R22 Accident Analysis 1979-1994
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
Posts: 2,132
Likes: 0
Received 0 Likes
on
0 Posts
With a grain of salt
To: Irlandes
The crash analysis report you posted should be taken with a grain of salt. It first appeared on the website of a Robinson dealer in Connecticut, USA and is slanted in support of the Robinson design.
If you want to know the true facts log on to http://www.ntsb.gov/publictn/1996/SIR9603.pdf
This is the NTSBs analysis of all of the loss of rotor control accidents up to the date of publication.
The crash analysis report you posted should be taken with a grain of salt. It first appeared on the website of a Robinson dealer in Connecticut, USA and is slanted in support of the Robinson design.
If you want to know the true facts log on to http://www.ntsb.gov/publictn/1996/SIR9603.pdf
This is the NTSBs analysis of all of the loss of rotor control accidents up to the date of publication.
Thread Starter
Join Date: May 2001
Location: London
Posts: 528
Likes: 0
Received 0 Likes
on
0 Posts
UK helicopter accident stats for the period 1992 to 1999 were collated by PLH Associates in 2001 from CAA maintenance returns. They showed that while the Robinson R22 now constitutes more than half the UK single-engine fleet, it accounts for far less than half of all accidents - despite the fact that it is used in the most accident-prone pursuits, like ab initio training and low-time self-fly hire. It recorded one fatal accident for every 115,000 hours. Only the single Squirrel performed better.
Despite the monotonous bell-tolling of the monomaniac Zuckerman, or the chauvinism of those too numerous to mention who have never flown Robinsons but who are only too happy to give up the benefit of their experience of the type here on pprune, the R22 remains one of the safest helicopters in the air. Don't take a lend of it and it won't let you down.
There are sound reasons why the R22 outnumbers all the others put together, and why its numbers to continue to rise in proportion to the rest.
Despite the monotonous bell-tolling of the monomaniac Zuckerman, or the chauvinism of those too numerous to mention who have never flown Robinsons but who are only too happy to give up the benefit of their experience of the type here on pprune, the R22 remains one of the safest helicopters in the air. Don't take a lend of it and it won't let you down.
There are sound reasons why the R22 outnumbers all the others put together, and why its numbers to continue to rise in proportion to the rest.
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
Posts: 2,132
Likes: 0
Received 0 Likes
on
0 Posts
Back to the fruit stand.
To: t'aint
Quote: the R22 remains one of the safest helicopters in the air. Don't take a lend of it and it won't let you down.
Response: Once again you are comparing apples to oranges. Maybe by your statistics the Robinson is the safest helicopter flying in the UK. However if you consider that there have been at least five rotor incursion, rotor loss, mast bumping incidents on Robinson’s in the UK in the last four years compare that to the number of other helicopters that have suffered loss of rotor control in that same time period. In order to keep this accident rate down the aircraft must be flown with limitations on its’ flight characteristics. There are not many other helicopters that have these draconian limitations placed upon them.
Quote: There are sound reasons why the R22 outnumbers all the others put together, and why its numbers to continue to rise in proportion to the rest.
Response: I can only think of one and that is its’ price. You will please note that in all of the comments I have made relative to the safety of the Robinson design I never attacked its’ reliability. To my knowledge there has only been one accident due to the failure of a part. Discount very early rotor blade failures.
If everything is done correctly in the design of the aircraft then safety is maintained by engineering. In the case of the R-22 R-44 the operator at the controls is the final control of safety and the manufacturer absolves themselves by placing suggested restrictions on the operation of the aircraft.
Quote: the R22 remains one of the safest helicopters in the air. Don't take a lend of it and it won't let you down.
Response: Once again you are comparing apples to oranges. Maybe by your statistics the Robinson is the safest helicopter flying in the UK. However if you consider that there have been at least five rotor incursion, rotor loss, mast bumping incidents on Robinson’s in the UK in the last four years compare that to the number of other helicopters that have suffered loss of rotor control in that same time period. In order to keep this accident rate down the aircraft must be flown with limitations on its’ flight characteristics. There are not many other helicopters that have these draconian limitations placed upon them.
Quote: There are sound reasons why the R22 outnumbers all the others put together, and why its numbers to continue to rise in proportion to the rest.
Response: I can only think of one and that is its’ price. You will please note that in all of the comments I have made relative to the safety of the Robinson design I never attacked its’ reliability. To my knowledge there has only been one accident due to the failure of a part. Discount very early rotor blade failures.
If everything is done correctly in the design of the aircraft then safety is maintained by engineering. In the case of the R-22 R-44 the operator at the controls is the final control of safety and the manufacturer absolves themselves by placing suggested restrictions on the operation of the aircraft.
T'aint natural: Thanks for that, I am sure the recorded stats speak for themselves. However, this does throw up an anomoly:
Read the NTSB report, it is in direct opposition to your sourced findings. R22 use in the States far exceeds UK usage. It is classified as a high risk helo in the US.
I suspect the statement "one of the safest helicopters".... is your personal opinion and not fact.
I also suspect the real reason why the R22 has taken to the air in disproportionately large numbers, is simply because of one fact: COST, and nothing else.
One doesn't have to be an R22 pilot to be aware that there is something strange surrounding the track record of R22's. The R44 doesn't seem to be cursed with the same problems. [You don't have to be a reliant robin driver to have an understanding of its shortfalls].
There is most definitely a problem with the R22 picture, it is either:
1. Badly designed.
2. Very unforgiving.
3. Very dangerous in the wrong hands (inexperienced pilots).
As far as the yanks are concerned, it seems No3 is the culprit.
Read the NTSB report, it is in direct opposition to your sourced findings. R22 use in the States far exceeds UK usage. It is classified as a high risk helo in the US.
I suspect the statement "one of the safest helicopters".... is your personal opinion and not fact.
I also suspect the real reason why the R22 has taken to the air in disproportionately large numbers, is simply because of one fact: COST, and nothing else.
One doesn't have to be an R22 pilot to be aware that there is something strange surrounding the track record of R22's. The R44 doesn't seem to be cursed with the same problems. [You don't have to be a reliant robin driver to have an understanding of its shortfalls].
There is most definitely a problem with the R22 picture, it is either:
1. Badly designed.
2. Very unforgiving.
3. Very dangerous in the wrong hands (inexperienced pilots).
As far as the yanks are concerned, it seems No3 is the culprit.
Thread Starter
Join Date: May 2001
Location: London
Posts: 528
Likes: 0
Received 0 Likes
on
0 Posts
Thomas Coupling:
I don't want to go over this in nauseating detail again, but let's put in the bare bones. The NTSB report is not new, and pertains to a time before changes in procedures, mostly driven by Frank Robinson himself with his safety courses, his insurance arrangements, his demands of the FAA and his requirements of pilots.
Back then, the Robinson massively increased the number of civilian helicopter pilots and the number of low-time pilots. As a result, quality of piloting was poor, and the accident rate in the US was high. The situation was exacerbated by the 50-hour rule, which held that any fixed-wing instructor who had 50 hours rotary time could open up the boot of his car and set up shop as a helicopter instructor. Frank Robinson petitioned the FAA time and time again to have that rule rescinded, to ensure that only qualified helicopter instructors could instruct on helicopters. Sounds logical, doesn't it.
Any two-bladed rotor is unforgiving of low-G. The Army taught Vietnam-era pilots how to avoid getting into low-G problems in the UH-1 and others. Robinson didn't invent the two-bladed rotor, and he didn't invent low-G. Knowledge of how to recognise the problem and avoid turning it into an accident is fundamental to good instruction - unless, of course, you're a fixed-wing instructor who just happens to have 50 hours rotary time.
The R22, and later the R44 - which despite your post displays far worse low-G characteristics than the R22 - has always suffered from the attempts of other manufacturers to do it down. I attended the Paris air show some years ago with representatives of a major US helicopter manufacturer who made no bones about the fact that, especially since Robinson was producing the R44 "which aims to eat our lunch" he was a target. In the main they have made a good job of spreading fear and uncertainty about the R22, which by its performance, its reliability and its excellent safety record has nonetheless answered all critics.
As to your assertion that cost is the only reason why the R22 now outnumbers all other singles put together - don't be so bloody stupid. The R22 is bought by pilots who don't give a damn about costs, where their safety is concerned. If your claim were true, the sky would be black with RotorWays. Many cheaper helicopters have come and gone, so don't talk drivel.
Lu Zuckerman's got stuck in a groove that he can't get out of, despite his arguments having been comprehensively destroyed time and time again in this forum by authorities on rotor design and high-time pilots. He has long since blown his credibility on the Robinson, and anything he says about Robinson can safely be disregarded. Look at the facts, and don't just recycle the taproom prattle.
I don't want to go over this in nauseating detail again, but let's put in the bare bones. The NTSB report is not new, and pertains to a time before changes in procedures, mostly driven by Frank Robinson himself with his safety courses, his insurance arrangements, his demands of the FAA and his requirements of pilots.
Back then, the Robinson massively increased the number of civilian helicopter pilots and the number of low-time pilots. As a result, quality of piloting was poor, and the accident rate in the US was high. The situation was exacerbated by the 50-hour rule, which held that any fixed-wing instructor who had 50 hours rotary time could open up the boot of his car and set up shop as a helicopter instructor. Frank Robinson petitioned the FAA time and time again to have that rule rescinded, to ensure that only qualified helicopter instructors could instruct on helicopters. Sounds logical, doesn't it.
Any two-bladed rotor is unforgiving of low-G. The Army taught Vietnam-era pilots how to avoid getting into low-G problems in the UH-1 and others. Robinson didn't invent the two-bladed rotor, and he didn't invent low-G. Knowledge of how to recognise the problem and avoid turning it into an accident is fundamental to good instruction - unless, of course, you're a fixed-wing instructor who just happens to have 50 hours rotary time.
The R22, and later the R44 - which despite your post displays far worse low-G characteristics than the R22 - has always suffered from the attempts of other manufacturers to do it down. I attended the Paris air show some years ago with representatives of a major US helicopter manufacturer who made no bones about the fact that, especially since Robinson was producing the R44 "which aims to eat our lunch" he was a target. In the main they have made a good job of spreading fear and uncertainty about the R22, which by its performance, its reliability and its excellent safety record has nonetheless answered all critics.
As to your assertion that cost is the only reason why the R22 now outnumbers all other singles put together - don't be so bloody stupid. The R22 is bought by pilots who don't give a damn about costs, where their safety is concerned. If your claim were true, the sky would be black with RotorWays. Many cheaper helicopters have come and gone, so don't talk drivel.
Lu Zuckerman's got stuck in a groove that he can't get out of, despite his arguments having been comprehensively destroyed time and time again in this forum by authorities on rotor design and high-time pilots. He has long since blown his credibility on the Robinson, and anything he says about Robinson can safely be disregarded. Look at the facts, and don't just recycle the taproom prattle.
We have heard from certain "one trick ponies" ad-nauseum about the "dangerous" Robbo, and numerous snipes from those who haven't flown it at all. We have also heard from those who currently fly and admire the Robbo.
I would really like to hear from experienced drivers who have flown a few different types as well as logged significant time in the Robbo. I know they are out there!
I would really like to hear from experienced drivers who have flown a few different types as well as logged significant time in the Robbo. I know they are out there!
RE: the R-22
I don’t know if I’m the guy you’re asking for What-ho, but for these five minutes until someone more qualified responds, I’ll tell you what I think.
I’m not going to bore you with my full CV only the relevants: I did my initial training in the r-22 in the eighties, gave 2,500 or so hours of instruction in them and then moved on through a dozen or so other types.
I think the r-22 is a fine machine. Can it be a dangerous machine? Yes, without question. The things I learned how to do in an r-22 have helped me on every flight in every other aircraft I have ever flown. It demands a delicate touch that translates perfectly into Instrument flying as well as high altitude and precision long-line. The R-22 teaches you things about power and rpm management that a turbine-trained pilot may never know. I never operated it outside its envelope.
When I taught in the r-22, we used the Robinson curriculum which required us to demonstrate and teach the low-g recovery technique. R-22 instructors performed the low-g maneuver thousands and thousands of times without incident, to the benefit of the students they were training. Today I believe the maneuver can only be verbally discussed. I think that was a knee jerk reaction by the FAA to the University study, believing they had to respond.
After reading the study, by Georgia Tech I believe, I noticed one commonality on many of the flights. Regardless of the experience of the PIC, you’ll notice that the person in the other seat was taking a demo flight.......or was going for his first helicopter ride with his friend........or words to the effect that the person at the controls may have been flying for the first time.
My opinion is that the person flying made large, sudden and unexpected control movements that exceeded the PIC’s ability to correct. I believe the aircraft attitude was way beyond normal or even aggressive maneuvers and even beyond what we experienced in the low-g recovery technique, closer to acrobatic. The R-22 is extremely controllable and as a result, very unstable. The rotor system will do exactly what you command it to do, and will do it immediately. I think it produced attitude changes or more correctly rates of attitude changes that even the experienced PICs hadn’t seen before. I think that it would be possible to cut off your own tail or even the left side of the fuselage while accidently entering the low-g regime and then responding with large and incorrect responses. Read the report, see what you think. Anyway, it’s just my opinion.
I’m not going to bore you with my full CV only the relevants: I did my initial training in the r-22 in the eighties, gave 2,500 or so hours of instruction in them and then moved on through a dozen or so other types.
I think the r-22 is a fine machine. Can it be a dangerous machine? Yes, without question. The things I learned how to do in an r-22 have helped me on every flight in every other aircraft I have ever flown. It demands a delicate touch that translates perfectly into Instrument flying as well as high altitude and precision long-line. The R-22 teaches you things about power and rpm management that a turbine-trained pilot may never know. I never operated it outside its envelope.
When I taught in the r-22, we used the Robinson curriculum which required us to demonstrate and teach the low-g recovery technique. R-22 instructors performed the low-g maneuver thousands and thousands of times without incident, to the benefit of the students they were training. Today I believe the maneuver can only be verbally discussed. I think that was a knee jerk reaction by the FAA to the University study, believing they had to respond.
After reading the study, by Georgia Tech I believe, I noticed one commonality on many of the flights. Regardless of the experience of the PIC, you’ll notice that the person in the other seat was taking a demo flight.......or was going for his first helicopter ride with his friend........or words to the effect that the person at the controls may have been flying for the first time.
My opinion is that the person flying made large, sudden and unexpected control movements that exceeded the PIC’s ability to correct. I believe the aircraft attitude was way beyond normal or even aggressive maneuvers and even beyond what we experienced in the low-g recovery technique, closer to acrobatic. The R-22 is extremely controllable and as a result, very unstable. The rotor system will do exactly what you command it to do, and will do it immediately. I think it produced attitude changes or more correctly rates of attitude changes that even the experienced PICs hadn’t seen before. I think that it would be possible to cut off your own tail or even the left side of the fuselage while accidently entering the low-g regime and then responding with large and incorrect responses. Read the report, see what you think. Anyway, it’s just my opinion.
I have flown on R-22 150 flight hours. Not so much to be an "robbo" expert, but enough to made my own picture of the helicopter. Compared to the other (10) different types of helicopters i'am rated, it's not the "easycopter". And i would like to say from flight handling, concentration to flight controls and to hold anything inside "green" it's a very demanding, challenging helo.
In my opinion only from the view out of the flightcharacteristics and not costs, it's not the starting helicopter for our new pilots. The "green" range is very small and the possibilities to recover safe conditions are limited. May be that on the other side pilots, who are able to fly that thing safe, are really helicopter qualified. But loosing good guys under the known circumstances is allways very sadly. Robinson have made some design changes, improvements and awareness courses, but mostly after deadly accidents and under the pressure of insurances, authorities, pilots and owners. I' was able to meet Mr. Robinson after an deadly accident. Two of my longyear friends, professional pilots died in an R-44 crash. Same time to the funeral was the official date. What causes the crash was at the time absolutely unclear. Authority wished to ground all the robbos in country up to new informations but Mr.Robinson and his lawyer was able to make to much pressure. "My helicopters are safe under all conditions and if accidents happens, it's a pilots problem". Shure it's a pilot problem if he is not in line with the flight manual. But it's easy to write in a flight manual avoid this and avoid that... . If you are a line dancer 30 ft above the ground, simple! hold your center of gravity above the line! If you are injured on the ground - have you read the manual? It's a dancer problem... Simple hold the center...
We couldn't solve the robbo question but we can discuss and talk about. But TC and t ain't leave the guns at home.
In my opinion only from the view out of the flightcharacteristics and not costs, it's not the starting helicopter for our new pilots. The "green" range is very small and the possibilities to recover safe conditions are limited. May be that on the other side pilots, who are able to fly that thing safe, are really helicopter qualified. But loosing good guys under the known circumstances is allways very sadly. Robinson have made some design changes, improvements and awareness courses, but mostly after deadly accidents and under the pressure of insurances, authorities, pilots and owners. I' was able to meet Mr. Robinson after an deadly accident. Two of my longyear friends, professional pilots died in an R-44 crash. Same time to the funeral was the official date. What causes the crash was at the time absolutely unclear. Authority wished to ground all the robbos in country up to new informations but Mr.Robinson and his lawyer was able to make to much pressure. "My helicopters are safe under all conditions and if accidents happens, it's a pilots problem". Shure it's a pilot problem if he is not in line with the flight manual. But it's easy to write in a flight manual avoid this and avoid that... . If you are a line dancer 30 ft above the ground, simple! hold your center of gravity above the line! If you are injured on the ground - have you read the manual? It's a dancer problem... Simple hold the center...
We couldn't solve the robbo question but we can discuss and talk about. But TC and t ain't leave the guns at home.
Join Date: Jul 2002
Location: Finland
Posts: 301
Likes: 0
Received 0 Likes
on
0 Posts
This (thread) is very interesting. Out of interest, is there a consensus about WHAT small 2 person helicopters are good for training in/the first-time newly "solo"-ed flyer (which are available in Europe/cheap to run/good to service).
Inthegreen
Thanks for your post. 2,500 hrs instructional - I would think you know your way around a Robbo!
Your view seems logical, and in line with the opinion I am forming on the machine, having read through lots of info on the web (here and other places). I am about to get endorsed on the machine, so am very keen to get some balanced views from experienced aviators. So, thanks for taking the time to respond.
By the way, where can I see this University Report?
Your view seems logical, and in line with the opinion I am forming on the machine, having read through lots of info on the web (here and other places). I am about to get endorsed on the machine, so am very keen to get some balanced views from experienced aviators. So, thanks for taking the time to respond.
By the way, where can I see this University Report?
Tecpilot
Thanks for your reply also.
You say it is challenging, then quote about an R44 crash that killed your friends - does this make you think there is something sinister about the machine, or are you referring to the fact that it is sometimes a difficult helicopter to fly?
You say it is challenging, then quote about an R44 crash that killed your friends - does this make you think there is something sinister about the machine, or are you referring to the fact that it is sometimes a difficult helicopter to fly?
Join Date: Sep 2001
Location: In the Haven of Peace
Age: 79
Posts: 600
Received 0 Likes
on
0 Posts
I must say that I totally agree with 'in the green'. I flew more than 1200 hours ab-initio instruction in the R22 with no problems, nor did anyone else at the commercial training school where I was working have any problems with the aircraft. I had been instructing on Bell 47s before and was very much against the Robinson, but once I started flying it and instructing in it my views changed. From the way I felt before flying it I can understand how other pilots who have not flown it may feel, but all I can say is that they should try it and gain some experience on it and see if it changes their views. The R22 is one of 14 types I have flown commercially and I believe it to be a good training aircraft because its rather unforgiving characteristics teach pilots sound helicopter piloting techniques. The point has been made time and time again that as long as the R22 is operated in accordance with the procedures laid down by Robinson it is unlikely to cause a problem. It does, however, require good instruction from experienced instructors not, as has been said, someone with a fixed wing instructor rating and 50 hours helicopter setting himself up to teach others something he is barely competent to fly, let alone instruct on.......waits to get shot down in flames!!
@What-ho Squiffy!
I wouldn't say R-helos are unsafe. Like any other a/c they have their limits und known or unknown bugs. By the time lot's of it are built, much flight time is logged. Therefore the problems are easy to see. Technical failure isn't a main problem. The main problem and you can count nearly all pilots errors in this category are flights, flightconditions or pilot inputs outside the limitations of the flight manual. That's the limited small "green" range. Within the "green" i'm shure it's a safe helicopter. But we have to think about: it's really alltimes possible to stay in green? Especially on commercial operations or unexperienced pilots? How easy is it to overload the a/c? Our R-22 were overweighted with simply 2 adults and the aux fuel tank filled. All you R pilots, you are the whole flight time so concentrated on the a/c as necessary? On our ship we missed the governor. Is gusting wind in the mountains so unusual? Up to 1995 we hadn't speed restrictions. Outside the straight and level flights the R needs an special eye on the RPM and the pilot inputs. The small "green" isn't only Mr. Robinsons problem. It's a question to operators, owners and pilots. The question is: is the Robinson really the ship you need for the mission and conditions? Or is it only the cheapest? My friends died on the starting phase of R-44 operations. They operated the a/c outside the limitations, after the first awareness courses. But to this time Mr. Robinson tells everyone R-44 is to compare with the light turbines. Fly and pay piston and feel like turbine. Mistake or PR? Low G, strength, performance and handling on Robinson isn't to compare with low G or the others on turbines... (of course the principles of low g are the same) In my opinion should Mr. Robinson first line think about his promotion campaigns. Business is ok but... It seems to me that a dangerous flight condition is faster to reach on Mr. Robinsons ships. Today any comparison between BH 206 or MD 500 and R-44 is a joke. But that view was deadly to get...
I wouldn't say R-helos are unsafe. Like any other a/c they have their limits und known or unknown bugs. By the time lot's of it are built, much flight time is logged. Therefore the problems are easy to see. Technical failure isn't a main problem. The main problem and you can count nearly all pilots errors in this category are flights, flightconditions or pilot inputs outside the limitations of the flight manual. That's the limited small "green" range. Within the "green" i'm shure it's a safe helicopter. But we have to think about: it's really alltimes possible to stay in green? Especially on commercial operations or unexperienced pilots? How easy is it to overload the a/c? Our R-22 were overweighted with simply 2 adults and the aux fuel tank filled. All you R pilots, you are the whole flight time so concentrated on the a/c as necessary? On our ship we missed the governor. Is gusting wind in the mountains so unusual? Up to 1995 we hadn't speed restrictions. Outside the straight and level flights the R needs an special eye on the RPM and the pilot inputs. The small "green" isn't only Mr. Robinsons problem. It's a question to operators, owners and pilots. The question is: is the Robinson really the ship you need for the mission and conditions? Or is it only the cheapest? My friends died on the starting phase of R-44 operations. They operated the a/c outside the limitations, after the first awareness courses. But to this time Mr. Robinson tells everyone R-44 is to compare with the light turbines. Fly and pay piston and feel like turbine. Mistake or PR? Low G, strength, performance and handling on Robinson isn't to compare with low G or the others on turbines... (of course the principles of low g are the same) In my opinion should Mr. Robinson first line think about his promotion campaigns. Business is ok but... It seems to me that a dangerous flight condition is faster to reach on Mr. Robinsons ships. Today any comparison between BH 206 or MD 500 and R-44 is a joke. But that view was deadly to get...
Last edited by tecpilot; 15th Jul 2002 at 15:30.
Head a fraction above the trench, using mirrors to see t'aint naturals position, seeing it's all quiet, creeps forward very slowly, very very quietly...looks over the top and spies t'aint, re-loading his foghorn
TC reaches for his 700 watt megaphone, points it squarely at t'aint and within 1 inch of his ear, and screams....
TOLD YOU SO..IT WAS NUMBER 3 
then gets up and runs like f**k for cover
TC reaches for his 700 watt megaphone, points it squarely at t'aint and within 1 inch of his ear, and screams....
TOLD YOU SO..IT WAS NUMBER 3
then gets up and runs like f**k for cover
Thread Starter
Join Date: May 2001
Location: London
Posts: 528
Likes: 0
Received 0 Likes
on
0 Posts
(very quietly)
Listen mush.
If indeed it was number three, consider this. When an R22 flies, it is number three (less quietly now) the majority of the time. This being so, the record of the machine is all the more notable.
BMWs are involved in more road accidents than Bristols, but only Lu Zuckerman would argue that the reason for this is a hidden (from everyone but Lu) defect in the design of the former.
Listen mush.
If indeed it was number three, consider this. When an R22 flies, it is number three (less quietly now) the majority of the time. This being so, the record of the machine is all the more notable.
BMWs are involved in more road accidents than Bristols, but only Lu Zuckerman would argue that the reason for this is a hidden (from everyone but Lu) defect in the design of the former.