Vance Harral Posted April 20, 2022 Report Posted April 20, 2022 Posting this in Vintage Mooney discussion because the screw in question is used to attach the ram air door to its control linkage in older Mooneys. But the question is somewhat general. The fastener spec'd in the IPC for this application is an "NK526–1032R5". Good old AN526-1032 machine screws are a dime a dozen (well, a little more expensive nowadays, but not much). R5 is a slightly-unusually-short length, but not rare. But the "NK" specification confounds me. "NK526" doesn't turn up anything in searches at Aircraft Spruce or Chief or Skygeek, and a more general web search on "NK screw" returns ambiguous results. One of my airplane partners thinks this is a Mooney-specific part, but that seems hard to believe. I can easily thread an AN526-1032 screw into the hole that's supposed to receive this NK526-1032 screw, so they're obviously similar. The component the screw threads into isn't a Tinnerman nut or other locking fastener, just a tapped hole into what appears to be common steel. So my guess is that an NK screw is "special" in some way that makes it less likely to back out on its own. But that's just a guess. Anyone know what this kind of screw this is, and - more importantly - where to buy one? I stripped the head on one of the three screws used to hold the ram air door on, and thus need a replacement. Quote
carusoam Posted April 20, 2022 Report Posted April 20, 2022 Sounds familiar….. Because the sheet metal screws are or were PK screws… there is some logic for screw names around here somewhere… Good luck with the search… that’s a Google search for such tiny detail… Best regards, -a- Quote
Guest Posted April 20, 2022 Report Posted April 20, 2022 5 hours ago, Vance Harral said: Posting this in Vintage Mooney discussion because the screw in question is used to attach the ram air door to its control linkage in older Mooneys. But the question is somewhat general. The fastener spec'd in the IPC for this application is an "NK526–1032R5". Good old AN526-1032 machine screws are a dime a dozen (well, a little more expensive nowadays, but not much). R5 is a slightly-unusually-short length, but not rare. But the "NK" specification confounds me. "NK526" doesn't turn up anything in searches at Aircraft Spruce or Chief or Skygeek, and a more general web search on "NK screw" returns ambiguous results. One of my airplane partners thinks this is a Mooney-specific part, but that seems hard to believe. I can easily thread an AN526-1032 screw into the hole that's supposed to receive this NK526-1032 screw, so they're obviously similar. The component the screw threads into isn't a Tinnerman nut or other locking fastener, just a tapped hole into what appears to be common steel. So my guess is that an NK screw is "special" in some way that makes it less likely to back out on its own. But that's just a guess. Anyone know what this kind of screw this is, and - more importantly - where to buy one? I stripped the head on one of the three screws used to hold the ram air door on, and thus need a replacement. I’ve never heard of that prefix for a screw. You could install a 526 series screw with a drop of blue Loctite, or AN 501/502 Philister head screw with safety wire to keep them in place. Clarence Quote
Greg Ellis Posted April 20, 2022 Report Posted April 20, 2022 5 hours ago, N201MKTurbo said: It seems to be NYLOK screws. I think you are correct. This website lists Nylok screws with the NK prefix. Screw Nylok – NSN Parts, Aerospace Parts Sourcing (asap-aerospace.com) Quote
Vance Harral Posted April 20, 2022 Author Report Posted April 20, 2022 Thanks for the replies, all. I have a message out to LASAR about this. Local thoughts are that an AN screw with a drop of blue loctite fits the bill, but I'll wait for further info before flying. It's not hard to understand why some extra caution is warranted here. If these screws back out in flight, they're likely to enter the intake path to the fuel servo. Just one more reason why I've come to believe ram air is generally more trouble than it's worth, even on the older birds with the less optimum cowl and intake path. 1 Quote
PT20J Posted April 21, 2022 Report Posted April 21, 2022 8 hours ago, Vance Harral said: Local thoughts are that an AN screw with a drop of blue loctite fits the bill, Picture from Nylok’s website. Apparently they just put a drop of loctite or similar on the screw. Probably makes sense in a production environment to save time. 1 Quote
carusoam Posted April 21, 2022 Report Posted April 21, 2022 Find out what the temp limits are for the screw…. and compare to the environment they are living in… PP idea for comfort only, not a mechanic… Best regards, -a- 1 Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.