Main gear tire pressure cover screws

[Mooney200]

I add some air to my '97 M20J tires every 5 weeks or so.  The main gear tires lose about 5 lbs between checks.  To access the valve stems requires removing the metal covers that are held in place by 3 small screws and washers.  I need some of those small screws and washers to replace the current ones which are getting stripped. Anyone know where I might find them?

[DonMuncy]

51 minutes ago, Mooney200 said:

I add some air to my '97 M20J tires every 5 weeks or so.  The main gear tires lose about 5 lbs between checks.  To access the valve stems requires removing the metal covers that are held in place by 3 small screws and washers.  I need some of those small screws and washers to replace the current ones which are getting stripped. Anyone know where I might find them?

Take a look at my album and check out my wheel covers. If yours are aluminum, it is fairly easy to adapt them so you can add air without removing them.

[laytonl]

I believe they are 8-32R5 (5/16”).  Lee

[Ron McBride]

Michelin air stop tubes solves the problem. 

[PT20J]

+1 on Michelin air stops. A lot of people just leave the PITA wheel covers off.

[KB4]

I got these a few years back from Lopresti and don’t regret it. Looks like spruce carries now 

HUBBA HUBBA CAP - HUB CAP WITH ACCESS DOOR 275/pair 

[Eight8Victor]

3 hours ago, Mooney200 said:

 I need some of those small screws and washers to replace the current ones which are getting stripped. Anyone know where I might find them?

Your wheels are probably stripped, not the screws. Wheels are aluminum, screws are steel. I had the same issue with mine. I drilled and tapped mine to the next larger size screw. Don’t drill or tap too far, you'll breach the wheel. When installing the covers, be super light on the torque. 

[carusoam]

Nothing like checking the air pressure every weekend and inflating the tires...

My wife thought there must be something wrong... why don’t you fix that..?

 

+1 for getting the right tubes...

Welcome aboard,

-a-

[PT20J]

1 hour ago, Eight8Victor said:

Wheels are aluminum

Worse...magnesium, actually.

[Mooney200]

Many thanks for the feedback so far.  The current screws have a Phillips head--that is what is actually getting stripped, not the wheel itself.  I will head for Home Depot or Lowe's and see if I can find some replacement screws and lock-nut washers, thanks to laytonl for the size.  The Hubba covers are a bit pricey and crawling under the wheel-well monthly does allow me to check things.  And, N803RM, those Michelin air stop tubes must leak some air!  I can't believe they don't.  How often do you check tire pressures?  I have owned my J for 5 years and have learned that if the main tires get close to 20psi instead of the normal 30psi, the airplane becomes a potential "bounce house" and risks a prop strike unless a "grease job" landing is done.  My nose tire loses at least 10 lbs psi or more below the recommended 49 psi, between inflations.  I figured one of the secrets of respectable Mooney landings was not only approach speeds but also proper tire inflation.  Do other owners find tire pressure quite important as a factor in smooth landings?

[Hank]

I've had Air Stop tubes for several years, added when tires were changed. Tires never seem to lose more than 2-3 psi, and I generally top them off spring and fall. Lose a little more pressure if I don't fly regularly; sitting causes lots of things . . .

[RogueOne]

No, not really to your last question.  Speed control and full flaps are my “secrets” to consistent quality landings that give gentle nods from the co-pilot/critiquer in charge.

[Guest]

I doubt that you’ll find any Mil spec screws at the hardware store.  You need MS35206-242(pan head 8-32 5/16” long) and MS35333-38 lock washers.

Clarence

 

[jaylw314]

11 minutes ago, Mooney200 said:

Many thanks for the feedback so far.  The current screws have a Phillips head--that is what is actually getting stripped, not the wheel itself.  I will head for Home Depot or Lowe's and see if I can find some replacement screws and lock-nut washers, thanks to laytonl for the size.  The Hubba covers are a bit pricey and crawling under the wheel-well monthly does allow me to check things.  And, N803RM, those Michelin air stop tubes must leak some air!  I can't believe they don't.  How often do you check tire pressures?  I have owned my J for 5 years and have learned that if the main tires get close to 20psi instead of the normal 30psi, the airplane becomes a potential "bounce house" and risks a prop strike unless a "grease job" landing is done.  My nose tire loses at least 10 lbs psi or more below the recommended 49 psi, between inflations.  I figured one of the secrets of respectable Mooney landings was not only approach speeds but also proper tire inflation.  Do other owners find tire pressure quite important as a factor in smooth landings?

That seems a little much in terms of pressure loss.  I have had "El Cheapo" main tire tubes installed 2 years ago, and I have yet to see any significant pressure loss (less than 2 psi) every 4 months at oil changes.  My prior nose tube was losing about 10 psi every oil change which I thought was a leaky valve.  When they swapped it out last year, they found significant cracks in the rubber around the base of the valve, so dodged a bullet there.

So if you're losing any measurable amount every few months, that's more than I would expect...

[BillC]

I have Michelin tires and air stop tubes on all three gear. They still lose a few pounds over time, regardless of the temperature. It always amazed me that my vehicles, which do not have tubes, can go year round without needing air.  (no radical summer/winter temp changes). I even use nitrogen. 

[Mooney200]

Thank you M20 Doc for those part numbers.

[jaylw314]

49 minutes ago, BillC said:

I have Michelin tires and air stop tubes on all three gear. They still lose a few pounds over time, regardless of the temperature. It always amazed me that my vehicles, which do not have tubes, can go year round without needing air.  (no radical summer/winter temp changes). I even use nitrogen. 

Hah!  Mine is the other way around--my aircraft tube tires never need refilling, but my car tires lose about 10 psi every 3-4 months.  

[carusoam]

+1 for getting your hardware from a decent source...  aircraft spruce is a good one... there are some that are even better...

Aviation hardware tends to have different dimensions in weird ways...  when you are only buying a handful... the price won’t make a difference...

Over time, you will have a bunch of hardware stored up... it will be a bear to know which ones are the good ones...  

Best regard,

-a-

[PT20J]

3 hours ago, M20Doc said:

I doubt that you’ll find any Mil spec screws at the hardware store.  You need MS35206-242(pan head 8-32 5/16” long) and MS35333-38 lock washers.

Clarence

 

There you go -- delving into the Illustrated Parts Catalog again 

[Jan Charles Potter]

On 8/20/2019 at 5:54 PM, Mooney200 said:

Many thanks for the feedback so far.  The current screws have a Phillips head--that is what is actually getting stripped, not the wheel itself.  I will head for Home Depot or Lowe's and see if I can find some replacement screws and lock-nut washers, thanks to laytonl for the size.  The Hubba covers are a bit pricey and crawling under the wheel-well monthly does allow me to check things.  And, N803RM, those Michelin air stop tubes must leak some air!  I can't believe they don't.  How often do you check tire pressures?  I have owned my J for 5 years and have learned that if the main tires get close to 20psi instead of the normal 30psi, the airplane becomes a potential "bounce house" and risks a prop strike unless a "grease job" landing is done.  My nose tire loses at least 10 lbs psi or more below the recommended 49 psi, between inflations.  I figured one of the secrets of respectable Mooney landings was not only approach speeds but also proper tire inflation.  Do other owners find tire pressure quite important as a factor in smooth landings?

The key to any good landing is a stabilized approach.  In my Mooney 201 which I have thousands of night and day hours and on many short stripes, always use full flaps. Tire pressure is very important especially carrying heavy loads.  The pressure is important to tire ware.  I have landed a number of times with low pressure in the nose tire but keeping the nose up with good elevator control stops any bouncing.