Suggestions please - Dodgy first start on my JetBox

[JTobias]

Administrators - is there any chance you could leave this thread to gain some momentum before you move it to the Jet Ranger thread - please?

Fellow Aviators,

Please help with this puzzling conundrum. :ugh:

First start of the day on my Jet Ranger is poor. (Not unusual, I know!) It struggles to get above 12% and I sometimes have to come off the starter and try again (Fuel not yet introduced).

The second attempt will often see the N1 sail through 12% and the engine can be fired. It's as if the first attempt loosens something allowing the second one to be much easier.

Subsequent starts throughout the day are usually no problem.

Today the first two attempts were aborted so we used a CoolSpool (GPU) which would traditionally provide more than enough power to get the N1 sailing through to 14% ready for the engine to be fired. However today when using the GPU we couldn't even get to 9% or 10%.

We immediately tried the GPU on another Jet Ranger and it worked perfectly so we knew the GPU was fine. (In any case it's brand new and only been used half a dozen times.)

The only way we managed to start the machine this morning was to switch the battery on and start it in conjunction with the GPU which then worked fine - however this is not an approved method and we don't want to be doing this again.

The battery on the JetBox is also brand new.

Next week, we are going to try swapping out the starter/generator to see if this is the problem, but I am curious to see if anyone has any thoughts on the issue.

Cheers, Joel :ok:

[chopjock]

Have you tried walking the rotor blades backwards first to loosen any coked on oil in the second stage? just a thought.:)

[JTobias]

Cheers ChopJock

Yep - every morning the first thing we do is rotate the blades backwards .
We've also adjusted the FCU a few times.

Joel:ok:

[FH1100 Pilot]

I'm no mechanic, but...

Voltage problem, eh? Either the proper voltage is not getting to the starter, or the starter is the problem. My money would be on the latter. How close is it to overhaul?

You can walk the blades backward from now until doomsday and it won't help your problem although the physical exercise certainly will be beneficial for you. The starter turns the N1/compressor, remember. Nothing...and I mean nothing happens in the N2 (to which the MR blades are rumored to be connected) until you get a fire going inside there somewhere (hopefully the engine, not the cabin). And it ain't the FCU of course, because this problem manifests itself long before squirting any kerosene juice into the can with that sparkumplug thingie snapping away.

When it does run, how your trend check? N1 where it ought to be? 93% or so? Compressor rubbin', maybe?

[JTobias]

Thanks FH1100

Everything else is fine once it's fired. We are going to change the starter on Tuesday so that may be the solution. I appreciate the response and any other ideas are appreciated.

Joel

[PEASACAKE]

Its nothing to do with carboning up, or turning the blades before starting, that only affects 3rd and 4th stage wheels.

I would check my starter generator brushes, sounds like they have deteriorated over the last few hours of use.

If not the brushes then its the starter /generator

Good luck :ok:

[JTobias]

Cheers,

Everything pointing to the Starter/Generator me thinks?

Joel

[blackhand]

Everything pointing to the Starter/Generator me thinks?

Have a look at your N1 rpm indication system, you maybe getting an erroneous indication.

The only way we managed to start the machine this morning was to switch the battery on and start it in conjunction with the GPU which then worked fine - however this is not an approved method and we don't want to be doing this again.

When you apply Aux power to the Jetranger the ships battery is taken offline.

[trackdirect]

When you apply Aux power to the Jetranger the ships battery is taken offline.

Frayed Knot!!!

When the external power is plugged in it will energise the ground power relay, but you can still turn the battery switch on which also energises the battery relay and both will then power the start.
Try it out yourself by switching on the battery when motoring over on ground power!!

You can charge a ground power batery too if you leave it plugged in and turn on the generator, but ensure you don't turn the gen on when using a start cart!!!

[blackhand]

Frayed Knot!!!

Mmmmm - let me check

[JHR]

The company I work for had a simalar problem on a long ferry trip. After changing the starter generator then the engine gear box then the turbine the problem was fixed by a new N1 tack. VERY embarasing!!:ugh:

JHR

[blackhand]

problem was fixed by a new N1 tack. VERY embarasing!!:ugh:KISS - mechanic's axiom

[Koryolis]

Bad N1 tach sounds good.
If you have replaced the hot end with a zero time one and then the problems started, it could be the overhaul.. N1 turbine is too tight and loosens up when it's hot..:)

[Scissorlink]

What does the N1 sound like its doing ?? Does the noise levels correspond with the gauge?

[Heli-phile]

Just like when your flying a H300 you can tell the correct RRPM "by ear" - same with the C20b N1 speed, My H500 had a sluggish N1 gauge and although the N1 "sounded" ready to rock the N1 gauge would drag (always 1st flight of the day) soon realised when, at lightoff the TOT was normal even with the apparent 12% N1.
It was the Gauge!!!. Whilst cranking I found a magic tap tap with digit brings the needle to the magic 15%

A good example of how clockwork systems and lateral thinking by the pilot allow flexibility and reduced down time on machines. Fadec would have got stroppy and spat the dummy. Not good when you are in a remote area!! (been there done that!!)

[paco]

When the blades start moving just on battery power, you have around 15%.

Phil

[JTobias]

People,


Cheers for all your replies. I'll be going through the responses with my maintenance company.

I'm going to see if I can get the N1 guage swapped too - that's a good idea, but I'm (reasonably) confident that it isn't this because we have fired the machine once or twice and then aborted the start due to higher than normal TOT acceleration - which indicated to me that we hadn't achieved sufficient N1 in the first place. It's worth checking though.

Cheers team, any other ideas will be appreciated.


Joel :ok:

[pitot212]

If you have no luck on here these people will be able to help you Essential Turbines Inc. (http://www.a250.com/)

Just email them your problem and I'm sure they will crack it for you. Good luck:ok:

[Saint Jack]

JT - I believe Scissor Link and Heli-phile are on the right track, i.e. does the noise level equate to the observed N1. If you're sceptical about accurate N1 indications simply swop the N1 and N2 tacho-generators over (they're identical) and see what happens. You said you have access to another JR, then try that N1 indicator in you machine - do the easy things first. If the problem is not with indication, then I would look at the starter-generator. check that the three connections are tight (pull the rubber covers back one at a time and check the torque of the nut, also check that the large firewall connector at the Fwd R/H of the engine compartment is tight.

If all of this is satifactory, remove the starter-generator and examine the brushes; a) are they worn, b) are they in the guides the right way around (they can be fitted backwards), c) are the springs making firm contact with the brushes, d) is any brush jammed in the guide, e) what is the condition of the comutator etc. etc. By the way, what is the TSN/TSI/TSO of the starter-generator?

It's still a little too early to be considering a replacement starter-generator and way too early to consider a turbine change.

An unusual problem, let us all know what was wrong when it's all settled.

[JTobias]

Thanks Pitot and Saint Jack,

I'll get maintenance to investigate your ideas also.
Really useful answers and I'll be sure to update you all shortly.

Joel :ok:

[rotormatic]

Another thing to check is the buss bar between the battery relay and the ground power relay in the nose by the battery.

This buss bar, along with the large wire going back to the start relay behind the hat rack, are made of aluminum. The buss bar is subject to corrosion, which will create some resistance between the battery relay, and the ground power relay. The wire going to the back of the ship attaches to the ground power relay.

Remove the wire and buss bar, clean or replace the buss bar, make sure the terminal and wire are in good condition, and see if that helps. Also, there is a junction block above the pilot’s head that the big wire goes to before branching off to the back. Had one of those get loose somehow once, and we had an intermittent battery charge problem. Took a while to figure out that one. May want to check that too.

[JTobias]

Rotormatic,

Thanks for this, I will get it checked out.
Really appreciate the suggestion.

Joel:ok:

[topendtorque]

JT
As Rotormatic and others have hinted on;
May I make the suggestion that you go all the way from the (power in) source, either way negative or positive, to the (power drain) source on both wires. Especially your earthing wires.

Truly, I have no idea just how many starter motors, and baterries, regardless of the type of machinery that were changed simply beacause the earth wire was not up to it.
I have Absolutely no idea how many helicopter gauges have been changed in my proximity, and many at cost to myself, simply because the same damm earthing circuit was not up to it.
Right now I have a problem with the engine instruments on two of our R22's in that regard. Every experienced driver will have a similar story to relate.

Many times I have seen that a starter motor will actuate because of the sudden high impulse it will crack an otherwise tenuous connection. I.E. one that will not allow a small current such as a battey recharge across the same connection. Result? flat battery.

I reckon that if you have fluctuating, RPM from either, of your ships or external power source, then you have a power transfer problem.

Voltage may well be really good in the unloaded state but current, as water, will only flow when you have a proper tap opening. That is proper cable cross section, and proper connection integrity, every connection and every cable, of which in your situation there are several.
cheers tet

[JTobias]

Thanks all,

The update now, is that I can't get it started at all today. I've tried on the battery, on external power and using both together, but I can't get sufficient N1 to fire the engine. On two attempts I have had to abort in order to avoid a hot start.

I've now asked my maintenance organisation to read through this thread and we're going to explore the ideas tomorrow. I will keep you all posted and really appreciate the suggestions.

Joel :{

[chopper_doctor]

I have seen wires switched on Jetbox sarter/generators. Makes for a LONG and SLOW start, all else is normal. Have your engineers confirm that the wires are on the starter/generator terminals the correct way.

[JTobias]

Hi All,

The update is (actually not much) that my maintenance team are coming tomorrow to look at all the connections, relays etc and they are bringing with them a replacement starter/generator as well.

We've printed off this thread and we'll be considering all the suggestions in turn. We think it will probably end up being the S/G, but let's see.

I'll put an update on here as soon as we get to the bottom of the problem.

Once again, thanks for all your responses.

Joel :ok:

[pitot212]

Good luck Joel, hope it's not a too expensive fix:ouch:

[JTobias]

Cheers Pitot,

I've started to sell a few things on e-bay to cover the cost. My wife isn't too happy as she says she will miss the items and is going to require them.

I've explained that she has duplicates of most of the items and really doesn't need both eyes, two arms or more than one kidney.

Women! ;)

Joel :ok:

Only kidding, - I'm not selling her Kidneys!

[JTobias]

UPDATE

Right team, so far so good. My JetBox is in the air again after having it's starter generator replaced. Once it was done and I pressed the starter it motored through 12% (a previous sticking point) up to 14%/15%.

A subsequent start on my APU was just as good and it seems a happy bunny now. We'll have to see how the next few starts are, particularly, the first one's of the day.

Thanks very much for all your help.

Joel:ok:

[biggles99]

Joel, BUT

I was just about to recommend that you changed the B206III for a R44R1 and a set of jump leads........ so your update ruined my post.

However, it does give me an opportunity to recount an old story when my Jetranger (yes, I have had the pleasure) wouldn't start coz I had left the battery on all day when I was parked up in the London Docklands (a private site, now a housing estate).

We spotted an AA patrol man who had just fixed woman's car that had conked out.

I ran down the embankment and asked him if he had both a battery and his clever power pack -- he did.

He sorted the battery and power pack so it chucked out 24v, put some jump leads on the 206 battery and we click click click boofed. Away we went.

he got a tenner tip, didn't bother with the paperwork, and had a great tale to tell.

Those were the days.......


Big Ls.

[birrddog]

heh Biggles99, I was in Botswana, Francistown airport with a dodgy battery in a 407, scratching my head where I was going to get a boost.

A chat with the nice commander of the BDF (Botswana Defence Force) and the loan of a battery from an Islander and some jump cables, a piece of wood to separate the crocodile clips and Bob's your uncle.

I think they had a good story to tell as well :)

Perhaps this could be a start of a new thread... "Strange jumper cable stories and those who helped you out"

Joel, glad to hear it worked out for you.

[JTobias]

Thanks guys for all your good wishes and suggestions.

Joel :ok:

[Brilliant Stuff]

Banjo and I had to fix our Jetranger's cowling with some cellotape once at a very posh hotel. Just to add to the stories.

Glad to hear you are back in the air, i hope you get a refund on the old SG.

[pitot212]

I had a JetBox that had a dodgy starter/generator, sometimes when you pressed the button nothing would happen. The s/g needed a tap with a piece of wood to get it to go. Not funny when you’re at Battersea with a cabin full of passengers and I had to jump out open up the cowling and give it a whack! Passengers never said a word to me all the way to Heathrow!! Funny thing is I used to have Mini that need the same treatment!!!

I can see a new thread starting here...

[JTobias]

I bet the starter for the mini was cheaper though!! ;)

Joel

[pitot212]

yep, but its all relative the bill hurt just as much back then:}