SL-00139

SL-00139 Alternate Rivet Types (Rev 0, 22 Sep 2026) is Van's written guidance on alternate and flush rivets in the RV-15. Read it first. Required action: none. In short: AN426AD and AN426B solid countersunk, and AK4xH closed-end countersunk blind rivets, are accepted in place of LP4 skin rivets in the wing and empennage; CS4 and AN470AD are not.

The rest of this page is builder experience on doing the work. Unless a line says otherwise, it predates SL-00139.

For those thinking about using flush rivets, it is recommended you review the following VAF Threads.

• RV-15 Flush Rivet Leading Edges Thread — wing
• Wing Leading Edge Rivets Thread — wing
• Wing Leading Edge Stiffener Only — wing
• Flush Rudder Skin Rivets Thread — empennage

Status: Van's has told builders the kit was designed with flush solid rivets in mind (note the LE access holes and rib flange orientation), but declined to provide written guidance (source), and as of May 2026 had not identified a flush pull rivet they liked (source). Update (OSH 2026): Brian Hickman and Rian Johnson told a builder at Oshkosh that machine-countersinking the main spar is acceptable; their only concern was the rivets closest to the strut attach, which carry higher loads and warrant something stronger than the standard aluminum pull rivets (source). One builder is using zinc-coated steel POP SK 42 BS flush pull rivets (phosphate-coated mandrel) there; another reports bucked AN426AD solid rivets - including at the strut bracket - exceed the strength of any supplied pulled rivet (source). Update (August 2026): Van's also approved countersinking the horizontal stabilizer spars, by phone — see Empennage below. Van's has separately said that recessed/flush solid rivets on the leading edges will be on its forthcoming list of alterations accepted for E-LSA - see E-LSA vs E-AB. Update (22 Sep 2026): rivet selection is now covered in writing by SL-00139, above. The spar and HS-spar countersinking approvals remain verbal builder reports, not written Van's guidance.

Wing

You may want to modify the order of steps in Sections 29-31. Three builders have completed the wing leading edge successfully; the options below were gathered from their posts (thank you) and run through an AI model, so verify each step on your own.

Choose your scope

• Option A — Stiffener only (easiest, soloable): Flush rivet only the stiffener on top of the wing forward of the spar. No helper needed. See sequence below. (source)
• Option B — Leading edge forward of the main spar (the standard version): Dimple and flush-rivet everything forward of the main spar; keep the KAI's pull rivets on the spar line and aft. Done by MCA, johnvanbladeren, and RVbySDI.
• Option C — Aft of the spar as well: Requires machine-countersinking the main spar flange (0.062" thick — source). Van's gave no written guidance on countersinking the -15 spar, but see the verbal OSH 2026 guidance in Status above. Blind rivets are unavoidable along the spar at the fuel tank (zero interior access). SL-00139 accepts the AK4xH closed-end countersunk blind rivet (AK41H / AK42H / AK43H cover typical grips) in place of LP4 in wing and empennage skins; no RV-15 leading edge built with it has been reported yet. The earlier search predates that letter and found nothing acceptable: dimpling a #30 hole to 100° enlarges it beyond Cherrymax hole tolerance (source); the Avdel BSCQ-04-03 (120°, $0.18) failed a grip test in .032+.025 dimpled coupons (source); CR3242 oversize Cherrymax quoted at $55+ each. RVbySDI did flush-rivet the top skin aft to the rear spar (outboard of the tank) by machine-countersinking the spar flanges (source).

Rivets

• Approved in writing (SL-00139): AN426AD and AN426B solid countersunk, and AK4xH closed-end countersunk blind, in place of LP4 skin rivets throughout the wing and empennage. Cherry CCC-32 in place of AN426AD3 in the inboard tank (Sections 18-19) — CCC-32 is hole-size sensitive and an oversized hole risks mandrel pull-through. CS4 is not acceptable (yields at lower load and shorter fatigue life than LP4 despite equal rated shear), and neither is AN470AD. Avoid any countersink that develops a knife edge.
• AN426AD4-4 throughout the LE worked for MCA and johnvanbladeren — 3x gun at 40 PSI, tungsten bucking bar; "no need for softer rivets" (source, source).
• Softer alternative: AN426B4 / MS20426B4 (5056 alloy, ~295 lbf vs ~330 for AD — noticeably easier with a hand squeezer; source). RVbySDI used B4-4 for skin-to-rib and AD4-5/-6 at the spar flanges (source).
• Determine lengths yourself from your stack-up: dimple scrap in the same thicknesses, set rivets, and find the shortest length giving a proper shop head. Do NOT add dimple height to the length formula (source).
• Skin thicknesses for reference: inboard 0.025, middle 0.032, outboard 0.020 (source).

When to decide

Before installing the nose ribs on the main spar — the ribs need dimpling too. Dimpling ribs already on the spar is possible but harder (source). A dry run first: cleco the LE ribs and skins on and confirm you can reach every rivet with your bucking bar before committing (source).

Option A sequence (stiffener only)

Cleco the three LE skins together, cleco the stiffener on, and test-fit the whole assembly to the wing skeleton. Remove it, back-rivet the stiffener to the skins on the bench (leave the three skins clecoed together), then carry the assembly to the wing — the .032 center section keeps it stiff enough. Install per the KAI with one change: start clecoing the first row on the TOP side rather than the bottom. Leaves only rivet rows in line with the slipstream proud. The landing light bracket can also be flush riveted with a deep-throat squeezer. (source)

Option B sequence (synthesized from MCA's completed wings)

Sections affected: 29, 30, 31 — the KAI order still applies; only the listed deviations change.

1. Prep/dimple (during Section 29 prep): dimple the nose ribs, landing light bracket, and 1/4 rib; dimple the LE (nose) skins. Careful at the inboard and outboard skin edges — the fairing holes there do NOT get dimpled; Sharpie-circle the holes that do. DRDT2 or C-frame for the skins. (source)
2. Keep the LE empty: install NOTHING on or in the nose ribs until all riveting is done — no plastic clips, pitot/AOA lines, snap bushings, landing light bracket + 1/4 rib, or wiring harness (deviation from KAI Section 30 order). Think through the re-install sequence around the landing light bracket before you start. (source)
3. Pull the two nose stringers and leave them out until the top half is riveted — they slide out the wing end and back in later. The two short stringers are different; only one works per side. (source)
4. Cleco every hole on the nose skins (every-other on ribs). (source)
5. Rivet per the KAI sequence — where it calls a pull rivet, pull it; where the nose skin is called, shoot the 426s. Top half first, then install the stringers, then flip. An inspection mirror and light are a must; expect awkward body positions. The hardest rivets are the inner column of the double-row skin splices at the outboard sections — a second skilled person is strongly advised. (source)
   • Alternative sequence (johnvanbladeren): cleco ALL skins to the structure; pull-rivet the main skins top and bottom only; then remove the clecos from the bottom of the three LE skins with the leading edge hanging over the table edge — this opens hand access to the double columns; back-rivet the top skins to ribs and stringer; then pull the bottom skins back into place with 1" cargo straps and finish. (source)
   • RVbySDI bucked with the wing flat (top skin first — fighting gravity underneath); recommends a vertical wing stand instead for the second wing. (source)
6. Accept some imperfection: expect a spread of rivet quality and some minor skin marks. Drill out true rejects; leave acceptable "uglies" — every drill-out carries its own risk. (source)
7. Reinstall systems after all riveting, in this order at the outboard bay: wiring clamps → small support rib → landing light bracket → remaining brackets and harness. Tedious but necessary. (source)

Empennage

• Van's approved countersinking the horizontal stabilizer (August 2026). A builder who shared the concern that countersinking the HS spars for 1/8" rivets could weaken them — RV-10 spars take 3/32" rivets and a much smaller countersink — called Van's and was told the countersinking was approved. This is a phone approval reported by the builder, not a written statement. (source — the concern)
• Rudder, vertical fin and horizontal stabilizer done flush. One builder flush-riveted the rudder stringers to the skin, the vertical fin, and the HS top skins. Method for the rudder: dimple with a squeezer to within about three holes of the bend and hand-dimple the last three; open the rudder skin far enough to back-rivet the solid rivets; then close the skin back to the correct angle using the same shop-made brake used for the flap top skin. The rudder skin to spar attachment was left as pull rivets — solid rivets there would have meant unbending and re-bending the skin. (source)