Precision Airmotive Carburetor line sold?

This just in from the AVweb;

"Precision Airmotive has reached a tentative deal with ?a group including Tim Henderson, President of Aero Accessories, and others involved in the manufacture of the Tempest brand of general aviation products,? to buy Precision?s line of MSA aircraft carburetors, according to a news release from Aero Accessories/Tempest issued Monday. The group says it plans to move the manufacturing facilities for the carbs to a facility in an undisclosed location in North Carolina. Precision announced earlier this month that it was suspending manufacture and distribution of the carbs and parts after it was unable to obtain product liability insurance. There?s no mention of the insurance issue in the Henderson Group?s release."

Great! It's always just a matter of time before someone picks up where someone else left off. Carbs'll be around for a long time...

The Cost?

If Precision had insurance issues, I would expect the new players would have them as well. If the insurance goes up, the price of the Carburators and the replacement parts will increase.

I saw this back in the 1980's when the float kit was only $25. Then a few months later it jumped to $50 (that's when I bought my kit). A few months later it jumped to $75.

Hold on for another wild price ride..........

Paul

Lycoming fall out - new SB

Sounds like a Lycoming CYA attempt...

Not applicable to our Experimentals, of course, but a check for loose carb. screws probably would be prudent...

From an e-mail I got....

Lycoming has released a new Mandatory Service Bulletin with a 100 hour repetitive inspection. The screws that hold the bowl to the carburetor body are to be re-torqued at intervals on all float carburetors.

http://www.lycoming.textron.com/support/publications/service-bulletins/pdfs/SB366A.pdf

gil A

I've seen it...

az_gila said:

Not applicable to our Experimentals, of course, but a check for loose carb. screws probably would be prudent...

Click to expand...

Gil, I know we just took this OT a bit, but this is a notable issue and glad you posted it.

Strangely enough, I saw this happen, and coincidentally on an RV at that. A friend's buddy had visited our airport two years ago as I was building my -8. They went for a ride in his -6 and noticed that it was running very rough shortly after take off, so they came back and landed immediately. The -6 guy wasn't the builder and didn't have any experience, so they asked if I'd take a look.

We took the lower cowl off and I poked and prodded around the carb - my first instincts were that it was a mixture issue of some sort. I inadvertently bumped my hand on the FAB and it MOVED! "Holy carp Batman!" As it was getting dark out and my friend was holding the flashlight at the back of the carb I was able to see light coming through the gasket between the carb body and the float bowl. Sheesh, no wonder....

The screws had started backing out. I gave them new star washers and loctite and buttoned everything up. Ran perfectly after that. But, I emplored them to consider drilling and saftey-wire the screws together. I thought it was a bad design not to have safety wire considering how much vibration the carb sees. After all, they safety wire the heck out of their fuel injection servos.

Anyway, some good FYI fodder for the archives. Carb owners, do yourself a favor at your next oil change or annual and drill safety wire holes in those screws. Be sure to replace those star washers any time you loosen an item that uses them. It's super cheap insurance to prevent a potentially catastrophic failure.

Safety wire

N908RV said:

......
The screws had started backing out. I gave them new star washers and loctite and buttoned everything up. Ran perfectly after that. But, I emplored them to consider drilling and saftey-wire the screws together. I thought it was a bad design not to have safety wire considering how much vibration the carb sees. After all, they safety wire the heck out of their fuel injection servos.

Anyway, some good FYI fodder for the archives. Carb owners, do yourself a favor at your next oil change or annual and drill safety wire holes in those screws. Be sure to replace those star washers any time you loosen an item that uses them. It's super cheap insurance to prevent a potentially catastrophic failure.

Click to expand...

Apparently the older carbs. used safety wired washers before the change to those little bent tab washers..

Safety wiring sounds like a better approach to me too... looks like they are 1/4-28 X 7/8 from the parts manual - should be easy enough to get some cap screws with drilled heads, or even slotted screws with drilled heads...

gil A

Sorry for the thread creep.... Can I ask a 'dumb' question on this issue...

Could slightly longer drilled shank bolts be used and the safety done on the 'upper' side of the bolt.

Is safety wiring the shank of a bolt a no no?

I can't find a supplier of UNC 1/4" drilled head (or shank) 'aircraft' bolts - I was assuming grade 8 commercial would be used.

Thanks,

Carl

socket heads

My approach will be to use drilled socket head screws at this location. Easy to find, and easy to drill and wire. Anyone else considered this??

Regards,
Chris

az_gila said:

Apparently the older carbs. used safety wired washers before the change to those little bent tab washers..

Safety wiring sounds like a better approach to me too... looks like they are 1/4-28 X 7/8 from the parts manual - should be easy enough to get some cap screws with drilled heads, or even slotted screws with drilled heads...

gil A

Click to expand...

In my experience, the screws have gotten loose because the bowl gasket shrinks, not because of poor locking devices.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

I don't have .01% the experience that Mahlon does, but I think I like his explanation. I had the bottom half of my carb come loose in the same way on my Grumman (many years ago), and the lock tabs were still tight up against the screw heads. None of the screws had turned or pulled out - it MUST have been the gasket.....

Paul

Don't just tighten the bowl screws without checking everything:



First photo: At the tip of the knife blade is one of three legs on the one-piece venturi pressed into the upper carb body. The upper surface of the leg is standing proud of the carb body parting face rather than being flush. Precision Service Bulletin MSA-2 detailed the replacement of two-piece venturis with this style one-piece venturi. Page 4 contains a specific note of interest here; the venturi is to be pressed in using Tool M-83, and the tops of the legs are to be flush with the carb surface. However, it can't happen if the carb body isn't counter-bored deep enough.

In the second photo you can see where the little tab on the gasket was pinched severely between the venturi leg and a corresponding boss on the float bowl body. This pinching was present at all three leg locations. Since the three little tabs on the gasket will compress just so far and no more, it was holding the carb halves apart and not allowing full compression of the rest of the gasket surface. Thus the fuel leak (pretty obvious from the blue stain on the gasket), and probably an internal or external air leak.

Subject was is a Precision MA3 with less than 100 hours. Larger models are similar, yes?

Vibration

mahlon_r said:

In my experience, the screws have gotten loose because the bowl gasket shrinks, not because of poor locking devices.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

Click to expand...

Mahlon.... David Fletcher on the Grumman list provided an alternate explanation.

He believes it is vibration from the weight of the extra stuff that is hanging on the carb. These 6 (I think) screws hold the weight of the airbox and filter assembly as well as the carb. bowl.

First the problem usually occurs on aircraft that have a collection of airbox, filters, frames and ducts bolted to the bottom of the carburetors. Shaking, vibration and the weight of these parts are directly absorbed through the (4) 3/16 cap screws that are torque with a gasket under them. Nearly all Lycoming updraft engines since the 1940 are built this way.


Another engine overhaul place said...

The float bowl mounting screws have a course thread and the lock plates do allow a small amount of rotation of the mounting screws. Even the slightest rotation of the course threaded mounting screws is going to quickly reduce clamping pressure at the float bowl gasket. Due to the SEVERE vibration the carburetor is subjected to any loosing of the float bowl mounting screws and reduction in their clamping pressure will allow the throttle body and bowl to move continuously in relationship to one another. This movement will wear away the paper float bowl gasket thus further reducing the mounting screws clamping ability. This is not a safe condition at all!!

Both repair facilities had seen many planes with loose bowl screws. Their vibration thesis seems to be held up by the fact that the horizontal design of the HA-6 carbs (on the Tigers) do not seem to have loose bowl screws... in these carbs, the weight of the filters is taken by the carb. body, not through the bowl.

Hanging extra weight on the bowl screws seems like poor design....

gil A