So, what about these hydraulic flaps?

[DaV8or]

I have never flown a plane with hydraulic flaps. How do they work and how reliable are they? Are they easy to use? It seems like anything with hydraulics means leaks. Is it worth it to convert to electric?

[N6843N]

I love my hydralic flaps and would never convert to electric. There is a little pump under the floor that is connected to a handle under the instrument panel. You can adjust the pitch attitude infinitely by how much you pump. The only maintenance I have done on mine in the 10 years I have owned it was to replace the hoses which were original to the plane and flush the system out. They are rock solid dependable, that can't be said for anything electrical.

[231Pilot]

The two items I hated to give up when I sold my M20C to buy my M20J were the hydraulic flaps and the manual gear.  Both are dependable, with no electric motors to fail at inoportune times (the only oportune times for failure are during annual when the plane is on jacks).

[mooneygirl]

Lew, you forgot to mention that your right arm and left arm are now the same size.  I love my flaps and manual gear in my E model.  Although having my right arm so beefy gives me the the illusion that I could deck someone if ever I met an unruly person in a dark parking lot.  In my head I think I am a 250 lb male. Mitch reminds me I am not! HA

[KSMooniac]

I wish my J had the hydraulic flaps, and to a lesser extent, manual gear.  There should be no worry whatsoever about getting a Mooney with either system.

[piperpainter]

The only thing i've done so far was replace a seal. That cost me about  $0.50 and took me all of maybe 30 minutes to do on my own...after my mechanic told me what to do! I probably wont have to worry about it for another decade now haha!

[Ned Gravel]

Quote: DaV8or

I have never flown a plane with hydraulic flaps. How do they work and how reliable are they? Are they easy to use? It seems like anything with hydraulics means leaks. Is it worth it to convert to electric?

[eaglebkh]

A few months ago I was just doing some pattern flying when the generator failed.  Nice to know you can configure the plane for landing without drawing a sinlge milliAmp of precious battery power!

[DaV8or]

So I guess there's an indicator of some sort somewhere to tell you how many degrees of flaps you have in and you just pump the handle back and forth like a car jack until you get what you need? How many stokes of the handle gets you to full flaps?

[danb35]

Full flaps is 4 pumps and change, and yes, there's an indicator on the pedestal.

[N6843N]

The only time I look at the indicator is for takeoff flaps. In flight I just pump enough to get a level attitude for the airspeed I am using.

[markejackson02]

Quote: DaV8or

So I guess there's an indicator of some sort somewhere to tell you how many degrees of flaps you have in and you just pump the handle back and forth like a car jack until you get what you need? How many stokes of the handle gets you to full flaps?

[Ned Gravel]

On mine, two pumps is for take off (practice pumping without looking and then check the result), third pump on base (if I need it) and fourth pump on final (depending on the crosswinds of course). 

I have heard that the first two pumps increase lift on our wings.  The third and fourth increase drag.

 

[piperpainter]

Quote: edgargravel

On mine, two pumps is for take off (practice pumping without looking and then check the result), third pump on base (if I need it) and fourth pump on final (depending on the crosswinds of course). 

I have heard that the first two pumps increase lift on our wings.  The third and fourth increase drag.

 

[carusoam]

M20C: gear, flaps , and trim - no electrons required.  Its a beautiful thing.

All of these devices have indicators, but I would bet nobody uses the indicator as primary indication.

Gear only has two positions. 

Flap position, by number of pumps.

Trim by number of turns for take-off, or attitude/speed for landing (probably full up for single pilot no pax).

-a-

[1964-M20E]

Has anyone considered converting the hydraulic flaps to the older style used in the B model with all push rods?

Now you do not even have hydraulic leaks to worry about.

I flew a B model once before I purchased my E and Iliked the simplicity of the flaps on the B modle not the the hydraulic flaps are that complicated.

 

[scottfromiowa]

Willmar has a flap pump "gasket kit".  Kit includes replacement O-rings.  I am changing rubber (tires) and doing brake rotation at annual.  I am also replacing all O-rings in flap pump handle and cleveland brakes as well as the brake lining that is exposed in the gear wells.  Looking forward to all new.  I currently have some loss of hydraullic fluid at pump and at brakes...and my left brake is due...

I love my hydraullic flaps.

[Ned Gravel]

I flew with Russ Anderson in his A model and it has the notched handle with the older manual flaps.  In comparison to my hydraulic flaps, his are more like the flaps in a Cherokee (handle position determines setting) and less like mine (indicator position determines setting).   I think the A models and the Cherokees have the advantage in that regard. 

However, I find I have too many other advantages to give up my E model for an A model (not even touching the woodwing aspect)

 

 

[carusoam]

Scott,

Be careful when taking the flap pump apart.  there are small check valve balls that are hard find after they bounce on the floor.  Changing the O rings is pretty easy and gives good results.  Check the quality of the aging hoses as well.  They get hard and crack.  Putting the check valve balls back in place, while the pump body is still in the plane, requires a little dab of grease (soluble in cherry juice).  Its like temporary glue.  (if all goes well this paragraph will meaningless.)

This is also an opportunity to set the flap retract rate.    When I got my M20C, the retract rate was instantaneous.  On a go around the flaps would pop back up, dumping all lift.  It is technically supposed to take 8 - 15 seconds (est.).  Check the maint manual for actual setting time....

The advantage of the hydraulic system over the mechanical.  Smooth, steady retract during a go around.  When you are busy, you don't want to be thinking about retract rate.  You would rather set it and forget it......  One hand on the yoke, one hand on the throttle, and one hand not on a flap handle...

Best regards,

-a-

[eaglebkh]

I believe I need to replace my O-rings as well.  A month ago I noticed the flaps had no pressure, but breaks were working fine.  So mechanic added fluid to flap reservior.  After a month, the flaps seem to be limp again - no pressure at the pump.  Have I just developed a leak?  Advice please...

[carusoam]

Brandon,  Things to consider...

It is easy enough to add fluid to the system.  If the reservoir is near empty, expect a leak.  Reservoir is behind your aspen, it can be easily reached from the outside.  Square blue nut on top is the fill hole.  Be neat, excess drops right on the rug inside...

To check for a leak, remove the belly pan,  The juice "dries" up with dust and is difficult to clean.  Plus it is red and hard to miss.

Be careful, the same fluid that supplies the flaps also supplies the brakes.  Flaps run out of juice first, then brakes if the level is allowed to drop.

My leak came from the supply hose between the pump and the reservoir.  40 year old hoses tend to age and crack after several decades.

If the pump (when full) is holding pressure, it is probably not an o-ring problem.  O-rings are easy to replace, so purchase the proper sizes (check parts manual) and be ready.  While you are in there it is a good idea to replace.

I did this type of work concurrently with my annual.  Otherwise expect a few hours of taking off panels and pump parts with your A&P.

Best regards,

-a-

 

[eaglebkh]

Carusoam,

No problem pumping flaps when fluid was topped off, so I guess it is a hose problem, then?  I am half-way from annual, so I might just pick a rainy day and take the belly off to see what it going on and make repairs.  I have noticed red pools of hydraulic fluid under the belly.

[N6893U]

 

Hello All,

My first post, apoligies in advance.  New owner of an M20C, read the owners manual about the common flap/brake resavor   Where is it and how do you service it?  Also, which fluid do you use?  I have also noticed my flaps under air load when retracted, a previous post mentioned adjusting that retracting time, how is that done?

Thanks to all of for the info.

Jerry

 

[Capt_CrashN_Burn]

OK, so I was flying around Alaska last winter in mah M20E ;-)

It was pretty cold, like 10 deg below zero or sumthin. As I was getting ready to land near Fairbanks, I could tell there was a problem with my hydraulic flaps, they weren't extending all the way. So after a rather high-speed  and sketchy landing, I brought my plane over to the local A&P. He took a look under my plane and could see hydraulic fliud leaking out. He said "It looks like you blew a seal son!", I said "No, that's just frost on my moustache".

Bah, dum, dum CHING!

[carusoam]

Jerry,

Welcome to Mooney ownership and the board....

[1] reservoir is behind the pilot side instrument panel, mounted on the interior side of the firewall.

[2] It is best accessed from the panel out in front of the windshield.

[3] The fluid is the red colored mil spec hydraulic fluid.  It is readily available around the world.  Before you put anything in your plane compare what you have in the can to what your POH or maint. manual prescribes.  This will preclude simple mistakes.  Be careful putting fluid in the reservoir any excess goes directly on your rug under your feet.

[4] Flap retract time is a simple adjustment needle valve that allows the pressurized fluid to leak back to the reservoir.  Same principle as a hydraulic jack to lift your favorite sports car.  This adjustment is on the actual pump mounted below the floor boards.  Access to the pump is obtained by removing the belly panel under the cockpit.  The procedure is outlined in the service manual for your airplane.

Consult your A&P on making the adjustment.  If the pressure dumps too quickly the configuration change / lift change is seriously disconcerting.  During a go-around, you will be busy flying the plane, you would like the flaps to retract slowly and controlled.  Not just flip up to zero degrees.  Using the car jack analogy, open the valve too much and the car drops to the ground at approximately 9.8m/s^2.  At low airspeeds, if the flaps come up in no time, the airplane could have a tendency to drop at the same 9.8m/s^2....

The challenge in getting the adjustment right:  The return time is a balance of forces, air pressure, fluid pressure, friction and a return spring.  What you set on the ground will take much longer than what you get while flying with air pressure assist.

Hope this helps get you going in the right direction.