Bell 412
I agree with Nooby
In any case do not forget that an engine is not just an assembly of compressors and turbines!
If there is a possibility of foreign material ingestion (even with no scratch or dent on the compressor), all the air system, pipes, pressure sensors,etc. must be duly checked. You never know when the least expected piece of fabric will be stuck into an air tapping, a pressure sensor, an oil jet... ruining your long over sea night transit!
Being a bit conservative never reduce flight safety level!
Cheers
Kami
In any case do not forget that an engine is not just an assembly of compressors and turbines!
If there is a possibility of foreign material ingestion (even with no scratch or dent on the compressor), all the air system, pipes, pressure sensors,etc. must be duly checked. You never know when the least expected piece of fabric will be stuck into an air tapping, a pressure sensor, an oil jet... ruining your long over sea night transit!
Being a bit conservative never reduce flight safety level!
Cheers
Kami
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The only advice that matters is that of the engine manufacuturer. Provide them all the details and follow their recommendations to the letter. Failure to do so will risk the life of anyone subsequently operating the aircraft.
FOD and overtemperature are not the only terms of the equation. Much of the stresses in a turbine engine occur during start and shutdown. Starting with an inlet cover disturbs the delicate balance of air and creates situations that may lead to significant fatigue related failures.
Starting an engine with inlet covers installed is something the happens more than you might believe.
FOD and overtemperature are not the only terms of the equation. Much of the stresses in a turbine engine occur during start and shutdown. Starting with an inlet cover disturbs the delicate balance of air and creates situations that may lead to significant fatigue related failures.
Starting an engine with inlet covers installed is something the happens more than you might believe.
Main Changes
Transmission improvements allow more power to be applied to main rotor. PT6T-3D engines give higher power and 2.5 min OEI N1 and ITT limits. Improved 3 axis AP with options of 4 axis and EFIS. Torque matching no longer automatic - beeper switch now moves lateraly as well as fore and aft to match the torques in flight (can also be used to control an engine approaching it's ITT limit when hovering hot and high).
Bell 412 HP & EP share the same drivetrain...no difference (including the the ITT/N1/Tq trim switch). They both use a mast torque (phase shift) system.
Differences are: PT6T-3D engine providing substantially more OEI power and DDAFCS (dual digital AFCS) which allows for optional 4 axis helipilot system. This provides search & rescue modes including auto-hover
.
Differences are: PT6T-3D engine providing substantially more OEI power and DDAFCS (dual digital AFCS) which allows for optional 4 axis helipilot system. This provides search & rescue modes including auto-hover
.
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412 Differences
The BELL 412 Series grew like this: 212 + 2 more blades (bolted another pair with a flex-beam on top of the original pair!)= 412 Classic (useless and non-upgradable to the more powerful/capable DF engine and drivetrain). Better off with a 212! At least then you have a High Inertia Rotor rather than the Low (as in NO) Inertia Rotor of the 412!
412 Classic 'upgraded to 412 SP (SUPER POWER!!!) with slightly better design to stop the airframe cracking up, but still with the old 212's BF engines and inability (due airframe tolerances) to upgrade to DF engines and upgraded powertrain.
412SP then upgraded to HP (HIGH POWER!!-marginally better engine power with later model BF engines - a/c handles better but still only single AFCS). The HP models onward equipped with overtorque warning system (co-pilots always comes on first - go figure!). The HP is easily upgradable to DF engines - becoming in effect the best performing of the 412 series as it works out (with DF engines & associated powertrain upgrade) about 450 lbs on average below the 412 EP basic weight. Changes include strengthened main box, shaft and drivetrain, + upgraded (but more sensitive) Mast torque system (split-type torquemeter replaces the old BF engine/212 Delta Torque type indicator).
Most models now retrofitted to the newer 8 hour digital CVR system - so that the boss can hear everything!
Last Model:
The 412 EP (EXTRA/EXTREME/ENDLESS POWER) now comes standard with the DF engines, Upgraded trannie etc, yaw trim (useless Bell crap), Dual Digital AFCS as opposed to the old single steam-valve-driven item in the Classic/SP/HP - which makes all the difference for decent 3 axis/ 4 axis (SAR models) IFR flight. EP gives you dual digital FD selectors as opposed to the previous single analogue unit. New bells and whistles, twitchier pedal actuator, left/right N2 governor beeper trim (also retrofitted to upgraded DF engined HP models) functions only by tweaking #2 engine up or down a tad and primarily to fix torque splits inherent with the far more lively/twitchy/hotter starting DF FCUs! Better compass system and gyros. If you want you can get the very nice aircon upgrade with the new EPs - but at a 450 lbs penalty - making a DF equipped HP about 900 lbs less in basic airframe weight than the full-option new EP! Future US military variant is supposed to have FADEC, Glass cookpit (can't write it properly or it gets edited out!), improved (possibly Cobra Z) head and blades to replace the old boltontopoftheotherbastard Bell bodge (rather than a single in-plane starflex like the fwoggy machines) and a new quieter and more powerful tail rotor. Still to be seen yet though. Bell should just have taken their best biggest machine ever after the Huey (the 214B) and got Soloy to do a twin engine fit with 4 Burping Blades and and air conditioner!
The joy (!) of the DF-engined aircraft is their ability (with at least 5 to 8 knots of wind) to operate off a helideck at MAUW up to about 42 degrees C. Good enough for most places. The BF engined SP/HP will start to lose HOGE power/load lifting ability above about 34 to 38 degrees. They are noticeably less foregiving! The DF has single-growth crystal Hot-end blades - so has a much spicier top-end/OEI performance when the SH1T does hit the fan! All of the 412 series suffer from crappy pedal performance though in the hover, as that second bolt-on set of blades induces naughty interference to the tail rotor - nasty when the relative wind gets past the beam or the aircraft gets too high in the hover! 4 feet is really the safe max for hovering a 412! It ain't got the manners of the 205 or 212, sadly!
If you can - avoid the airline seat fit - there's nothing like the flexibility of the old troop seats - and customers eventually realize this!
Hope this makes everything as clear as muck!!!
412 Classic 'upgraded to 412 SP (SUPER POWER!!!) with slightly better design to stop the airframe cracking up, but still with the old 212's BF engines and inability (due airframe tolerances) to upgrade to DF engines and upgraded powertrain.
412SP then upgraded to HP (HIGH POWER!!-marginally better engine power with later model BF engines - a/c handles better but still only single AFCS). The HP models onward equipped with overtorque warning system (co-pilots always comes on first - go figure!). The HP is easily upgradable to DF engines - becoming in effect the best performing of the 412 series as it works out (with DF engines & associated powertrain upgrade) about 450 lbs on average below the 412 EP basic weight. Changes include strengthened main box, shaft and drivetrain, + upgraded (but more sensitive) Mast torque system (split-type torquemeter replaces the old BF engine/212 Delta Torque type indicator).
Most models now retrofitted to the newer 8 hour digital CVR system - so that the boss can hear everything!
Last Model:
The 412 EP (EXTRA/EXTREME/ENDLESS POWER) now comes standard with the DF engines, Upgraded trannie etc, yaw trim (useless Bell crap), Dual Digital AFCS as opposed to the old single steam-valve-driven item in the Classic/SP/HP - which makes all the difference for decent 3 axis/ 4 axis (SAR models) IFR flight. EP gives you dual digital FD selectors as opposed to the previous single analogue unit. New bells and whistles, twitchier pedal actuator, left/right N2 governor beeper trim (also retrofitted to upgraded DF engined HP models) functions only by tweaking #2 engine up or down a tad and primarily to fix torque splits inherent with the far more lively/twitchy/hotter starting DF FCUs! Better compass system and gyros. If you want you can get the very nice aircon upgrade with the new EPs - but at a 450 lbs penalty - making a DF equipped HP about 900 lbs less in basic airframe weight than the full-option new EP! Future US military variant is supposed to have FADEC, Glass cookpit (can't write it properly or it gets edited out!), improved (possibly Cobra Z) head and blades to replace the old boltontopoftheotherbastard Bell bodge (rather than a single in-plane starflex like the fwoggy machines) and a new quieter and more powerful tail rotor. Still to be seen yet though. Bell should just have taken their best biggest machine ever after the Huey (the 214B) and got Soloy to do a twin engine fit with 4 Burping Blades and and air conditioner!
The joy (!) of the DF-engined aircraft is their ability (with at least 5 to 8 knots of wind) to operate off a helideck at MAUW up to about 42 degrees C. Good enough for most places. The BF engined SP/HP will start to lose HOGE power/load lifting ability above about 34 to 38 degrees. They are noticeably less foregiving! The DF has single-growth crystal Hot-end blades - so has a much spicier top-end/OEI performance when the SH1T does hit the fan! All of the 412 series suffer from crappy pedal performance though in the hover, as that second bolt-on set of blades induces naughty interference to the tail rotor - nasty when the relative wind gets past the beam or the aircraft gets too high in the hover! 4 feet is really the safe max for hovering a 412! It ain't got the manners of the 205 or 212, sadly!
If you can - avoid the airline seat fit - there's nothing like the flexibility of the old troop seats - and customers eventually realize this!
Hope this makes everything as clear as muck!!!
Last edited by Oracle; 11th Sep 2006 at 19:50. Reason: typos & censoring!
You may be interested to hear that there is an FAA STC to drop in a 3DF Twin-Pac into a 212 or 412.
Held by Heliponents I believe.
Pretty sure ADA bought a couple of the kits a few years ago for 212's.
Held by Heliponents I believe.
Pretty sure ADA bought a couple of the kits a few years ago for 212's.
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Mmmm Oh yes the 412 can really buck around with a right crosswind on a turbulent helideck!..... so ....
Are there any Ppruners out there that have any experience with the "Boundary LayerTechnologies" (?) tailboom slat STC which is said to very much tame the 205,212,& 412 twitchy tail rotor control behaviour ?
Are there any Ppruners out there that have any experience with the "Boundary LayerTechnologies" (?) tailboom slat STC which is said to very much tame the 205,212,& 412 twitchy tail rotor control behaviour ?
Spin,
Currently Bell is fussing with the folks that build the tailboom slat you mention.
The issue is some cracking on the tail boom (as if that is new to Bell"s) and Bell blames the mod....the mod folks blame Bell.
I flew them on 212's but really could not tell the difference as the machines I flew with them did not have any SAS...and all the other 212's I ever flew had SAS so it was hard to compare.
Currently Bell is fussing with the folks that build the tailboom slat you mention.
The issue is some cracking on the tail boom (as if that is new to Bell"s) and Bell blames the mod....the mod folks blame Bell.
I flew them on 212's but really could not tell the difference as the machines I flew with them did not have any SAS...and all the other 212's I ever flew had SAS so it was hard to compare.
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Spin,
Currently Bell is fussing with the folks that build the tailboom slat you mention.
The issue is some cracking on the tail boom (as if that is new to Bell"s) and Bell blames the mod....the mod folks blame Bell.
I flew them on 212's but really could not tell the difference as the machines I flew with them did not have any SAS...and all the other 212's I ever flew had SAS so it was hard to compare.
Currently Bell is fussing with the folks that build the tailboom slat you mention.
The issue is some cracking on the tail boom (as if that is new to Bell"s) and Bell blames the mod....the mod folks blame Bell.
I flew them on 212's but really could not tell the difference as the machines I flew with them did not have any SAS...and all the other 212's I ever flew had SAS so it was hard to compare.
Thanks,barryb
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SASsy........... thanks,
Would be nice to try one of those kits out on a 412 ....... with the EPs I fly at the moment manouvering out of wind (and of course below the 90% Tq limit!!!) can be a neck snapping experience due to the airflow breakdowns around the boom and t'rotor .....
..... and I just LUV how the master caution flashes just as you rotate off the deck when the fuel state gets to 920 lbs or so .... one of the Bells less desirable features!!! 
Cheers
Would be nice to try one of those kits out on a 412 ....... with the EPs I fly at the moment manouvering out of wind (and of course below the 90% Tq limit!!!) can be a neck snapping experience due to the airflow breakdowns around the boom and t'rotor .....
..... and I just LUV how the master caution flashes just as you rotate off the deck when the fuel state gets to 920 lbs or so .... one of the Bells less desirable features!!! Cheers
What I always liked was trying to remember the unusable fuel when the fuel system went south....not that the 412HP/EP fuel system is confusing or anything.
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Chaps:
Any tips on Sling Loads and Winching with the EP?
Moving from 212 to 412EP. We have 412 Classics but haven't been usuing them for the interesting work.
Chas A
Any tips on Sling Loads and Winching with the EP?
Moving from 212 to 412EP. We have 412 Classics but haven't been usuing them for the interesting work.
Chas A
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Be VERY VERY careful doing any MAXIMUM weight sling loads in turbulent air with the EP ....
Also be VERY cautious if the governors are not working as advertised ...cos you will have that yellow over Torque light flashing as the governors argue over who is in charge! (causeing Tq oscillations and the above mentioned Yellow light or even worse the dreaded "Dolls Eye"!!!)
Cheers
Also be VERY cautious if the governors are not working as advertised ...cos you will have that yellow over Torque light flashing as the governors argue over who is in charge! (causeing Tq oscillations and the above mentioned Yellow light or even worse the dreaded "Dolls Eye"!!!)
Cheers