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-   -   R22 Corner (https://www.pprune.org/rotorheads/162839-r22-corner.html)

sprocket 5th November 2003 14:53

I think A/spat has the patent on the way composite blades are manufactured (the way they are wound etc).

Might cost Frank a pretty penny to manufacture and set up.

Head Turner 5th November 2003 16:32

Although I consider the R22 an ideal recreational vehicle, I believe that in the role of training and working it's caperbilities are stretched to close to the limits.
Flown within it's limits and in fine weather the construction is adequate. Metal blades should cope as designed.
The 300 still has metal blades.
So could the problem be that Franks rotor head isn't suitable with the metal blades and Hughes design of fully articulated is OK?

RDRickster 5th November 2003 19:58

I'm sure it's been discussed and researched at RHC, but then look at the enormous in-house assembly line and custom manufacturing machines. To make a change from metal to composites would require prototypes, testing, certification, new machines, validations, new quality control measures, new procedures, and retraining their entire staff... all read as big $$$ with little ROI. Frank isn't going to do that on an old ship that is already proven... he won't even retrofit blade caps (the ones put on the R44) to the R22.

headsethair 6th November 2003 00:18

There is some composite in the R44 blade. This is also a SS skinned item - and the R22 will have similar soon.

deeper 7th November 2003 08:40

New AD on R22
 
A new AD has Just been issued relating to the fatal accident in WA.

The AD requires owners to remove the MR yoke A907 and MR clutch shaft joint A166, and inspect the joint for wear.

The apparent failure of this part has been put forward as the cause of the accident.

It is being said that an incorrect coating was used in the assembly of the componet on this machine.

The correct coating is meant to be straight zinc chromate,
whereas the machine in question (and many others) was assembled using what is commonly referred to as cocky !!!!, a thicker version of the paint that does not dry out.

The two bolts that hold the yoke onto the clutch shaft have sheered off. the theory is that the thicker paint stopped the bolts from reaching the proper torque and over time, allowed the bolts to become loose in the yoke.

The AD requires the shaft and yoke to be disassembled and inspected whithin ten hours active from November 12th.

Lu Zuckerman 7th November 2003 10:36

Cocky Shit??????
 
Here is something to consider. The statement was made that the “Cocky !!!!” version of the Zinc Chromate paint does not dry out. There is a possibility that the paint served as a lubricant on the threads of the bolts in question and instead of the bolts coming loose they were instead overtorqued due to the slippery threads and the bolts sheared due to tensile overstress.

But then again who listens to an old man

:E :E

Travelling Toolbox 7th November 2003 10:56

here it is:

http://www.casa.gov.au/avreg/aircraf...22/R22-051.pdf

[/B]deeper[/B]

Where do you get "broken bolts" out of that?

alpinehelicopter 16th November 2003 22:24

R22 BETA II Power loss
 
Dear experienced R22-pilots,

together with a student, during a slowly hover-turn to the left, we had an hard landing following a sudden power loss (rpm-drop) in a R22 BETA II. The engine didn't stop.

Conditions:
ALT: 6400ft (pressure altitude)
TEMP: OAT at 47°F/8°C (at 6400ft); dew point about 32°F/0°C.
QNH: 1025hPa
Wind: calm
Weight (TOW): 1316lbs/597kg
Height: 1ft/0.3m above ground

What the Flight Manual says:
In the performance graphic (AFM) it is possible to hover up to 10'000ft/msl (PA) with the conditions (weight, temperature, pressure) we had that day.

What do you think about the power avaible from the engine?
Is this normal?
Should we check the engine?

Thanks for your help.

Dantruck 17th November 2003 00:17

Question:

Did the low rotor rpm horn sound/warning light illuminate?

Also, you give due point as 'about 0degC.' Suggest you get an aftercast and be more sure of the figure. If the dew point was closer to your OAT - 8degC - and even if it is not, you may have experienced carb-ice.

Ask yourself...was the governor switched on? The governor can mask the build-up of carb-ice in Robinsons by gradually opening the throttle to compensate for the reduced airflow through the carb. You only know you have a problem when it reaches full throttle and the power starts to drop fast.

Carb-ice is also likely if you had recently started the machine from cold?

Having said all that, you were close to max TOW, 1370lb from memory, so the throttle setting in nil wind conditions would already have been near the max, reducing the likelihood of carb-ice. In any case, any power drop, perceived or real, should be checked out thouroughly. Suggest you start with the mags, then the compression. You might have valve trouble or all manner of things. Get it checked by a Lycoming man, and if he's happy get the rest of the machine checked over by a Robo mechanic!

Dan

Johe02 17th November 2003 01:04

I don't think carb icing would be a problem in those conditions but without doing the sums I think you just ran out of power.

I've seen a similar thing happen to someone attemping a downwind T/O over a cornfield :rolleyes: Just dropped into the corn.

Did you notice the manifold pressure?

overpitched 17th November 2003 07:15

From memory the mtow is about 622kg. So you were hovering heavy at over 6000 ft applying left pedal ???? What do you reckon happened ??

Tmflyer 17th November 2003 17:42

Sir:

With all due respect, two questions:

Do you comprehend the usual response from any helicopter that you have loaded to over 96% of maximum, hovered it at an rather high density altitude, and then practiced *left* pedal turns

How "hard" can any helicopter land *from 12 inches* above the ground with even total power loss. ?
In My Humble Opinion, Instructors often demo hovering autos from that altitude, and even if PIC does nothing (except apply pedal to maintain heading), the helicopter does not land "hard".

Floppy Link 17th November 2003 18:30

Aren't R22 (and R44) engines derated, so even if you were using full power the butterfly valve would not have been fully open, increasing the likelyhood of carb ice?

Russell
1840hrs turbine heli
5 hrs piston heli
so I may be talking out of my ar5e....tell me! :confused:

Bluegold 17th November 2003 18:40

Possible cause of hard landing
 
Alpinehelicopter,

Perhaps a pertinent question to ask would be; what characterized the terrain over which you were hovering?

If it was long grass or similar, the effects of recirculation could have substantially reduced the ground cushion which resulted in the hard landing you describe.

While by no means the sole cause, it could be a contributing factor.

Kind Regards
Bluegold

Head Turner 17th November 2003 19:19

Put some time into reading all you can about Carb Icing. You will be surprised to learn that Carb Icing can occur almost anytime. It just needs the right cocktail of ingredients.

MD900 Explorer 18th November 2003 03:43

R22 B2 Power Loss
 
At that altitude, did you have much carb heat on? Reason i ask is beacuse if you have full carb heat on and give it loads of left pedal, did you sneak by the 25 inches of manifold pressure :{

When was the last maintenance done on the aircraft, and like Bluegold said, what sort of terrain were you hovering over? Did you establish what the Dew point was?

Sorry to ask, but it could all be relevent.

MD 900 :ok:

Steve76 18th November 2003 04:03

Overboosted Mr Selfish??

Don't think so. If this robbie had been boosted it would not have hit the ground hard. The turbo would've pressurised the intake and forced atomised particles of air and fuel into the cylinder mimicing the characteristics of sealevel operation.

Since the R22 is not fitted with a turbo this is very impossible. Like you correctly said: the redline is the "derating". The limit is when the collective and the throttle will travel no further in a positive direction.

If this really did end in a hard destructive landing, then it is a sad example of how many people are being taught bad habits early on by inexperienced instructors. Like TMFlyer says.....12 inches is not a long way off the planet.

Carb icing is insidious. It won't end in a sudden power loss but a gradual degradation. In this case being at full throttle would negate this occuring as it usually occurs around the throttle butterfly during a partial open position. Hense why you apply carb heat prior to decent.

the coyote 18th November 2003 06:57

Stretching the memory, but with carb icing there is a couple of kinds.

Throttle icing as previously discussed, usually around a partially open throttle as the airflow velocity increases and the pressure drops, cooling the air to freezing.

There is also fuel icing, a cooling effect from the introduction of fuel as it soaks up latent heat energy to vaporise, like when you spill gas on your skin it feels cold. This is downstream of the throttle butterfly and can tip the temperature below freezing.

What I am trying to say is icing can occur in the carby and also downstream in the intake manifold, despite being at full throttle.

Johe02 18th November 2003 20:25

'alpinehelicopter' is very quiet!

'Floppy', I gotta tell ya. . :confused:

As you can see from the graph, in those conditions, full throttle is around 23.5"

I don't know why everyones bangin' on about carb icing!

Verdict: Overpitched

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

Steve76 18th November 2003 22:00

The last time I was at 9000ft in an R22, I confirmed that the throttle and the collective will come to the end of their travel at the same time. It was mostly a coincidence but interesting none the same. Without the fancy smancy lift formula it is apparent that the MR will bleed off.....:rolleyes:

Mr Selfish: "Over boosting" is a completely wrong term here for what happens when you exceed the redline on an R22. Unfortunately you are one of the many (engineers I have worked with included) who use this term incorrectly. It is the result of poor theory instruction in Aussie. I have never heard the term used elsewhere.

Overboosting is terminology used for super/turbo charged engines indicating that you are exceeding the allowable positive pressurisation of the cylinders for that power/throttle/engine condition. The result is detonation and wear to the piston and cylinder as it opposes the increasing pressure while the piston rises during the compression stroke.

SO! you cannot "overboost" a non-boosted engine....just impossible.

There is no term for using all the engines power and ignoring a little redline. Musterers have been doing it since last century.

The ramifications are increased wear....(maybe) and decreased component times. Despite the redline I know of very few O-520's that make it to a 2200hr overhaul without having new cylinders and pistons fitted.

I think Lu has a term stashed away somewhere for this ......


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