Pattern and landing speeds.

[MooneyMitch]

1 hour ago, Hank said:

It can be quite difficult stopping the prop when the engine isn't seized. But pulling the prop control all the way out to low pitch will significantly increase the gliding range. You can feel the airplane accelerate.

My real life experience when making a Mooney gear up landing years ago [actuator became disengaged from landing gear linkage during flight review flight], on final approach when I knew I had the field made, I did shut down the engine and tried [at least twice] to center the prop.  I eventually decided to forget that and concentrate on making the smoothest landing possible for the safety of my flight instructor and myself.  I left the concerns about the engine and propeller to the insurance company. 

Theory, planning and training of course is always good and we want all that to apply, but sometimes reality of the moment can change things.

[Ibra]

I guess one is expected to see low oil pressure on any "proper engine failure"?

If that is the case then prop pitch will be automatically set by the return spring in the spinner instead of the propeller lever, my guess this will be a fine propeller pitch near 0 deg on the Mooney like all singles which is more draggy but seems POH best glide speed/ratio are already calculated for full forward blue lever position and windmilling prop (?) for most multi-engines, in absence of oil pressure return spring will try to set close to 90 deg pitch to minimise asymmetric drag...

Edited March 20, 2020 by Ibra

[donkaye, MCFI]

1 hour ago, MooneyMitch said:

My real life experience when making a Mooney gear up landing years ago [actuator became disengaged from landing gear linkage during flight review flight], on final approach when I knew I had the field made, I did shut down the engine and tried [at least twice] to center the prop.  I eventually decided to forget that and concentrate on making the smoothest landing possible for the safety of my flight instructor and myself.  I left the concerns about the engine and propeller to the insurance company. 

Theory, planning and training of course is always good and we want all that to apply, but sometimes reality of the moment can change things.

I had a similar situation many years ago at a PPP in Palm Springs.  It was an M20K and we were doing the emergency gear extension demonstration when the plastic covering on the pull wire separated and jammed the mechanism.  As a last resort I pushed the circuit breaker in and hoped the actuator would overcome the jam.  Whew!  It did and the gear came down.   That was the last time I did the gear emergency in actual  practice.  In my opinion it should only be practiced during Annual when the plane is on jacks or in an actual emergency.

[gsxrpilot]

34 minutes ago, donkaye said:

In my opinion it should only be practiced during Annual when the plane is on jacks or in an actual emergency.

I like this a lot.  A gear failure isn't an emergency.

1. Assuming I have the fuel, I'll go somewhere, set my autopilot to fly a hold, get out the book, and see if I can get the gear down as per the instructions. 
2. Worst case scenario, I'll land and call @Parker_Woodruff

Neither scenario is a life or death emergency. So I'm not going to go practice #1 at the risk of #2.

[MooneyMitch]

Just now, gsxrpilot said:

I like this a lot.  A gear failure isn't an emergency.

1. Assuming I have the fuel, I'll go somewhere, set my autopilot to fly a hold, get out the book, and see if I can get the gear down as per the instructions. 
2. Worst case scenario, I'll land and call @Parker_Woodruff

Neither scenario is a life or death emergency. So I'm not going to go practice #1 at the risk of #2.

We performed your #1, extensively.....unfortunately nothing in the POH regarding a mechanical failure with linkage becoming un-linked ! 

Eventually we executed your #2, except we didn’t call Parker-Wodruff.  I’m making an educated guess, that that fine young gentleman was not in existence way back then. 

One of the most distasteful sounds you could experience is hearing the bottom of your beloved Mooney scrapping to a rapid grinding halt on the pavement! 

[Blue on Top]

Ironically, the Mooney gear is not like most other retractables, all three gear are mechanically interconnected.  Note: the Bonanza gear is similar.

There are pros and cons with mechanically connected landing gear … they all go together (yes, unless something is broke or bent).  One of the drawbacks is that there is no free-fall option.  Due to all the springs and things (and even if you could get the landing gear actuator motor out of the system), the gear will hang mid-way out.  They are designed to over-center in both directions (up and down).

On a really bad note, they are identically the same as all other retractables in that they are far too often left in the up position upon arrival.  

[MooneyMitch]

I apologize for the thread drift!

Yep, I was a new Mooney person with my gear issue.  I had no idea of the gear system other than it was electric.  And I knew how to operate it in the event of an electrical failure. 

When the linkage failed, the retraction had begun so over center it went and that’s where it ended up..... semi/retracted over center.

Not knowing, we pulled lots of serious G forces, attempting to have the wheels drop back down.....nope!

Probably an extremely rare occurrence.

[Parker_Woodruff]

2 hours ago, donkaye said:

 In my opinion it should only be practiced during Annual when the plane is on jacks or in an actual emergency.

Your opinion is strongly shared by Don Maxwell.

[gsxrpilot]

Just now, Parker_Woodruff said:

Your opinion is strongly shared by Don Maxwell.

If we get agreement from @carusoam... that would complete Trinity. 

[carusoam]

I’m not touching that device until needed...

DMax checked it on the first Annual/PPI...

I’m not even sure if it is on every annual after that...?

-a-

 

[Rick Junkin]

1 hour ago, carusoam said:

I’m not even sure if it is on every annual after that...?

Ha!

I've asked to do the emergency gear extension check myself on each annual since I had a jammed gear issue. Emergency extension didn't work in that case because of some mechanical deformation, but that didn't keep me from pulling on the extension cable about what seemed like 100 times because I didn't know what it was supposed to feel like. It ended well.

Cheers,
Rick

 

 

[Blue on Top]

To be honest, the electric gear is not a very good design.  I had a very good and experienced mechanical systems engineer in Chino look at a redesign (which should still be done … and might be required if the actuator supply dries up).  The specification on the actuator alone is out of this world complicated and tight … which is why the actuators are sooooooooo expensive … and no one wants to build them.  All of this is due to a manual gear system (which was artfully beautiful and simplistic) transformed into the current electric system that has also been "stretched" a couple times with the different body lengths.  The items that made the manual gear so beautiful (interconnected, springs and over-centers) are the same items that make Don M. (and all those that rig the gear) so full of colorful sailor language.  The manual gear extension system is not designed for "normal" use.  Look at the engagement mechanism and drive socket when an airplane is in service.

So, getting half way back on topic, keep your pattern speeds and procedures simple.  Simple is good. 

[PT20J]

Good design practice would dictate that a backup system should not share critical components with the system it is backing up. Mooney violates this in that the mechanical system is identical for the electric and emergency extension means. So, the failure modes protected against are electrical only.

Cessna singles have a similar issue in that the normal and emergency systems both require hydraulic fluid so a leak will make neither available. 

I always marveled  at the utility and simplicity of the Piper Cherokees. For the gear, there are no up-locks — hydraulic pressure holds the gear up. Pretty much any failure results in the gear extending. There are a lot of other things about the Cherokee design that are well thought out. If they were just faster...

Skip

[Blue on Top]

29 minutes ago, PT20J said:

I always marveled  at the utility and simplicity of the Piper Cherokees. For the gear, there are no up-locks — hydraulic pressure holds the gear up. Pretty much any failure results in the gear extending. There are a lot of other things about the Cherokee design that are well thought out. If they were just faster...

Skip

@PT20J  That's interesting,  I wonder if they had to extend the landing gear at Vne (redline) like the "Angel" aircraft did (twin, pusher, for missionary work).  It's a single-point failure … but that was decades ago, and OEMs and the FAA were friends back then (and often former coworkers).  On the "Angel" the landing gear switch/handle was actually the valve to bring the gear up or down .

[PT20J]

31 minutes ago, Blue on Top said:

@PT20J  That's interesting,  I wonder if they had to extend the landing gear at Vne (redline) like the "Angel" aircraft did (twin, pusher, for missionary work).  It's a single-point failure … but that was decades ago, and OEMs and the FAA were friends back then (and often former coworkers).  On the "Angel" the landing gear switch/handle was actually the valve to bring the gear up or down .

The emergency gear extension system was just a pressure release that let the gear free fall into the down locks. Vle was less than Vne, but only about 10 knots lower than cruise speed. 

Skip

[Ibra]

9 hours ago, PT20J said:

For the gear, there are no up-locks — hydraulic pressure holds the gear up. Pretty much any failure results in the gear extending.

Yes Mooney electric gear mechanism complexity and the suspension comfort were not really well thought of 

But hey who buys an aircraft for comfort of the ground taxi ride? or smoothness of gear extension/retraction?

[Hank]

2 hours ago, Ibra said:

But hey who buys an aircraft for comfort of the ground taxi ride? or smoothness of gear extension/retraction?

At annual last year, my new IA adjusted the nose wheel doors, leaving a God-awful thump with shaking of the yoke and a severe twitch in the pedals. And he was proud of the work he did. He is not doing my annual right now . . . .

A quick trip to Cole Aviation and now my gear opens and closes the smoothest it has ever done in my almost 14 years of ownership. I used to like the comforting thump as they locked in the Up position, and the lesser thump as they locked into Down, but.now there is virtually no feeling at all, just the sound of the electric motor starting and stopping. 

[EricJ]

18 hours ago, PT20J said:

The emergency gear extension system was just a pressure release that let the gear free fall into the down locks. Vle was less than Vne, but only about 10 knots lower than cruise speed. 

Skip

On the Arrow II that I used to fly before I got the Mooney, the gear came down faster with the emergency release button than it did powered with the pumps on.    I always thought that was kinda cool. 

 

[PT20J]

7 minutes ago, EricJ said:

On the Arrow II that I used to fly before I got the Mooney, the gear came down faster with the emergency release button than it did powered with the pumps on.    I always thought that was kinda cool. 

 

I noticed that, too. I think the idea was probably to cushion the descent with the hydraulics during normal extension, but have it free fall faster to ensure it engages the down locks when you release the pressure. I always liked the Arrow III with the longer wing best. The T-tail screwed up the IV — no one I know could ever get a smooth liftoff with that one. Biggest gripe with the Cherokees was that stupid hydraulic seat adjustment. Hit it my mistake and the seat goes to the floor and it’s almost impossible to raise it again while seated. 

[jetdriven]

On 3/20/2020 at 3:09 PM, Blue on Top said:  One of the drawbacks is that there is no free-fall option.  Due to all the springs and things (and even if you could get the landing gear actuator motor out of the system), the gear will hang mid-way out.  They are designed to over-center in both directions (up and down).

I am not so sure the gear goes over center in the up position. But due to the design of the actuator (a jackscrew), pulling on the gear to lower it won’t work. It’s like a worm gear, torque only transmits in one direction...from the motor. The Johnson bar system is similar, but as soon as you unlatch the Johnson bar, the gear  comes out. The latch on the Johnson bar is the only thing holding the gear  against the upstop. But either way, that motor shaft jams, and you are screwed.

[Blue on Top]

4 hours ago, PT20J said:

... but have it free fall faster to ensure it engages the down locks when you release the pressure.

@PT20J  This would be the problem on Moonies.  The mains are heavier than a battleship, but they would be fighting the nose going forward.  One time shot.  Yawing wouldn't help as one main would fight the other  

[larrynimmo]

You all are conjecturing about the flawed landing gear actuation is.....I ask...1. How many times has there been an accident where you cannot get the gear to lower safely?  2. Has anyone ever had a no- back spring failure?   

My contention is that there is at least a 20/1 ratio of pilots that fail to deploy compared to a mechanical/ electrical issue preventing extension.

yes, you bend a pushrod...it won’t extend...yes you break the spring it won’t extend...yes if the gear jams...it won’t extend...other than these items, you should be able to do the cable pull emergency extension.  
 

the Mooney gear extension design is very good, and can actually handle pretty severe landings without damage.  Every design has its weaknesses....but it’s me the Mooney one has withstood the test of time.

[Blue on Top]

3 hours ago, larrynimmo said:

You all are conjecturing about the flawed landing gear actuation is.....I ask...1. How many times has there been an accident where you cannot get the gear to lower safely?  2. Has anyone ever had a no- back spring failure?   

3. My contention is that there is at least a 20/1 ratio of pilots that fail to deploy compared to a mechanical/ electrical issue preventing extension.

4. yes, you bend a pushrod...it won’t extend...yes you break the spring it won’t extend...yes if the gear jams...it won’t extend...other than these items, you should be able to do the cable pull emergency extension.  

5. the Mooney gear extension design is very good, and can actually handle pretty severe landings without damage.  Every design has its weaknesses....but it’s me the Mooney one has withstood the test of time.

@larrynimmo  I agree with what you're saying, but I would like zero failures (more simplicity and lighter, too).  The reason for alternate gear deployment (per regulation) is to lower the number (percentage) of failures closer to zero.  Mechanically interconnected landing gear has pros and cons.

1.  I have heard of a few (not many), but all of which the secondary extension didn't help.  2. Yes.

3.  The ratio is actually MUCH higher than 20:1.  I would like to find a way to lower the number of "distracted" pilots too … in more areas than just no lowering the landing gear.

4. The socket engagement for manual gear extension pull is one of the larger weak points in the system.  This is why most owners only do the manual extension when the airplane is on jacks (without air loads and not critical if it doesn't work).

5.   I like the Mooney landing gear design.  Donuts don't leak … and are simple and inexpensive.  There are no up locks or down locks to fail (less parts).  The jackscrew (or handle lock on manual gear) is the up and down locks.  Simple is elegant.

(trying to get back on topic)  The time/airspeed to lower the gear is BEFORE one hears the scraping.  

[Hank]

@Blue on Top, Zero Defects is an admirable goal in manufacturing. To achieve it in global operations by thousands of people daily, with no control over those operators, is unachievable. To insist on this is lunacy. Even planes whose gear is welded down and immovable have issues--ive read of pilots landing badly with flat tires; tires blowing on rollout; bad takeoffs and botched landings / go arounds knocking off tires, wheels and sometimes entire legs . . .  

"Perfection is the enemy of good enough." No system will ever be perfect . . . . 

Nothing is foolproof to a sufficiently talented fool.

[Ibra]

 

1 hour ago, Blue on Top said:

I agree with what you're saying, but I would like zero failures (more simplicity and lighter, too)

Given that we have many "talented fool pilots" around, including myself , better to aim for 100% simplicity first, then 75% perfection

Then we can predict pilot failures easily !

 

Systems (engineers) or humans (pilots) to blame? I am sure we can always blame humans even for crash in self-flying airplanes 

"Since no system has ever built itself, since few systems operate by themselves, and since no systems maintain themselves, the search for a human in the path of failure is bound to succeed"

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3115647/

Edited March 24, 2020 by Ibra