Last Thursday we took the ailerons off the wings at Mangrove, with the intention to closely inspect the hinges and associated fittings. This inspection is difficult to do at the back of the hangar, and we had suspected excessive free play in some of those connections. Here’s what we found and intend to rectify:

In a nutshell, what we assumed were worn bushes should actually be called shaft sleeves, the shafts being the hinge bolts. The above sketch illustrates the intended reforbishment plan. The issue of standard local high tensile bolt dimensions vs those of LN standard bolts is therefore redundant, as the bolt diameter is no longer that critical. We will replace all bolts with high tensile 8.8 or 12.9 Grade socket head cap screws with appropriate shank lengths and threads trimmed to suit. We will also investigate using all-metal lock nuts in lieu of nylok nuts, since the latter seemed not very firm on the M4 hinge stubs.

When we got the ailerons off we didn’t take more than half a minute to decide that while they might pass a Form 2, the Polyfiber fabric would certainly have to be replaced for the 10 year survey. So another 5 metres of sky blue Oratex is on order. This will also provide an opportunity to inspect and if necessary repair any underlying wood structure.

When we got the ailerons back to Bonnells Bay, I removed all the hinge fittings.

The findings:

The fittings are structurally sound. Some have superficial corrosion which will be fixed by grit blasting and powder coating.

The M4 attachment bolts are free of corrosion, while the nylok nuts where only moderatly torqued. Maybe the wood structure shrunk a bit?

The wood screws which are really only the braces to the belts of the M4 bolts are seriously corroded and will be replaced with stainless steel screws properly embeded wirh epoxy/flok mix per West System guidelines.

The existing Polyfiber fabric job has the wrap around the ailerons joined, very precisely, at the leading edge without any overlap or tape.. Unsurprisingly, it’s easy to prise the fabric away at that junction.