Retractable Step

[Jerry 5TJ]

Vintage Mooney can still get it up....

 

http://youtu.be/oe37S_5ukKM

 

Step begins to retract at engine start. 

Vacuum about 3" Hg at idle. 

 

Thanks to Dave N for the video. 

[FlyDave]

As WC Fields would say, "Yes, yes, Some of the finest videography I've seen!"

[aviatoreb]

That's so cool - I never seen it!!!

Why did they stop making that?

[orionflt]

it uses a brittain vacuum servo to retract the step, problem is parts are hard to get right now.

[DaV8or]

it uses a brittain vacuum servo to retract the step, problem is parts are hard to get right now.

 

Actually, the step servo is easy to get from Brittain. They also can be patched up in a pinch. I got a rebuilt one off the shelf from LASAR a few years back. I think $180. To my knowledge, rebuilt is all you can get and it's done with a core charge for your old one.

[DaV8or]

That's so cool - I never seen it!!!

Why did they stop making that?

 

I think they stopped partly because they discontinued Brittain as their auto pilot supplier, partly to save money, complexity and construction time. The speed penalty is small and they more than made up for it elsewhere with the 201.

 

I have always wished that the system could have evolved to electric. A simple rack and pinion system, or perhaps just a big solenoid. It would be nice to have an indicator light so we can be sure it is fully up. I have toyed with the idea of building this electric step, but then I remind myself that this is a "certified" plane and it would require a bureaucratic nightmare and heaps of cash to be legal.  

 

I also wonder if there are any modern Mooney owners that have retrofitted the vacuum system? I think that might just be a log book entry as it is already covered under the type certificate.

[rbridges]

I think they stopped partly because they discontinued Brittain as their auto pilot supplier, partly to save money, complexity and construction time. The speed penalty is small and they more than made up for it elsewhere with the 201.

 

I have always wished that the system could have evolved to electric. A simple rack and pinion system, or perhaps just a big solenoid. It would be nice to have an indicator light so we can be sure it is fully up. I have toyed with the idea of building this electric step, but then I remind myself that this is a "certified" plane and it would require a bureaucratic nightmare and heaps of cash to be legal.

 

I also wonder if there are any modern Mooney owners that have retrofitted the vacuum system? I think that might just be a log book entry as it is already covered under the type certificate.

 

I love mine, but I also wish there was a way to convert it to something besides vacuum.  I would like to get rid of my vacuum gauges, but I'm still stuck with the step.  I guess I'll cross that bridge when I get to it.

[Rhumbline]

it uses a brittain vacuum servo to retract the step, problem is parts are hard to get right now.

 

Actually, the step servo is easy to get from Brittain. They also can be patched up in a pinch. I got a rebuilt one off the shelf from LASAR a few years back. I think $180. To my knowledge, rebuilt is all you can get and it's done with a core charge for your old one.

 

I spoke with Brittain recently to see about getting the servos for the PC system and the step overhauled.  PC servos are no problem ($140 a pop) but they are having trouble getting the rubber bellows (my nomenclature) for the step servo.  I was advised it would be available at some point in the future but not presently. 

 

For anyone interested, the associated turn coordinator overhaul is $450-$600 depending on what's needed. 

[orionflt]

Actually, the step servo is easy to get from Brittain. They also can be patched up in a pinch. I got a rebuilt one off the shelf from LASAR a few years back. I think $180. To my knowledge, rebuilt is all you can get and it's done with a core charge for your old one.

wish that was true, been in contact with brittain, they told me they had to get the seals manufactured and were having difficulties with the new molds. I'm on the call back list for when they get the first batch in. Meanwhile I used gorilla tape to make Jacks step try to work.

Brian

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[Jerry 5TJ]

..... They also can be patched up in a pinch...

Annual service is pretty easy, too.   New 'boot sealant tape' aka black plastic electrical tape every few years at the ends of the boot per the Brittain procedures.    Generally no lubricant on the step arm itself lest it gum up. 

 

Pulley and cable in my "C" appear original and OK after what must be 4000-5000 cycles. 

 

I doubt that the retracted step adds as much as 12-14 knots.  

[DaV8or]

I doubt that the retracted step adds as much as 12-14 knots.  

 

Not even close. I think it's about 1-2 knots.

[DaV8or]

wish that was true, been in contact with brittain, they told me they had to get the seals manufactured and were having difficulties with the new molds. I'm on the call back list for when they get the first batch in. Meanwhile I used gorilla tape to make Jacks step try to work.

Brian

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That sucks. I wonder if you could use cement from an inner tube patch kit and thin inner tube material from a bicycle tube to make a better repair?

[carusoam]

RB,

Good news for you...?

I believe the vaccuum source for the step is related to intake manifold vac.

You can have the vac pump removed and keep the vac operated step...

I don't recall perfectly well, I never worked on the step in a decade of ownership, except for cleaning dried grease off the spring.

Can anyone verify this statement?

65' M20C experience,

-a-

[orionflt]

That sucks. I wonder if you could use cement from an inner tube patch kit and thin inner tube material from a bicycle tube to make a better repair?

thought about that, but the rubber is beyond that, the rip is over 6" long. I was just trying to keep from having to pull and cap the vacuum line.

Brian

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[orionflt]

RB,

Good news for you...?

I believe the vaccuum source for the step is related to intake manifold vac.

You can have the vac pump removed and keep the vac operated step...

I don't recall perfectly well, I never worked on the step in a decade of ownership, except for cleaning dried grease off the spring.

Can anyone verify this statement?

65' M20C experience,

-a-

No, it is hooked into the vacuum system.

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[carusoam]

Sorry,

Thought the extra load would be handled better by manifold vac...

Balanced by... What would happen when a leak develops...

I would not want a leak of unfiltered, outside air in either system...

It seems that it could significantly effect instruments performance if the leak is large enough to cause a low vac situation.

The modern FAA doesn't want us to connect things to pitot/static systems unless they are approved. Additional care becomes important when selecting the proper tape and rubber pieces.

Best regards,

-a-

[1964-M20E]

Not even close. I think it's about 1-2 knots.

I believe it is about 3 to 5kts when I had my 64 E model with the manual retract I forgot to retract it on more than one occasion and is was noticeable. However that step is not designed to be in the wind unlike the fixed step which would be less of a gain if removed as some have done.

 

[yvesg]

I had my step boot overhauled by Brittain about a year ago. It took a while to get it back (3-4 months I believe). Brittain mentionned issues getting their subcontractor providing the part... looks like this is still an issue.

I had my mechanic secure the step in the "up" position all that time. The wife complained quite a bit about the high step to get in but she managed. She was happy when it got fixed right.

Yves

[rbridges]

No, it is hooked into the vacuum system.

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I agree.  I can test the step out in the hangar using the backup electric pump.  thanks anyway.

[N601RX]

The "servo boot" is better known as rolling diaphragm. We use a lot of them in water flow products we manufacturer.  The company below has many stock sizes to choose from.  They may have something that will fit if you know the measurements. They start on page 17.

 

http://www.marshbellofram.com/bellofram-corporation/files/2012/07/design_manual1.pdf

[Bob_Belville]

Not even close. I think it's about 1-2 knots.

More like 7-8 k. Mine was inop for several months and I did not realize it until a buddy videoed a take off. There was the step hanging down.

 

www.youtube.com/watch?v=NuG8dtRBPgQ

 

I had been pulling my hair out about why this E was so slow with all the speed mods. With a rebuilt servo it is now 159 k @ 75%. That's what I'm talking about. 

 

Now comparing the retractable to a more aerodynamic step that is designed to stay down might be a couple of knots. But dragging that square tube not only cost a lot of speed it creates some yaw.

[orionflt]

now we just have to pull one to get the dimensions 

[1964-M20E]

I've got a spare one I'll check on it but it may take a few days. I do not know if it is at the hangar or at the house. Hopefully, one day they will be the same a an airpark.  

[pinerunner]

I'm glad mine is manual. As I think of it though, a few times I haven't bothered to put it back down again when I stopped for gas it was so easy to just step/hop down over the flap and step back up again that I think, in a pinch, that fixing it in the retracted position and doing without a step is a viable option. You'd have to be careful about your passengers of course but I think we do anyway.

 

Dave

[orionflt]

mine is also and for the most part I keep it up, infact the times I put it down for passengers I usually forget to retract it.

 

Brian