Horizontal Stabilator - 2

02/24/2013 49 hours Cum time -  I decided for this subassembly that I’d do all the prep work prior to assembling any portion of the kit. This would include any drilling, countersinking, sawing to separate parts, etc.  The first components to be drilled where the stabilator spars and spar caps. These were countersinks primarily for nutplates and for the spar box assembly. The countersinking when well with a couple of exceptions. I got a little assertive with the flange countersinks.

03/03/2013 4 hours 53 hours Cum -As you can see, the right two countersunk holes look significantly larger than 0.125. When I insert a CS4-4 rivet there looks to be a lot of play. Multiple attempts to measure the holes diameters aand I came up with 0.140 and 0.156. I’m a little nervious, this is like the backbone of the stabilator assembly. I went on line to see what information I might find regarding remedies for oversized holes. I found that the maximum allowable hole size for a 0.125 rivet is 0.135. This information came from both Van’s public specs and engineeredge.com/rivet.

So I did a little more searching and I found a conversation, think it was vansairforce about an oversized blind rivet. CR3243 4-4. I found the rivets at Aircraft Spruce and ordered 18. More to come…..

I then discovered cracks in the large lightening holes on two of the six HS-1204 inboard  ribs. I searched and found Van’s Notification 05-17-11.

NOTIFICATION 05-17-11

Date Released: May 17, 2011

Date Effective: May 9, 2011

Subject: Cracking in Stabilator Nose Ribs

Affected Models: RV-12 EMP/CONE Kits and individual parts shipped

 between November 5, 2010 and May 5, 2011.

Recommended Action: Inspect all HS-1204 FWD INBD RIBS (6/kit) for cracks.

Time of Compliance: Prior to installation of the ribs or before the next condition

 inspection.

Synopsis:

Prior to installation, customer found crack in stiffening flange of HS-1204 FWD INBD

RIB. Structurally these cracks do not present a safety of flight risk. However, builders are

encouraged to inspect affected parts and to take corrective action if cracks are found.

Parts shipped before November 5, 2010 are not affected by this notification.

Method of Compliance:

In order to comply with this notification the following action should be taken:

1. Inspect all HS-1204 rib stiffening flanges for cracks. See illustrations on page 2.

2. If crack is found repair rib per the modification procedures listed below.

3. If rib is installed and not accessible to repair make a log book entry and inspect for

propagation at or before next annual condition inspection. Contact Van's Aircraft for

further instructions.

Replacement and Modification Procedures:

PART NUMBER

HS-1204 FWD INBD RIB

MODIFICATION PROCEDURES

Repair by stop drilling using #40[2.5mm] drill bit.

Although the notification applied to the small lightening hole, I repaired per instructions above.

After drilling, deburring and sanding the spar box components, it's time to apply primer.

03/06,07/2013 1 hour - 54 hours cum- Primer applied!

 03/08/2013 7 hours - 61 hours cum- Okay, back to the oversized countersink and rivet story. The rivets arrived yesterday. The shanks are 0.140 diameter. They don’t fit in any of the holes I thought were oversized.

I’ve decided I’m going to use them. I’m convinced the holes are over the 0.135 limit and the CS4-4 are pretty loose when place in the countersunk holes.

I put all the primed components in temporary storage and decided to do all the prep work on the remaining stabilator components. I didn’t take pictures of this activity because it was pretty standard. Sawing, deburring, sanding and fluting to straighten the ribs. Thanks to a youtube video, fluting ended up being an easy operation. Ansley Gilmore's video can be found on youtube. What do you think? Pretty straight I’d say.

Last operation of the day- cleaning the parts, prep for primer coat! Acetone, Scotchbright and soap and water.