Control Wheel U-joint

six.zero.charley · Post by **six.zero.charley** » Sat Jun 24, 2006 9:18 pm

Just to be sure, is the Aircraft Spruce u-joint approved? I read the above adage about it being ok because it's MIL-spec, but can anyone tell me anything solid? I asked my IA about it and he asked if it was PMA'd, which I don't see in the Spruce catalog. George, you seem pretty sold on these units from Spruce, would you just drop them in and call it good based on the MIL-spec basis?

blueldr · Post by **blueldr** » Sun Jun 25, 2006 2:09 am

I've never seen such hand wringing over a simple little item like that U joint. I hope you guys don't think that Cessna builds them. The ones sold by Grainger et all are exact duplicates and are prouduced for any number of other applications. If I were you I'd find a more practical AI to inspect my airplane. One with some common sense.

squaretail · Post by **squaretail** » Sun Jun 25, 2006 3:58 am

Your email will not work. Try mine for some.

Post by **GAHorn** » Sun Jun 25, 2006 5:37 am

six.zero.charley wrote:Just to be sure, is the Aircraft Spruce u-joint approved? I read the above adage about it being ok because it's MIL-spec, but can anyone tell me anything solid? I asked my IA about it and he asked if it was PMA'd, which I don't see in the Spruce catalog. George, you seem pretty sold on these units from Spruce, would you just drop them in and call it good based on the MIL-spec basis?

Ask your IA if he has a problem installing AN hardware as replacement for AN hardware on airplanes. What about NAS hardware? And what about MS hardware? (These u-joints are MS hardware: MS 20271)
Their Mil Spec is Mil-J-6193A.
If he does, I'd explore blue elders recommendation on IA selection.

six.zero.charley · Post by **six.zero.charley** » Sun Jun 25, 2006 4:27 pm

I'm inclined to do what I think makes sense, but I'm new at this and still trying to get a feeling for the often overcomplicated and overregulated spectrum of "approved" parts and procedures. Thanks for the insight.

spiro · Post by **spiro** » Thu Jun 29, 2006 11:05 pm

gahorn wrote:
six.zero.charley wrote:Just to be sure, is the Aircraft Spruce u-joint approved? I read the above adage about it being ok because it's MIL-spec, but can anyone tell me anything solid? I asked my IA about it and he asked if it was PMA'd, which I don't see in the Spruce catalog. George, you seem pretty sold on these units from Spruce, would you just drop them in and call it good based on the MIL-spec basis?
Ask your IA if he has a problem installing AN hardware as replacement for AN hardware on airplanes. What about NAS hardware? And what about MS hardware? (These u-joints are MS hardware: MS 20271)
Their Mil Spec is Mil-J-6193A.

gahorn wrote: the thing to remember is that just because a part is "approved" for generic or specific use, is not the same thing as approval for installation on a particular airplane model.

there are plenty of AN, NAS, and MS numbers in the parts catalog, but the u-joint only has a Cessna pn. If it was a standard MS part, wouldn't they list it that way? On what basis do you conclude that Cessna pn 0411257 is an MS 20271?

(for discussion purposes only - as a practical matter I agree w/ BL)

Post by **GAHorn** » Thu Jun 29, 2006 11:43 pm

When I called the Cessna Distributor (Yingling) they confirmed it, and Spruce lists it as such. (To be more exact, that particular part number was not challenged, but I was informed that all Cessna singles control u-joints were mfr'd to that specification. In order to call it that part number, the mfr would have to have a PMA. By producing it to the MS standard, no PMA is required.)
I admit, a phone call is not the same as written approval from Cessna but, in my opinion, it (the MS20271) meets the "equivalent" intent of the rule.

(If you agree with my opinion, feel free to use the info and the u-joints without charge from me. If you disagree, send me a note explaining your reasons for such, written in 25 words or less on a $20 bill. My address is in the directory.)