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lowew79

J41 start lock (Question form a non owner... yet)

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Hey all,

 

The start lock horror stories are scaring me a bit.  If I understand it correctly, you have to engage them at shutdown, or the engines will ker-splode at the next startup?  Assume you are starting the thing up in the morning, how can you tell if the guy last night engaged them or not?

 

What the heck do you do if they weren't engaged?  Is the plane just unflyable?  What if you're in a brand new one?  Does the factory engage them before it leaves the assembly line?

 

I don't own the plane yet, so there may be some obvious answer that i don't know about.

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The start locks function is pretty simple, they prevent the propeller from feathering when the oil drains from the propeller governor after shutdown. Because of the nature of geared turboprops, they can be unable to overcome the resistance of a feathered prop during startup. In the J41 simulation it can lead to big engine problems during start. In it's predecessor, the J31/32, you will not see such dramatic effects but will have a hung start.

 

The way for a crew to see if the locks are on when coming to the aircraft, is to simply look at the propeller blades. If they are feathered, the locks are off. If they have a regular flat pitch, the locks are on.

 

If the locks are off, the engines are fitted with small pumps that get some oil pressure into the propeller governor to get them to a flat enough pitch that they fall into the start locks.

 

It really is a non-issue made exciting by flight simmers blowing up engines ;).

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After reading the 'horror stories' myself I decided to practice shutting down and restarting the engines, big mistake.

You'll spend a few hours scratching your head and putting out fires until you read the egt gauge, make a coffee and letting it cool down. Then trying again.

It's a great plane to fly I hope you enjoy it.

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In my opinion there is nothing to be scared of. You just have to understand how it works, and it's not a problem at all.

If you have to cool down the engine after unsuccessful, there is a ventilation procedure to speed it up.

 

And the plane is very good, nice to hand fly. I like it a lot.

 

Pawel

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There are literally only two things to remember...

 

- Pull the power levers into reverse during shutdown when RPM passes 50%

- Don't start the engines with an EGT over 200C

 

Any horror stories come from people skipping over reading the manual :).

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There's also a procedure described in the tutorial, in case you've forgotten about the start locks during shutdown.

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You're more likely to break the starter/generator shaft when spinning those big feathered props for too long, and the starter will no longer spin the engine.

 

I think the JS41 is one of the most fun to fly simulations available, simply because it is a realistic simulation of a real airplane that did not have much in the way of 'automatics' like modern big tubes have.  It is a good example of what pilot workload was in the period between basic 3-axis autopilots and fully automated flight management systems.  Sure, there is GPS and a FMS but these are rudimentary and not certified for GPS-based approaches.

 

More importantly:  It is a lot of fun to fly and handles like an airplane should IMHO.  I am asking PMDG every chance I get to update her for P3D.

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I covered this very issue in a fair bit of detail at http://viaintercity.com/forums/bae-jetstream-41-%28bae-js4100%29/faq-%28frequently-asked-questions%29-and-tips-for-bae-js4100/

 

As Propane mentioned, if the propellers aren't on the start locks then you use a small pump to generate oil pressure for the props to unfeather, then engage the locks. In reality this is a hand pump in the cockpit floor, but in FSX you can use the unfeather toggle on the pedestal (in reality this was only used in flight)/

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I got the plane today YAH!!  The tutorial did explain it very well, no problems.  I did burn up the engines after the locks were released though because I apparently moved the throttles too far forward too quickly (I just wanted to make sure they were all the way out of beta lol). At least thats my guess.  I heard the call out lol.

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I must be a slow learner since I can't even count the number of times I've destroyed the engine DESPITE sitting with the tutorial in front of me...  Gotta install it right away! We are truly spoilt with incredible aircraft add-ons for FSX and it's not just PMDG anymore. Sad thing there just isn't enough time!

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