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Leak Down Tester


Louie
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Looking to buy a reasonable quality leak down tester to be used on Jabiru engine and note many different brands available. Any recommendations?

 

 

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I

 

Looking to buy a reasonable quality leak down tester to be used on Jabiru engine and note many different brands available. Any recommendations?

paid $110 at narromine from sky shop

Works well , but had to make an adapter out of 18mm spark plug ,hack the guts out of it & braise it to the hose .image.jpg.a26ce996a860455abbe1887a53210b4b.jpg

 

 

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just make sure its the model for small bore engines, there is a different sizing for P&W radials etc. I got the ACS one, brazed a fitting for the small plug

 

 

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I purchased one off ebay but since then noticed that the 2nd gauge that measures pressure in the cylinder instead of being in PSI has a scale of percent(%) rather than PSI. The percentages only work out to be accurate on mine if the inlet pressure is 100psi and in aviation we measure with inlet of 80psi so 80% as indicated on the second gauge is actually 100% of inlet..... The gauges are the same so it isn't hard to convert percent to PSI by looking at the 1st gauge but I wish they were both in PSI....

 

In talking to Keith Rule he tells me that the small restricting orifice between the 2 gauges is sized according to the capacity of the engine you are testing and for jabs there is a specific orifice size that is needed....unfortunately I cant recall what it was. I seem to recall that the orifice size is something that doesn't change often and perhaps for a D12 Caterpillar Dozer engine, which presumably has 2.2L of capacity per cylinder, it might well be different to that used for Jabs, I think that ones rated for car engines of similar engine capacity as we have will likely be right but its probably best that you check that yourself.

 

As Avocet found be careful in selecting one that has the right spark plug hole adapter, some car ones only come with one size, others, like mine came with about 4 different sizes, as long as you have an 18mm adapter your fine.

 

Perhaps last point to make, when everything is fine and the internal leakages are as per new then the volume of air needed from the compressor is low, however if something isn't good and you have to rock the piston around to work out whats going on the volume of air a cheap direct drive compressor can supply might mean that you have trouble maintaining 80psi on the inlet.....bottom line is that a better compressor might be money better spent than the rolls Royce of leakdown testers... Also remember if you get electric (but don't have mains power at the hangar) that most generators need a lot of overhead above the 10amps needed to start the compressor, once running 10amps is more than fine......2400w genset wont run a compressor once its just kicking in to top up the storage tank....

 

A quick search on ebay identified these:-

 

http://www.ebay.com.au/itm/Engine-Cylinder-Leakdown-Leak-Tester-Kit-/131240377930?pt=LH_DefaultDomain_0&hash=item1e8e893e4a

 

http://www.ebay.com.au/itm/Colortune-Compression-tester-14mm-to-18mm-thread-adaptor-kit-washer-hex-key-/121206439330?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c38777da2

 

 

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Ipaid $110 at narromine from sky shop

 

Works well , but had to make an adapter out of 18mm spark plug ,hack the guts out of it & braise it to the hose .[ATTACH=full]31459[/ATTACH]

I did the same on the same unit. I braised a male hose end on the cutoff spark plug so the tester hose can be clipped on and off - same end result.

 

 

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I believe that the leakdown tests that Jab calls for in its maintenance manuals is exactly the same checks and processes as the Lycomings and Continentals and other air cooled aircraft engines require as well.

 

In my case I found an issue well in advance of finding it in the air.......It was if left untouched, going to be an engine stopping problem that was well on the way to being a disaster if not addressed.

 

 

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Aircraft Spruce sell one for small-capacity engines with the 18mm adapter.

Thanks for that. Had a look and not sure which one it is.

Would you be able to have a look and post the link?

 

 

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Is

 

I purchased one off ebay but since then noticed that the 2nd gauge that measures pressure in the cylinder instead of being in PSI has a scale of percent(%) rather than PSI. The percentages only work out to be accurate on mine if the inlet pressure is 100psi and in aviation we measure with inlet of 80psi so 80% as indicated on the second gauge is actually 100% of inlet..... The gauges are the same so it isn't hard to convert percent to PSI by looking at the 1st gauge but I wish they were both in PSI....In talking to Keith Rule he tells me that the small restricting orifice between the 2 gauges is sized according to the capacity of the engine you are testing and for jabs there is a specific orifice size that is needed....unfortunately I cant recall what it was. I seem to recall that the orifice size is something that doesn't change often and perhaps for a D12 Caterpillar Dozer engine, which presumably has 2.2L of capacity per cylinder, it might well be different to that used for Jabs, I think that ones rated for car engines of similar engine capacity as we have will likely be right but its probably best that you check that yourself.

 

As Avocet found be careful in selecting one that has the right spark plug hole adapter, some car ones only come with one size, others, like mine came with about 4 different sizes, as long as you have an 18mm adapter your fine.

 

Perhaps last point to make, when everything is fine and the internal leakages are as per new then the volume of air needed from the compressor is low, however if something isn't good and you have to rock the piston around to work out whats going on the volume of air a cheap direct drive compressor can supply might mean that you have trouble maintaining 80psi on the inlet.....bottom line is that a better compressor might be money better spent than the rolls Royce of leakdown testers... Also remember if you get electric (but don't have mains power at the hangar) that most generators need a lot of overhead above the 10amps needed to start the compressor, once running 10amps is more than fine......2400w genset wont run a compressor once its just kicking in to top up the storage tank....

 

A quick search on ebay identified these:-

 

http://www.ebay.com.au/itm/Engine-Cylinder-Leakdown-Leak-Tester-Kit-/131240377930?pt=LH_DefaultDomain_0&hash=item1e8e893e4a

 

http://www.ebay.com.au/itm/Colortune-Compression-tester-14mm-to-18mm-thread-adaptor-kit-washer-hex-key-/121206439330?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c38777da2

is 80 psi ok for jab engines ?

I've been doing mine at 70 psi .

 

I got told that by jab a long time ago.

 

Mike.

 

 

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  1. 9.18.2 Pressure Differential Test:

    •  
       
       As an alternative to a compression test, a pressure differential test (Leak down) can be carried out. This is a much better test of the condition of rings, bore, head sealing and valve. This is the normal test used in aviation and is strongly recommended by Jabiru Aircraft. It requires specific test equipment.
       
       
       
       
    •  The test is carried out with the engine in warm to hot condition.
       
       
       
       
    •  Remove 1 spark plug from the cylinder to be tested and fit the leak-down tester in its place.
       
       
       
       
    •  Pressure input is set to 80 PSI; a second gauge reads the differential. This is done with piston
       
      on TDC on the firing stroke. A SUN or BOSCH tester pressure loss or leakage tester is used.
       
       
      AVOCET
      This is from the current maintenance manual i.e. 80psi Page 68. (At least on the 3300 motor, I have never looked for the 2200 but I would assume they would be the same, it is pretty standard)
       
       

 

 

 

 

 

 

 

 

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Excuse my ignorance , flying tornado ?

Fly tornado is the fella with the coffee avatar. Known in some circles as Captain Negative:hide:043_duck_for_cover.gif.77707e15ee173cd2f19de72f97e5ca3b.gif (couldn't help myself sorry FT)

 

 

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There’s two different types used in aviation, one has what is called a master orifice, you must use this type to check a continental, however either type is fine for a Lycoming. Aircraft spruce sell 20cm long adaptors that screw into the spark plug thread and have an air fitting on the other end, every time you Leak test a jabiru use 80PSI, and in order of service I suggest you run the aircraft up to warm, check your figures ie idle rpm, full static rpm, voltage etc and write them in the book, then de-cowl and drop the oil, whilst the oil is draining start your leak down ( never do a leak down cold) as you can hear air leaking passed the rings better with the drain plug out. Expect greater than 70/80 if its lower than start looking for an explanation ie hours on engine etc, if its approaching 60 find the issue before further flight. I once got a reading of 40/80 from a J230 that had just flown in for its 100 and the engine was still running fine with a slight lope at idle, (valve seat) you could hear it when pulling the prop through.

 

 

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I've found that the leak down test is safer performed by two people , one to take charge of the prop ,

 

Another trick is to have a pen behind you ear and record press. on pieces of masking tape on each head .

 

Cheers and BE CAREFUL .!!

 

A prop that let's go in a leak down test could do serious injury , or death !!!

 

 

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An old collegue of mine had sweaty hands and was doing a leakdown on an IO360, steel prop slipped and cut his shoulder open along a 20cm line to the bone.

 

As AVOCET says have a friend hold the prop, I do the leakdowns on Jabiru's solo but anything with a larger piston becomes a handfull and easily a life threatening situation. Respect that prop! on a side note I once had an aircraft owner at a club and his wife walk over and start talking to me leaning on the prop and so on, even though I wasnt working on engine at the time I reminded them how dangerous the prop is and I'm not comfortable with them standing in the arc, they were about 2 meters away when the starter relay failed internally and the engine started cranking! only way to stop it was to diconnect the battery! Turns out Jabiru recalled that brand of starter relay due to issues like this! very close call for them and a great reminder to me, never ever get complaicent with that prop!

 

 

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Aircraft Spruce Differential Pressure Tester Model E2A stock number 12-01012.The 18mm adapter is stock number 12-00830.

Thanks for that. Much appreciated!

 

 

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The 18mm thread will fit the Jabiru spark-plug hole, but the air-fitting may need to be changed. It looks like a Ryco fitting. I prefer high-volume Nitto, and just to confuse the issue, there is yet another fitting fairly commonly encountered, called a Jamec-fitting. The Nitto is the one to use, but it all depends on what fitting your compressed-air hose has on the end of it.

 

You could make an adapter, or just remove the Ryco fitting and replace it with a Nitto. A hydraulics/compressed-air/air-tools specialist shop will have the necessary hardware. BOC Gases, Gasweld, Hare & Forbes etc are good suppliers. Bunnings probably won't have these fittings, although they might have Nitto, if they sell air-tools.

 

 

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