Block Pressure Test
 

I am pressure testing 2 8Ba blocks. how much air pressure should i use?

Re: Block Pressure Test
 

Hi Jack, we use anywhere from 60# to 80#, if it shows good at 60# we go to 80# just to be safe!

Thanks, Gary in N.Y.

P.S. All the years we've done pressure testing here on both blocks and heads we've never had one "bounce".

Re: Block Pressure Test
 

No need to go wild on the pressure...more important to leave it for a longer period of time to find any real small flaws.
If i can leave it over night and it holds pressure then im pretty happy.

Re: Block Pressure Test
 

Gary: If i get into trouble with my assembly of my 2 8ba blocks, can i bring them to you? I need a good outcome on both of them.
Thanks,...
jack

Re: Block Pressure Test
 

Some of the old French Aerospatiale helicopters fixed pressure indicators to the steel tube frames so that they could pressure them up with nitrogen gas. It was a daily requirement to check the BIM indicator for loss of pressure. It will indicate a crack if one forms in a structural part so equipped. They are also used on main rotor blades by some manufacturers.

Re: Block Pressure Test
 

Jack you can be confident Gary will take care of you and steer you right

Re: Block Pressure Test
 

I know very little about heavier than air craft, but I have heard that helicopters need a reliable drivetrain to stay aloft. I trust what you say about their mechanics.

Re: Block Pressure Test
 

As I told my youngest son, a Marine Corps Cobra pilot, there is no bigger collection of parts that, when they are in motion, want to completely disassemble themselves, than on a helicopter. Unlike fixed wing there is no way out if something fails.

Re: Block Pressure Test
 

Pressure testing can be carried too far. I was given the block that is in my pickup after a guy pressure tested it at 160 psi and blew a pea sized hole in the #5 intake valve pocket. I repaired it and have put 12,000 miles on it with no problems but a little prudence would likely have saved a lot of trouble.

Re: Block Pressure Test
 

While having a cold one or two at NCO club in the Army we always gave the airborne guys a hard time about only "two things that fell from the sky, fools and bird shit". That was until a helicopter crew chief added, "and broken helicopters".

Re: Block Pressure Test
 

I know it's off topic but just to add.

On a helicopter, you don't really want out of it in a failure mode until it stops moving. The good thing about them is that they autorotate if the engine fails. There is enough inertia in the rotor to slow you down before there is ground contact. You don't need a 3500 + foot landing field to put one down like an airplane. They will actually land in a pretty tight space if there is one to spare at any given pucker factor moment. Good pilot's practice autorotations on a regular basis just in case.

It's not how much air pressure a block will hold as much as it is how long it will hold pressure. It doesn't take as much pressure as some folks think it might. We only use 80 psi input pressure for engine differential compression checks but that's enough to tell if it will hold some of it.

Re: Block Pressure Test
 

I tested at 40lbs.
had 20 lbs after 30 minutes
had 13 lbs after 60 minutes
had 9 lbs after 90 minutes
Do i have a problem?

Re: Block Pressure Test
 

Check where you have the leakage...spray soapy water and find the leak.
Sometimes getting the pressureplates to seal is quite a challenge if surfaces are a bit rough.

Re: Block Pressure Test
 

I had a hard time getting 1/4" thick aluminum waterpump block-off plates to seal. I finally went to steel plates.

Re: Block Pressure Test
 

Thanks for the tips. I appreciate the help.

I found a semicircle crack about 1/4" to 5/8" in from the flange area of the center exhaust port where the exhaust manifold bolts on.
Total length about 1".
Ideas, anyone?

Re: Block Pressure Test
 

So you don't put liquid in the block, only air? I'm making plates right now to test a 21 stud block. I thought I should put coolant or something inside to show leaks.

Re: Block Pressure Test
 

Just air and then check with a spray mixture of detergent and water. You are looking for bubbles forming where the leaks are, like checking a tire for a leak.

Re: Block Pressure Test
 

That's how i found the crack in the exhaust port close to the manifold flange.

Re: Block Pressure Test
 

Got it, thanks. I worry about having a leak up in an exhaust port where I can't see it. Does that ever happen?

Re: Block Pressure Test
 

I fill my blocks with water and then put 60 psi air pressure in. When there is a leak it can often be in the exhaust crossover. Kind of hard to see any bubbles in there or deep in an exhaust port.