What is the legality of removing my step and patching the resulting hole?

[Grandmas Flying Couch]

Hello, my 67F has a retractable (vacuum) step that no longer functions.  I have it safety wired up and do not need it.  My mechanic worries about the legality of removing it.  Would this be a minor alteration, major alteration?  Please advise, I'm interested in removing all the extra stuff the plane has gained over the years and getting it re-weighed since my W&B is 20 pages long and highly doubt it's still accurate.  

Would like to remove:

KLN 89b doesn't work 

Marker beacon 

Step

Maybe Britain autopilot (can't get parts) servos are bad and don't want to pay $200 each for servos that may last 1 day or 1 decade.  

remainder of oxygen system that is ancient and partially missing

Any help would be awesome.  Useful load sits at 1025lbs which is great, I want to see if I can get this sucker up near 1100lbs with a 200hp Mooney!  Thanks in advance! 

Edited February 19, 2021 by Grandmas Flying Couch

[eman1200]

“What step?!?” Winkity wink wink

[jamesm]

I have a  Vacuum step servo if you are interested.

 

James '67C

[Shiny moose]

Takair has a wonderful electric mod for the step, I would keep the step just for the cool factor

[MB65E]

My step has been removed for 40 years. It’s not listed in the TCDS. It is not required for flight. I even found a right side wing root faring that was clean with no holes drilled or cut into it. Thus no ugly patch. Minor modification. Doesn’t meet the criteria for a 337.
I’m impressed that you have a 1025 UL already. 
Keep the step for the future owner. 
-Matt
 

[steingar]

When looked I saw a number of examples that had undergone a step-ectomy.  Kinda like a Mooney bris in a way.

[Grandmas Flying Couch]

1 hour ago, Shiny moose said:

Takair has a wonderful electric mod for the step, I would keep the step just for the cool factor

I don't want to keep the weight, I like the cool factor but I think making the plane cheaper and simpler to maintain is cool too!  Also removing save a couple hundred and 5-10lbs.  

[Grandmas Flying Couch]

32 minutes ago, MB65E said:

My step has been removed for 40 years. It’s not listed in the TCDS. It is not required for flight. I even found a right side wing root faring that was clean with no holes drilled or cut into it. Thus no ugly patch. Minor modification. Doesn’t meet the criteria for a 337.
I’m impressed that you have a 1025 UL already. 
Keep the step for the future owner. 
-Matt
 

Thank you this is most helpful.  I will look for fairing, imagine they are rare without some sort of step cut out.  I'll let my mechanic know! 

[Grandmas Flying Couch]

2 minutes ago, steingar said:

When looked I saw a number of examples that had undergone a step-ectomy.  Kinda like a Mooney bris in a way.

 LOL!  Time for her to undergo the change.  I don't want to remove just a part of the step so a bit more than a bris.  

[Shadrach]

4 hours ago, Grandmas Flying Couch said:

I don't want to keep the weight, I like the cool factor but I think making the plane cheaper and simpler to maintain is cool too!  Also removing save a couple hundred and 5-10lbs.  

Not sure what it weighs but it can't be much.  I don't know how long you've been flying but what changed for me about about year 15 as a pilot is that I became more acutely concerned about passenger experience.  The old adage  "You never get a second chance to make a first impression" is very true.  You may not need the step but there is a good chance that you have friends and/or family that will feel way less comfortable going from ground to wing and vice versa in its absence.  I would also say that if I were plane shopping, I would consider this kind of "modification" a con not a pro. As to the may last "1 day or 1 decade" comment ours has been working for 5.5 decades with nothing more than a lube every few months. In the last 5 years, I've started treating all of the boots to a silicone bath at annual. at 54 years old our F model has all of it's original servos. I started buying serviceable servos years ago in anticipation of a failure that has never come. All of the rubber on our bird is supple, but I have seen servos that are in awful shape.  I think the best course of action for the value of the plane and the comfort of any passengers is to sort out the problem.

Good luck on your airframe diet plan.  I have thought about what it would take to get our 67F to 1100lbs useful.  As it stands we're not that far at 1059lbs even with a geriatric generator.  An alternator and an MT propeller would likely get us very close.

Edited February 19, 2021 by Shadrach

[EricJ]

13 hours ago, Grandmas Flying Couch said:

Hello, my 67F has a retractable (vacuum) step that no longer functions.  I have it safety wired up and do not need it.  My mechanic worries about the legality of removing it.  Would this be a minor alteration, major alteration?  Please advise, I'm interested in removing all the extra stuff the plane has gained over the years and getting it re-weighed since my W&B is 20 pages long and highly doubt it's still accurate.  

The step wasn't installed on very early J models and I think was an option for a while.  I think it'd be a minor alteration, but your IA's opinion is the one that matters.

[carusoam]

The retract step has the cover / faring related to the hole on the bottom of it...

Know any good sheet metal guys?

Blocking the hole properly would be a great.  it is probably a trapezoidal shape...

PP thoughts only, not a mechanic...

Best regards,

-a-

[jetdriven]

1 hour ago, EricJ said:

The step wasn't installed on very early J models and I think was an option for a while.  I think it'd be a minor alteration, but your IA's opinion is the one that matters.

Read the FAR part one definition of a major alteration, and then use that as your guide. It’s black letter wording.  Minor is anything not defined as major.

[EricJ]

1 hour ago, jetdriven said:

Read the FAR part one definition of a major alteration, and then use that as your guide. It’s black letter wording.  Minor is anything not defined as major.

And yet so many 337s get filled out and STCs sold for things that aren't defined as major alterations...   

[BDPetersen]

Steps have some attraction to the older aviator. If you plan on aging or selling to one who fits that category, the option for a step might be worthwhile. In my youth I once was able to do a spin-leap onto the wing of DC-3. Now I sometimes wonder how I will get up from sumping the fuel . . .

[drapo]

My question is: how many knots would it cost having it permanently hanging down while removing the servos and related hardware thus saving the added weight? 

[Shadrach]

24 minutes ago, drapo said:

My question is: how many knots would it cost having it permanently hanging down while removing the servos and related hardware thus saving the added weight? 

Given the "aerodynamic design" of the retractable step, I'm guessing it's more than anyone would want to accept. In addition to its parasitic drag it may necessitate a little left rudder to keep the ball centered, so a touch of additional induced drag as well.

[takair]

1 hour ago, drapo said:

My question is: how many knots would it cost having it permanently hanging down while removing the servos and related hardware thus saving the added weight? 

One of my favourite topics.  I know people are skeptical, but we actually did some testing and on an old Mooney it is significant.  Depending on your target speed the penalty of the step is 1 to as much as 4 kt.  4kts is WOT and trying to achieve true max cruise speeds.  1 kt is at slower “loiter speeds”.   The reason is not purely the drag caused by the step....which is significant, but also because it puts the aircraft out of optimal trim.  You can see this by looking at the ball with the step up vs down.  With the step down you will induce an out of trim condition which impacts best cruise speed.  You could of course keep your foot on the left rudder to counter this, or one could rig it out if strapping the step down.  I would estimate the the speed penalty is about half drag and half trim.  So, for as much money as we spend on Mooneys to go fast, this can be quite a penalty.  You can see said speed comparison in a video on our web site....but it is like watching paint dry. (Correction...video is not linked in this version of web site, but I can dig it up if someone is interested). By the way, modern long bodies have a shorter step due to the ground posture of the aircraft.  They are also more aerodynamic and sit more in the wake of the wing.  All this accounts for a much smaller speed penalty.

[Ragsf15e]

1 hour ago, takair said:

One of my favourite topics.  I know people are skeptical, but we actually did some testing and on an old Mooney it is significant.  Depending on your target speed the penalty of the step is 1 to as much as 4 kt.  4kts is WOT and trying to achieve true max cruise speeds.  1 kt is at slower “loiter speeds”.   The reason is not purely the drag caused by the step....which is significant, but also because it puts the aircraft out of optimal trim.  You can see this by looking at the ball with the step up vs down.  With the step down you will induce an out of trim condition which impacts best cruise speed.  You could of course keep your foot on the left rudder to counter this, or one could rig it out if strapping the step down.  I would estimate the the speed penalty is about half drag and half trim.  So, for as much money as we spend on Mooneys to go fast, this can be quite a penalty.  You can see said speed comparison in a video on our web site....but it is like watching paint dry. (Correction...video is not linked in this version of web site, but I can dig it up if someone is interested). By the way, modern long bodies have a shorter step due to the ground posture of the aircraft.  They are also more aerodynamic and sit more in the wake of the wing.  All this accounts for a much smaller speed penalty.

You’re making a good sales pitch for the electric step!  Mine is a ‘68, so fixed.  Making it retractable would entail making a bigger opening in the side of the airplane for it to pull up?  Does water get sprayed up there during ground ops?

[orionflt]

My aircraft is a 1962 C model, when my step cable broke I debated just removing it and closing the hole (minor alteration) but my wife uses the step constantly and was frustrated with me for not fixing it, I had it locked in the up position. I ended up putting in @takair electric step conversion. it is easy to install and drops a few oz of weight after I remove the old cabling and crank. as for the speed penalty, closing the hole would be a net zero, but as stated earlier on my aircraft keeping the step down is very noticeable. I never checked to see exactly how much speed I lost but the trim is defiantly out and i would spend part of the flight trying to figure out what was wrong until i realized I forgot the step. (I do not use the step so I keep it up, my wife does so I put it down for her and forget to pull it up afterwards)

Brian

[EricJ]

2 hours ago, drapo said:

My question is: how many knots would it cost having it permanently hanging down while removing the servos and related hardware thus saving the added weight? 

I think every Mooney since and including the J model has fixed steps, so apparently not that much. 

Do any since the J have retractable steps?

[jetdriven]

the early J models had no step.

[Shadrach]

17 minutes ago, EricJ said:

I think every Mooney since and including the J model has fixed steps, so apparently not that much. 

Do any since the J have retractable steps?

Not all Mooney steps were created equal. The retractable steps have a much higher profile and extend further down and outward.

[carusoam]

The square tube of the retractable step is an aero ouch point...

The aerodynamic enhancement added to the permanently fixed steps makes a significant difference...

If you have considered the drag penalty of antennas... you are not going to leave a square tube dangling in the wind... 

 

So...

Modernizing the step works well...

It allows for the best aero when stowed...

It allows for the best use when deployed...

It weighs less than the original equipment...

It doesn’t allow outside air into your instrument system...

It allows for being left up permanently...

If you want it to be down permanently for testing... you can do that too...  

The step on the Long Body is so small and far away...  it takes extreme confidence, and good focus, and some concentration, to be comfortable stepping off the wing...

You need to know what is going to happen next... because the job is only half done...

Gravity happens quickly...

PP thoughts about the step...  I’d prefer an elevator...   hey Rob... how big of a Servo motor would I need to lower a 175# pilot to the ground..?

-a-

 

[Ragsf15e]

1 hour ago, Shadrach said:

Not all Mooney steps were created equal. The retractable steps have a much higher profile and extend further down and outward.

True, there’s some “middle ground” fixed steps before they got to the more aerodynamic ones.  My ‘68 isn’t square like a retractable one, but it isn’t aerodynamic either.  It’s a 1” diameter steel tube with a big fat step on the bottom.  No fairing on the tube.  Like an antenna, a circular tube has a pretty bad drag profile.