I dont believe that there is any risk of long term damage to anything other than the plugs

I have an EDM700 in my Robin 180 ( Lycoming 360) with a 'lean find' mode. In the early days I used to go through the 'lean find' exercise only to find that the optimum setting for anything below 5000ft was pretty much full rich anyway so I dont bother now.

At 500 hours from new the engine is as sweet as the day I took delivery of the aircraft.

I am also very happy with the 40 litres per hour it burns. 'Saving a tenner' on a long trip has too many downsides for me. The heli is a whole new ball game with sudden engine failure likely to be the first indication that you pulled the knob out too far.

Happy to accept your reasons and logic - it just isnt for me ( especially with only 46 hours tt in my heli logbook).

All the best and thanks again for the fascinating posts. As a newbie I have found them extremely helpful.


Hairyplane

[Gaseous]

Hi H,
Enstroms are equipped with graphic engine monitors with EGT sensors which make it feasable to run lean. You are quite right that without this, and vernier mixture adjustment, and experience, and training leaning should not be attempted.

In terms of engine life, Enstroms seldom make TBO as most pilots do not run them at optimum mixtures. (in my opinion). Often they do not make more than 400 hours without a top end overhaul!!

A correctly managed engine will last longer than one thats run full rich all the time. As likely as not it will do 1500 lean hours no problem.

Full rich, valve gear is usually first to fail due to stem fouling. Bearing loads are higher when full rich and oil contamination is worse. Temperatures are hotter. All these things shorten engine life.

All that said, without the right equipment, training and experience, DO NOT mess with the mixture.

I wouldn't lean a Robbie either.

Your Robin lean find technique is probably not ideal. You need to be on the other side of peak. Check out John Deakins 'Pelicans perch' writings on AVweb. Maybe your Robin's mixture distribution is too poor to run lean. That can happen, even with injection.

Its not just about saving a tenner. It also allows my helicopter a 30% increase in range or an increase in payload by not needing extra fuel, which is worth more than money, as well as all the other benefits.

Sudden engine engine failure is not an issue with a vernier mixture adjustment as if you do go too far, the heli will warn you in good time by increasing roughness and gradual power loss with yaw. You just bang the mixture back to rich and do it again.

Cheers

Phil

[qwerty300]

Governor Runaway Up

A pilot reports a governor runaway on a R44.
During the resulting overspeed inspections, no damage was found (thankfully!). However, when the magnetos were stripped several of the points on the right-hand magneto were in a very sorry state, one in particular, and so have been replaced.

Question is, would this have caused the governor overspeed?

[bladewashout]

As I understand it, the governor works off the magneto so if it detects a lower rate of output signals than it expects, it will increase the throttle to compensate.

A faulty magneto contact may not generate a signal, hence yes, it could be the cause.

BW

[Mongrel Dog]

qwerty: Yep both mags have two sets of points. The second set in the LH mag retards the timing for starting and the RH mag has the tacho points which is one of the inputs into the governer controller. If these points close up the gov won't work.

quindici: I've never seen anyone try to repair a damaged stabilizer, but I expect a decent sheety would be able to give it a good dab. Easier to replace in my opinion. The upper and lower vertical stabs unbolt and remove and the horizontal one can be replaced individually. Expect to pay a rediculous price. Can look it up on Monday if you like and let you know.

[helicopter-redeye]

44 Tail Horiz Stab

It will be a while before its looked at, in the meantime to satisfy depressive curiosity are these generally non-repairable parts

Correct, it is non repairable (if you want to buy a bust one I have one in the garage ...)

The whole Horizontal tail stab to replace in the UK is :-

To Remove Stabiliser Assy, Dismantle, Inspect and Reassemble with New Horizontal Stabiliser £ 170.00
To Paint Strip Crack, Check and Repaint as Required £ 170.00

Time Spent to Travel to Sheffield Airport and Inspect & Return

2 Hrs + 50 miles @ .42p/mile £ 106.00

Cost of new Stabilizer & Hardware £ 1,495.88

This includes and engineer driving 40 miles rtd to inspect and patch up the ripped end before the machine was flown into maintenance.

The cost of the parts and labour were not the issue. It was the month it took to get the parts from RHC during peak flying time (total revenue loss £5800) and then the time spent arguing with a certain airport to get them to pay up for the damage they caused.

In the end we reclaimed the cost of the work and parts, and consequential loss and recalimed all based charges paid while out of action and off site (all thanks to AOPA who helped).

So if you bust it you have the cost. If somebody else did it then you know the drill ....

h-r

[WLM]

We have a Raven I with 900 hours TT. I got a new canopy cover made about 6 months ago using the old one as original pattern. A few weeks ago I noticed a few spots (small bubble type) showing up on the bottom of the doors. Now it is all over the front and side of the aircraft, looking like a type of white chicken pox... Pierced one bubble expecting to see water maybe but nothing. SO is this a result of high condensation under the canopy cover (Tropical Moonson weather) or simply a case of faulty factory painting? Has anybody else experienced it?

[Gaseous]

I have seen this before . Usually due to contamination of the prepared surface before the paint is applied.(see the dirty blade thread about the evils of silicone polish) Occasionally it is due to incompatible paint chemistry but this should not be a problem with a new aircraft!

Is it just paint or is the gel coat blistered? I have also seen this happen and is again a production fault.

Covering paint with a canopy will not harm it if it is properly applied, however hot, wet or cold it is.

You imply it has not been resprayed so Robinson is responsible. I bet they try to blame you though.