Bleeding the hydraulic system 1964c to get flaps to work correctly

[Jim Peace]

Does anyone know of a mechanic in Florida who would know how to properly bleed the hydraulic system on a C model?

[Shadrach]

6 hours ago, Jim Peace said:

Does anyone know of a mechanic in Florida who would know how to properly bleed the hydraulic system on a C model?

Any competent A&P/IA should be able to sort through it. 
 

That being said, I assisted AMS in West Palm Beach with sorting one out over the phone earlier this year. Not sure they’ll have much enthusiasm to do another but you can try them.  Bob was the tech that I worked with. He seemed bright and competent.

https://amspalmbeach.com/contact/

[Utah20Gflyer]

I’m interested in learning more about bleeding the flap system.  I’ve done the brakes before and have a good feel for that but at my last annual the IA noted there was a hydraulic hose for the flaps in the belly area of my plane that looked worn and the plan is to fix it at the next annual.  We will obviously introduce a lot of air into the system when that hose is removed and replaced.  
 

Without actually hearing from someone with experience I am thinking the way to do it would be to apply vacuum to the system to suck the air back up into the reservoir?   What have you all done to bleed the flaps??

 

[bcg]

I’m interested in learning more about bleeding the flap system.  I’ve done the brakes before and have a good feel for that but at my last annual the IA noted there was a hydraulic hose for the flaps in the belly area of my plane that looked worn and the plan is to fix it at the next annual.  We will obviously introduce a lot of air into the system when that hose is removed and replaced.  
 
Without actually hearing from someone with experience I am thinking the way to do it would be to apply vacuum to the system to suck the air back up into the reservoir?   What have you all done to bleed the flaps??

 

I replaced that hose last year. We used a pressure pot on the reservoir and bled to the valve in the belly on the right side near the back of the wing, or just behind it. Then pumped and released, pumped and released, pumped and left overnight. They didn't release any so we had the air out.

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[Shadrach]

32 minutes ago, Utah20Gflyer said:

I’m interested in learning more about bleeding the flap system.  I’ve done the brakes before and have a good feel for that but at my last annual the IA noted there was a hydraulic hose for the flaps in the belly area of my plane that looked worn and the plan is to fix it at the next annual.  We will obviously introduce a lot of air into the system when that hose is removed and replaced.  
 

Without actually hearing from someone with experience I am thinking the way to do it would be to apply vacuum to the system to suck the air back up into the reservoir?   What have you all done to bleed the flaps??

 

 

I always backfill from the actuator (lowest point in the system).  Consider switching to synthetic fluid (Royco 782).  You will need a barbed AN fitting and vinyl hose to attach to the reservoir and a catch can to collect the overflow.

 

[Jim Peace]

Thanks for all the info...I just want to fly in and have it done if I can.....I dont have a good hangar situation to do this nor the tools etc....

[N204TA]

When my hydraulic flaps start needing extra pumps to work correctly, I’ve had good luck leaving the release switch in the “flaps up” position and just pumping the handle until I lose interest.  Twenty, thirty times.  That usually clears out any bubbles and I’m back to 4 1/2 pumps for full flaps.

[Shadrach]

4 hours ago, Jim Peace said:

Thanks for all the info...I just want to fly in and have it done if I can.....I dont have a good hangar situation to do this nor the tools etc....

What are the symptoms?  Some issues can be corrected with non invasive techniques. 

[Jim Peace]

On 8/27/2024 at 8:29 PM, Shadrach said:

What are the symptoms?  Some issues can be corrected with non invasive techniques. 

got in it yesterday and it fixed itself.....4.5 pumps for full flaps....

Flew from NJ to Florida.....

[Shadrach]

1 minute ago, Jim Peace said:

got in it yesterday and it fixed itself.....4.5 pumps for full flaps....

Flew from NJ to Florida.....

Self healing Mooney ailments are rare…glad it’s working again.

Every system that I have bled is 4 pumps to full (pump cylinder volume is 25% of the actuator cylinder volume.)  

Just in case there is a some air upstream of the pump, I would ensure that the reservoir is full and then pump the flaps half down and leave them for a day or two.

[Jim Peace]

2 hours ago, Shadrach said:

Every system that I have bled is 4 pumps to full (pump cylinder volume is 25% of the actuator cylinder volume.)  

I thought book value was 4.5 pumps to full extension

[Shadrach]

1 hour ago, Jim Peace said:

I thought book value was 4.5 pumps to full extension

I remember reading that in one of the books. I don’t recall if it said 4.5 or gave an I don’t recall if it said 4.5 or if it gave a range of 4-4.5.  I’ve never bled a ‘64 model. However, I have verified that 1965 and later when properly bled are precisely 4 pumps to full deployment. That said, there are a lot flying around that are not properly bled. Another member of the forum speculated the the 4.5 book number may have been a catch all for the factory so they didn’t need to spend hours and hours getting every last air bubble out of the system.

One of the nice things about four pumps is that deployment is divided into fourths. You don’t really need to look at the indicator at all and the handle doesn’t stick halfway up when fully deployed.

This is what it should look like when perfectly bled and adjusted to factory specs.

 

[tony]

19 hours ago, Jim Peace said:

got in it yesterday and it fixed itself.....4.5 pumps for full flaps....

Flew from NJ to Florida.....

That has been my experience as well.  I have a little valve on the actuator.  I pressurized the system with a syringe by the reservoir and then opened that valve.  The result wasn't great but after a flight or two the system was rock hard again.

[Shadrach]

58 minutes ago, tony said:

That has been my experience as well.  I have a little valve on the actuator.  I pressurized the system with a syringe by the reservoir and then opened that valve.  The result wasn't great but after a flight or two the system was rock hard again.

What type of valve? Do you have a pic?

I’ve been thinking of ways to install a bleeder valve at the actuator.