Robinson R44
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With the hydraulics defaulting to on when electrical power is off could make for an even more interesting flight, should you have a servo fail at the same time as an electrical failure.
[This is just an observation as I realise the odds of that happening are very low.]
Normally, a hydraulic warning light on a Raven would have the same effect as having an engine out warning light. It will tell the pilot what he already knows.
In helo's that use dual hydraulic systems, the warning light for each system does serve a purpose.
A lot of aircraft systems have an electrical auxillary pump installed which act as a backup in case of main pump failure or for activating systems when the aircraft is not operating.
Can anybody enlighten me as to why helicopters dont use aux hyd. pumps?
[This is just an observation as I realise the odds of that happening are very low.]
Normally, a hydraulic warning light on a Raven would have the same effect as having an engine out warning light. It will tell the pilot what he already knows.
In helo's that use dual hydraulic systems, the warning light for each system does serve a purpose.
A lot of aircraft systems have an electrical auxillary pump installed which act as a backup in case of main pump failure or for activating systems when the aircraft is not operating.
Can anybody enlighten me as to why helicopters dont use aux hyd. pumps?
My understanding - and this comes from the one trip I did in an R44, with an instructor - is that the CB is pulled to isolate the switch, should it fail, and therefore restore hydraulics. The inference for me is that switch failure is more likely than complete hyd. failure.
Any comments ?
Any comments ?
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The Raven is silky smooth with hyrdraulics - I love it...
I do the hydraulics off bit on the annual check - hate it! Hovering is like stirring treacle and lots of sideways pressure at 75knots.
Totally agree, warning light not needed - you would know!
I do the hydraulics off bit on the annual check - hate it! Hovering is like stirring treacle and lots of sideways pressure at 75knots.
Totally agree, warning light not needed - you would know!
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The hydraulic system is functionally similar to the B206 system for example, which also does not have a light or a gauge (similar to many light single engine helicopters that use hydraulic power-assistance controls, as distinct from hydraulic power control). The hydraulic system is powered from a pump mechanically driven from the MGB transmission and is controlled electrically, because it is not practical to route the hydraulic system direct to the cockpit. The electrical control system is "fail safe" in that if anything shuts off the wigglies to the valve that dumps the hydraulic pressure, it fails so that hydraulic pressure remains ON.
When a helicopter has only one hydraulic system, failure of that single system is foreseeable and it must be possible to cope with such a failure in flight. That's why the aircraft can be flown without hydraulics and we practice hydraulic failures in types that have such single systems. If not, you would need at least 2 entirely redundant systems.
The light or gauge would not really help you much - you notice almost immediately if you lose hydraulics in flight!
When a helicopter has only one hydraulic system, failure of that single system is foreseeable and it must be possible to cope with such a failure in flight. That's why the aircraft can be flown without hydraulics and we practice hydraulic failures in types that have such single systems. If not, you would need at least 2 entirely redundant systems.
The light or gauge would not really help you much - you notice almost immediately if you lose hydraulics in flight!
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Just done my B206 TR and taught as follows:
- Check the hyd switch is on
- If it is, check the CB - pull it out to try the fail safe
- If hydraulics do not come back on, you must reset the hyd
switch to off in case the hydraulics come back on when you're not expecting it and applying a lot of effort on the controls
- Do a hydraulics off landing
- Check the hyd switch is on
- If it is, check the CB - pull it out to try the fail safe
- If hydraulics do not come back on, you must reset the hyd
switch to off in case the hydraulics come back on when you're not expecting it and applying a lot of effort on the controls
- Do a hydraulics off landing
Avoid imitations
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On an aircraft with switchable hydraulics I would recommend the following actions, some of them already covered by other contributors:
1. Move the switch!
If it's OFF you want it ON; if it's ON you need it OFF. Simple. If nothing happens (hydraulic assistance not restored) confirm which way it is now selected.
2. Check the pressure if a gauge is fitted. Check the CB.
3. Before resetting the CB ensure the switch is OFF. You do NOT want to restore hydraulic assistance by the CB with the controls not covered.
4. Switch the hydraulics back ON if appropriate. Expect the controls to jump and expect to overcontrol for a few seconds. Think about what stage of flight you are in before re-selecting the hydraulics ON.
5. A running landing should be planned for.
Final caution. Hydraulic fluid is flammable, especially when in aerosol form so think about the possible further consequences. (Minor consideration: It also melts tarmac so concrete is a better surface to avoid later embarrassment)!
1. Move the switch!
If it's OFF you want it ON; if it's ON you need it OFF. Simple. If nothing happens (hydraulic assistance not restored) confirm which way it is now selected.
2. Check the pressure if a gauge is fitted. Check the CB.
3. Before resetting the CB ensure the switch is OFF. You do NOT want to restore hydraulic assistance by the CB with the controls not covered.
4. Switch the hydraulics back ON if appropriate. Expect the controls to jump and expect to overcontrol for a few seconds. Think about what stage of flight you are in before re-selecting the hydraulics ON.
5. A running landing should be planned for.
Final caution. Hydraulic fluid is flammable, especially when in aerosol form so think about the possible further consequences. (Minor consideration: It also melts tarmac so concrete is a better surface to avoid later embarrassment)!
Last edited by ShyTorque; 15th Jun 2002 at 18:33.
R44 Raven 2
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SFIM
I've also heard this and that it will be an option (ie the existing model will continue). Look for a price differential of $25-30K and 100lb more in mtow.
I've also heard this and that it will be an option (ie the existing model will continue). Look for a price differential of $25-30K and 100lb more in mtow.
Raven 2 True!
The was a joint HeliAIR/Sloane Robinson conference at Helitech 2001 at which Frank Robinson was scheduled to speak & answer questions. However due to 9/11 he could not attend because of difficulties at the factory due to the flight restrictions opposed on US airspace at the time.
In his place one of his senior engineers provided a telephone conference to the audience. I believe his name was Pat Cox. During this one of the features that he commented on was that Robinson was currently flight testing an R44 with a fuel injected engine. So its true. That of course assumes that no other technical difficulties arised in the testing program!
I quizzed him about a turbocharged version instead (more power) but although a turbocharged engine has been tried, it cannot be used because it gets too hot. It is only cooled by the same squirrel cage fan.
There were some articles in the aviation press about a Lycomming 580 model, if you look at the Lycomming web page you'll see this engine is available so this might also be being considered - though i've heard no follow up on this.
As to the R66 I heard rumours about this machine back in 99 when I was in LA but it is unlikely to materialise in my opinion. The 22 and 44 slot directly into gaps in the market and provide very cost effect solutions due to the cost savings made by FR in his airframe design. In small piston engined helicopters this is a significant proportion of the cost due to the relatively small cost of piston engines for aircraft. If you try and apply the same technique to a turbine helicopter the saving wouldn't be as significant. There are no 'cheap' light turboshaft engines available for helicopters, and for light turbine helicopters the cost of the engine is very significant in terms of the overall cost of the aircraft therefore the cost saving approach Robinson has adopted for the 22 and 44 will be ineffective for a R66. Hence he will end up with an aircraft that costs roughly the same as the competition and doesn't do anything 'specific' better than the competition - Jetranger, EC120 etc etc. Since he wouldn't be able to make them any cheaper, he would get his volume and hence couldn't make his margin - it's not really worth his while pursuing the program.
He would also have to consider aesthetics a little more carefully too with a bigger turbine machine if he were to dent the competition! 
Hope this helps
CRAN
In his place one of his senior engineers provided a telephone conference to the audience. I believe his name was Pat Cox. During this one of the features that he commented on was that Robinson was currently flight testing an R44 with a fuel injected engine. So its true. That of course assumes that no other technical difficulties arised in the testing program!
I quizzed him about a turbocharged version instead (more power) but although a turbocharged engine has been tried, it cannot be used because it gets too hot. It is only cooled by the same squirrel cage fan.
There were some articles in the aviation press about a Lycomming 580 model, if you look at the Lycomming web page you'll see this engine is available so this might also be being considered - though i've heard no follow up on this.
As to the R66 I heard rumours about this machine back in 99 when I was in LA but it is unlikely to materialise in my opinion. The 22 and 44 slot directly into gaps in the market and provide very cost effect solutions due to the cost savings made by FR in his airframe design. In small piston engined helicopters this is a significant proportion of the cost due to the relatively small cost of piston engines for aircraft. If you try and apply the same technique to a turbine helicopter the saving wouldn't be as significant. There are no 'cheap' light turboshaft engines available for helicopters, and for light turbine helicopters the cost of the engine is very significant in terms of the overall cost of the aircraft therefore the cost saving approach Robinson has adopted for the 22 and 44 will be ineffective for a R66. Hence he will end up with an aircraft that costs roughly the same as the competition and doesn't do anything 'specific' better than the competition - Jetranger, EC120 etc etc. Since he wouldn't be able to make them any cheaper, he would get his volume and hence couldn't make his margin - it's not really worth his while pursuing the program.
He would also have to consider aesthetics a little more carefully too with a bigger turbine machine if he were to dent the competition! Hope this helps
CRAN
Last edited by CRAN; 27th Aug 2002 at 17:01.
Cool as a moosp
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On the May 2002 Robinson Flight Safety course, Frank as usual gave the first 45 minutes briefing. Ref the improved power version of the '44, he seemed pretty confident that it would fly.
The requirement came out of some hot and high operators of the R44 that were asking for more power. Their engineers looked at many ways of providing same and seem to have firmed up on a positive maybe of valve changes and fuel injection which adds 30-35 bhp. Unfortunately it will be around 55 lbs heavier to give an AUW of 2500lbs, but the power excess is worthwhile. Fuel burn looks about the same.
When pressed on costs, Frank was cautious and simply suggested that it would cost more. He said that the standard R44 will still be produced for those of us that do not need the extra performance.
My two cents...
The requirement came out of some hot and high operators of the R44 that were asking for more power. Their engineers looked at many ways of providing same and seem to have firmed up on a positive maybe of valve changes and fuel injection which adds 30-35 bhp. Unfortunately it will be around 55 lbs heavier to give an AUW of 2500lbs, but the power excess is worthwhile. Fuel burn looks about the same.
When pressed on costs, Frank was cautious and simply suggested that it would cost more. He said that the standard R44 will still be produced for those of us that do not need the extra performance.
My two cents...
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Raven II
This new model will be produced alongside the existing Raven, and features:
Fuel injected Lycoming IO-540 engine
Increased power
Max take-off weight increased from 2400 lb to 2500 lb
28 volt system
Larger main rotor blades
This option will be priced at no more than $30,000 over the standard Raven list price.
Copied from the UK importer of Robinson products website.
Fuel injected Lycoming IO-540 engine
Increased power
Max take-off weight increased from 2400 lb to 2500 lb
28 volt system
Larger main rotor blades
This option will be priced at no more than $30,000 over the standard Raven list price.
Copied from the UK importer of Robinson products website.
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Frank Robinson once told me (1995) that his whole approach was predicated on the fact that pistons were much more cost-effective that turbines and that he would never produce a turbine helicopter. So fat so true.
CRAN: 7/11? Frank got stuck in a convenience store?
CRAN: 7/11? Frank got stuck in a convenience store?
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Enstrom manage to get a turbocharged O360 to cool OK and produce 225 BHP - The same as the 5 minute rating for the R44 540.
It can be done.
And the Enstrom is fuel injected -no carb heat, max UAW 2600 lb
The Enstrom design is 27 years old - and reliable - and cheap(ish)
Price comparisons not valid as only 3 pax.
Its about time Robinson stopped fobbing us off with carburettor equipped lycomings and dragged themselves into 1970s technology.
I would still rather have an R44 - even an Astro, though!
It can be done.
And the Enstrom is fuel injected -no carb heat, max UAW 2600 lb
The Enstrom design is 27 years old - and reliable - and cheap(ish)
Price comparisons not valid as only 3 pax.
Its about time Robinson stopped fobbing us off with carburettor equipped lycomings and dragged themselves into 1970s technology.
I would still rather have an R44 - even an Astro, though!
Last edited by Gaseous; 18th Jun 2002 at 00:40.
Iconoclast
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UK & Oz R-44 operators. Are you aware of this?
SUPPLEMENTARY INFORMATION: On March 26, 1999, the FAA issued Priority Letter AD 99-07-18, applicable to RHC Model R44 helicopters, which requires, before further flight, inserting a Special Pilot Caution into the Normal Procedures section of the RFM. That action was prompted by several reports of sprag clutch assemblies, including one from wreckage of an accident that occurred within the past year, with cracked or fractured sprag ends. The sprag clutch failures, determined to be due to a change in the manufacturing process, could result in loss of main rotor RPM during autorotations. The intent of that priority letter AD is to alert pilots of the potential for the sprag clutch failing to overrun during autorotation, loss of main rotor RPM, and subsequent loss of control of the helicopter.
The FAA has reviewed Robinson Helicopter Company R44 Service Bulletin SB-32, dated March 22, 1999, which describes procedures for checking whether sprag clutches with certain serial numbers are installed and replacing certain serial numbered sprag clutches, and inserting a Special Pilot Caution in the Normal Procedures section of the RFM.
Since the unsafe condition described is likely to exist or develop on other RHC Model R44 helicopters of the same type design, the FAA issued Priority Letter AD 99-07-18 to alert pilots of the potential for the sprag clutch failing to overrun during autorotation due to the failure of the sprags within the sprag clutch assembly and loss of main rotor RPM. The AD requires, before further flight, inserting a Special Pilot Caution into the Normal Procedures section of the RFM which primarily addresses autorotation maneuvers and a before every flight sprag clutch (split tach needles) check for proper function of the sprag clutch. Inserting the Special Pilot Caution is an interim action. The FAA will issue an AD to supersede this AD and require replacing the clutch assembly when parts become available from the manufacturer. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity of the helicopter. Therefore, inserting a Special Pilot Caution into the Normal Procedures section of the RFM is required before further flight, and this AD must be issued immediately.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on March 26, 1999, to all known U.S. owners and operators of RHC Model R44 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.
The FAA estimates that 200 helicopters of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hour per helicopter to insert the caution into the RFM, and that the average labor rate is $60 per work hour. Based on these figures,
The FAA has reviewed Robinson Helicopter Company R44 Service Bulletin SB-32, dated March 22, 1999, which describes procedures for checking whether sprag clutches with certain serial numbers are installed and replacing certain serial numbered sprag clutches, and inserting a Special Pilot Caution in the Normal Procedures section of the RFM.
Since the unsafe condition described is likely to exist or develop on other RHC Model R44 helicopters of the same type design, the FAA issued Priority Letter AD 99-07-18 to alert pilots of the potential for the sprag clutch failing to overrun during autorotation due to the failure of the sprags within the sprag clutch assembly and loss of main rotor RPM. The AD requires, before further flight, inserting a Special Pilot Caution into the Normal Procedures section of the RFM which primarily addresses autorotation maneuvers and a before every flight sprag clutch (split tach needles) check for proper function of the sprag clutch. Inserting the Special Pilot Caution is an interim action. The FAA will issue an AD to supersede this AD and require replacing the clutch assembly when parts become available from the manufacturer. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity of the helicopter. Therefore, inserting a Special Pilot Caution into the Normal Procedures section of the RFM is required before further flight, and this AD must be issued immediately.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on March 26, 1999, to all known U.S. owners and operators of RHC Model R44 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.
The FAA estimates that 200 helicopters of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hour per helicopter to insert the caution into the RFM, and that the average labor rate is $60 per work hour. Based on these figures,
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Lu, this is old news as Robinson authorised service agents were some of the first to hear about this and all our Robinson helos had the modified sprags fitted yonks ago....
PPRuNe Enigma
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Yeah, we had a copy of this bulletin up on our notice board shortly after it was issued and we've all seen it.
Sprag clutch needle split check is part of the standard preflight anyway.
It was a long time ago - why raise it now ?
Sprag clutch needle split check is part of the standard preflight anyway.
It was a long time ago - why raise it now ?
Iconoclast
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To: Rotor Nut
My reason for posting the above was as a result of some communications I have had with the CAA AIB relative to their communications with the FAA in respect to the R-22 and R-44 POHs.
It seems that the FAA had taken a different approach to elements of the two POHs as opposed to what the CAA Safety Regulation Group had indicated what they were going to do regarding the same material. The Safety Data Unit advised me that they were going to issue a GASIL making the material mandatory as opposed to the FAA making it a recommendation. That was in November of 2000 and to my knowledge that action is yet to be taken. The Safety office was supposed to notify me by letter when that action was taken. Nothing to date. So when I saw the above AD I thought I would post it just in case it was not disseminated within Oz and the UK. There was no malice intended.
:o
My reason for posting the above was as a result of some communications I have had with the CAA AIB relative to their communications with the FAA in respect to the R-22 and R-44 POHs.
It seems that the FAA had taken a different approach to elements of the two POHs as opposed to what the CAA Safety Regulation Group had indicated what they were going to do regarding the same material. The Safety Data Unit advised me that they were going to issue a GASIL making the material mandatory as opposed to the FAA making it a recommendation. That was in November of 2000 and to my knowledge that action is yet to be taken. The Safety office was supposed to notify me by letter when that action was taken. Nothing to date. So when I saw the above AD I thought I would post it just in case it was not disseminated within Oz and the UK. There was no malice intended.
:o
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There's not much point putting the information in the handbook because all Robbos in the UK will have been modified. It was a maintenance issue anyway. I don't see the need for a page in the handbook - its history, been and gone...
You say there's been no action - sorry, I think there has - the really relevant action (to fix the problem) has been done. Give the CAA and Robinson some credit - the information was clearly disseminated and acted upon.
And as Grainger said, we check the sprag clutch every startup - a SOP.
Lu, you may have safety at heart but by being so pedantic you just become irritating, out of date, and spoil any valid point you might have had to make.....
In contrast, when Dick Sanford imparts something Robbo related, I get elephant style ears and take in every word he has to say and it gets fixed in the memory bank.... its not the number of words... its the way they are delivered!
You say there's been no action - sorry, I think there has - the really relevant action (to fix the problem) has been done. Give the CAA and Robinson some credit - the information was clearly disseminated and acted upon.
And as Grainger said, we check the sprag clutch every startup - a SOP.
Lu, you may have safety at heart but by being so pedantic you just become irritating, out of date, and spoil any valid point you might have had to make.....
In contrast, when Dick Sanford imparts something Robbo related, I get elephant style ears and take in every word he has to say and it gets fixed in the memory bank.... its not the number of words... its the way they are delivered!