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Elsmoko

JS41 Startup

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I'm fairly new to the JS41 and sometimes an engine won't start on the first try.  After a failed engine start,  I have found no practical

method of doing a restart.  I've even tried waiting for (many) minutes to allow the engine temp to drop well below 200 deg and then of

course ensuring that the prop is feathered and the throttle lever is in the proper position prior to the restart attempt.  What typically

happens when restart is attempted is that the Gnd switch will not remain in the Gnd position after the Start switch is pressed >> the

Gnd switch promptly snaps back to OFF and of course the startup is aborted.  Then,  I must end the flight and shutdown / restart FSX

if I am to have any hope of starting the engines successfully.  I've read several threads (including some excellent stickies) regarding

engine starting but I haven't seen a solution for this problem.  Is there a graceful method for performing a JS41 engine restart or must

FSX the flight be reloaded...................?

Thank you,

Ken Boardman

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I've even tried waiting for (many) minutes to allow the engine temp to drop well below 200 deg and then of
course ensuring that the prop is feathered and the throttle lever is in the proper position prior to the restart attempt. 

 

You can ventilate the engine by using either the ENG START button or moving the START MASTER switch to the applicable engine (don't use both at the same time). This will reduce the EGT much quicker.

 

 


What typically
happens when restart is attempted is that the Gnd switch will not remain in the Gnd position after the Start switch is pressed >> the
Gnd switch promptly snaps back to OFF and of course the startup is aborted. 

 

I think that the TTL computers working their magic. Maybe try turning them off (I don't know if that will work or not).

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Your symptoms suggest the propeller isn't on the start locks, the props should be UNfeathered, you'll need to manually unfeather them before attempting a restart.

 

I've done a comprehensive J41 FAQ that details how to check the props are on the start locks and how to unfeather them if they aren't:

http://viaintercity.com/forums/bae-jetstream-41-%28bae-js4100%29/faq-%28frequently-asked-questions%29-and-tips-for-bae-js4100/

 

I can start the J41's engines after a failed-start without reloading FSX, sometimes I use the "ventilation run" mentioned above by Kenny too, this consists of motoring the engine for up to 30 seconds, without introducing fuel or ignition, in order to draw cool air through the engine. Before engaging the starter you need to move the "MANUAL START" rotary selector to the 3 o'clock "ENERGISE" position.

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Thank you for the replies Kenny and Chris.  I am aware of the importance of the start locks and unfeathered condition and I've paid

careful attention to their status while starting.  Next time I'm faced with this situation I will try the "ventilation run" technique and the

"Energize" position of the manual Start switch.  I'll also be thinking about the TTL computers. 

  Thank you for the tips.  I'll follow up later.......

Best regards,

Ken

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It doesn't appear that the engine is windmilling with the Start Master Sw or the Start button (for an engine restart) >> the RPM gauge  

stays at ~zero RPM.  Am I missing something?  Seems like the RPM gauge should come up off zero when windmilling.

Checked to make sure that the GPU was running ~:)

Ken

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If the prop is just windmilling due to wind, then the rotational speed may be too low to register on the %RPM gauge. The start motor should increase RPM's at least above 10%, probably at least as high as 15% but it's been awhile since I flew her.

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Sometimes a reload is best. I've had the situation the OP reports where the starter won't remain engaged. I've also seen the propeller turning slowly and irregularly in the VC view, but stationary in the external spot view. There is nothing that I'm aware of that you can do to overcome this. There seem to be situations where the engine model does illogical things and can't be recovered from. Also the start locks don't always seem to be effective. You can put the levers in reverse and unfeather both props and put the levers back to idle.That should engage them, but the props seem to move slowly towards feather all the same. By the time the first engine is started the second engine is feathered. If you delay the start for some reason you get a failed start or a fire because it won't accelerate enough. The failed start is the most frustrating. The engine appears to light and spool up succesfully only to run back down to zero rpm again.

 

Now whenever such things happen I reload FSX and then the J41 because trying to recover the situation is rather hit and miss. It would be nice to have a discrete indication somewhere that the start locks were properly engaged after using the unfeathering procedure. If they aren't you are in for a miserable time. As it is you only get an aural announcement when they are disengaged.

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I usually confirm start lock engagement by spot view look edgewise at the prop blades. If the props are thin they are locked, if they are thick they are feathered.

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I know that your question is really about attempting to start after a failed start, but this tutorial really helped me start this finicky bird up: 

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Many thanks for tips, video and moral support ~:)

I finally got a successful dual engine start and I'm on my first (test) flight.   Not sure but I think that starting up with default Cessna and then loading the

JS41 did the trick.  Then everything seemed to work as advertised.  Should have tried that sooner,  but I trusted the "canned" tutorial flight >> and knocked

myself out trying to get it to work   :Skull:  

  Very nice handling plane in air and on ground,  but I've still got much to learn about it.  I Copied all the pdf docs onto my "Nook" so I can put them under

my pillow and absorb them while sleeping.

Best to all,

Ken

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Ah you didn't mention you were using the included tutorial flight, someone had exactly the same problem with that on the forums last week!

 

Whilst you can load the J41 cold and dark, it's generally not recommend as it wasn't designed to do this and can lead to engine start issues (exceptions being is you use FS2Crew or the Lua script). It's best to load the J41 running normally and shut it down yourself as this takes less than 45 seconds. When you load the J41 you should ensure your hardware throttles are set to idle.

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I usually confirm start lock engagement by spot view look edgewise at the prop blades. If the props are thin they are locked, if they are thick they are feathered.

That confirms the blades are fully fine. It does not confirm the start locks are engaged to keep them there. You can go through that whole procedure then watch as the blades slowly move back to fully feathered.

 

There is something not right about start lock engagement. If you shutdown the engines normally the locks work perfectly. If you load the sim with engines off and the locks are not engaged it seems impossible to engage them. The workaround I use is to start one engine immediately after unfeathering then unfeather the other engine again before starting that.

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See the use of the Unfeather Switch on pg 65 of the Intro document.

 

The blades will usually go to full feather in the absence of either oil pressure or engaged start lock. It's the nature of all constant speed props that I've flown anyway... but there are some electrically operated props around but JS41 is not one of them.

 

The unfeather switch runs a small oil pump to build up pressure in the prop dome, which causes the blades to go to flat pitch. It takes time, but once the blades are in flat pitch you can engage the start locks. The procedure is in the AOM.  See Ch 8 page 4.

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Thank you again for all of the useful and interesting information.  I just completed my second successful flight in the JS41.  Did an auto ILS approach

to Cairns RW15 and it went fairly well > the next one should be better.  I like the plane.  Definitely a different experience than what I'm accustomed to ~:)

It's likely in the docs, but when setting the DH, where does it read out on the instruments.   Also had an issue with the FMS >> about half way through the

flight all of the push buttons stopped working.  The FMS continued to appear to be functioning but there was no way to communicate with it.  I first

noticed the problem after I had undocked the FMS.  I had also dragged it over to my secondary monitor so perhaps that's what caused the problem.

Still,  was a fun flight.

Best to all,

Ken

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See the use of the Unfeather Switch on pg 65 of the Intro document.

 

The blades will usually go to full feather in the absence of either oil pressure or engaged start lock. It's the nature of all constant speed props that I've flown anyway... but there are some electrically operated props around but JS41 is not one of them.

 

The unfeather switch runs a small oil pump to build up pressure in the prop dome, which causes the blades to go to flat pitch. It takes time, but once the blades are in flat pitch you can engage the start locks. The procedure is in the AOM.  See Ch 8 page 4.

I know how the system works and I've read the procedure. But you can get into a situation where you think you've unfeathered the prop (checked they look full fine) but you still get a failure to start (the engine shuts itself down after not quite reaching idle) or a fire. I check the prop visually immediately before a start, but even then I've had problems. Sometimes I get no trouble at all, other times the engines just won't behave. It may be to do with how the sim loads in FSX or it may "operator error". Whatever the reason, an indication that the latch was engaged or not would be reassuring and save a lot of frustration.

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"an indication that the latch was engaged or not would be reassuring and save a lot of frustration."

I certainly agree Kevin.  I've had good luck lately with the engines.  I've been reading the tutorial and practicing.

Ken

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