Guimbal Cabri G2
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So basically the G2 tail is like any other standard Fennestron tail in terms of its characteristics and therefore required skill level for competent flight. I have to say that 14 accidents amongst 110 hulls sounds pretty high to me, but obviously the fact that none of them have been fatal is a huge plus for the machine. And in fairness, of the seven R22s I have flown within the Cabri's operational life, three of them have been written off. Sadly one resulted in a fatality.
I just can't help thinking that had it been designed with a standard tail rotor, we wouldn't be looking at 14 accidents so far, but I guess Fennestrons are safer in terms of tail protection. I need to get a flight in one and judge for myself I think.
I just can't help thinking that had it been designed with a standard tail rotor, we wouldn't be looking at 14 accidents so far, but I guess Fennestrons are safer in terms of tail protection. I need to get a flight in one and judge for myself I think.
Pilot walks away from forced landing in NZ
http://www.stuff.co.nz/the-press/news/71992920/helicopter-makes-emergency-landing-in-rolleston
No details available other than what is in the article at the moment.
No details available other than what is in the article at the moment.
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Has anybody pulled the reports from any of these accidents to see what the cause was?
There seems to be a lot of assumptions that several or all were somehow connected to the Fenestron, but nothing to back that up.
I will try to dig some up and share any info.
Rigidhead
There seems to be a lot of assumptions that several or all were somehow connected to the Fenestron, but nothing to back that up.
I will try to dig some up and share any info.
Rigidhead
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I think there could be other factors, 14 accidents from 110 aircraft does sound high (ish) but look at the facts.
This is the first fully articulated rotor headed helicopter with a fan and partial glass cockpit - It has advanced engineering and probably has some interesting flight characteristics as well. I would like to know the type hours of the pilots involved before drawing any conclusion, it would also be interesting to know what the accident rate was with the R22 when it first came out.
This is the first fully articulated rotor headed helicopter with a fan and partial glass cockpit - It has advanced engineering and probably has some interesting flight characteristics as well. I would like to know the type hours of the pilots involved before drawing any conclusion, it would also be interesting to know what the accident rate was with the R22 when it first came out.
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Early R22 accidents
Hi MM,
Here is some info on the early accident history of the R22 and a little informed(?) insight into the Cabri.
A search of the US NTSB database shows that the first recorded accident for an R22, post certification, was in May 1980 and claimed two lives.
The next nine R22 accidents claimed a further four lives.
The next ten R22 accidents claimed seven lives.
Things improved with the next ten accidents as no lives were lost.
The next ten accidents went on to claim five lives.
A variety of probable causes are listed with failure to maintain RRPM and Main Rotor Divergence being prominent.
Having owned five Robinsons over 22 years I did consider my self somewhat high risk in switching to the Cabri. Not because the Cabri is at all difficult to fly, it's a delight, but it is different from Robinsons. More on this later.
The two most obvious differences being the direction of rotor rotation and the fenestron.
Attending the RHC factory safety course in 1994, Frank Robinson acknowledged that the course was born out of the early R22 accident record where many instructors were ex military and failed to appreciate the characteristics of a light helicopter as against a Huey, for instance.
The R22 itself improved with the later addition of a Governor, although this was optional at first. Training too improved, no doubt helped along by SFAR-73.
The majority of Cabri accidents have had Instructors on board and sometimes two. Some of the Cabri accidents have involved misunderstanding and mishandling of the fenestron.
This brings me back to considering myself a high risk Cabri pilot. Just as with driving a car there are certain frequent actions where you develop muscle memory. In a helicopter one of these is the application of additional anti torque pedal when losing translational lift and applying power to bring the helicopter into the hover.
In my R44, muscle memory applied just the right amount of left pedal.
The Cabri required me to develop a new muscle memory, not just because of using the right pedal but because of the larger pedal movement required due to the fenestron thrust not being directly proportional to pedal movement.
The chances are that low hours Cabri instructors will also be high hours Robinson instructors and, especially if switching types between consecutive flights, have been known to get muddled and fail to apply sufficient right pedal. Some UK Flight Schools now prohibit low hours Cabri Instructors from switching back and forth to other types on the same day until they have accumalated a substantial number of Cabri hours.
The Cabri POH now includes a section on the fenestron characteristics with advice on handling and appreciation of the non linear thrust characteristics are also now taught as part of the syllabus, at least here in the UK.
Since the R22 was certified in 1979 the number of cars in the UK has roughly doubled yet in car fatalities have dropped from 2,429 to 785 in 2013. No doubt there are a number of contributory factors but higher car safety standards will have played a major role.
The inherent safety of a 21st Century helicopter certified to 21st Century standards played a large part in my decision to abandon my choice of more than twenty years and move to the Cabri.
Taking a final look at searchable databases, the UK fleet of R22 now stands at 148, down from circa 200 in 2008 and the last factory new R22 to be put on the UK register was in 2007. There are currently 14 Cabri on the UK register and, I understand, a further 10 on order. Hmmm.
Here is some info on the early accident history of the R22 and a little informed(?) insight into the Cabri.
A search of the US NTSB database shows that the first recorded accident for an R22, post certification, was in May 1980 and claimed two lives.
The next nine R22 accidents claimed a further four lives.
The next ten R22 accidents claimed seven lives.
Things improved with the next ten accidents as no lives were lost.
The next ten accidents went on to claim five lives.
A variety of probable causes are listed with failure to maintain RRPM and Main Rotor Divergence being prominent.
Having owned five Robinsons over 22 years I did consider my self somewhat high risk in switching to the Cabri. Not because the Cabri is at all difficult to fly, it's a delight, but it is different from Robinsons. More on this later.
The two most obvious differences being the direction of rotor rotation and the fenestron.
Attending the RHC factory safety course in 1994, Frank Robinson acknowledged that the course was born out of the early R22 accident record where many instructors were ex military and failed to appreciate the characteristics of a light helicopter as against a Huey, for instance.
The R22 itself improved with the later addition of a Governor, although this was optional at first. Training too improved, no doubt helped along by SFAR-73.
The majority of Cabri accidents have had Instructors on board and sometimes two. Some of the Cabri accidents have involved misunderstanding and mishandling of the fenestron.
This brings me back to considering myself a high risk Cabri pilot. Just as with driving a car there are certain frequent actions where you develop muscle memory. In a helicopter one of these is the application of additional anti torque pedal when losing translational lift and applying power to bring the helicopter into the hover.
In my R44, muscle memory applied just the right amount of left pedal.
The Cabri required me to develop a new muscle memory, not just because of using the right pedal but because of the larger pedal movement required due to the fenestron thrust not being directly proportional to pedal movement.
The chances are that low hours Cabri instructors will also be high hours Robinson instructors and, especially if switching types between consecutive flights, have been known to get muddled and fail to apply sufficient right pedal. Some UK Flight Schools now prohibit low hours Cabri Instructors from switching back and forth to other types on the same day until they have accumalated a substantial number of Cabri hours.
The Cabri POH now includes a section on the fenestron characteristics with advice on handling and appreciation of the non linear thrust characteristics are also now taught as part of the syllabus, at least here in the UK.
Since the R22 was certified in 1979 the number of cars in the UK has roughly doubled yet in car fatalities have dropped from 2,429 to 785 in 2013. No doubt there are a number of contributory factors but higher car safety standards will have played a major role.
The inherent safety of a 21st Century helicopter certified to 21st Century standards played a large part in my decision to abandon my choice of more than twenty years and move to the Cabri.
Taking a final look at searchable databases, the UK fleet of R22 now stands at 148, down from circa 200 in 2008 and the last factory new R22 to be put on the UK register was in 2007. There are currently 14 Cabri on the UK register and, I understand, a further 10 on order. Hmmm.
Cabri down in South Africa - 16 Oct 2015
Mossel Bay Advertiser | Opvolg: Vlieënier val met helikopter
Single PPL pilot, presumably hire & fly, minor injuries.
One of Starlite's machine. Helicopter is a write off.
Single PPL pilot, presumably hire & fly, minor injuries.
One of Starlite's machine. Helicopter is a write off.
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Cabri G2 Service Letter
There exists also a Guimbal service letter which explains the root cause, recovery and prevention measures for the phenomenon which had at some stages been called "Fenstron Stall". If you can get a peek it's really well written with some very clear diagrams.
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Thanks Hillerbee, the link was dead for me 
Yes, that would be a satisfactory result, though I'm sure there will be much introspection.
Still no serious injuries or fatalities, all but 8 years after certification.
Yes, that would be a satisfactory result, though I'm sure there will be much introspection.
Still no serious injuries or fatalities, all but 8 years after certification.
a) By now Bruno probably regrets sticking with right turning EC rotor instead of mimicking the left turning competition á la S300 and R22/44. Considering that many R22(44) pilots/instructors might jump aboard a G2, but only a small number of Colibri and Squirrel pilots will, that wasn't the smartes of design choices, as is increasingly becoming evident.
b) I'm by far no mechanical engineer, but I know that the S-300C, typically lacking the expensive governor option, does a nice job of adding throttle when lifting pitch. Not that precisely, that the rpms will stay in the green arc all by themselves, but the pitch to throttle coupling mechanism apparently is quite well designed, with regard to pilot workload reduction. Imagine a different mechanical setup of pedal-action to fenestron AoA translation and people/FIs would have found the tail response they've got used to over the years.
If a) and b) would have been adressed wisely the G2 would be a perfect drop-in replacement for all the R22s, and I'd bet the accident rate would have been much lower.
In the current situation the Guimbal PR dept. has a lot of work to do to shift blame onto the pilots to avoid tainting the reputaion of an otherwise modern and safe piece of engineering. In hindsight the lack of consideration for points a) and b) at design time will lead to an unsightly, R22-like crash ratio, (albeit w/o the R22's death toll, mind you) and if things continue like they did, someone might prescribe a "SFAR-G2" supplemental training requirement. High time to "optimize" the fenestron's action instead of distributing information leaflets. The rotor's direction, however, is here to stay, sadly.
b) I'm by far no mechanical engineer, but I know that the S-300C, typically lacking the expensive governor option, does a nice job of adding throttle when lifting pitch. Not that precisely, that the rpms will stay in the green arc all by themselves, but the pitch to throttle coupling mechanism apparently is quite well designed, with regard to pilot workload reduction. Imagine a different mechanical setup of pedal-action to fenestron AoA translation and people/FIs would have found the tail response they've got used to over the years.
If a) and b) would have been adressed wisely the G2 would be a perfect drop-in replacement for all the R22s, and I'd bet the accident rate would have been much lower.
In the current situation the Guimbal PR dept. has a lot of work to do to shift blame onto the pilots to avoid tainting the reputaion of an otherwise modern and safe piece of engineering. In hindsight the lack of consideration for points a) and b) at design time will lead to an unsightly, R22-like crash ratio, (albeit w/o the R22's death toll, mind you) and if things continue like they did, someone might prescribe a "SFAR-G2" supplemental training requirement. High time to "optimize" the fenestron's action instead of distributing information leaflets. The rotor's direction, however, is here to stay, sadly.
Last edited by Reely340; 20th Oct 2015 at 07:56.
I bet he doesn't.
The Cabri is a French helicopter. French helicopter rotors turn clockwise. And as such, that makes the Cabri the ideal an-initio platform for pilots progressing onto other helicopters in the Eurocopter/Airbus 'stable'.
The Cabri is a French helicopter. French helicopter rotors turn clockwise. And as such, that makes the Cabri the ideal an-initio platform for pilots progressing onto other helicopters in the Eurocopter/Airbus 'stable'.
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thanks for the info and stats Chalmondleigh, made interesting reading. I think the G2 would have benefited with a right turning motor as Reely340 said, I think it could have had a slightly larger fan to help with fan stalls as well but that said, if this machine had been around when I started to learn to fly then I probably would have picked the G2 over the R22.
I am just finishing a type rating on the R44 before moving on to a turbine, but did have 90 minutes in a R22 for old times, skittish comes to mind, when I learnt the R22 didn't come with a governor, which meant is was very easy to lose RRPM if you were not 100% on it.
I am just finishing a type rating on the R44 before moving on to a turbine, but did have 90 minutes in a R22 for old times, skittish comes to mind, when I learnt the R22 didn't come with a governor, which meant is was very easy to lose RRPM if you were not 100% on it.
Reeley
S300 correlator is really good and better than you say. If you follow the factory teaching which is
set 2200/2300 rpm with flat pitch. Lift the lever slowly to get to 19inches and 3000rpm then forget about it the rpm will be held in the green right up to about 25 inches. It is only at the top of Manifold Pressure that you might need a squeeze of throttle.
However, health warning it does depend on how good the linkages are !
S300 correlator is really good and better than you say. If you follow the factory teaching which is
set 2200/2300 rpm with flat pitch. Lift the lever slowly to get to 19inches and 3000rpm then forget about it the rpm will be held in the green right up to about 25 inches. It is only at the top of Manifold Pressure that you might need a squeeze of throttle.
However, health warning it does depend on how good the linkages are !
Tried that got a "mate, we don't want to be in the low 2000 rpm region for prolonged time as this is the resonant frequency of the fuselage and we'd like to avoid inducing ground resonance" 
But from various hover square practizing one learns that indeed there is a sweet rpm setting at full pitch down, that will result in perfect rpm for hover, w/o having to mess with the throttle.
Of course, FI was fully aware of that trick and required me to roll off the throttle before commencing takeoff.
What might sound like hostility was part of his training regime.
He'd admit that he'd have the governor removed from a would be training S300Cs,
as "you guys should learn proper rpm control ab initio" (kind of built in SFAR73)
But from various hover square practizing one learns that indeed there is a sweet rpm setting at full pitch down, that will result in perfect rpm for hover, w/o having to mess with the throttle.
Of course, FI was fully aware of that trick and required me to roll off the throttle before commencing takeoff. What might sound like hostility was part of his training regime.
He'd admit that he'd have the governor removed from a would be training S300Cs,
as "you guys should learn proper rpm control ab initio"
(kind of built in SFAR73)