Squat-method landing gear disc replacement

[FlyingDude]

I just looked and can't locate them on spruce. Namely:

914004

914003-501

914007-3 and -5

914020-19.

The other AN## parts are standard hardware, so that's not too hard.

Are there alternative part numbers? Or a bundle which contains all of these?

Thanks for your help

[Prior owner]

I believe the collar bolt on the main gear strut is not a standard AN part, at least it wasn’t on my ‘64... Mooney does recommend replacing that bolt anytime the collar is removed, but I don’t know whether that is a common practice. I had to buy those bolts from Mooney. If I remember correctly, all the other gear bolts going through bushings were standard AN, except for the retract link bolt. Could be different on later models...

[FlyingDude]

I replace all nuts and washers regardless. They're cheap. Bolts, depends. Landing gear is under a lot of stress, so I'm on board with this practice.

But...

All those parts starting with 9 are Mooney parts. Aren't there any replacements? Apart from the cost, availability is a big problem...

[Tcraft938]

On 1/8/2021 at 9:01 PM, FlyingDude said:

This is a good tip. Thanks. How high do you jack the plane up? I built my own jack with a threaded central rod. Same height adjustment range as the ones on spruce. I just don't trust myself with lowering those hydraulic lifts... Bounced the car on the ground too many times. Don't want to repeat it with the plane

How do you lift the nose? By the engine lift, jack under the prop or pull down on the tail? The engine method should be the official method now but finding a hoist is not that easy around here...

Thank you.

The proper nose lift point is to use an engine lift and connect to the hook on the engine case, which is of course under the doghouse.  There is guidance saying not to connect to the prop or pull down from the tail, but I know many who have done it successfully for years.  If you don't have an engine hoist, you can use two fairly sturdy step ladders on either side of the nose, run a few 2x4x between them and use a come along strap to pick up the nose.  Pretty easy and dirt cheap, useful for other thing as well.  I know an A&P that does engine installs that way. 

I will be interested your progress on the shock pucks.  I have a feeling they will be in my not too distant future.  Right now working on cowl flap cable replacement and it is murder to get at it between engine and firewall.  Getting plenty of "Mooney Marks" on my arms.

[Guest]

There are many methods of lifting the plane.  Hartzell says no prop jacks, Mooney says to use the engine lift ring, Lycoming says the engine lift ring is meant to lift the engine only.

So it can’t really be done.

Clarence

Edited January 11, 2021 by M20Doc

[Andy95W]

1 hour ago, M20Doc said:

There are many methods of lifting the plane.  Hartzell says no prop jacks, Mooney says to use the engine lift ring, Lycoming says the engine lift ring is meat to lift the engine only.

So it can’t really be done.

Clarence

It can be done safely and securely and in accordance with all restrictions.  Use straps around the engine mount top bar directly behind the engine hooked to a cherry picker.  A tail stand to keep from pulling the nose up too high.

(Not my idea, BTW.  A major Mooney shop does it this way also.  LASAR or DMax, etc.)

[MikeOH]

5 hours ago, M20Doc said:

...Mooney says to use the engine lift ring, Lycoming says the engine lift ring is meat to lift the engine only.

Hmm, me thinks Mooney's logic is way better than Lycoming's...

Say the engine weighs 300 pounds (yes, I'm certain that's not accurate, just play along, please) and Lycoming is fine and dandy with lifting ALL 300 pounds by the engine lift ring.

Now, we know that with NO engine in the plane the tail hits the ground. Finally, applying advanced tensor integral calculus (or, just common sense if you're a little rusty on the former) says the plane is taking AWAY the lifting force required.

Ergo, LESS weight on the lifting ring when changing out the donuts.

I'm missing the flaws in my, and Mooney's, logic...anyone care to elucidate?  Bueller??  Lycoming??

[FlyingDude]

my AP said lifting by engine mounts is a good way, because we're lifting the engine in the end. 

I also found the bolts but they're damn expensive. Let me ask it this way: 

"Has anyone used AN bolts instead and regretted it?" 

"How/why are these bolts so Special?" They only thing I notice is that they're smooth (no threads) along their shaft and have threads only at the tips. Is that it?

 

[MikeOH]

Not really a direct answer to your question, but when faced with a similar decision tree I always ask myself what percent of the total project cost is tied up in the WAY overpriced widget that I'm annoyed about.  In your case, IIRC from when I had my donuts replaced, that EACH rubber biscuit was quite pricey.

Just how expensive are these couple of special bolts compared to the cost of donuts?

[FlyingDude]

That's EXACTLY what my wife said. She said "is it really that expensive or is this your latest thing to obsess over?"

~$700 special bolts (part numbers starting with 9 in the parts manual + AN9 bolts because standard AN goes up to 8)

~1350 donuts (11 x 122$)

~$50 generic bolts (AN bolts)

Hence my b*tc*ing and whining.

Well, if Mr Al Mooney designed them to be such rare commodities, then I'll only be thankful for the guys who still carry such items... Imagine what if you can't find them anywhere :-S

 

Edited January 12, 2021 by FlyingDude

[carusoam]

Looks like donuts continue to creep higher....

-a-

[MikeOH]

1 hour ago, FlyingDude said:

That's EXACTLY what my wife said. She said "is it really that expensive or is this your latest thing to obsess over?"

~$700 special bolts (part numbers starting with 9 in the parts manual + AN9 bolts because standard AN goes up to 8)

~1350 donuts (11 x 122$)

~$50 generic bolts (AN bolts)

Hence my b*tc*ing and whining.

Well, if Mr Al Mooney designed them to be such rare commodities, then I'll only be thankful for the guys who still carry such items... Imagine what if you can't find them anywhere :-S

 

$700!!!!  Holy crap and good grief!

Yeah, I think I'd be looking at options, too!

Wish I had an answer for you.  Good luck!

[FlyingDude]

Thanks

[Super Phreek]

I had to replace one of shock tower bolts (914003-501), I ended up going the salvage route.  I think they were like thirty bucks a piece. 

[mike20papa]

There are several suppliers of AN bolts and hardware that the "ususal" go to's don't carry.   Search AN9-(determine the length) and you maybe surprised.  For example SKYGEEK carries AN9-52 .. Good Luck.  If you are looking for the retaining bolt for the collar at top of shock tower - look at "clevis bolts"

[FlyingDude]

I'll definitely check them out. Thanks 

[FlyingDude]

26 minutes ago, mike20papa said:

There are several suppliers of AN bolts and hardware that the "ususal" go to's don't carry.   Search AN9-(determine the length) and you maybe surprised.  For example SKYGEEK carries AN9-52 .. Good Luck.  If you are looking for the retaining bolt for the collar at top of shock tower - look at "clevis bolts"

I just did a search. Even spruce carries clevis bolts! So are these 9### bolts actually clevis bolts? Does anyone have a correspondence/equivalency chart? Thanks in advance

[carusoam]

With a name like sky bolt....  they have to have what you are looking for...   

http://skybolt.com/wp-content/uploads/2017/12/Skybolt-AN-MS-NAS-Hardware-12-7-2017.pdf

They specialize in aviation fasteners...   aka plane bolts, and fancy ones too...

Best regards,

-a-

[Prior owner]

Actually.... you are lifting the engine and the prop if you use the engine lift ring.

[Guest]

On 1/12/2021 at 9:41 PM, FlyingDude said:

I just did a search. Even spruce carries clevis bolts! So are these 9### bolts actually clevis bolts? Does anyone have a correspondence/equivalency chart? Thanks in advance

While it functions like a clevis bolt, it isn’t a standard AN 25 series Clovis bolt.  I don’t know that I’ve ever replaced one in all the years working on Mooney airframes.  Do you really need them?  If you do, they’re $66.75 each.

Clarence

Edited January 15, 2021 by M20Doc

[FlyingDude]

I can't answer if I"need" that bolt. My mechanic said I should replace it. Since I won't be able to retire, I might dig deeper.

Edited January 13, 2021 by FlyingDude

[67 m20F chump]

From what I remember the head of the bolt is milled down on the Mooney part.  I’m thinking a regular AN will not fit.  I think that what is on the main struts.

[RLCarter]

The lower bolt in the tower has one flat milled on the head so it will clear on the nose gear, I paid 50ish for it 7 years ago from LASAR, all the other hardware was reasonable through LASAR

[FlyingDude]

Yeah all roads lead to buying official hardware. It seems it's worth the expense. They put some work in it.

[RLCarter]

My E had had the ORIGINAL disk (old style), had to get new shock towers (3) to go to the new style disks. I called Dan at LASAR and had him send me ALL the parts (collars, bushings, towers, disc...etc) plus all new hardware, it was spendy for everything