Electric Flaps Disconnected from Motor

[Steveolyo]

The Electric Flaps won’t retract on our 1969 M20F. The motor still hums like it is still spinning but the flaps don’t retract. Also the white indicator mark in the cockpit has slid out of sight.

 

A few weeks ago I noticed that the motor would still hum even when flaps were either at 0 or 33 degrees. It may always have been that way, we've only had the plane 7 months.

I don’t know if there is a stop switch that is supposed to prevent the motor from trying to go beyond 0 or 33, but if there is, the switch hasn't been working which could be part of what has led to this failure.

 

Does anyone know where to look to inspect the motor and shaft? I think it’s a belly panel since it wasn’t the area behind the luggage area where the battery is located.

Thanks.

[Yetti]

center line belly panel under the baggage storage area. A bit to rear of the flaps.   There should be two limit switches on top of the actuator arm

[Marauder]

The Electric Flaps won’t retract on our 1969 M20F. The motor still hums like it is still spinning but the flaps don’t retract. Also the white indicator mark in the cockpit has slid out of sight.

 

A few weeks ago I noticed that the motor would still hum even when flaps were either at 0 or 33 degrees. It may always have been that way, we've only had the plane 7 months. I don’t know if there is a stop switch that is supposed to prevent the motor from trying to go beyond 0 or 33, but if there is, the switch hasn't been working which could be part of what has led to this failure.

 

Does anyone know where to look to inspect the motor and shaft? I think it’s a belly panel since it wasn’t the area behind the luggage area where the battery is located.

Thanks.

I created a thread about issues I had with my electric flaps. I will find it and post it here.

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[Marauder]

Here you go. Maybe this will help: Electric Flaps Troubleshooting

http://www.mooneyspace.com/index.php?/topic/16679-Electric-Flaps-Troubleshooting

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[Steveolyo]

Thanks! Without the limit switch could it unwind the worm gear all the way off? That is probably what has happened. I'll report back with pictures.

[Yetti]

I would think it could blow out the drive bearings.  The later ones look like they use a couple of ball bearings captured as a drive nut.

[Steveolyo]

So when I removed the belly access panel (30 screws by the way!) I found the flap drive shaft was hanging. 

[Steveolyo]

And on the worm drive side with the motor, well that shaft was also hanging unattached.

[Steveolyo]

I reattached the shaft, adjusted it for 33 degree max deflection and tightened the small set screws on the side. The female side of the shaft has two very small allen set screws opposing each other. Those should hold it from coming off again.

Here is the shaft reattached.

Curiously, there is not limiting switch to prevent you from holding the flap switch on and putting pressure on this shaft, which in time could loosen it when it is at the limit on either side.

I will make sure not to keep the switch engaged when the flap is at the limit, but I think it should have a limit switch. I guess the electric windows on most cars work the same.

There is no limit switch to stop the motor once the end of the working area has been reached. 

[Marauder]

5 minutes ago, Steveolyo said:

I reattached the shaft, adjusted it for 33 degree max deflection and tightened the small set screws on the side. The female side of the shaft has two very small allen set screws opposing each other. Those should hold it from coming off again.

Here is the shaft reattached.

Curiously, there is not limiting switch to prevent you from holding the flap switch on and putting pressure on this shaft, which in time could loosen it when it is at the limit on either side.

I will make sure not to keep the switch engaged when the flap is at the limit, but I think it should have a limit switch. I guess the electric windows on most cars work the same.

There is no limit switch to stop the motor once the end of the working area has been reached. 

What year and model Mooney? I just had to deal with mine on a 75 F model. Mine has sensors all over that motor.

[Marauder]

This is what my dirty one looked like.

[Marauder]

Another angle.

[Steveolyo]

Its a 1969 F model. Strange that it has no limit switches like yours. They must have added them later. It must have a clutch of some kind which allows it to slip after the limits are reached because the motor still seems to spin after those limits are reached. You can hear it whine, a strained whine, but a whine nonetheless.

[Yetti]

Kind of looks like a clutch arrangement on the motor output shaft.  In other news I would say it is bad form to tie wires to the PC leveler tubing (although one pic looks like it is a factory tie job)   The tubing gets hard, vibration would cause it to break faster.  According to Brittian the port wing tubing is the one that goes first

[Yetti]

oh and wait till you pull all the screws out for an annual inspection

[ArtVandelay]

This is what my dirty one looked like.

This is inside the fuselage, where is the dirt coming from, I'd expect a little dust, but that looks like mud?

[Mooneymite]

My 74 C flaps are just like Steveolyo's.  No electric limit switches.  The drive motor runs the jack screw to the end of the threads (either full up, or full down) and then the motor can continue running, but there is no further movement of the jack.  The switch in the cockpit is a simple three position switch spring loaded to the off position.

The switch can be held in either up, or down positions after full flap travel and you can hear the motor run, but because the end of the jackscrew has been reached, nothing else moves.  The limits are mechanical, not electric.  Flaps may be positioned at any intermediate position.

[Marauder]

This is what my dirty one looked like./uploads/monthly_2015_12/566a594fab81b_Flap4.thumb.jpg.b30439c4edfe88db83648bdb9eed6c36.jpg" alt="566a594fab81b_Flap4.thumb.jpg.b30439c4edfe88db83648bdb9eed6c36.jpg">

This is inside the fuselage, where is the dirt coming from, I'd expect a little dust, but that looks like mud?

There are two nice openings on either side. I think Lasar sells a kit to cover them. I will take a picture and post it sometime. Charlesusal came to one of our fly-ins and was crawling under my plane looking at these holes. He has the same ones on his highly modified 67 F.

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[carusoam]

Review of what I see in this thread...

1) The original post indicates the flap motor continued to run.  The pilot was unaware if this was normal and was seeking help.  Go MS!

2) sounds like the flap switch failed to spring back to the middle position of 'off'.

3) The early motorized flaps are powered up and down.  The positioning is solely controlled by the pilot, using the eyeballs.

4) Pilot either looks out the window or at the flap indicator in the cockpit.  Looking out the window is near impossible to set right.

5) There isn't a 1960's electric motor that is designed to run continuously in GA.  Current and heat limitations were truely 'limiting'.  They would wear out in a couple of years, not decades.

6) POHs of the time didn't include the detail required to cover failure modes.

7) Maintenace manuals would be the place to find this detail.  Even then, we (this community) spent a week reviewing the more modern limit switch operation and how tricky they can be.

8) That first year of ownership is full of surprises. Especially if you haven't seen what's below the belly panels.  PPI is a good time for this.

9) hydraulic flaps aren't any better or worse.  Both are too simple compared to modern expectations.  They can both fail.  Usually, in the up position.  Pilots have broken the minor spar by leaving flaps down or putting them down at too high speeds.

Take the understanding here, and then apply that to the electric gear and then everything else in general...  60's technology was great for its time.    There are few automatic safety limitations or even proper seat belts in some of our planes.

Normal in the 60’s is not the same as Normal 60 years later.

We have come a long way,

-a-

[Yetti]

#7 - the 75 F electric flaps is not covered in the MM or the Parts list

[carusoam]

Ralph Nader (Unsafe at any speed) was focused on the automobile in 1965.  It took aviation decades to catch up to having more proper standards including the documentation.  In the Pharma business, if it's not documented, it didn't happen.  The food industry is still learning how challenging safety standards are. (Chipotle this week)

The purpose of having serialization and having a hull number is to know exactly what is inside the machine from it's birth, before working on it.  Logs are a method of continuing the tradition.

This is a really modern manufacturing technology.  Bar codes on every small part are still coming.  They will be scanned through the grease and dust using your iPhone or other...

As Yetti points out, in the 70's, the documents covered the basic primary machine. But, failed to cover some important options. Electric gear, electric flaps and FI? Who needs these? 

Electronic records stored on the Web infinitely, accessible to you at your leisure, shareable only to people that you want to have it, for as long as you want them to be shared...

best regards,

-a-

[Mooneymite]

While you're working on those flaps, don't miss an opportunity to grease the drive gears.  First time I checked mine, it was pretty obvious that what was in the drive train was left over from whatever Kerrville put in there in 1974!

[Yetti]

And lube the trim shaft u joints.   What looks like grease is just some hardened gunk that is asking for some triflow and Shell #6

 

[Steveolyo]

#2: Switch did not fail to spring back. Switch is held until either at full flap during final or flaps up after takeoff.

Because there is not limit switch, the pilot may hold it down or up for a 1/2 second or so before realizing the flaps are at the end of the gear limit.

Small amounts of this error over time amount to a lot, but without a limiting switch the overrun has to happen to some degree.

 

 

[carusoam]

From the initial post...

i thought the motor continued to run, after release of the switch...

since everything was working properly until it broke...

How are other people using this set-up?

Do they just let go of the switch prior to the flaps reaching their final location?

What does the POH say regarding how to handle this system?

Modern (non-aviation) systems measure the current flow in the motor. When they hit the end of their travel, the current increases. Sensing the increased current, the device gets turned off.  Picture Firebird and Corvette headlight doors the gear turns until the door opens fully or closes fully.  With a failure the system has a particular time to finish or the voltage gets removed. A small computer is used to handle the logic.  (Not the vacuum driven ones of the older days...)

it can't be a normal procedure to keep the switch on when the motor has reached the end of it's travel. Things will break or wear out at a high rate.  I would have expected the CB to have tripped prior to breaking apart...

I'm only a PP, not a mechanic.

seek additional detail to get a complete understanding.....

Best regards,

-a-