Bell 412
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100% NR Cruising
Greeting fellow 412-ers!
Sorry nothing still on file from Bell, but I did get confirmation that Bell had definitely come back to our company and pointed out that they recommended all 412 operators maintain 100%NR throughout the flight range and that particular attention had to be paid to the 412 EP model to ensure that no climbs with RRPM less than 100%NR were carried out (non-emergency, that is!) .
I can, therefore, only suggest that you guys who are still ''beeping for victory'' in the cruise consider getting your companies to contact Bell directly on this subject if you have any doubt - or otherwise just to change your SOPs and FRAM damper tunings to 100% as covered in my previous posting. . I suspect that you will indeed find that such a common-sense move will result in much less wear and tear being experienced on both the rotating components of the rotorhead and on your gearboxes/power trains.
Salaams,
Sorry nothing still on file from Bell, but I did get confirmation that Bell had definitely come back to our company and pointed out that they recommended all 412 operators maintain 100%NR throughout the flight range and that particular attention had to be paid to the 412 EP model to ensure that no climbs with RRPM less than 100%NR were carried out (non-emergency, that is!) .
I can, therefore, only suggest that you guys who are still ''beeping for victory'' in the cruise consider getting your companies to contact Bell directly on this subject if you have any doubt - or otherwise just to change your SOPs and FRAM damper tunings to 100% as covered in my previous posting. . I suspect that you will indeed find that such a common-sense move will result in much less wear and tear being experienced on both the rotating components of the rotorhead and on your gearboxes/power trains.
Salaams,
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external kit?
Oracle, does your 412 fleet have any external kit mounted (skis, floats, hoist, etc)? We were advised by Bell a few years ago to only operate at 100% Nr with external kit, but in a clean bird 97% is still authorized. Food for thought...
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Ya Matt, I just took a few months off to let you catch up to me in your knowledge of the 412. Looks like you might be needing to get back into the books again 
or maybe I should stay at home longer to give you more time? Enjoy your three weeks of classes 
or maybe I should stay at home longer to give you more time? Enjoy your three weeks of classes
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100% is Divine!
G'day!
Well, in the end you guys will have to make your own minds up! However, as I have said before, Bell 'strongly recommends' that 412 operators maintain their RRPM at 100% throughout the flight envelope. The particular known problem of excessive head component wear on the 412EP Model in particular during climbs made at 97% RRPM would seem to suggest that the sensible option for all variant operators is to stick with 100% RRPM as a standard for all non-OEI flight phases and to minimize OEI rate of climb for training purposes (not that one needs much help with that!).
Apart from amending your company's maintenance and flight test procedures to retune your aircraft's FRAM dampers to 100% for the cruise/Vne segment of the vibro (part of the vibro is obviously still done at 97% to ensure that nothing shakes itself to bits during OEI ops!) and adding a decal on the instrument panel to indicate this change (and educating your staff that not cruising at 97% is in their best interests), there seems little to be gained from retaining the old 204/205/212/214B twin-blade cruise RRPM setting.
Besides the fact that fuel saving with the composite blades on the 412 is marginal/minimal at 97% as opposed to the normal 100%NR, if your company's engineers don't strictly 'time' your beep trim actuators, you might/will undoubtedly find that even the most fleeting operation of an over-excitable 'beep' actator [especially when torque is already at or near the 'top of the green'] might lead to accidental/inadvertent overtorquing of the main rotor (>105 KIAS). Particularly when the beep is used to restore 100%NR from a cruise setting of 97%NR. This 'beeping up' can lead to a nasty, if not positively savage, degree of rapid mast torque fluctuation in EP's that do have such a 2 to 5 second full-range beep timing (Bell recommends 8 to 11 seconds, I believe, - like the 205/212). In some companies, the beep actuator timings on their fleet aircraft are all different! Someone getting out of a sedentary SP therefore and straight into a 'hyper' EP might easily ruin their whole day/career in a moment of tired inattention at the end of an 11-hour day! Not worth it in my humble opinion!
In the end, choice of cruise NR setting is still left up to the individual operator, but one suspects that by 'advising' customers to operate their EPs (and therefore their whole 412 fleet for sensible standardisation) in this manner, Bell have covered their liability 'Six' and will not entertain any prospective cries of premature or excessive wear, or other inexplicable damage to rotating components from customers who have not complied with their 'advice'! Having seen such components removed from a new EP with less that 100 hours on the clock, I am quite convinced that maintaining a steady 100% NR throughout the normal operating envelope is the most sensible way to go!
I hope that this post may help you decide likewise!
Well, in the end you guys will have to make your own minds up! However, as I have said before, Bell 'strongly recommends' that 412 operators maintain their RRPM at 100% throughout the flight envelope. The particular known problem of excessive head component wear on the 412EP Model in particular during climbs made at 97% RRPM would seem to suggest that the sensible option for all variant operators is to stick with 100% RRPM as a standard for all non-OEI flight phases and to minimize OEI rate of climb for training purposes (not that one needs much help with that!).
Apart from amending your company's maintenance and flight test procedures to retune your aircraft's FRAM dampers to 100% for the cruise/Vne segment of the vibro (part of the vibro is obviously still done at 97% to ensure that nothing shakes itself to bits during OEI ops!) and adding a decal on the instrument panel to indicate this change (and educating your staff that not cruising at 97% is in their best interests), there seems little to be gained from retaining the old 204/205/212/214B twin-blade cruise RRPM setting.
Besides the fact that fuel saving with the composite blades on the 412 is marginal/minimal at 97% as opposed to the normal 100%NR, if your company's engineers don't strictly 'time' your beep trim actuators, you might/will undoubtedly find that even the most fleeting operation of an over-excitable 'beep' actator [especially when torque is already at or near the 'top of the green'] might lead to accidental/inadvertent overtorquing of the main rotor (>105 KIAS). Particularly when the beep is used to restore 100%NR from a cruise setting of 97%NR. This 'beeping up' can lead to a nasty, if not positively savage, degree of rapid mast torque fluctuation in EP's that do have such a 2 to 5 second full-range beep timing (Bell recommends 8 to 11 seconds, I believe, - like the 205/212). In some companies, the beep actuator timings on their fleet aircraft are all different! Someone getting out of a sedentary SP therefore and straight into a 'hyper' EP might easily ruin their whole day/career in a moment of tired inattention at the end of an 11-hour day! Not worth it in my humble opinion!
In the end, choice of cruise NR setting is still left up to the individual operator, but one suspects that by 'advising' customers to operate their EPs (and therefore their whole 412 fleet for sensible standardisation) in this manner, Bell have covered their liability 'Six' and will not entertain any prospective cries of premature or excessive wear, or other inexplicable damage to rotating components from customers who have not complied with their 'advice'! Having seen such components removed from a new EP with less that 100 hours on the clock, I am quite convinced that maintaining a steady 100% NR throughout the normal operating envelope is the most sensible way to go!
I hope that this post may help you decide likewise!
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Oracle, the post really does nothing without the advice from Bell. Have you found any correspondance that actually details this, or is this change to your companies maintenance and operational procedures merely based on word of mouth?
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Bell 412 NR
Well, my dears, I wasn't going to waste more time wading through 4 years of correspondance to find the actual letter from Bell, - but if you choose not to believe me (despite the halo) and are SO durned desperate for written proof, why don't you just drop Bell Customer Support a line yourselves - or don't you guys talk to them at all?
Unless you are based in Iran, Bell will probably respond and may even satisfy your every need (within the constraints of product liability legalities)!!! If you are, then best not to email or call them at all - you might find some GPS targeted munitions from GWB incoming onto your bonce!
Seek and ye shall find, Glasshopper!
Unless you are based in Iran, Bell will probably respond and may even satisfy your every need (within the constraints of product liability legalities)!!! If you are, then best not to email or call them at all - you might find some GPS targeted munitions from GWB incoming onto your bonce!
Seek and ye shall find, Glasshopper!
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I think that's our points as well. You seem to be the only one that has heard of this. You have no correspondance to verify this. We're all in regular contact with Bell. We still have 97% cruise in our manuals.
What if I told you that Bell said you can't start engine #2 first (they didn't say this). Would you then change your procedures? Even if nobody provides evidence or even supports this claim?
It's not that we don't trust you, just that a change like this requires more than one opinion from the internet.
What if I told you that Bell said you can't start engine #2 first (they didn't say this). Would you then change your procedures? Even if nobody provides evidence or even supports this claim?
It's not that we don't trust you, just that a change like this requires more than one opinion from the internet.
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Mmmmm....
Well I am going to have to side with Oracle on this one .....
The company I work for has also been advised by Bell to do the 100% Nr operating RPM thing and it makes quite a difference!
With 15 odd 412s (mostly EPs) it has made life much easier for the maintenance crews and with our higher (than most) DA ops it seems to me the aircraft like it better too!
Cheers
P.S. ...... just 'cos Bell have advised the operating RPM change does NOT mean they have to ammend Flight Manuals to reflect that opinion.
Well I am going to have to side with Oracle on this one .....
The company I work for has also been advised by Bell to do the 100% Nr operating RPM thing and it makes quite a difference!
With 15 odd 412s (mostly EPs) it has made life much easier for the maintenance crews and with our higher (than most) DA ops it seems to me the aircraft like it better too!
Cheers
P.S. ...... just 'cos Bell have advised the operating RPM change does NOT mean they have to ammend Flight Manuals to reflect that opinion.
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412 Cruise NR
Thank you SPINWING!
Dudes - just ASK BELL and find out for yourselves!!!!!!! We did and that's what they came back with some 4 or 5 years ago.
Is that TOO difficult? Don't keep on qveching at me to go did into 20 years of correspondance for the letter from Bell - no time for that, I am only trying to help you (as requested in the original thread) by telling you what has gone on in my company for the last 7 years. You must be responsible for your own flight operations/SOPs and how you decide to operate your aircraft.
A Bell recommendation - as my friend SPINWING points out - is not necessarily going to appear in the PTM or Flight Manual! We live in a litigious world, my friend! 30% of your spares' cost is to cover possible litigation!
Also - if you haven't renewed or updated your 412 Flight Manual since you got your aircraft, its worth getting the latest EP ones from Bell (about $200 each I think) because it has some extras -OEI Fuel burn charts etc. which many opeators haven't seen yet because they haven't amended or renewed their Manuals in the aircraft since they took delivery!
So - drop Bell an email and find out what they say!
Dudes - just ASK BELL and find out for yourselves!!!!!!! We did and that's what they came back with some 4 or 5 years ago.
Is that TOO difficult? Don't keep on qveching at me to go did into 20 years of correspondance for the letter from Bell - no time for that, I am only trying to help you (as requested in the original thread) by telling you what has gone on in my company for the last 7 years. You must be responsible for your own flight operations/SOPs and how you decide to operate your aircraft.
A Bell recommendation - as my friend SPINWING points out - is not necessarily going to appear in the PTM or Flight Manual! We live in a litigious world, my friend! 30% of your spares' cost is to cover possible litigation!
Also - if you haven't renewed or updated your 412 Flight Manual since you got your aircraft, its worth getting the latest EP ones from Bell (about $200 each I think) because it has some extras -OEI Fuel burn charts etc. which many opeators haven't seen yet because they haven't amended or renewed their Manuals in the aircraft since they took delivery!
So - drop Bell an email and find out what they say!
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Interesting to read 7 yrs of 412 EP ops. RAF Shawbury's DHFS experienced operators beep down on nav sorties to reduce the mast Tq and therefore achieve even more IAS but moreover in this PC world less noise from the extemely loud tail rotor. We did an unofficial trial last year and the difference was you could get about 2nm closer to the bad guys before you were heard at 120kts. But flying at 97% in OIE condition is not good, but that's wehy it's in the FRC's to ensure that you beep back up to 100% post an engine failure.
Blue skies and light landings.
Blue skies and light landings.
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Does your 412 have a 2S11 switch to enable you to couple the busbar post an under volt/ flat battery otherwise you ain't going to commit aviation? We start o ur 412's #1 engineon odd days and #2 on even days without any probs.
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412s..............
Yup, Wings, the 2S11 switch is pretty standard these days. Anyone who ever suffered from the old 212 roof relays failing during starter load, with the resultant loss of 5 to 8 volts during the critical phase of start will remember why! (The engine hangs up at @12% NR, you have no voltage left to blow it through and the hot end burns out happily as the ITT passes 900 degrees C going UP!). Starting one of those puppies with flat ni-cads was a one-armed paperhanging exercise! The 2s11 switch 'remedies' this problem as only Bell (Product Liability) Textron Corp could. Problem is, all Bells were designed to start Number 1 engine first and 2 second (an Army pilot arithmentical logic process, I believe) so there is that bias in the (il)logic of the electrical system design, rather than true parity. As most 212 and 412 operators alternate 'first start' engines each day to spread wear, this can make it 'interesting' when starting number 2 first - especially on the odd-ball machine having a reluctance in its No 2 self-energizing generator relay! This is why it is often easier when starting Number 2 to quickly 'whip' the No. 2 start/gen switch straight up to reset and then straight back down to ON without stopping halfway (after 70% has been attained) to get the genny on line. When starting No 1, the Start/Gen switch will normally just switch straight on as advertised without resetting first. Similarly, some starter-generators will drop the respective battery bus switch off when start button has been engaged. This often confuses newbies until the magic finger reaches up, reselects the affected Bat Bus Bar Switch back ON and the start continues as advertised. - It was so just so much easier on the UH-1/B205!!! Of course then you had to remember NOT to try selecting the starter/generator on if you had been foolish enough to start with a falling battery voltage during crank (<14v) as one of my old Squadron Commanders proved when - despite warnings - he did this and several horrified people (inlcuding himself) watched the nosedoor and battery blow off the front of the aircraft! The Halcyon Days of knackered Ni-Cads! Lead-acids are the real deal!
As for 412 EP fits. -Standard offshore machines with external float kit, internal ADELTs (as all are now, I believe). I gather some operators without the floats do get slightly more from beeping down for cruise, but as I warned of before, the damage done to the rotating components (EP especially in climb) at 97% by far outweighs the perceived minimal fuel-burn saving, let alone the transient beep switch torque spikes which have been known to catch far too many tired 7-hour a day offhsore pilots without their brains-in-gear! As for quietness - well, man - IT'S A BELL! A little blade-slap is your personal acoustic signature! Heading Front Line with a 412? Definitely want 100% on!!!! (and clean underwear and lots of Kevlar Armour-plating - preferably in a 412B!)
In the end, Keep It Simple Stupid usually works better as a company policy in mixed-crew reality - so 100%NR across the non-OEI board is easier, safer and protects the aircraft, crew and passengers better from unintentional transient 'beeping' damage and excessive wear on your precious rotating 'bits'!
Happy Trails!
As for 412 EP fits. -Standard offshore machines with external float kit, internal ADELTs (as all are now, I believe). I gather some operators without the floats do get slightly more from beeping down for cruise, but as I warned of before, the damage done to the rotating components (EP especially in climb) at 97% by far outweighs the perceived minimal fuel-burn saving, let alone the transient beep switch torque spikes which have been known to catch far too many tired 7-hour a day offhsore pilots without their brains-in-gear! As for quietness - well, man - IT'S A BELL! A little blade-slap is your personal acoustic signature! Heading Front Line with a 412? Definitely want 100% on!!!! (and clean underwear and lots of Kevlar Armour-plating - preferably in a 412B!)
In the end, Keep It Simple Stupid usually works better as a company policy in mixed-crew reality - so 100%NR across the non-OEI board is easier, safer and protects the aircraft, crew and passengers better from unintentional transient 'beeping' damage and excessive wear on your precious rotating 'bits'!
Happy Trails!
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412 Normal operating RPM
ORACLE and Spinwing are on track. The latest information from BHT is that they are planning to amend the Flight Manual to say that 100% N2/NR is to be set for all Normal operations.
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Thanks for that!
Excellent news! Thanks for that, mate!
I had written to Bell last week about this, but not had any reply yet - perhaps they have now decided to make it 'official' at last!
Cheers,
Oracle
I had written to Bell last week about this, but not had any reply yet - perhaps they have now decided to make it 'official' at last!
Cheers,
Oracle
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About time it was official, flogging around at 97% NR/N2 never made any sense to me, lots of disadvantages and bugger all advantages in my book. Though I am sure some will disagree!!!
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