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JensVerschueren
Topic Author
Posts: 9
Joined: Mon Dec 24, 2018 11:59 am

Anti-ice system JT8D engine

Sat Apr 25, 2020 2:02 pm

Hi,

I got a an assignment on the JT8D engine, but due to the COVID 19 crisis, I can't go to the school's library to access the technical datasheets I need. Does anyone here know where I can find the specific data I need to solve these questions?

The questions are about the anti-ice system of the JT8D engine. When "the anti-ice valve " is the cause of a fault, how are you going to disassemble it from the engine, what are you going to check to fix the problem and how are you going to reassemble it to the engine? 

Kind regards,

Jens Verschueren
 
Dalmd88
Posts: 3157
Joined: Fri Jul 28, 2000 3:19 am

Re: Anti-ice system JT8D engine

Sat Apr 25, 2020 3:11 pm

First is which anti-ice valve? Is it a fuel anti ice problem? Or is it an inlet anti ice problem? There are four nearly identical anti ice valves on the JT8D-219. The fuel anti ice valve is special. That p/n can go in any of the four locations but the only that p/n is allowed in the fuel position. It is a no go item. The other three are MEL items. Most operators like to keep at least two of the fuel p/n installed on every engine. They are line replaceable so if the fuel location goes bad you can swap with the other one and MEL the other location.

It's pretty easy to troubleshoot. Have someone in the flight deck select the heat and watch the valves. They have a little lever on the side that shows the valve position. You can take the electrical connector of the bad one and do a wiring check to confirm it is a bad valve and not wiring. It's usually the valve.

Once you find which one is bad if you don't have one you either safety the inop one closed per the MEL or do the swap for the fuel position. They have eight bolts connecting to the inlet and outlet tubes. If it's on an MD88 it's either the top one or the one next to the pylon. They are the hardest to get to.

This is a typical valve:https://picclick.com/Pratt-Whitney-JT8D-Aircraft-Engine-Anti-Ice-Valve-232137956082.html

I couldn't find a location pic or drawing. One is located at 12 o'clock for the inlet cowl. two more are at about 2 and 10 with tubing going to the first stage stators at 3 and 9 o'clock the fuel one is righ above the fuel control.
 
CanadianNorth
Posts: 3264
Joined: Sat Aug 24, 2002 11:41 am

Re: Anti-ice system JT8D engine

Sat Apr 25, 2020 7:11 pm

Yes I recall there are a couple of valves for different things on the JT8D-17s that I worked on that could be considered anti-ice vavles.

Troubleshooting is fairly easy, you could get someone to run them while you watch as I believe most of them had some kind of an indicator on the valve you could see move, and also a lot of those sorts of things you could stick your ratchet in there and turn them by hand to see if they feel normal or if they seem stiff or crunchy or something. Usually the valve itself was the issue, if not then probably a power or ground wire going to it might be bad, or could be the switch itself. Also could be indication issue, which is why I usually start with trying to watch the actual valve to see if it moves or not, that narrows down the options fairly fast.

To change air valves on most turbine engines just remove any wiring plugs, disconnect any control air tubes, and then remove a couple of clamps attaching the valve body to the main bleed air ducts, and it should pop right out. Not always the case and you definitely want to check the maintenance manual first, but that's usually how it goes.

In airline line maintenance you usually don't disassemble valves themselves, you'd just confirm the valve is the problem, remove it from the airplane, install an equivalent valve from off the shelf in stores, test it, do the paperwork and send it on its way. Afterwards red tag the valve you took off and stores will arrange for it to go to a component shop for repair.
HS-748, like a 747 but better!
 
JensVerschueren
Topic Author
Posts: 9
Joined: Mon Dec 24, 2018 11:59 am

Re: Anti-ice system JT8D engine

Wed Apr 29, 2020 2:52 pm

Thank you for the info! I have had a conversation with the teacher about the questions and he means the Engine anti-ice system to heat up the cowling of the engine to prevent foreign object damage from chunks of ice building on the inlet of the engine. Now I have found an instruction video on the Boeing 727's engine anti-ice system, does it apply to the JT8D engine or is it another engine described here?
https://www.youtube.com/watch?v=Tc__-JuKwDE
Also, I know that these valves are electrically controlled, but pneumatically operated, what does that mean, and do they run on 115VAC?
 
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fr8mech
Posts: 8083
Joined: Mon Sep 26, 2005 9:00 am

Re: Anti-ice system JT8D engine

Wed Apr 29, 2020 6:18 pm

JensVerschueren wrote:
Thank you for the info! I have had a conversation with the teacher about the questions and he means the Engine anti-ice system to heat up the cowling of the engine to prevent foreign object damage from chunks of ice building on the inlet of the engine. Now I have found an instruction video on the Boeing 727's engine anti-ice system, does it apply to the JT8D engine or is it another engine described here?
https://www.youtube.com/watch?v=Tc__-JuKwDE
Also, I know that these valves are electrically controlled, but pneumatically operated, what does that mean, and do they run on 115VAC?


I’ve forgotten more about the B727 than I remember, so take what I say with a grain of salt.

The video referenced above is for wing anti-ice, not engine inlet anti-ice. Different valves involved.

An electrically controlled valve, pneumatically operated means that the valve is “unlocked” or biased using electricity, but needs pneumatic pressure for the valve to open...or close depending on the bias.

As far as I remember, the inlet anti-ice valve is not electrically controlled, pneumatically operated. It is straight electrical. Hit the switch and the valve opens. But, again, it’s been a long time

Found this, it may be helpful.

https://www.slideshare.net/mobile/milad ... ine-manual

And this:

https://picclick.com/Pratt-Whitney-JT8D ... 56082.html
When seconds count, the police are minutes away, or may not come at all.
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JensVerschueren
Topic Author
Posts: 9
Joined: Mon Dec 24, 2018 11:59 am

Re: Anti-ice system JT8D engine

Thu Apr 30, 2020 6:06 am

fr8mech wrote:
JensVerschueren wrote:
Thank you for the info! I have had a conversation with the teacher about the questions and he means the Engine anti-ice system to heat up the cowling of the engine to prevent foreign object damage from chunks of ice building on the inlet of the engine. Now I have found an instruction video on the Boeing 727's engine anti-ice system, does it apply to the JT8D engine or is it another engine described here?
https://www.youtube.com/watch?v=Tc__-JuKwDE
Also, I know that these valves are electrically controlled, but pneumatically operated, what does that mean, and do they run on 115VAC?


I’ve forgotten more about the B727 than I remember, so take what I say with a grain of salt.

The video referenced above is for wing anti-ice, not engine inlet anti-ice. Different valves involved.

An electrically controlled valve, pneumatically operated means that the valve is “unlocked” or biased using electricity, but needs pneumatic pressure for the valve to open...or close depending on the bias.

As far as I remember, the inlet anti-ice valve is not electrically controlled, pneumatically operated. It is straight electrical. Hit the switch and the valve opens. But, again, it’s been a long time

Found this, it may be helpful.

https://www.slideshare.net/mobile/milad ... ine-manual

And this:

https://picclick.com/Pratt-Whitney-JT8D ... 56082.html


Hi, I'm sorry I posted the wrong link in my previous message. Here is the correct link: https://www.youtube.com/watch?v=paiFNAfRlYs

Thanks for the info it helped a lot!
 
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fr8mech
Posts: 8083
Joined: Mon Sep 26, 2005 9:00 am

Re: Anti-ice system JT8D engine

Thu Apr 30, 2020 11:48 am

JensVerschueren wrote:

Hi, I'm sorry I posted the wrong link in my previous message. Here is the correct link: https://www.youtube.com/watch?v=paiFNAfRlYs

Thanks for the info it helped a lot!


Yes, this is a JT8
When seconds count, the police are minutes away, or may not come at all.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere

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