Marty d's CH-701 build log

[IBob]

I did not test my cooling system, but went looking for any leaks are drips following initial engine runs.

For fuel, the Facet pump has a non-return valve. I did my initial runs with wings off, so had the fuel return line blanked off, and that part of the system held pressure on the steam gauge after the pump had been run then turned off. (Incidentally, on normal prestart you are looking for that pressure to fall away quite promptly once the Facet pump is off: this tells you that the fuel return orifice is clear and doing it's job.)
I would be getting some gravity feed from wing height down into the receiver tank. Mine developed seepage from one of the tank top connectors and that wasn't evident until it began to wet the sides of the tank. So I would be looking hard at that area.

For the oil system, there is an essential Rotax priming procedure to push oil round the system after engine installation. This involves light pressurisation of the oil tank while turning the prop many times, and would allow you also to check for leaks.

[IBob]

I would not pressure test the wing tanks in situ, as they sit against the upper skin, and even minimal pressure will exert a considerable force, bugging out the top and the bottom of the tank.
I don't have the exact tank size, but eg: if it's 20" x 20" that's 400 sq inches. Give it 2PSI and that 800lb over that surface area....

[Marty_d]

Yes I wouldn't pressure test the tanks.  This is my question though, is it standard practice to pressure test the rest of the fuel system?

[Moneybox]

3 hours ago, Marty_d said:

Yes I wouldn't pressure test the tanks.  This is my question though, is it standard practice to pressure test the rest of the fuel system?

 

I doubt it but if it has an automotive type of pressure cap then and automotive coolant pressure tester would be an easy option. You only have to pressurise the system to the pressure stated on the cap.

 

Anywhere beyond the electric pump if you have one would be tested as soon as the pump is activated otherwise you could temporarily install an electric pump near the tank end so that all plumbing is tested.  

[Thruster88]

The best way to pressure test engine systems is to run the engine. This is what we do on all new or overhauled engine installations, aircooled lycons or liquid rotax. Have a second person double check all connections. First start cowl off have an observer. Stop engine check for leaks, repeat as necessary. 

[Marty_d]

Fantastic, thanks guys.

 

How about general logistics about starting... special equipment, ground etc?

 

What I mean is, my plane is currently in a farm shed.  The paddock in front of the shed slopes down slightly - there's no flat land.  Currently hosts a flock of duck.

My general plan is to roll the plane out til it's clear of the shed, shut the doors to avoid blowing everything around behind the plane, tie the main gear to trees/fenceposts, chock as well, put the wings back on and prep for starting.

 

Are there other considerations?  Is it best to peg down carpet under the plane or is that more of a risk than it's worth?  Guessing it's a good idea to rake away any gravel / sheep shit etc in front of and around the plane first also?

 

Any hints and tips would be appreciated, thank you.

 

 

[spacesailor]

The D. H. COMET was 'PRESSURE TESTED ' UNDER-WATER ', So as to hold the hull INTACT ! .

spacesailor

[rgmwa]

I wouldn't put carpet anywhere near the prop but definitely sweep away all the gravel from the area and anything else that's loose.  

[Blueadventures]

From your image face plane towards the big door. Have prop line just forward of the drain grate line.  Chock the wheels good, maybe even level up the lower main wheel. Add a double securing with rope or a strap to a secure point behind the plane so it does not travel forward when engine running.  This way you won't pick up any stones or rocks.

 

[Moneybox]

I was considering laying a bit of concrete or laying a area of artificial grass that is pegged down with sand laid in it. Here at Myrup, Esperance they have a circular patch of concrete, about 30m from the gravel airstrip, that looks like the top of a tank of some kind. It's about 3m across and does the job nicely.

Edited 2 hours ago by Moneybox