R22 Corner
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More thoughts...
Accidentally switching off and on is not only ugly for transmission, it often results in an exhaust system like a peeled banana due to igniting unburned fuel in the muffler.
Idle check may be gone because rapid RPM changes upset the internals of the engine (crank twisting and upset balance).
Another odd one my CFI told me about... a recommendation to switch on governor at 82% RPM. This procedure avoids accidental flying without governor, but causes a slight overspeed (tried it this morning, under adult supervision).
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More volts, Igor
Accidentally switching off and on is not only ugly for transmission, it often results in an exhaust system like a peeled banana due to igniting unburned fuel in the muffler.
Idle check may be gone because rapid RPM changes upset the internals of the engine (crank twisting and upset balance).
Another odd one my CFI told me about... a recommendation to switch on governor at 82% RPM. This procedure avoids accidental flying without governor, but causes a slight overspeed (tried it this morning, under adult supervision).
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More volts, Igor
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Chips,
Glad you brought that up - The new startup requies the pilot to switch the governor on from 75% (of course it will not work and the throttle will have to be opened).
My concern is just as you say - Many a/c will overspeed due to the governor continuing to open the throttle until it gets the signal it wants, but the lag in engine RPM response will cause RPM to continue to overspeed (not huge) but this does mean that in the life of the a/c this can happen 3000 times, 2000 x average flights of 40 mins......
Glad you brought that up - The new startup requies the pilot to switch the governor on from 75% (of course it will not work and the throttle will have to be opened).
My concern is just as you say - Many a/c will overspeed due to the governor continuing to open the throttle until it gets the signal it wants, but the lag in engine RPM response will cause RPM to continue to overspeed (not huge) but this does mean that in the life of the a/c this can happen 3000 times, 2000 x average flights of 40 mins......
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Interesting, I shall have to try it out too and see what it does for me.
Even thought the POH hadn't mentioned it prior, I had alwys finished up things in the cockpit, got my MP values, transponder to Alt, before coming back up to 100% Nr and engaging the governor. This so that while doing the previous I wouldn't inadvertantly move cyclic at 100% Nr.
I hadn't noticed an overspeed when bringing up the throttle to the 80's and engaging, but will go back and look closer.
Even thought the POH hadn't mentioned it prior, I had alwys finished up things in the cockpit, got my MP values, transponder to Alt, before coming back up to 100% Nr and engaging the governor. This so that while doing the previous I wouldn't inadvertantly move cyclic at 100% Nr.
I hadn't noticed an overspeed when bringing up the throttle to the 80's and engaging, but will go back and look closer.
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That is one of the ones I didn't write about yet!
The third involved a jacket sleeve...
I'll post it -
ARMED JACKET KILLS ENGINE......
An R22 pilot had flown out early to the hills. Sensibly dressed for the early morning chill and the bush terrain he was to land at, all seemed well planned. The doors were removed before flight began as the weather was forecast to become hot and hunting was the aim.
The first landing was on a ridge. The sun was up and insolation made the temperature rise in the bubble, even with the doors removed. The Pilot didn't want to shut down, but he did want to remove his jacket. A solution - Slip off the jacket and slide it down the seat, sit on it. No need to make the passenger get out to put it in the seatbox, no need to shut down.
All fine then?
NO....! Later, during an approach to a confined area one sleeve of the jacket became lose and flapped out of the door aperture. Why would this be a problem? It couldn't go anywhere because it was firmly attached to the jacket, sat upon by the Pilot.
But engine air intake is on the right hand side, behind the door aperture. The sleeve flapped over it and was held there by suction. The engine requires more air as power demand (as in the late stages of a confined area approach) increases. As the Pilot added power to arrest ROD the sleeve was sucked harder and harder onto the intake until it blocked it completely.
The engine was starved of air.
It stopped.
Thankfully this happened at a height of 2ft. The Helicopter settled onto the level area the Pilot had selected for landing.No damage or injury was sustained and the sleeve (intake suction now gone as the engine breathed no more) innocently slid off and hung downwards.
Lucky, just so LUCKY!
The Pilot's summary of the occurence?
"I won't do THAT again......!"
( I'll bet he won't !! )
The third involved a jacket sleeve...
I'll post it -
ARMED JACKET KILLS ENGINE......
An R22 pilot had flown out early to the hills. Sensibly dressed for the early morning chill and the bush terrain he was to land at, all seemed well planned. The doors were removed before flight began as the weather was forecast to become hot and hunting was the aim.
The first landing was on a ridge. The sun was up and insolation made the temperature rise in the bubble, even with the doors removed. The Pilot didn't want to shut down, but he did want to remove his jacket. A solution - Slip off the jacket and slide it down the seat, sit on it. No need to make the passenger get out to put it in the seatbox, no need to shut down.
All fine then?
NO....! Later, during an approach to a confined area one sleeve of the jacket became lose and flapped out of the door aperture. Why would this be a problem? It couldn't go anywhere because it was firmly attached to the jacket, sat upon by the Pilot.
But engine air intake is on the right hand side, behind the door aperture. The sleeve flapped over it and was held there by suction. The engine requires more air as power demand (as in the late stages of a confined area approach) increases. As the Pilot added power to arrest ROD the sleeve was sucked harder and harder onto the intake until it blocked it completely.
The engine was starved of air.
It stopped.
Thankfully this happened at a height of 2ft. The Helicopter settled onto the level area the Pilot had selected for landing.No damage or injury was sustained and the sleeve (intake suction now gone as the engine breathed no more) innocently slid off and hung downwards.
Lucky, just so LUCKY!
The Pilot's summary of the occurence?
"I won't do THAT again......!"
( I'll bet he won't !! )
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talkturn :
To my knowledge on the R22, there's no breather pipes because the tanks caps are vented. The fuel is gravity fed as well, so that's out. The only thing I've heard of is a problem with the connecting tube from the aux tank which was a factor in a fuel starvation incident some time ago, but that's about it.
Otherwise the only fuel starvation incidents are plain old none left in the tanks, or ( as I once heard ) a passenger who used the fuel cock as a convenient place to hang his coat, which turned it off !!
To my knowledge on the R22, there's no breather pipes because the tanks caps are vented. The fuel is gravity fed as well, so that's out. The only thing I've heard of is a problem with the connecting tube from the aux tank which was a factor in a fuel starvation incident some time ago, but that's about it.
Otherwise the only fuel starvation incidents are plain old none left in the tanks, or ( as I once heard ) a passenger who used the fuel cock as a convenient place to hang his coat, which turned it off !!
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Nr,
Sorry to clash, there are indeed breather pipes on the R22 and it has no vent holes in the caps to my knowledge.
The fuel tank vent pipes are hidden behind the mast cowling and jointed in at least one place by soft tubing (plastic material).
In at least one case in the UK the soft tubing had 'kinked', causing a lack of venting to the tank. The result was an engine stoppage due to fuel starvation.
A directive was issued and some aircraft had these pipe assemblies changed for a type that
had the fault designed out.
The problem has not recurred in the last 3 or 4 yrs (to the best of my knowledge).
BEWARE if the dual fuel gauges do not decrease at a similar rate during flight (from equalised contents) because this can indicate that one tank's vent is blocked.
The second occurence (that I have not 'written up yet')happened in California, the inside of the air intake tubing delaminated and blocked off induction. The engine stopped in the hover.A friend of mine was the pilot. He landed it with a slight yaw but held it upright and no damage was sustained, no injury either, thankfully. He made a really good job of a 'REAL' EOL in the hover!
The air intake tubing has been changed under directive, favouring a type and construction that cannot allow delamination.
SPS
Sorry to clash, there are indeed breather pipes on the R22 and it has no vent holes in the caps to my knowledge.
The fuel tank vent pipes are hidden behind the mast cowling and jointed in at least one place by soft tubing (plastic material).
In at least one case in the UK the soft tubing had 'kinked', causing a lack of venting to the tank. The result was an engine stoppage due to fuel starvation.
A directive was issued and some aircraft had these pipe assemblies changed for a type that
had the fault designed out.
The problem has not recurred in the last 3 or 4 yrs (to the best of my knowledge).
BEWARE if the dual fuel gauges do not decrease at a similar rate during flight (from equalised contents) because this can indicate that one tank's vent is blocked.
The second occurence (that I have not 'written up yet')happened in California, the inside of the air intake tubing delaminated and blocked off induction. The engine stopped in the hover.A friend of mine was the pilot. He landed it with a slight yaw but held it upright and no damage was sustained, no injury either, thankfully. He made a really good job of a 'REAL' EOL in the hover!
The air intake tubing has been changed under directive, favouring a type and construction that cannot allow delamination.
SPS
Guest
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So is mine..... 
Anyway, as you mentioned the coat/fuel cock
issue I thought I'd post this picture of the NZ solution to this problem.
At risk of being boring the whole article is on my site, through 'NZ flying' -'Deerhunting'and any that care to visit will see why it is relevant to that subject.
And the solution? Well, the simplest ideas are often the best!
Anyway, as you mentioned the coat/fuel cock
issue I thought I'd post this picture of the NZ solution to this problem.
At risk of being boring the whole article is on my site, through 'NZ flying' -'Deerhunting'and any that care to visit will see why it is relevant to that subject.
And the solution? Well, the simplest ideas are often the best!
Guest
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NR / SPS
I am a expert on the fuel venting systems on the r22 having owned one of the machines which suffered engine stoppage in the UK.
The aircraft G-OSEE a beta with approximateley 1550 hours total time had just been fitted with a new main rotor gearbox. Whilst completing the works i was offered a new replacement kit to replace the fuel vent pipes due to reports that following inspection of some aircraft the rubber sleeves had started to close and shrink after prolonged time submersed in the fuel tanks.
Although there were no reports of engine stoppage at the time i thought a bargain at £85.00 sterling.
I was not flying the aircraft at the time but the pilot concerned explained he had flown approximately 1 hour when the engine coughed several times next thing he new the aircraft yawed violently and down he went.
At five hundred AGL with wires ahead he dumped the lever and made for a grass field he flared the aircraft a little to high perhaps and raised the lever a little to early. I estimated at about six AGL the RPM decayed the aircraft landed hard and the slowing rotor see sawed and cut clean off the tail cone just before the strobe.
He did extremely well for a pilot with 200 hours who had not flown a helicopter for five months !!!!
Back to the point the fuel caps are not vented. There are two completely seperate aluminium vent pipes one to each tank which are attached to the mast assembly. The fuel tanks are connected via a seperate vent pipe. My retro kit had been installed wrong i believe and when the aux fuel tank ran dry it created a vancum between the tanks straving the engine of fuel.
An expensive days flying with a £5000 excess on the insurance and £8500 just paid for the new gearbox but thankfully nobody was hurt.
I am a expert on the fuel venting systems on the r22 having owned one of the machines which suffered engine stoppage in the UK.
The aircraft G-OSEE a beta with approximateley 1550 hours total time had just been fitted with a new main rotor gearbox. Whilst completing the works i was offered a new replacement kit to replace the fuel vent pipes due to reports that following inspection of some aircraft the rubber sleeves had started to close and shrink after prolonged time submersed in the fuel tanks.
Although there were no reports of engine stoppage at the time i thought a bargain at £85.00 sterling.
I was not flying the aircraft at the time but the pilot concerned explained he had flown approximately 1 hour when the engine coughed several times next thing he new the aircraft yawed violently and down he went.
At five hundred AGL with wires ahead he dumped the lever and made for a grass field he flared the aircraft a little to high perhaps and raised the lever a little to early. I estimated at about six AGL the RPM decayed the aircraft landed hard and the slowing rotor see sawed and cut clean off the tail cone just before the strobe.
He did extremely well for a pilot with 200 hours who had not flown a helicopter for five months !!!!
Back to the point the fuel caps are not vented. There are two completely seperate aluminium vent pipes one to each tank which are attached to the mast assembly. The fuel tanks are connected via a seperate vent pipe. My retro kit had been installed wrong i believe and when the aux fuel tank ran dry it created a vancum between the tanks straving the engine of fuel.
An expensive days flying with a £5000 excess on the insurance and £8500 just paid for the new gearbox but thankfully nobody was hurt.
Guest
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Don't really know, but here's a stab.
I remember someone telling me that the Bell 212 tail rotor went the other way to previous models (eg 205) because it was more effective aerodynamically to have the tail rotor blades 'chopping' up into the rotor wash rather than rotating back and away from it.
It seems to make sense that if the advancing blade was the one at the top of the disc, it would maybe get faster relative airflow in forward flight.
Could be just crap, but it sounded convincing to me at the time!
[This message has been edited by Arm out the window (edited 23 March 2001).]
I remember someone telling me that the Bell 212 tail rotor went the other way to previous models (eg 205) because it was more effective aerodynamically to have the tail rotor blades 'chopping' up into the rotor wash rather than rotating back and away from it.
It seems to make sense that if the advancing blade was the one at the top of the disc, it would maybe get faster relative airflow in forward flight.
Could be just crap, but it sounded convincing to me at the time!
[This message has been edited by Arm out the window (edited 23 March 2001).]
Guest
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AOTW
I agree with your T/R efficiency theory - inboard blade rising in to M/R downwash as in the R44.
Question is why the R22s T/R turns in the opposite direction (Frank Robinson being a T/R designer (Bell I think) before Roninson Helicopters)
I agree with your T/R efficiency theory - inboard blade rising in to M/R downwash as in the R44.
Question is why the R22s T/R turns in the opposite direction (Frank Robinson being a T/R designer (Bell I think) before Roninson Helicopters)
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talkturn :
I thought FR worked for Hughes before he did his own thing.
As for the T/R on the 22 turning advancing blade down, rather than up into the main rotor downwash, my understanding is that it was purely a weight and cost thing. With the main rotor turning anticlockwise, the easiest and lightest thing to do is a normal bevel gear on the main rotor shaft. This would make the T/R shaft turn anticlock when viewed from the rear. Another simple bevel gear in the T/R gearbox means the tail rotor turns in the direction we all know and love on the R22.
Solutions and possible disadvantages ? Extend the T/R drive shaft past the 90 degree final drive shaft, and a simple bevel gear would now make the T/R advancing blade go up into the T/R downwash at the expense of making the T/R gearbox longer and heavier. Similarly putting the T/R on the opposite side of the boom would obstruct the airflow in precisely the direction you want to push it, so you'd have to have larger T/R blades and so on and so on.
Even with the T/R as installed, at 80% NR in an IGE hover at a reasonable density altitude there's plenty of T/R authority to turn against torque, or even to arrest a slow turn with torque ( but not recommended !! ).
As a final comment, I believe FR was working at Hughes on the T/R design for the OH-6, as it suffered from LTE problems in its early life.
I thought FR worked for Hughes before he did his own thing.
As for the T/R on the 22 turning advancing blade down, rather than up into the main rotor downwash, my understanding is that it was purely a weight and cost thing. With the main rotor turning anticlockwise, the easiest and lightest thing to do is a normal bevel gear on the main rotor shaft. This would make the T/R shaft turn anticlock when viewed from the rear. Another simple bevel gear in the T/R gearbox means the tail rotor turns in the direction we all know and love on the R22.
Solutions and possible disadvantages ? Extend the T/R drive shaft past the 90 degree final drive shaft, and a simple bevel gear would now make the T/R advancing blade go up into the T/R downwash at the expense of making the T/R gearbox longer and heavier. Similarly putting the T/R on the opposite side of the boom would obstruct the airflow in precisely the direction you want to push it, so you'd have to have larger T/R blades and so on and so on.
Even with the T/R as installed, at 80% NR in an IGE hover at a reasonable density altitude there's plenty of T/R authority to turn against torque, or even to arrest a slow turn with torque ( but not recommended !! ).
As a final comment, I believe FR was working at Hughes on the T/R design for the OH-6, as it suffered from LTE problems in its early life.
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Buying an R22
I recently posted a message re Rotorway Execs v R22's. I would like to own and operate a helicopter from home, and not being rich, am considering the two most financially viable aircraft. The RW 162F is interesting, but I trained on a Robby & most people consider them much safer & more robust. Can anyone point me in the right direction to find a Robby with say 300ish hours left but at least 5 years to TBO as that would seem to be a financially viable alternative to the 162F.