Horizontal Stabiliser Rear Spar Riveting

The Horizontal Stabiliser has been sitting down the side for quite a few months as I'd created an issue with one of the small tabs on the inside of one of the ribs in a difficult place to get to.

Today, the expert dropped around to help me fix it. Unfortunately, I didn't take any shots of the fix although I'm fairly sure I included some photos of the broken tab. What we did to fix it was to make another small reinforcement plate that the set rivet clamped down on, holding the damaged tab firmly in place between it and the skin.

Getting ready to finally rivet the rear spar on after all these months.

There they are - all done!!

Another piece to find a long term storage location for.

Oh, that's right - I don't have anymore space.

Need to sell this one and buy a bigger shed....I mean, hangar

HS - One out of two

This first rivet kicked a little sideways which also made one side of the flush head on skin sit proud a little bit which I wasn't happy with. I may have been able to improve how the rivet was sitting if I squashed a little more paying more attention to the angle of the bucking bar and rivet gun. That however, wasn't assured. 

So I drilled him out and set him again. Gotcha!

This rivet was in a difficult spot on the HS front spar. This should've been around a AN426AD3-4.5 rivet. By the time I'd messed it up a couple of times, I needed to try an Oops rivet (NAS426AD4). Even then, I'd damaged the flange enough that it wouldn't sit flush against the spar.

....and then the inevitable happened...

I decided at this point is was best to turn the lights off and walk away for now.

Hmmm, better drill that out...

Unfortunately, I'm getting better at drilling rivets out. It doesn't look too bad from this side, but I didn't take a photo of the shop-head so let's not focus on that shall we?

For the record, I thought I'd add a sequence of images showing the removal of a rivet set that didn't go quite according to plan.

1) For the simple reason I don't want to drill any section of the skin or structure of the plane, I need to make sure (as much as I can) that I'm drilling out only the rivet. That being the case, I find it best to start drilling in what you think is the centre of the rivet. For various reason (lighting; width of drill; angle of drill), sometimes I may not be able to know I'm not actually drilling in the centre of the rivet. Therefore, I drill for few short revolutions and check. Below is not quite in the middle but at this point it can be straightened.

2) Change the angle of the drill slightly so I'm drilling more towards the centre but being careful not to increase the angle too much or the drill bit may go skidding off down the skin.

3) Drill about 1-2mm into the rivet and break off the rim of the rivet head as below

4) At this stage, I would normally grab the other side of the rivet with a small pair of side-cutters and gently wiggle it free which works most of the time.

5) I can't recall why (at the time of writing this), but I've drilled right through the rivet which obviously makes it difficult to grab whatever's left. I'm assuming the shop head, was so damaged I couldn't get a grip on it which meant I was forced to push the remnants through with a punch.

Maybe there's a better way to do this, but I haven't seen it yet.

It's not all flutterbys and unicorns

Time to remove dodgy rivets in the Horizontal Stab.

The following images show the horizontal stabiliser skins mostly riveted to the spars and ribs. As help was a little scarce, I decided that as I could reach both sides at the same time if I stood above the HS when sitting in the stands, I'd give it a go with the bucking bar and rivet gun.

Most looked pretty good, but when the shop end of the rivet was analysed a little closer, they weren't very acceptable. As a result, I went through and inspected the shop head on the inside of the skins on all four sides and marked the rivets I needed to drill out and re-do.

Sorry - not a very exciting post, but it shows how many I had to drill out and re-do. Maybe I should've tried a bit harder to bribe a friend to come and help... 

Horizontal Stab almost done!!

At this point, I'd finished all the rivets except the ones holding the rear spar to allow a final inspection by our friendly CASA Rep(Steve) prior to closing the Horizontal Stabiliser for hopefully a very long time.

Inner Horizontal Flange Rivets

These rivets....I was looking forward to.

Why? .....because the pneumatic squeezer makes life so much easier. If you're squeezing rivets and you haven't purchased one yet, do  yourself a massive favour (early birthday or Xmas pressie) and get one - you need one.

Even if you're not squeezing rivets, get one anyway - it'd look great on the wall.

There was not one of these I was unhappy with - awesome!

..a short clip of the work...

More Horizontal Stabiliser rivets

Not really happy with this chubby rendition of myself - but this will be motivation to reduce my MTOW. Luckily I should have around 3-4 years up my sleeve. Either that or I figure out how to put a turbine in it.

The next photo shows one of the tabs that should be flush on the spar flange. I didn't take note why I had to remove the whole Stringer Web Assembly, but I did when re-installing it, I should've bent the tabs slightly outward again.

A small mistake that attempted to rectify using a series of different thickness specially designed pieces of rubber with a hole to fit the rivet, but just the right thickness to compress the tab and set the rivet at the same time.

The tab didn't rivet totally flush, but I was happy enough.

Below is one of the better skin rivets. 

Sorry - this one is a bit of a pose but for a Builder's log, I really don't have many photos showing me doing the building. Rocket's a good mate who's been assisting pretty much whenever I've asked. He's a good bloke who'll probably get one of the first flights......if he wants it. I may have to drag him kicking and screaming (he can be a child sometimes)

Ahhh, one side done. The edge rivets can be done later with the pneumatic squeezer - soooooo much easier.

More horizontal stab riveting...

There hasn't been much happening in the workshop lately as my current roster has me away from home three out of four weeks.

I did find some time to smack some rivets in though while y very tolerant girlfriend was at work...

This video unfortunately doesn't show a lot except myself and a mate riveting HS rivets over a couple of days. It really doesn't show the effort or time required to put this section together.

In the horizontal stabiliser skins alone, there are exactly 766 rivets and 10 screws. I didn't count how many I had to drill out re-do, but I'm sure the number would've been over 30.

Riveting the Horizontal Stabiliser

I encountered a few issues at this stage mainly due to (what I deduced as) the skin not being perfectly aligned with the rib flanges and as a result, the rivets being set bent over during the process.
One in particular failed so many times, I had to replaced it with an 'oops' rivet as the hole was too enlarged for an AD3 rivet. This rivet was a leading edge rivet where I couldn't manipulate the rib at all to align any better.

Below are some photos of the Horizontal Stabiliser(HS) skins being clecoed ready for riveting...

It never gets old seeing almost a whole skin with completed rivets

All rivets just below the HS-914 Stringers had to be set sight unseen due to the limited distance between the ribs and skins.

Luckily, I've had a chance to rivet quite a few of these little suckers now and I've got a good feeling for it.

Back to the Horizontal Stabiliser

When I left this to finish off the rudder, I'd clecoed the HS-901-1 skins to the skeleton for safe-keeping.

Some photos of inside the assembly...