+20 year old donuts (1966 M20E)

[aviatoreb]

Just a thought - It's my guess that most of the wear on our donuts occurs in the long stretches of time the airplane is sitting - on its donuts - sitting in our hangars.  Even say an airplane that is flying a lot - say 10 hours a week - that's a lot by anyone's standard except for maybe a part 135.  There are 168 hours in a week.  If it flies 10 hours - then it is just sitting there on the ground on the donuts 158 hours a year.  That's 94% of the time.  For most of us, it sits on the ground, on the donuts, a lot more than that.

What if in our hangars we lift the weight off the donuts?   Jack the plane up - just a bit - say relieve a thousand pounds, or maybe 1500lbs worth, but still touching the ground?  As a standard hangar day to day storage idea. I bet this would dramatically extend the life of donuts.  Maybe to the point that we would never have to replace them in a 20 or 40 year ownership lifetime?  

Im thinking of a new device.  If we wanted to do this we could use our standard jacks, but maybe a special automatic jack that pumps in 500 or 750 lb automatically at each jack would do the trick and be easy to put on and off and less of a crisis of being so careful since the wheels would still be on the ground.  Such a thing would be quick on and quick off to use on a daily/weekly basis.

[Vance Harral]

This idea of jacking up your airplane while in the hangar has been discussed before, and I even know of one Mooney operator at my local airport who does it.  But I find it ridiculous, and a good example of inappropriately de-emphasizing a significant risk to address a much less interesting/important risk.

The risk of a Mooney falling off the jacks is pretty small if it's only done once per annual.  It's significantly higher if you're doing it literally every time you fly the airplane.  The cost of the airplane falling off the jacks would be 50x the cost of a set of gear pucks (for the average Mooney), not to mention weeks/months of repair time (or infinite if the aircraft is totaled).  It requires extra equipment to maintain, extra procedures, and extra caution telling everyone who comes by your hangar to be careful and not lean on the airplane.

On a lesser note, it makes you the laughing stock of the airport: "Haha... I guess those Mooneys are OK airplanes.  But the landing gear design is so dumb that owners jack up their airplanes in the hangar".

Overall, just a really bad idea.  To each their own, but if this really became de rigueur for Mooney owners, I'd sell the airplane.

[cliffy]

The Australian Mooney Pilots Association has designed and uses a set of small jacks that relieve the weight on the pucks.

They go in the gear leg hole and lift only until the weight is off the pucks. 

They are small and light weight and don't have the risk of a jack going through the wing

IIRC they have a limitation in AU that says only a shop can lift all 3 wheels off the ground so these jacks leave the tire just touching the ground but with weight off the pucks. 

If the a Mooney flies 75 hr per year then it sits on the pucks, not moving, more than 99% of its life squashing the pucks.

[Ragsf15e]

If we didn’t have pucks, we’d have leaking strut O rings to worry about, or maybe cracking on the “flex” point of a spring gear leg. Actually, I think I like the pucks more after writing that! Airplanes require maintenance.  Pucks are expensive for what they are, sure. I just hope they’re available when I need a set!

[corn_flake]

Agree on the risk using traditional jack on the lifting points.  Us California pilots will always worry about the earth quake. 

 

The risk of airplane falling off the jack can easily eliminated if we design a spacer to keep the landing gear in a extended position.   I'll see I can come up with something later today. 

[Vance Harral]

1 hour ago, Ragsf15e said:

If we didn’t have pucks, we’d have leaking strut O rings to worry about

Correct.  But the fix for that costs pennies in the way of O-rings, hydraulic fluid, and air; and it doesn't require special tools most shops don't have.  Mooney "pucks" were a fine idea in their time, but the current state of the parts and service market makes them undesirable.  Bonanza/Commanche/etc. owners aren't contemplating whether they should jack their aircraft up off the gear after every flight. 

1 hour ago, Ragsf15e said:

I just hope they’re available when I need a set!

Buy them now.  They have a decent shelf life when stored indoors, uninstalled; and the price and availability are only going to get worse between now and when you need them.

[corn_flake]

If the price continue to go up, at some point someone is going to figure out an alternative for OOP.  

I seem to remember a post on MS discussing the possibility of cutting the puck out of commercially available rubber sheets.    

[Vance Harral]

1 hour ago, corn_flake said:

If the price continue to go up, at some point someone is going to figure out an alternative for OOP.  

If you read back through this thread, you'll see that @Gert did exactly that for his own purposes, and tried to help out other owners by making parts available at https://avunlimited.co/product/mooney-landing-gear-shock-disk/

There was some predictable skepticism about the degree to which this qualified as OPP, but I think most of the group here was enthusiastic and supportive.  Response elsewhere (Facebook posts) was less kind.  The parts on that web site have been listed as "out of stock" for years, and Gert hasn't visited this board in 3 years.  I don't know what all may have gone on in the interim, but it renders me pessimistic that there's an OPP solution for the masses.  Only, perhaps, one-off installations by individuals who stay quiet about it.

[cliffy]

So what's the job going to cost  $2400 maybe?

That's $20 a month for 10 years. 

We burn more in taxi gas than that.   Cost of admission 

[corn_flake]

4 hours ago, cliffy said:

So what's the job going to cost  $2400 maybe?

That's $20 a month for 10 years. 

We burn more in taxi gas than that.   Cost of admission 

I suppose we can always settle and accept defeat....  J/K. 

I happen to believe GA should be accessible to more people.  Finding ways to reduce cost would go a long way to achieve that goal.