Question about electric landing gear systems

[NotarPilot]

I’m planning on doing my commercial add-on this Monday but my DPE wanted to meet with me and my instructor on Wednesday to go over my logbooks, aircraft logs, etc.  He even went over some of the questions he was going to ask me about on the oral.  One question kind of stumped me.  He asked how is the landing gear held in the UP position on the Mooney.  The manual doesn’t give much info and the Mooney Pilot Proficiency Program manual has good info but doesn’t answer the question.  A google search also did not yield the answer.

Does anyone here know where I might find the answer to this?  Thanks.

[DualRatedFlyer]

Mooney space wouldn't be nearly as useful if every question was answered via cell as opposed to over the forum. 

[Jerry 5TJ]

You point to the uplock block between the seats and say, “The Johnson bar latches into this and that’s what keeps the gear up.”  

Oh, a J model:   Here’s what I recall— The electric gear uses the pushrod mechanism like the manual systems but the J bar is replaced by a motor driving via a gear with a high reduction ratio.  

The motor drives the gears which pushes the rods and moves the three landing gear legs.  When the gear is raised and fully in the wheel wells electric limit switches stop the motor.  

At that point the motor shaft is motionless.  The gearbox multiplies the torque required for the gear to spin the shaft.  The gear’s weight is unable to overcome the motor/gearbox resistance and the gear is held in place.  

(If you have a manual gear Mooney and the J bar somehow comes unlatched during cruise flight the gear will come down Right Quick.)

[Tommy]

I think you should ask him "how is this knowledge going to make any difference to my flight training?" 

[N201MKTurbo]

24 minutes ago, Jerry 5TJ said:

You point to the uplock block between the seats and say, “The Johnson bar latches into this and that’s what keeps the gear up.”  

Oh, a J model:   Here’s what I recall— The electric gear uses the pushrod mechanism like the manual systems but the J bar is replaced by a motor driving via a gear with a high reduction ratio.  

The motor drives the gears which pushes the rods and moves the three landing gear legs.  When the gear is raised and fully in the wheel wells electric limit switches stop the motor.  

At that point the motor shaft is motionless.  The gearbox multiplies the torque required for the gear to spin the shaft.  The gear’s weight is unable to overcome the motor/gearbox resistance and the gear is held in place.  

(If you have a manual gear Mooney and the J bar somehow comes unlatched during cruise flight the gear will come down Right Quick.)

On a J Bar Mooney, If it cones unlocked, it will come 1/2 way down. The springs balance it at the mid point.

[carusoam]

Its one thing to have the knowledge... Like Andrew certainly does for the landing gear... and the pics...

But, the key is being able to explain it in a simple understandable way...

Make it a two step process...

1) gather all the detail... digest it...

2) practice your delivery... Deliver the explanation here...

 

i like Jerry’s explanation. But The manual operation really has an up lock block...

The electric version has the motor, and sensors, plenty of friction in the 20:1 gears, more in the 40:1...

There is that one last piece. You feel in the seat... Something is going over center and locking things in place... Expect that there is an over center lock at both ends... up and down...?

Use Yeti’s video of the gear operation up on jacks.  You can really see things as they go through the motion...

Don’t forget the important details of locking out the emergency gear system... and its operation... and what goes wrong when the E-system interferes with the electric system...  Andrew has the details on that as well...

Be ready for the flap operations as well...

Those are the two major systems we have, to possibly be discussed...

How will you handle a safe landing if the gear is stuck... up, down, mid way....

Same with flaps... up, down, midway... know what keeps them from splitting and having one get deployed and not the other...

 

PP thoughts only, not a mechanic or CFI...

Best regards,

-a-

 

[Mooneymite]

When dealing with a DPE, or FAA examiner, the key is to keep answers short.  Make them dig, if they want more.

Q:  How is the gear held in the up position on a Mooney?

A: On a manual gear the J-bar lock; on an electric gear Mooney by the jack-screw.

Next question?

Edited July 12, 2019 by Mooneymite

[KSMooniac]

You might consider printing the system pic from the maintenance manual and pointing at the components as you explain it. Keys are the motor and actuator, linkages, and over-center locks.

Sent from my LG-US996 using Tapatalk

[Jerry 5TJ]

3 hours ago, N201MKTurbo said:

On a J Bar Mooney, If it cones unlocked, it will come 1/2 way down. The springs balance it at the mid point.

That is certainly true when the plane is on jacks at zero airspeed.    At normal operation speed some force is needed to push the bar into the downlock.  The faster you go the more the gear is pulled down, I suppose by air loads on the gear and doors.   

Example one-time event:  When the bar unexpectedly popped out of the uplock block on my E at around 160 mph the J bar did not float: It moved “without undue delay” through 90 degrees & into the downlock block. 

[N201MKTurbo]

15 minutes ago, Jerry 5TJ said:

That is certainly true when the plane is on jacks at zero airspeed.    At normal operation speed some force is needed to push the bar into the downlock.  The faster you go the more the gear is pulled down, I suppose by air loads on the gear and doors.   

Example one-time event:  When the bar unexpectedly popped out of the uplock block on my E at around 160 mph the J bar did not float: It moved “without undue delay” through 90 degrees & into the downlock block. 

It’s possible it had enough inertia to carry it through the swing.

[PT20J]

It's a fair question because landing gear is a critical system to understand and different airplanes have different systems. Some have mechanical up locks, some are held up only by hydraulic pressure.

The Mooney electric gear doesn't have up locks per se. The electric worm drive/ball screw actuator is an irreversible mechanism (the motor can move the gear, but the gear cannot turn the motor) and holds the gear up.

Skip

[Shadrach]

1 hour ago, Jerry 5TJ said:

That is certainly true when the plane is on jacks at zero airspeed.    At normal operation speed some force is needed to push the bar into the downlock.  The faster you go the more the gear is pulled down, I suppose by air loads on the gear and doors.   

Example one-time event:  When the bar unexpectedly popped out of the uplock block on my E at around 160 mph the J bar did not float: It moved “without undue delay” through 90 degrees & into the downlock block. 

This is unique to you and maybe one other person on this forum.  My gear popped out of the up lock once in cruise and it did not go anywhere near the down lock.  I thought one of the rear seat passengers was tapping me on the elbow trying to get my attention.  I turned to find the J- Bar gently swaying in the 40-50° range. This is how the gear should work.  Those that claim to have had a violent gear movement in cruise should have their gear checked out.  It is not normal nor acceptable to have a steel club swing through the cockpit at cruise speed. If that has happened then something is wrong. I don;t think Mooney would have gone to production with a system that does such a thing nor would the FAA have certified it.

Edited July 12, 2019 by Shadrach

[PT20J]

1 hour ago, Shadrach said:

This is unique to you and maybe one other person on this forum.  My gear popped out of the up lock once in cruise and it did not go anywhere near the down lock.  I thought one of the rear seat passengers was tapping me on the elbow trying to get my attention.  I turned to find the J- Bar gently swaying in the 40-50° range. This is how the gear should work.  Those that claim to have had a violent gear movement in cruise should have their gear checked out.  It is not normal nor acceptable to have a steel club swing through the cockpit at cruise speed. If that has happened then something is wrong. I don;t think Mooney would have gone to production with a system that does such a thing nor would the FAA have certified it.

Agree with Ross. Many years since I flew a C. But I recall doing a number if checkouts in a club Ranger. No one gets the gear retraction motion right the first try. So I had a lot of experience with the Johnson bar at half mast. It always seemed to rest around 45 deg as I recall. 

Skip

[Jerry 5TJ]

3 hours ago, Shadrach said:

....Those that claim to have had a violent gear movement in cruise.....

 It must be a fake memory, then.  

Reminds me of the time Glen Curtiss and I were flying his float plane, yessir, must have been in 1913 or thereabouts.  He and Jimmy Doolittle used to call me for advice frequently, and long distance phone calls weren’t cheap back then, neither.  Anyway, Glen says to me....

[PT20J]

1 minute ago, Hyett6420 said:

Yes but f you use the search function you will find this information on ms in spades.  

We have a search function? I can’t find diddly with it. Must have been programmed on a Friday by a summer intern. Maybe Anthony could teach a class on how to use it.   

[NotarPilot]

This is a lot of good info. I think I have a pretty good understanding of it. At least enough to talk my way through the oral. Thanks everyone.

[Shadrach]

1 hour ago, Jerry 5TJ said:

 It must be a fake memory, then.  

Reminds me of the time Glen Curtiss and I were flying his float plane, yessir, must have been in 1913 or thereabouts.  He and Jimmy Doolittle used to call me for advice frequently, and long distance phone calls weren’t cheap back then, neither.  Anyway, Glen says to me....

Where did I suggest that it did not happen? I suggested and stand by that if it happens, something is out of adjustment.

Edited July 12, 2019 by Shadrach

[Hank]

3 hours ago, Hyett6420 said:

Google helps with that i find, lol.  Little trick i learnt from @carusoam on here.   . 

Try it like this:  go to Google, enter "mooneyspace: xxxxxx" where xxxxxx is what you need. Works good!

[Jerry 5TJ]

3 hours ago, Shadrach said:

Where did I suggest that it did not happen? I suggested and stand by that if it happens, something is out of adjustment.

Ah, directly in your post. 

No matter, hence my attempt at an ironic reply.  

[BDPetersen]

Tangentially related, I suppose. On a recent G model gear up landing in this area, the FAA determined that the gear motor had seized. Said that was a first for them. I’m not electric gear qualified, so I can’t comment other to ask if it is unusual.

[Shadrach]

10 hours ago, Jerry 5TJ said:

Ah, directly in your post. 

No matter, hence my attempt at an ironic reply.  

Negative. You misread my post and misreplied accordingly.  If it was directly in my post it should’ve been easy to quote.

[81X]

1 hour ago, BDPetersen said:

Tangentially related, I suppose. On a recent G model gear up landing in this area, the FAA determined that the gear motor had seized. Said that was a first for them. I’m not electric gear qualified, so I can’t comment other to ask if it is unusual.

Funny. Is electric gear qualified similar to being manual transmission qualified in a car?  

[Yetti]

On 7/12/2019 at 7:15 AM, Jerry 5TJ said:

You point to the uplock block between the seats and say, “The Johnson bar latches into this and that’s what keeps the gear up.”  

Oh, a J model:   Here’s what I recall— The electric gear uses the pushrod mechanism like the manual systems but the J bar is replaced by a motor driving via a gear with a high reduction ratio.  

The motor drives the gears which pushes the rods and moves the three landing gear legs.  When the gear is raised and fully in the wheel wells electric limit switches stop the motor.  

At that point the motor shaft is motionless.  The gearbox multiplies the torque required for the gear to spin the shaft.  The gear’s weight is unable to overcome the motor/gearbox resistance and the gear is held in place.  

(If you have a manual gear Mooney and the J bar somehow comes unlatched during cruise flight the gear will come down Right Quick.)

Pretty close for electric gear.   Not to discount some of the mechanical advantage and overlock.  At least in the ITT actuator and probably the dukes for an F model.  There is a brake in the back of the motor actuator.   When power is not applied, then the brake is holding the armature of the motor.   This keeps the gear from "chattering" down.  which was a problem for some of the earlier electric gear.  Power is applied during the gear sequence to release the brake.   This is done via the 4 pole ford tractor solenoid.   The 4th pole is 12v. used to release the brake.    Normally you need 2 wires to a motor to make it go forward and reverse by switching polarity.   Always worriesome when you see 4 wires to a motor and you expect 2.   So 2 grounds.  1 for the motor, one for the brake.

 

 

[Yetti]

The better question for you to answer is how the f do I get the gear down when the motor fails.

In the crank method.     The lever in the cockpit engages the emergency gear disconnect on the gear actuator.

which the large spring in the picture below is attached to.   That engages the cable that is connected to the crank.   Center left of the first pic.   Which then cranks the gear down manually while you huff and puff in the cockpit.    The video above is manually cranking the gear down.

I would build a powerpoint complete with video and give him a detailed explanation so you can burn time there and have less time for other questions.

I took my dad's Aluminum E6b to the oral so we burned time talking about it.

[N201MKTurbo]

1 hour ago, Yetti said:

The better question for you to answer is how the f do I get the gear down when the motor fails.

In the crank method.     The lever in the cockpit engages the emergency gear disconnect on the gear actuator.

which the large spring in the picture below is attached to.   That engages the cable that is connected to the crank.   Center left of the first pic.   Which then cranks the gear down manually while you huff and puff in the cockpit.    The video above is manually cranking the gear down.

I would build a powerpoint complete with video and give him a detailed explanation so you can burn time there and have less time for other questions.

I took my dad's Aluminum E6b to the oral so we burned time talking about it.

The grease leaking from your actuator gearbox doesn't appear to have any moly in it. It should be black.