Positive Engagement ?

[Gone Flyin]

Can someone please explain Positive Engagement as it relates to bolts used in our airplanes.

When did the FAA suggest (if that's the correct word) using PE over the older "2 1/2 threads out" method of securing bolts?

Is PE mainly for use with bolts that dead-end inside a metal part (flange, casing, etc.) as opposed to bolts that have a nut on the end of them?

Thanks, much!

 

[bnt83]

Pretty simple, mechanics look for more than three threads sticking out of a nut, if there are a lot more chances are the bolt isn't actually tight and the nut is simply jammed up against the non-threaded shank part of the bolt, IOW the bolt is too long for whatever material(s) it is clamping together. At least 1 thread sticking out confirms that bolt is not too short and that all the threads of the nut are holding the joint together.

Obviously if I can't see the end of the fastener I like to count how many turns it takes to tighten it to confirm the above.

Fully threaded fasteners? Well I don't want to damage anything by using too long of a screw and I don't want to have to turn a whole mess of extra threads & turns (extra work) and have an airplane full of extra weight (too long of fasteners)

 

[Gone Flyin]

Pretty simple, mechanics look for more than three threads sticking out of a nut...

I'm glad you were the first to reply to this thread... because you are completely wrong.

However, you're in good company because the two mechanics working on my annual believe the very same thing as you.

Let's see if anyone has the correct answer and we can discuss why so many A&P and IA's are getting this wrong..... at small GA plane owners time and expense.

 

[MauleSkinner]

My mechanic always said one full thread sticking out.

here’s what the AMT Handbook says...

After the nut has been tightened, make sure the rounded or chamfered end of the bolts, studs, or screws extends at least the full round or chamfer through the nut. Flat end bolts, studs, or screws should extend at least 1⁄32 inch through the nut.

 

[Bell206]

Let's see if anyone has the correct answer and we can discuss why so many A&P and IA's are getting this wrong..... at small GA plane owners time and expense.

It actually depends on which reference the mechanic uses. For example, AC 43.13 calls for 1 thread past the nut, the Standard Aircraft Handbook calls for 1 to 3 threads past the nut, and the AMT reference above is different as well. But none are wrong unless the MM procedure calls for a specific thread length. All are considered acceptable data. So I don't follow how that costs owners time and money?

But I don’t recall the use of “positive engagement” in the context you present. Got a reference?

 

[donjohnston]

I'm glad you were the first to reply to this thread... because you are completely wrong.

However, you're in good company because the two mechanics working on my annual believe the very same thing as you.

Let's see if anyone has the correct answer and we can discuss why so many A&P and IA's are getting this wrong..... at small GA plane owners time and expense.

That's some TomD level trolling there.

Ask a question. When someone tries to help by responding, you tell them they're wrong.