Suggestions please - Dodgy first start on my JetBox
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Suggestions please - Dodgy first start on my JetBox
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.
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
Fellow Aviators,
Please help with this puzzling conundrum.
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
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?
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?
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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
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
Slow start
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
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
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Everything pointing to the Starter/Generator me thinks?
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.
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When you apply Aux power to the Jetranger the ships battery is taken offline.
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!!!
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True Story
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!!
JHR
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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..
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..
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I could see that coming!!!
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!!)
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!!)
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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
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
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If you have no luck on here these people will be able to help you Essential Turbines Inc.
Just email them your problem and I'm sure they will crack it for you. Good luck
Just email them your problem and I'm sure they will crack it for you. Good luck
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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.
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.
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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
I'll get maintenance to investigate your ideas also.
Really useful answers and I'll be sure to update you all shortly.
Joel