Retractable Step Repair

[davecusto]

I'm the new owner of an M20F, with vacuum actuated retractable step.  The step didn't retract and the vacuum line had been plugged.  The problem, of course, is that the rubber actuator boot had broken.  In my case, broken in half, the half that fit over the retraction cylinder, and the half that reached over the piston.  I suspect this is the typical break, as the rubber "boot" has to invert at each retraction.  The first try was to use only the cylinder half, put a plastic bag over the whole thing, and start the engine.  It worked.  Once.  The step retracted, came back out, and never retracted again.  The problem was that the piston part fell off of the cylinder part, lost it's alignment with the cylinder, and was doomed to to jam instead of sliding up into the cylinder.  The fix?  Of Course.  Duct Tape.  The idea was to extend the rubber cylinder boot far enough so that it supports the piston and hold it aligned with the cylinder.  One wrap of duct tape was enough.  First, I wrapped some upholstery fabric around the piston, enough so that it would stretch the boot a bit when the boot was stretched over it.  Second, a plastic sheet placed over the upholstery fabric. (I used a reusable grocery bag.) Third, the boot stretched over the wrapped piston.  This is the form.  Next: very loosely wrap one layer of duct tape around the piston form, overlapping the boot and extending the cylinder an inch and a half or so.  Remove the piston form.  The plastic will stay with the boot because the sticky side of the tape is stuck to the plastic, not to the upholstery fabric.   Trim the excess plastic, that is, all the plastic not stuck to tape.    This SHOULD yield a boot-half that is now long enough that the piston will not "fall off" of the rubber/tape cylinder when the step is extended.  It is important that the piston slide easily in the new, longer boot-half.  If it's own weight will not slip the (unwrapped) piston through the new tape and rubber boot-half, then the upholstery fabric was too thin, or the wrapping too tight.  Try again.  I got it on the second try...

  Lastly, reassemble the whole business, placing the whole assembly in a plastic bag.  I used a tropical fish bag.  Not the smallest, but the next size up.  It was plenty long and wide enough that it fit over the metal cylinder.  Wrap electrical tape around the bag/cylinder to make the seal, making sure the bag is loose enough when the step is fully extended.

  It's fixed.  Engine vacuum will suck the air out of the big plastic bag. The piston will suck into the cylinder. The rubber/tape boot will invert.  The step will come up as long as the vacuum holds.  The weight of the step will extend it, and the tape/rubber boot will hold the piston in alignment with the cylinder. An AI will probably not sign it off, but the step will retract and extend.  I don't know for how long, but for a while, I think.

I hope this made sense, and I also hope you've got  enough parts...

Edited May 11, 2021 by davecusto
misspelled word and additional tag

[jamesm]

Takair makes the auto step which Is replacement for the Vacuum step.

Easy installation, simple, and works great.

http://www.flightenhancements.com

But if you insist on having a driven vacuum step. I have Vacuum actuator That Removed a few years ago. From '67C That was working at removal.

[Shiny moose]

There is a small coiled steel spring to help witht the extension, they do break. 

As Jamesm stated! Do the takiar mod, reasonable cost, its easy to install , works great, removes a servo from your system(less leak locations).

 I connected mine to the beacon, beacon on step up, beacon off step down. 

 

[davecusto]

That's a good one.  I don't have the spring.  The weight of the step lowers it.   I kind of like all the nonelectrical stuff on the airplane.  Maybe I'll get over it...

[Shiny moose]

Here is the spring info (#11) just incase you want it 

 

[skydvrboy]

8 hours ago, nosky2high said:

Plus one for the electric step replacement. Love mine. 

Plus one for getting a used one from someone who upgraded to electric. Yours is still working great and I love it. Thanks!

 

[carusoam]

You haven’t lived until you go to clean the big spring....

And watch as it finds it’s preferred state of equilibrium...  which isn’t nicely coiled as expected... 

Welcome aboard Dave!

 

Some people prefer their all manual Mooneys...

Others are proud members of the CB club...

Either way...  Go Mooney!

Best regards,

-a-

[Pasturepilot]

I've also heard that one of those long-armed rubber gloves (like you'd wear washing dishes) with the hands cut off work as a boot for the step actuator. Haven't had to try that one - my factory boot is still good for now. 

[davecusto]

I think that's a good idea.  I'll probably try it if, or when, the pet store bag fails.  The glove might even pass muster!  I doubt the bag will...

[Igor_U]

Few years ago someone posted a link to this  Rolling Diaphragm catalog by Marsh BellowFram. I might be able to find a direct or similar replacement for Step; I remember they posted a p/n good for aileron servo.

https://web.marshbellofram.com/belgas/files/2012/05/design_manual.pdf

It is worth a try. All my servos are still good (some I sent to Britain before the closed) so I have no need (or time) to do the research.

Good luck

 

 

 

 

[davecusto]

Thanks Igor_U,  a very interesting catalog...

[RightrudderM20E]

Buying a M20E with inop step , just ordered the electric upgrade thanks for the info posted …