AAIB Feb 2004
 

Februarys AAIB Bulletin is out.

Just seems to be this one helicopter related, this month.

http://www.aaib.gov.uk/publications/...ta__g_bytd.cfm

V.

extract from the report:

>The aircraft ran on with sufficient force to break the skids off the aircraft at this point. Impact marks also indicate one of the rotors then hit the ground and that the aircraft rolled over, causing considerable damage and shattering the canopy,

Blimey! Thats sounds scary...

Day one at piston engine helicopter school - carb icing kills. Will people never learn?

You can teach some poeple what you like very time you fly with them but the day after they get their licence they think they know better, bring back aptitude test's I say.

How long will it remain defensible/ethical to produce helicopters with carburettors?

Gaseous,

It's the most defensible and ethical way to rid the world of idiot pilots unable to follow simple check lists.

Gaseous : is your knee jerking ? There's a crucial line in this report : "However, again, his relative inexperience lead to difficulties in controlling the aircraft and resulted in a heavy and fast run-on landing."

A 70-hr pilot.

A carburretor is the least of his problems. You might as well say that the collective, cyclic, pedals and throttle control shouldn't be there - and that the instruments are useless.

Any more incidents like this and we'll be getting our own version of SFAR 73 for all helicopters in the UK. Would that be a bad thing - forcing pilots to do more training up to, say, 150 hrs ?

Be good news for the schools and instructors :ok:

Unfortunate as such accidents are....

Hands up anyone who's never been inexperienced before they gained experience, and who's never made a mistake. :(

:ok: ME! Whirly.

I was born a natural, highly experienced helo pilot, but by the age of 10 I was down to being merely mediocre. By 20 I was described as adequate, and by 30 people would just shake their heads and wonder how I got the damn thing off the ground never mind back down again.:(

Oh the ravishes of time….. :{

Hair

My, my, we are defensive arn't we. Certainly my knee jerks and my eyes water when I pay my insurance premiums. This is hardly the first R22 to suffer carb icing. This guy was put in a position where his experience was inadequate because the helicopter had not got fuel injection and he made an error. Had the aircraft had injection it would not have crashed. No carb, no ice problem.

The pilot did apply carb heat but not enough. Hands up anyone who flies an R22 and has never completed a descent and found they omitted the carb heat, but got away with it.

I haven't checked but I bet there are no Raven 2 carb ice incidents!

If injection is not required why did Frank bother to put it on the Raven2???

I'd save your energy if I was you. It's quite hard to get carb icing if there isn't a 'carb'... :E


But then, you already know that...:}


Because the Raven2 was designed specifically for hot and/or high operations. The Fuel Injectors are obviously going to give you more power than the 'carb' version. The lack of carb icing is an ancillary benefit. Or at least that's my understanding of the situation.


Regards,

B73

B73
I did know!

I would take issue with this.

The Fuel Injectors are obviously going to give you more power than the 'carb' version.

There are many more things (cam profiles, compression ratios, etc.) that determine power output than carb or FI. Not least where Frank paints the red line on the MAP gauge. (I know all about pressure/density altitude so don't come back with that).

Lycoming engines were developed for fixed wing and the primary reason for fuel injection is better fuel distribution to each cylinder which allows better leaning. As far as I know ( I dont fly one) this is not recommended with a Raven2. There is loads of information on leaning on the net.

I would suggest the main reason FI was put on the Raven 2 was avoidance of induction icing. Just my opinion.

Its a pretty good reason though.

Well Gaseous, somebody seems to have rattled your cage.

Without resorting to mudslinging, let me respond to a few of your points:

Exactly. Which is why I said: Of course there are. But I'm a great believer in the KISS principle (I need to be!). And, by and large, a FI version of the SAME engine will produce more power than the carb version.

Not only not recommended, but not allowed. (At least not during flight).

Of course it is but I'm afraid that's it's wrong. Frank needed more performance from the same engine so he chose the FI version. Even the Robinson website says as much: The Raven II is equipped with a fuel-injected, angle-valve, tuned-induction, IO-540 Lycoming engine which produces substantially more power and gives the Raven II greater altitude performance, more payload, and increased speed. (My emphasis). The lack of a carb icing problem is an ancillary benefit.

I'm by no means an expert on any of this but it's amazing what you learn on the RHC safety course...


Fly safe,

B73

Those who trouble to read it, will have noticed that for much of the last year GASCo's Flight Safety magazine has been having a "ban carb heating" campaign.

There are more than one way to do eliminate carb icing without a hot air carb heater, and FI is certainly one means. I can't help also noticing that it's almost impossible now to buy a "normally" carburated car any more, whilst small flying machines (with their ultra hi-tech 1950s technology engines) are still by and large using carbs.

Flying machine engines are, I'm afraid, a bit behind the drag curve !

G

OK Gaseous. You know everything.

Maybe.

Sadly the majority of new pilots don't. There are many things they need to know almost as a sixth sense - and the addition of carb heat in certain conditions is just one.
There are many things that could have caused this pilot to have his accident - he's just fortunate that his failed memory (or lack of training) didn't kill or seriously injure him.
We've all done it - we've all forgotten something.

Putting FI onto the R22 engine is an impossibility.

But educating pilots to follow a well-worn, effective procedure is easy.

It seems to have worked for the vast majority of R22 pilots for 25+ years.

Rattled, no. pedantic yes.

Im glad you don't resort to mudslinging as reasoned discussion is so much more productive.

Does leaning appear in the limitations section of the POH for a Raven2. It doesn't in my old Astro POH (old and out of date) so aint illegal. I still wouldn't do it in an Astro.

KISS? It is simpler and cheaper to put in higher compression pistons than to put FI on an engine if the sole intention is more power.

The Robinson website? He would say that wouldn't he. Lawyers can read too.

I wonder if the carb issue is one of the reasons we hear rumours about the cessation of R22 production. i.e cheaper to axe it than update it - and more profitable to produce injected Raven2s without the risk of litigation from icing victims and their families.

Incidently, Lycomings solution to hot and high is to turbocharge.

See the excellent Lycoming Flyer articles on their website.

HSHair.
Why could you not put FI on a R22?. Have you checked. Have a look at a HIO360C1A or C1B.

Is the obstacle engineering or certification and cost?

Quote

But educating pilots to follow a well-worn, effective procedure is easy.

Yeah Right. Thats why this is the first R22 carb icing incident ever.


(sarcasm - not mud!)

Yep, Gaseous knows everything. Apparently.

Does leaning appear in the limitations section of the POH? Unfortunately, I don't have a copy of the POH in front of me and I won't for the next couple of weeks as I'll be out of the country. Watch this space.

The KISS was in reference to my explanation (and thinking) rather than engine design. I haven't got an engineering background but higher compression pistons implies to me greater pressures in the cylinders. This, in turn, would require either a more substantial block to withstand these pressures (and hence more weight) or reduced reliability and higher maintenance requirements. Both of which are contrary to Robinson's design ethos. I, of course, stand to be corrected.

See the excellent Lycoming Flyer articles on their website. Have you got a link?

Incidently, Lycomings solution to hot and high is to turbocharge. Are you sure? My understanding (once again, I refer you to the last 'S' of KISS) is that turbocharging is still susceptible to a loss of performance with altitude. To avoid this, you've got to look at supercharging. Which is expensive, heavy and requires even more maintenance. (All contrary to Robinson's design ethos).

But anyway, let me sum up your argument if I may be so bold. In order to avoid carb icing and the associated problems, Robinson introduced the fuel injected Raven2. According to your argument, the ancillary benefits are increased power, altitude performance, payload, speed etc etc. And this was all part of some conspiracy to avoid litigation from icing victims and their families. Right?

Well, if that was so, WHY IS THE CARBURETTED RAVEN1 STILL AVAILABLE FOR SALE?????


And if I may also answer one of your points to headsethair:
But educating pilots to follow a well-worn, effective procedure is easy. Yeah Right. Thats why this is the first R22 carb icing incident ever. Well, unfortunately, there are still a lot of stupid/forgetful people flying helicopters. :sad:


Fly safe,

B73

So, hands up those that think injected engines don't suffer from icing! I think you just substitute the words 'carb icing' for 'intake icing' (albeit without the refrigeration effects).

B73. Enjoy your trip abroad.

I try to know about what I write.

Quote
"I haven't got an engineering background but higher compression pistons implies to me greater pressures in the cylinders. This, in turn, would require either a more substantial block to withstand these pressures---."

Er no, actually. Lycoming do make a variety of castings and forgings but basically they don't beef up the higher output engines by much in terms of weight. They do certainly alter them with modified oil systems, pistons, bearings and different ancillaries but the big lumps are basically the same. I seem to recall that since the crank fracturing episode a few years ago all 540s now use the strongest crankshaft. Im sure someone will correct me if this is not so. If you're really interested I could dig up some weights for different output 360s & 540s.

quote:
or reduced reliability.
Whats the difference between taking more power by adding FI(if that is what gives more power - see below) or changing the valve timing. Both increase volumetric efficiency and in lay terms, cylinder pressures. If you take out more power by whatever means, there is a penalty whatever Robinsons design ethos is.

Incidently, Lycoming do not cite increased power as a reason for using injection. They suggest lack of icing and fuel economy.

quote:
"Have you got a link?"
have you got a search engine link on your PC? I'll assume not so I have done it for you.

Its at the bottom.

quote:
turbocharging is still susceptible to a loss of performance with altitude. To avoid this, you've got to look at supercharging:

Er no actually.
From Lycoming flyer Page 62

In simple terms, the turbocharger provides an air pump which allows us to supply the engine with dense air not only at sea level, but also when operating in the thin air at altitude.

In a standard atmosphere at 10000 ft you aint going to get more than 20 ish inches of MAP without forced aspiration. FI doesnt help this and is no better in this respect than a carburettor.

quote
WHY IS THE CARBURETTED RAVEN1 STILL AVAILABLE FOR SALE?????

For how long?

What I do know is that society is getting more litigous. Vapourisation carb ice is a known problem that can cause death. It is avoidable by changing to fuel injection. Will these 3 facts kill off carburettor equipped Robinsons?

That was the point of my original post.

Personally I would like to see an injection equipped R22. It would then continue to be the world beating aircraft it has been for the past 25 years. The rotary world would be poorer without it as costs for training will soar.

Quote:
According to your argument, the ancillary benefits are increased power, altitude performance, payload, speed etc etc.

No, because none of these are as a result of simply adding FI according to Lycoming. The benefit is better mixture distribution giving better economy and no vapourisation icing. The 540 in a Raven2 must have more tweaks than just FI to get significantly more power.

Conspiracy?
No. I see it as sensible business practice to eliminate known risk where possible by product improvement. Robinson are a reputable company and I would expect no less from them.

Quote:
Well, unfortunately, there are still a lot of stupid/forgetful people flying helicopters.

Yes and I'm one of them. Thats one reason I bought a fuel injected helicopter.

212 man. True.

According to Lycoming (PP48 of Flyer)

"In the case of fuel injection and pressure carburettors, it is the IFR type of flight condition which generally causes induction system icing. "

I agree, fly safe

Phil


Seriously, all users of Lycoming engines would benefit from reading their Flyer series. There is a lot of information on carb icing, maintainence, engine managment and a whole lot more besides. I have the original paper prints but its all available at:


http://www.lycoming.textron.com/main...nts/index.html

Gaseous: adding FI to an R22 would have many problems - and I don't think anyone outside the Robinson factory has the qualification or experience to comment. Including me. I'm sure if you email Pat Cox or Frank, you'll get an answer.
But - cost, certification, weight, space are all on the menu I'm sure. The Raven II engine is very different from the I inside.

But it's this "automation" thing that gets me. If we were to follow your idea the whole way, we would have a fully-automatic helicopter which required nothing from the pilot other than, possibly, flight control input.

We have developed cars along these lines. Owners are coddled by technology - they don't need to scan instruments because there aren't any. They don't need to chnage gear, because they've got an auto box. They don't need to check any fluid levels because the car will tell them when it needs something. In safety, we've surrounded them with airbags and ABS.

Has this made motoring safer ? No. For some drivers it puts them into a "sitting room" environment and they stop paying attention. They get bored - so they fill their time making calls and listening to the ICE. They think they're bombproof with their safety devices - so they start to drive beyond the limit of their capabilities, thinking that the car will rescue them. People truly believe that airbags will save their life.

Transpose this to helicopters and lowtime PPLs and you have a recipe for disaster. Carb heat requirement means that a pilot has to do a regular instrument scan to check for the "yellow" arc. And he may spot something else going on. Additionally, awareness of carb heat requirements means that a whole string of information processes through the pilot's brain - OAT, MP, governor, aircraft performance. It keeps the mind on the job of flying.

I reinforce this argument with the CAA's argument on power failure. A battery must be capable of supplying the aircraft with full power for at least 10 minutes - because the CAA think thats how long it would take a PPL to spot the alternator fail light.

If all the instruments were simply reduced to an "on report" status, I'm not all certain that the cockpit would be a better place. (Yes - I know that's the way it's gone at the expensive end. And don't they all just love their FADECs and EFISs ? No.)