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BVM PP 1/5th F16 air leak problem

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BVM PP 1/5th F16 air leak problem

Old 04-10-2021, 12:51 PM
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DAN AVILLA
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Default BVM PP 1/5th F16 air leak problem

I have been fighting a air leak for about a year now. Rob at BVM has been most helpful. My hope is getting feed back from other 1/5th owners. I had about 50 flights on it then the problem started. I have been flying Jets with air systems for over 20 years. The air leak is inconsistent and seems to be effected by temperature. Rob at BV sent me oversized Orings for the main and nose. At Tucson after cycling it flew great for 15 flights. Today at our field it was about 55 and when I turn it on I get a air leak. I cycle it a few times and the problem seems to go away as the day gets warmer. My thinking is the main rams are blowing by the Orings . I plan on getting some cold spray to put on the rams to get it to fail on the stand. Thanks In advance Dan Avilla
Old 04-10-2021, 05:10 PM
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Viper1GJ
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Hi Dan,
I had some leaks when mine was new. I talked to Rob and he thought it could possibly be blow by inside the cylinders. I treated both sides of each cylinder on gears and doors. Was a little tedious but after doing every one on both sides it solved the problem. I never discovered the exact cause but the leak stopped. The only other leak I had was a bad valve. I isolated it by swapping and eventually had to replace the valve.
Good luck. Its a great flying jet.
Gary
Old 04-10-2021, 11:01 PM
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Dave Wilshere
 
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To isolate which cylinder pinch the lines either end of each cylinder when it starts to leak (before any cycling) if you only changed the main seal it could be the rod seal in the end of the cylinder, it’s the most likely if you got so many cycles before it started to leak. I have seen ‘rough’ cylinder rods ‘sand’ away the o ring opening the clearance. You can also drip some silicone oil on the rod/cylinder end when it’s leaking and see if it bubbles.

Dave
Old 04-11-2021, 12:06 AM
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RC Derek
 
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Hi Dan,
I had an air leak in my line to the speed breaks. I simply disconnected the power connectors to the relevant air valves to isolate the problem. It might be a good first step to verify your leak is actually in the rams.
Cheers,
Derek
Old 04-11-2021, 06:32 AM
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DAN AVILLA
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This is good info. I like your idea Derek about unplugging the power connectors to isolate the rams. Dan
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Old 04-11-2021, 10:23 AM
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Len Todd
 
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Brand new BVM 1/5 L-39 - I found a couple air leaks where the tiny air lines fit over the fittings. They were intermittent at first. Ended up replacing several air lines. Some of the OEM tubing would just split when you pressed in on the fitting. The issues I found where both on the fittings where they transition from tiny air lines to normal sized airlines.
Old 04-11-2021, 12:04 PM
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yeahbaby
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Originally Posted by DAN AVILLA View Post
This is good info. I like your idea Derek about unplugging the power connectors to isolate the rams. Dan
works like a champ when isolating leaks across 9 door cylinders
Old 04-11-2021, 01:48 PM
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Originally Posted by RC Derek View Post
Hi Dan,
I had an air leak in my line to the speed breaks.
Cheers,
Derek
I actually fly with Derek and observed this leak. It was simply a blow-out in one of the tiny airlines along the inside of the fuselage towards the one airbrake. As Len has also observed, these tiny airlines are extremely fragile.

JanR
Old 04-11-2021, 02:24 PM
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DAN AVILLA
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Jan I had the same thing happen before . I replaced with a different color . I think I found the leak. It was a front door ram. Dereks idea unplugging the valves helped me find it. Thanks

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