The part of the landing gear door hinge which wears is riveted (with four really strong rivets, shared with another structure, which are a pig to change) while the part which doesn’t wear is easy to change by undoing the four screws!
The elevator trim tab hinges are exactly the same. The part which wears is riveted and quite difficult to change if you want to do a good job, because of the need for accurate alignment. Few mechanics do it right and often the new hinges wear out quickly. Moreover, after the rivets are drilled out, the back ends of them remain inside the elevator and rattle around… the correct method is to lift up the skin in one corner (another complicated job) enough to let them fall out. It is however possible (if the elevator is removed from the aircraft) to shake them out or hoover them out via some lightning holes around the middle.
Surely, one would use screws on the part which wears?
I wrote to Socata about this a while ago but they never replied, which is the usual mode these days.
What is the procedure for replacing rivets with screws, on an N-reg? I think it would be simple with the gear doors, but the elevator needs to remain balanced so one would need to choose equal-weight parts. From a conversation with one DER a while ago, they would need to be titanium to achieve the same weight as the rivets.
I think it would be simple with the gear doors, but the elevator needs to remain balanced so one would need to choose equal-weight parts. From a conversation with one DER a while ago, they would need to be titanium to achieve the same weight as the rivets.
I don’t know about FAA paperwork but to balance the elevator you don’t necessarily need light and expensive screws. The moment around the elastic axis or the turning axis is important and that can be balanced by counterweights.
What’s the big deal about replacing rivets ?
Seems lot’s of “younger” mechanics are afraid of them these days.
I don’t think twice about R & Ring rivets.
Peter wrote:
From a conversation with one DER a while ago, they would need to be titanium to achieve the same weight as the rivets.
WTF ?
SOCATA use titanium rivets in the H stab ?
Me thinks NOT !
Read my post again Michael 
No problem replacing rivets. Two issues:
The hinges come undrilled so the old ones have to be used as a template for drilling the new ones.
If they used screws it would have been 100x easier all around. By all means rivet the hinge half which doesn’t wear
Does seem the wrong way round, doesn’t it.
Next time the hinges are replaced might it be feasible to lock the bent end of the hinge pin to the riveted hinge half by moving that little ‘P’ section retainer to the other side of the hinge line? That way you’d only need one screw on the ‘fixed’ hinge side to hold that retainer in place, 3 rivets and 1 screw.
Peter wrote:
If they used screws it would have been 100x easier all around.
Not for an experienced mechanic that has the simple tools for the job.
You haven’t replaced them multiple times did you? If they wear out, every 15 years or so, that isn’t to bad is it?
As other said, there is a (quite large) range to balance your flight controls, if they are out of balance, they are balanced by removing or adding weight, there is no specified weight for complete flight controls.
Does seem the wrong way round, doesn’t it.
Next time the hinges are replaced might it be feasible to lock the bent end of the hinge pin to the riveted hinge half by moving that little ‘P’ section retainer to the other side of the hinge line? That way you’d only need one screw on the ‘fixed’ hinge side to hold that retainer in place, 3 rivets and 1 screw.
Damn good point!
Jesse wrote:
You haven’t replaced them multiple times did you? If they wear out, every 15 years or so, that isn’t to bad is it?
Exactly – it’s a non-issue.
As other said, there is a (quite large) range to balance your flight controls, if they are out of balance, they are balanced by removing or adding weight, there is no specified weight for complete flight controls.
Just last week I checked the balance on a Twin Comanche (has full flying H stab like TB20) and I found the balance to be out by a whopping 18 inch pounds !
Seems some $µ^% put abrasion boots on some years ago and didn’t bother to re-balance the h stab …
That said, this plane did over 350 hours and flew around the globe, often well over gross, with nary a hint of a potential problem !
