×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

REuse of HI-Lok Pins2

REuse of HI-Lok Pins

(OP)
Hello,

I have debate here with my colleague,

Is it possible to reuse the pin of an Hi-Lok once its been removed?

Thank you

RE: REuse of HI-Lok Pins

What's the prize for winning the debate?

RE: REuse of HI-Lok Pins

According to this 1991 Hi-Lok Installation Instructions document from Hi-Shear, section K.1 (page 11) states, "If not damaged during collar removal,the Hi-Lok pin can be reused." Sections K.2, K.3 and K.4 have similar statements. So at that time Hi-Shear apparently considered the reuse of pins to be acceptable practice in general. However, the practice may not have been permitted by company internal manufacturing procedures, or the maintenance/repair procedures for specific aircraft.

RE: REuse of HI-Lok Pins

(OP)
Thank you all,

I guess the risk of an unnoticed defect is too large.

And no one won any prize.

B.R.
Mor

RE: REuse of HI-Lok Pins

NAVAIR 01-1A-8 states they can be reused if threads are not damaged. Several SRM's also state they can be reused. Condition and common sense needs to prevail. But the technical answer is yes they can. Some SRM's might also prohibit reuse. Yes, unless specifically prohibited?

RE: REuse of HI-Lok Pins

2
MorTamir...

Quick review of my philosophy on male [screw-bolt-pin] fastener re-use in general... hope it makes sense.

If the assembly has never been placed in service, and bolt/pin is in clearance or transition FIT, then I generally agree that removal/reinstallation [may re-use the nut/washer if visually OK... but Collars and damaged parts must always be replaced. IF the Bolt/Pins are used in a low-stress mechanical installation, [pivot shaft, etc], then wear is usually not a factor... except for cad-plated steel [rusty?]. Notes. Most washers and Nuts, should be replaced if they have been in-service any length of time: they are cheap and not worth the time to inspect in detail.... unless of course, they are special nuts or are in a low-stress/benign environment... then I might have a different opinion about replacement.

IF the assembly has been in-service for any significant length of time, and IF bolt/pin is installed in clearance or transition FIT, and IF the R&R is to facilitate other maintenance... then common Dia/grip-length bolts/pins should only be removed/reinstalled IF there is a 'process in-place' for detailed inspection: NDI, DI, finish-condition, threads, heads etc... to re-confirm all aspects are serviceable. GENERALY, for small Dia, common grip-length Bolts/pins, the individual cost of inspections to mitigate risk associated with re-use, generally dictates that the bolts/pins be replaced. This assumes that the screw/bolt/pin removal does NOT damage the pin or the hole at that time!!!!

IF the bolts/pins are in any significant interference fit, then they are often damaged trying to remove [press/knock-them-out] them... so the risk/reward is very POOR... hence I just recommend 100% replacement. CAUTION: IF the bolts/pins are a VERY UNIQUE type [IE: Taper-Loks] or are a unique size [for me: over 1/2-inch or a weird oversize-Dia or grip], then the cost of trying to salvage them MAY be reasonable, relative to the high cost and/or long-lead-times in re-procurement. I have gone to extraordinary lengths to salvage large-Dia and/or long-Grip length Taper-Loks, simply because they are very expensive or very hard to get or require next over-size [tapered hole] if being replaced... which means a costly re-drilling process. IF I am salvaging these parts then I have to demand very specific/careful removal practices to ensure they, AND the HOLE, aren't irreparably damaged trying to get them out.

NOTE. Each unique fastener must be 'match-coded' to the specific hole that it was removed from, to have a high probability of a 'good fit'. IF the male-fastener-to-specific-hole match is 'lost' then the situation often is a waste of time/effort. Even though Bolts/Pins are technically identical, the parts are actually a wear-match to a specific hole from which it was removed from. NOTE: I usually insist that the part be reinstalled with grease/CPC [mechanical] or primer or sealant [structural].

NOTE. I have seen hardware [screws/bolts/nuts/washers] for panels, doors, etc that were "slap-ass-wore-out", simply because there was no procedure in-place to inspect the parts for serviceability; and field and depot maintenance had 'Catch 22' views on 'who' should spend the  to replace the hardware [not-in-my-budget]... so the old/worn-out stuff lives on. This is just wrong. GAAAAAAAAAAAAHHHHH!

NOTE.
IF this is a homebuilt aircraft, and I'm working-on-it and paying-for-it, then I tend to understand margins and might slide these statements around. Otherwise I won't mess with certificated aircraft and other lives on-the-line... or even a homebuilt if it has low margins of safety.

CAUTION. The FAA is very specific about parts: "last mechanic to touch-a-part for any reason [install/adjust/calibrate/etc] is ultimately responsible for it's airworthiness".

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!