Bell 206: JetRanger and LongRanger

[Hone22]

Hung starts B206

Hi all,

Well the ol battery in the 206 has been a wee tad low on the charge thing recently. 1st start today 25c 2000ft amsl, very slow to spool up to 12% - crack fuel modulate flow to keep TOT in hand. Turbine lights off but still slow in building to the 58% start cut out.

After a 1 hr flight, no probs genny or elsewhere, shutdown for about 3hrs. Try a restart, lucky to get 12%, crack fuel, lights off but going nowhere. Look after TOT but no accelaration whatsoever N1, Abort start go home drink wine and post this.

Comments? Any tips out there (apart from the obvious, new batt or grd pwr for starters).

Any Ol hands with the low down on 206 starts (ceco fuel governor) please add your pearls of wisdom re starts and general do's don't you follow with this darlin'

Cheers & fly safe. .Hone

[sprocket]

Wisdom can be a hard earned thing. Whatever you hear or do ...

1. Dont burn the the hot end off.

2. Get it looked at/fixed before somebody does burn the hot end off.

3. Oh, and did I mention, dont burn the hot end off!

Good Luck!

[Steve76]

Gidday Hone,. .Check the starter contactors in the nose, they contain a copper bar and we used to get a lot of corrosion on them around rotovegas.. .Sometimes a poor contact will prevent starting altogther. You should also clean and check the terminals on the genny and batt.. .Cher cher bro!. .

[Devil 49]

Gotta have more electrons. The battery is your source of power until the engine has the turns to keep the flame contained. The other demands on the battery, like boost pumps, etc., are minimal compared to getting the NG up to 58.. .When you have the techs attention, consider that starter/generator carefully. If you're using a nicad, you most likely have a simple battery and charging problem. But the starter could be getting weak too.. .Go easy on the introducing fuel at 12 per cent... That's the sorta thing that's great on occasion (emergency) but will cost you money in the long run. 14 or better makes me happy.

[tgrendl]

Look to see if you're getting coking also. When you shut down try to turn the blades back gently. If they don't want to go freely or are stuck you've probably got a coking problem in the motor.

If so increase cooldown times and immediately after blades stop rotate them backwards 2-3 revolutions.

This will work for a while but eventually you'll need the engine man in.

Good luck

[paco]

Although Allison have issued a letter stating that it's OK to crack the throttle at 12-13%, it's on the basis that the acceleration through that point is lively. If it's at all slow at that point, please, please don't attempt a start unless there's a polar bear coming! <img src="smile.gif" border="0">

OK Chief Pilot hat off...

Either the battery is not accepting a charge, in which case it might be sulphated (did someone leave it on before?), or it's not getting it, either because the genny is not sending it or there's something stopping it. I would certainly look at those bars (some guys even carry spares) and get the battery checked.

Hope that helps!

phil

[Lu Zuckerman]

This is from my deepest memory so I may get it cockeyed. If you have a lead acid battery then much of what Paco and the others have said is true along with the possibility of coking. You have a nickel cadmium battery then it requires periodic maintenance, which involves a complete discharge and recharging. A Ni Cad battery will develop a memory and with that memory it will only accept that level of charge and no more. If this is the problem then the battery does not have the ooomph to turn the engine over to light off speed assuming coking is not involved. Turning the main rotor backwards will give an indication of coking, as it will impede your ability to rotate the blades. If the coking level is low then the rotation of the blades backwards will break the engine rotor free. In either case, check the engine and check the battery log book to determine when the last maintenance was performed assuming a Ni Cad battery.

[Hone22]

Hi all,

Thanks for all the pearls, it's zackly what this forums about. Keep it up!!!

Battery's a Ni-Cad, deep cycled bout a mth ago.

What i learned from the postings.

1.Don't burn the hot end off.

2.Best min 14% before fuel intro, so as not to burn the hot end off.

3.Full batt ommphh, will help avoid burning the hot end off.

4.Check all terminals, said copper bar re-batt oommphh as per # 3.

5.As Batt deep cycled (& supposedly ok) probably a genny issue.

6. Coking could be a prob, but o'haul recently so maybe #5.

7. Don't burn the hot end off.

Thanks all. .Cheers & fly safe. .Hone.

Ps: Steve76 Kids from +40c to -40c, thank god they're so adaptable, ay! <img src="tongue.gif" border="0">

[tgrendl]

Hone 22

Overhauled recently scares me with that problem coming up.

Be carefull

[Steve76]

Right On Lu. Memory is a big prob. Well thought of.. .Hone - send me mail mate.. .Cher de cher kapai bro

[Hone22]

tgrendl said

Hone 22. .Overhauled recently scares me with that problem coming up.

Be carefull

Please elaborate, I'm all ears (eyes? ya get me)

cheers & flysafe. .Hone

[sprocket]

Hone22:

The coking problem mentioned above, as far as I’m aware only affects the N2 turbine labyrinth seal and will not cause the starting problems you originally mentioned. I have seen the N1 get up to 30% during start without the blades turning [due to a coked turbine] before the start was aborted. Up until then, the start sequence looked normal. [A bit like leaving your tie-down on]

I have not seen a 206 with a nicad for many years, unless the helicopter was new from the factory. They were usually modified soon after delivery to use a lead acid type. . .Are the nicads a better option for the colder/temperate climates?

BTW, I think you will find the starter contactor is behind the hat bin on the RH side of the A/C. The battery and external power contactors will be in the nose. <img src="tongue.gif" border="0">

Has anybody proved/disproved the theory that if you crack the throttle during start while the N1 is still accelerating, that it will start better? . .The original start procedure was to let the N1 peak with the starter before fuel was introduced. The argument against this was that the N1 turbine lost its acceleration momentum and needed more fuel/TOT to maintain its starting schedule.

[XV666]

H122,

Another possibility could be the starter gen, if it has badly worn brushes, or a duff commutator. Allison specifically require the throttle to be opened between 12-15% Ng, I have never subscribed to the technique of letting the Ng peak. Too much chance of no ergs left in the battery to properly spark the ignitors and give a clean start. I had Nicads in some 206's I operated, and haven't found much difference with lead acids, except a run of Sonneshein (sp?) units when they couldn't crank as advertised. Switched to Hawker batteries last year, and no further problems.

One 206 I fly has the fastest spin up of a C20 I've ever encountered, crack the throttle at 12% and it's past 15% before the fuel lights off! All other parameters are normal, it's been the same for years, even after a mini.

I'd be looking at the battery contactor in the nose, reckon Steve had the right idea there.

[TeeS]

Beware holding the temp too low during the start. As I understand it, during the early stages of the acceleration there is not sufficient air flow through the engine to 'shape' the flame, hence even though it appears to be a nice cool start you can be 'torching' the combustion can. A start that keeps the TOT towards the upper end of the limitations is preferable to a long slow one. That's my understanding of it anyway!

[paco]

I regularly use the technique put out in the Allison letter (sorry don't know the reference) which essentially is, as N1 accelerates through 12%, crack throttle (our machine likes 13% better for some reason), and accept slightly higher peaks. I can't prove this, but I do feel it gives me a better chance of starting in remote areas because the battery isn't worked so hard during its life.

phil

[tgrendl]

Hone 22

I think that statistically most engine failures happen within 100 hours of rebuild/reman. If the aircraft went in without the problem you mention and came out not quite right it's a cause for concern.

You mentioned you had light off but no increase in N1 at all.

During the start attempt did the gages fall to zero? For a 206 this is a last chance indicator of bad battery.

Did the health checks for that engine (and topping check) after rebuild show the engine as positive and staying or was it rapidly decreasing in performance?

Lots of variables to look at here but don't let safety become one of those variables. Best place to find something wrong is on the ground.

Let us know what's found please,

Thanks

[paulgibson]

tgrendl

Can you explain what you mean by a 'topping check'. I understand in a 212/412 OEI situation to check max N1, not so sure what you mean in relation to a 206. Pretty sad old compressor to 'top' a 206 though......

cheers

[b407driver]

Doesn't anyone want to ask whether he's flying a B-model or an L-model? I assume a B-model, but many of the posts reference correct answers for one or the other model...

Just a thought!

[sprocket]

I've assumed a 206B, because of the ceco system that was mentioned in Hones first post.

[Hone22]

Hi all,

yep, a 206b model and problem was traced to a shagged battery (more volts Igor!!)

Thanks to all who contributed, I'm sure others as well as myself are now more enlightened and once again the whole reason for this forum is to share the wealth of knowledge out there so mistakes aren't repeated endlessly.

Actually other reasons for this forum inlcude telling big whoppers, shooting the breeze, where is xxxx i flew with in 85' ..........Keep it up.

Any more pearls of info re- B206b greatly appreciated.

Cheers & flysafe. .Hone