Questions For Bell Training Pilots

[bleed air]

All of the medium pilots in our outfit seem to be pretty comfortable with the techniques of managing rotor RPM in our 204’s and our 205A-1 during various scenarios, i.e., to maximize lift, during left pedal jams, beeping back the N2 governor while in EMERG mode to reduce throttle sensitivity, auto’s, etc.

 

Our 205A-1 has just been upgraded with the 212 rotor system this past winter. I’ve heard a few stories about not letting the rotor RPM decay with these blades but other than that I haven’t any experience with them.

 

My 1st question then is: Are the rotor RPM management techniques mentioned above no longer applicable/safe in our 205? Any other “watch-out-for’s” that we need to be aware of?

 

2nd question: How much right pedal input is realistic while training loss of thrust scenarios in the Bell’s?

 

Cheers, folks.

[sharkbait]

I have never flown a 205 with a 212 Rotor System so really can't address your question from experience on type.

Our emergency procedures allow RPM to decay to 91 % during transition to single engine flight following the loss of an engine on a 212. The a/c seems to do this comfortably. RPM is returned to 97-100 by 58 KTS.

From STIMulator training on the 212 I can say that loss of tail rotor drive always led to a full on outo with a run on at the bottom- never could make that sucker fly with any combo of power and airspeed. Fun in the sim. We do not allow full ons in the 212 or any other twin for that matter so can't say how much right pedal truly simulates a loss of thrust except to guess " a bunch".

On a risk/benifit basis I don't think a completion of a touchdown when simulating this emergecy is to be recommended. Lot of things happening very quickly at the bottom end. The cost in skid shoes alone would be high and the trail of sparks and smoke from the skids impressive.

A lot of guys on this forum will be able to provide much better info and advice - chances are there is someone who has actually experienced the real thing.

In rereading this I can see I have offered no usefull info but will post it just so you know someone reads your posts.

[Biggles]

The following info was passed on to me from a source who is really really (like absolutely, positively and no doubt about it) in the know.

 

"The BH12 rotor is an asymmetrical airfoil and MUST be flown at 100%. Anything below that results in a decreasing lift. DO NOT FLY IT like a BH05 rotor !!!"

 

Voila !

Biggs

[VERTICAL REF]

The 212 blades will still fly at 85% NR. Pull into a IGE hover and squeeze the throttle off until the rpm indicates around 85...you will still be flying. (but remember 2 pilots half tanks etc - you will not wreck the a/c) And will feel what the 214B boys sit in.

 

Now try lifting 3500 lbs and if your not at 100% NR you will not move anywhere. Beep up from 98/99 to 100 and watch the good girl lift. The 212 blades are very rpm sensitive for maximum lift performance. Very aerodynamic blade, center of lift, center of pressure etc!

 

The dual tach does not change when you change blades...the min 97% in a 212 has no correlation to the min 90% in a 205. Has to do with the twin engine / single engine thing, being able to maintain rpm and OEI flight, certification etc.

 

"single engine torque, 58kts, full beep"...all in one motion!

 

 

IF ya need more info dont be afraid to PM!

[VERTICAL REF]

Bleed air, Sorry

 

Disregard the third paragraph, was getting all confused with power off limitations, while the boys were scoring a goal on TV there!!!

 

Here is the correct version.

 

Power on limitation for 205 or 212 blades is 97 to 100%. period.

With the 205 blades you are allowed to go down to 91 (yellow arc) below 30 kts. But continueous is still 97%. Thererfore the flying procedures or emergency procedures will not change from 205 to 212 blades. Old wives tale...

 

The dual tach DOES change with the STC - with the only difference is the removal of the yello arc! The power off limitations do not change when you change the blades!

 

Enjoy the smooth as glass flight and the entra lift at altitude, they work great at 13,000'

 

There, much better...

 

One more - this is for a 205 only 212 - totally different!!!

[Randster]

All of the medium pilots in our outfit seem to be pretty comfortable with the techniques of managing rotor RPM in our 204’s and our 205A-1 during various scenarios, i.e., to maximize lift, during left pedal jams, beeping back the N2 governor while in EMERG mode to reduce throttle sensitivity, auto’s, etc.

 

Our 205A-1 has just been upgraded with the 212 rotor system this past winter. I’ve heard a few stories about not letting the rotor RPM decay with these blades but other than that I haven’t any experience with them.

 

My 1st question then is: Are the rotor RPM management techniques mentioned above no longer applicable/safe in our 205? Any other “watch-out-for’s” that we need to be aware of?

 

2nd question: How much right pedal input is realistic while training loss of thrust scenarios in the Bell’s?

 

Cheers, folks.

<{POST_SNAPBACK}>

 

 

I don't know anyone who really trains for Loss of Thrust. That's pretty much a required "enter autorotation and if you have enough altitude you may be able to return to powered flight, at least long enough to pick a suitable area for landing. In any event, the landing should be power off."

 

Stuck pedals are a little different. If you want to train for them, then use a reasonable amount of power for takeoff for a stuck left. Use the chart in the limitations section. Also, go vertical so the fin doesn't unload the tail rotor and reduce the amount of left pedal.

 

For stuck right, use a reasonable amount of low power such as what you might experience on a normal approach... that's normal not fast.

 

And ... good luck

[cap]

Randster -----Simply put, try it yourself!. Pick an altitude that provides a 'comfort zone' and room/time for recovery and 'beep' it down yourself.....and mind the a/s. Try to keep that altitude and a/s while you're doing all this and you'll discover quickly what happens and how much of anything you have to adjust for. Whether 204, 205 or 212, she'll get real 'mushy' on all of the controls and when you reach the end of "your comfort zone" call it quits. The 212 at 94% NR is DESCENDING period. The 205 will go down to scary areas (91%) and still fly, but many are not comfortable at all down there or even close to it and never venture there ever. Also realize that when you are doing it, you are putting a big time strain on the drive train and you're making her "puff" and work up an undue stress. Engineers will look at you with beady little eyes if you do this too often. As a result, I operate in the 98% area most of the time, but if I have a headwind, she gets put to 100% and reduced a/s beause she 'hammerin' enough as it is and why torture the girl anymore than necessary in those conditions for another 5kts.

 

As far as 'beeping' in general is concerned for lifting, etc., it would be great if you could see a video that Bell has. I saw it decades ago and it was filmed at night with strobes on the ends of the blades on a 204 that was hooked to an anchor on a pad at Bell. What you see those blades doing from the roots outward, will 'blow you away' and give you added appreciation for what effect you are having on the drive-train when you 'beep-back'. What it does is make you 'pull back and re-load' when you drop the NR down and make all your movements getting that load off with added care and slowness........because you will NEVER EVER forget that video.

 

One added item that always 'bugs me'......NO there is No such thing as "War Emergency power, like they used in Vietnam", so that you can take it to 60PSI. There is NO such thing...it was never taught......with or without a change of blades types. If you had somebody trying blow your *** to **** you didn't look at guages.....you pulled until she wouldn't climb anymore and then tried to go forward. There was a valid reason for all this at 85% RH and 95F temps. So far to date, I've had no customers that were that angry with me.

 

 

Lastly.......pedal inputs?.....depends on how your a/c was set up. They might all supposed to be the same, but the fact is they are not and that's an item that you should check whenever you climb in one that you haven't flown before. Otherwise, you might have an 'intresting' problem' if you have to do an autrotation or anything else requiring some added input to keep her straight. Ditto for friction on the collective that's put in there for a reason. Don't like that friction?.......then be prepared for the possiblity of something else that's 'interesting' one of these days.

[bleed air]

Thanks for all the replies, everyone.

 

I had an interesting conversation with the holder of the STC for the 212 rotor blade conversion that was installed on our 205. His reply to my question as to why the change in NR limits was as follows:

 

“This is always an interesting question because it is a change driven by the certification basis rather than the specific configuration of the 205.

 

The N2 limit is driven by Bell and is based on the 212. When the 212 rotor was certified on the 205B the N2 limits were simply adopted without change. Consequently, when we certified the 212 rotor system on the 205, we based it on the certification of the 205B.

 

My understanding is that the limits are the result of how the PT6 recovers from low RPM situations vs.. the T53.”

 

He went on to say that there had not been that many complaints to justify the expense of amending the STC to reflect the T53 installation.

 

So, as CAP mentioned, we will try it ourselves and explore the NR envelope (with all due caution, of course!) and will report back our results.