Manually retracting electric gear

[Dream to fly]

Sorry,  I've got more questions...  I had a customer come into my shop today and noticed me working on parts to my plane.  He then starts informing me about all his experiences and time with everything from the war birds of the ice age all the way to the space shuttle.  He did say something that made me think.  He said that Mooney electric gear is fine but the manual levers are only good for a hand full of uses.  Is this true? and if so is there a way to make it reliable?  I can't picture it being sub-par but this guy could sell ice to an eskimo.

[Andy95W]

Unless his name was Don Maxwell, Paul Loewen, or it was Bill Wheat's ghost, I'd seriously question where he was getting his information.

[Mooneymite]

I've never seen any sort of limitation on the manual extension system for my electric gear.  It was obviously designed for emergency use, not normal extension.

Having said that, there are warnings in various Mooney publications against using the manual system to retract the gear using the manual extension system.  It is only a backup for gear extension, should the electric motor die.

[carusoam]

Which uses was he referring to?

1) the Jbar really is only good for two uses.  Gear up and gear down...

2) flap handle. Only one use. Flaps down...

Somebody with that much experience has probably developed a strange sense of humor...

a little bit of a communication gap I suppose.

You need to ask more questions when somebody like that stops in the shop.  What are you there for...  work? 

I just got back from my auto mechanic's shop.  I made him talk.  He can get distracted like any pilot I know...

Best regards,

-a-

 

Edited April 5, 2017 by carusoam

[Dream to fly]

OK!  I was hoping that was the consensus.  I figured it to be used once a year to make sure it works on jacks. 

[Mooneymite]

Just now, carusoam said:

Which uses was he referring to?

-a-

As written, I figured the OP was talking about electric gear Mooneys.....not the Johnson bar Mooneys.

Hard to tell for sure.

[carusoam]

Just be aware of the oddity of using electric gear with the manual back-up system engaged.

This is not a normal wear issue. This can be a damage issue based on not following the procedure.

There are a couple of different versions of the landing gear systems.  None work very well together normal vs back-up system.

Except the J bar.  The pilot has to decide if it is a normal gear extension or an emergency gear extension while he is putting the bar up and gear down... 

Best regards,

-a-

Edited April 5, 2017 by carusoam

[Dream to fly]

I had mentioned I had electric gear and he started with the manual override was a poor design and he just went on and on.  I really am new and trying to figure all this out.  A Cessna 172 was easy compared to this. 

[carusoam]

Life was simple, back in the day...

only problem was...it was simple!

The gear goes up for speed and efficiency.  It isn't super advanced because of cost, weight, complexity.

the gear system works very well. Lasts for 50+years.

Its biggest problems are it can easily be misused, or be completely forgotten.

A small number of motor systems were a challenge to find replacements.  They were expensive worm gear drives. Find out which one you have...  search around here to find out which model was the bigger problem.

Best regards,

-a-

 

Edited April 5, 2017 by carusoam

[1964-M20E]

With the Johnson bar the emergency extension procedure is as follows:

1. Have passenger in co-pilot seat reach down with left hand
2. grab Johnson bar and slide handle forward
3. follow the j-bar movement to the down lock block
4. push the top part of j-bar handle down and push forward
5. release handle into the lock block and ensure locking mechanism is engaged
6. give a slight pull on j-bar and ensure handle is fully extended into the down lock block
7. This emergency gear procedure can only be performed with a passenger in the co-pilot
8. Before doing a gear up landing try normal landing gear extension procedure one more time
9. If performing steps 7 & 8 are unsuccessful to lower the gear move to the co-pilot seat and try the emergency procedure
10. Should you get to step 9 and it is unsuccessful you should have bought a fixed gear Cessna

 

[midlifeflyer]

Manual gear extensions are a bit different in everything. The Arrow free-falls. Th 172RG is a hydraulic pump. The Mooney is pull the string to wind down the gear motor. They all have the plusses and minuses and all have one thing in common - they are for situations in which the electric gear doesn't work. And, I guess for checkouts and checkrides

To me, the worst is the Bonanza. You turn a crank that is behind and between the front seats in a position where you will scrape your hand raw on the carpeting while turning the thing about 50 times. I carry a pair of gloves in my flight bag, even in summer. When asked, I tell people they are my "Bonanza gloves."

 

[mooniac15u]

3 minutes ago, 1964-M20E said:

With the Johnson bar the emergency extension procedure is as follows:

1. Have passenger in co-pilot seat reach down with left hand
2. grab Johnson bar and slide handle forward
3. follow the j-bar movement to the down lock block
4. push the top part of j-bar handle down and push forward
5. release handle into the lock block and ensure locking mechanism is engaged
6. give a slight pull on j-bar and ensure handle is fully extended into the down lock block
7. This emergency gear procedure can only be performed with a passenger in the co-pilot
8. Before doing a gear up landing try normal landing gear extension procedure one more time
9. If performing steps 7 & 8 are unsuccessful to lower the gear move to the co-pilot seat and try the emergency procedure
10. Should you get to step 9 and it is unsuccessful you should have bought a fixed gear Cessna

 

The manual gear is a mechanical system. Any mechanical system can fail  When the manual gear system fails there is little chance of it spontaneously working again regardless of how many times you try step #8. 

[N201MKTurbo]

So, which electric gear system was he talking about? There are at least three different kinds. 

All the ones I have worked on looked like they would be good for thousands of cycles if you wanted to do that. 

Granted, with the dukes you can destroy it instantly by running the motor with the emergency engaged.

[carusoam]

22 minutes ago, mooniac15u said:

The manual gear is a mechanical system. Any mechanical system can fail  When the manual gear system fails there is little chance of it spontaneously working again regardless of how many times you try step #8. 

 

We have had one MSer have the nose gear collapse twice on his mechanical geared Mooney...

1) mechanical failure.

2) maintenance failure.

3) human error, pilot failure.

4) human error, owner failure.

5) human error, mechanic failure.

6) mechanical failure of a properly maintained system is possible. Just statistically unlikely...

7) a second failure in close succession would have me looking for a different plane, mechanic, and CFI...

 

Having the same problem twice was enough.  I believe he went with a different plane after that.

 

Best regards,

-a-

Edited April 5, 2017 by carusoam

[Mooneymite]

16 minutes ago, N201MKTurbo said:

So, which electric gear system was he talking about? There are at least three different kinds. 

All the ones I have worked on looked like they would be good for thousands of cycles if you wanted to do that. 

Granted, with the dukes you can destroy it instantly by running the motor with the emergency engaged.

Yeah, I'm  confused by the OP.  The title, "Manually retracting the electric gear" refers to something prohibited on my electric gear....and why would you want to?

Subsequent posts are dealing with the johnson bar....so, what is the question.?  And which system.

As it is there are lots of answers...and they're  all right!  htps//youtu.be/mIDFPgE4TC4

[Guitarmaster]

Although the "alternate" gear extension in my '75F is for "extension only," it is used (by guidance of the service manual) to retract the gear when doing work on the ldg gear system.

I have manually extended the gear probably 20 times while tracking down a problem in the electric portion of 'electric gear.'  No problems whatsoever. 

I suspect the 'no retraction' is due to the air loads while flying, but is fine in the shop.

[Vance Harral]

All emergency gear systems have failure modes, and I'm not inclined to think the one in "vintage" electric gear Mooneys (I have an F model too) is any worse than others.  In the honesty department, however, I'll say it has adjustment requirements that are something of a pain, and can be error-prone.  You'll run into this because properly maintaining an electric gear F model requires pulling the gear actuator every year or two for inspection, to comply with SB M20-190B.  On the plus side, this is an opportunity to inspect the whole system and understand how it works, check for wear, etc.  On the minus side, it provides a regular opportunity to screw up the delicate adjustment of the emergency engagement cable.

To wit, removing the actuator for inspection requires disconnecting the emergency extension engagement cable from the actuator.  The cable attaches to the actuator at two locations.  The first is the end of the cable which actually moves the engagement lever (first picture below).  Moving the engagement control in the cockpit forward pulls this cable to engage the manual crank.  Moving the cockpit control aft releases tension on the cable, and the spring you see in the photo is supposed to pull the lever to the disengage position.  If the spring gets reinstalled with the ends swapped, the positioning and tension changes.  Same if the complex collection of nuts and washers holding the cable gets re-ordered (and yes, it really is supposed to look like that, Rube-Goldberg-ish as it is).

But arguably those things aren't a big deal.  Just be careful, refer to the parts manual, and put everything back together the same way it came out, right?  Well, sorta.  In the second picture below, you'll see another attach point for the cable.  It's effectively stiffened by a support bracket that's just a big Adel clamp around the housing of the gear motor.  There is no detent in the housing to force the Adel clamp into a particular position, it just gets shoved on to the housing and tightened up.  In fact, you can see mine is a bit crooked in the photo, that was done on purpose.  When this clamp is re-installed, any minor change in position changes the relative location of the cable endpoint that attaches to the engage lever.  Get it too far forward and the emergency extension gear only partially engages when activated (it grinds and/or binds up).  Too far aft and the spring doesn't have enough tension to disengage the system, with the novel failure mode of the emergency gear handle whipping around wildly and beating your arms/legs when you retract the gear electrically.  To make matters worse, the system has observer effect, wherein operation for testing can move the Adel clamp around if it's not very snug, resulting in mechanical hysteresis.  Because of this, I'd never trust a single test of the system after a gear actuator R&R, I always do several.  I'm sure Mooney-savvy shops do the same, but not every shop is Mooney-savvy.

I've R&R'd our landing gear actuator numerous times over the last 13 years, and I consider myself pretty familiar with it.  I'm always careful with removal and re-installation, even under the "adult supervision" of an A&P.  And yet, about every other time I do so, a bit of tweaking is necessary to get the system adjusted properly so it reliably engages and disengages over multiple tests.  I've seen it misbehave when not perfectly adjusted (that's how I know what the failure modes are).  I've seen it work on a first test and not on a second one.  And if you need convincing this can fail "in real life", I refer you to the gear-up landing by a prior owner in our logbooks, which was blamed on this exact mechanism being mal-adjusted.  The pilot ran out of electrons, and when he attempted to lower the gear manually, the engagement lever didn't fully engage, and the crank jammed.

So... while I don't know your buddy's actual experience with Mooneys or exactly what his concern is, I think it's fair to talk about vulnerabilities in the system.  I think the basic idea of using a manual gear on the other end of the motor shaft to turn the system is sound, but the way that gear is engaged/disengaged doesn't seem especially well designed to me.  To be fair, the factory probably didn't envision everyone pulling the landing gear actuator out of the airplane every year or two when the system was designed, but that's the situation we have now.

[carusoam]

Nice writing, Vance!

Complete with photos.

Best regards,

-a-

[Mooneymite]

12 minutes ago, Vance Harral said:

  It's effectively stiffened by a support bracket that's just a big Adel clamp around the housing of the gear motor.  There is no detent in the housing to force the Adel clamp into a particular position, it just gets shoved on to the housing and tightened up.  In fact, you can see mine is a bit crooked in the photo, that was done on purpose.  When this clamp is re-installed, any minor change in position changes the relative location of the cable endpoint that attaches to the engage lever. 

Hmmmmmm?

My 74 doesn't use the adel clamp for the cable at all.  As I recall, it is anchored on the airframe, not the motor.  When the drive is re-installed, there is no "rigging".  Everything goes back just as it came out.

I'll be doing the AD here shortly (in 6.7 hours, but who's counting?), and I'll try to take some pictures.

[Yetti]

Ya I don't think Vance's is proper (deferring to the MM, too lazy to look it up)  Since mine still has the factory torque markers on it, I am going to say it has been that way since new.

Based on readings I would believe that the gear system is "fragile"   Like your buddy thought.   spending some quality time with the Emergency Disconnect part, I can say it is a very well made unit.  It uses good machine steel for the gears and such (unlike the plastic gears in your Magnetos).   The design is kind of deadman.   It has a snapping action by an internal spring that is held off by the lever/wire/handle in the cockpit.   So it is in tension when not engaged.  Slack in the cable lets the snapping spring to engage the 12 tooth gear coupler into the back of the motor shaft.   Then you are just turning the motor and running the gear down.

The reason for not raising the gear with it due to the "speedometer" cable.  As you know speedometer cables will unwind.

 

 

[N201MKTurbo]

Mine has a sheet metal bracket that is screwed to the back of the motor. A much better arrangement then the adel clamp.

[Vance Harral]

28 minutes ago, Mooneymite said:

My 74 doesn't use the adel clamp for the cable at all.  As I recall, it is anchored on the airframe, not the motor.

My (limited) understanding is the second attach point has changed over the years, depending on M20 model and the exact landing gear actuator installed.  The diagram in my parts manual actually shows a bracket attached to the back of the actuator to support the cable rather than an Adel clamp, but I believe that is specific to the Dukes 4196 actuator installed in earlier F models.  By the time our airplane was built (1976 model), the Dukes was no longer available, and Mooney had moved to the ITT LA11C2114 actuator.  That one lacks the bracket mounting holes shown in the parts manual diagram.  I'm guessing the Adel clamp is a workaround.  If yours doesn't have the clamp, I'd guess it has the bracket attached to the actuator.  It's possible the attach point is on the fuselage as you describe.  But in our airplane, the nearest fuselage stringer is too far away from the lever to make a good support point for the cable.

Interestingly enough, the ITT LA11C2114 actuator in our airplane isn't actually called out in SB-190B or either of the landing gear actuator ADs.  But we treat it as if it was, per advice from Don Maxwell.

[N201MKTurbo]

Don't lose those nuts on the cable. They are hard to come by.

[Vance Harral]

9 minutes ago, Yetti said:

Ya I don't think Vance's is proper

The picture in your post is an ITT LA11C2116 - different model than in my airplane (I think it's an even later follow-on to the LA11C2114).  It obviously has the mounting holes for the bracket.  Bracket(s), actually, I see yours has two.  I agree it's a superior arrangement, I wish we had it.

The only upside of having the LA11C2114 is that because it's technically not called out in the AD and SB, we don't have to strictly adhere to the 200 hour inspection limit.  I don't worry about it if we go something like 210 hours between inspections, especially since our unit has been rebuilt with 40:1 gears.

Edited April 5, 2017 by Vance Harral

[Yetti]

The two L brackets are attached via the through bolts that assemble the motor.