This erosion bovine excrement has to stop
R22Million
If your engineer gave you a hard time about paint erosion, he probably has a fixation based on the AD's about paint erosion and "delamination". (The correct term is in fact "disbonding".)
This is bovine excrement "bull****".
I am an expert in adhesive bond failure forensics, and I have examined fourteen R22/R44 blades and found evidence if erosion in only one case. I have seen disbonds well away from the blade tip where on the matching blade there was no evidence of any erosion of the paint.
The critical evidence is this: If the failure of the adhesive results in a layer of adhesive on BOTH surfaces, then it is a bond failure due to failure of the adhesive layer. This would almost certainly be a DESIGN and certification deficiency. The bond was not strong enough to carry the loads and the adhesive material itself failed.
If the failure is at the interface, then there will be no adhesive on some regions of the bond failure. If you see bare metal or a very thin adhesive layer, then it is not a design issue. This is a PROCESS deficency, and there are two causes. 1. There was contamination during the process, or 2. No matter how well the process was undertaken it was a deficient process. Interfacial deficiency can pass usual QA tests, yet fail in service because deficient processes result in hydration of oxide layers on the metal, and the hydration process leads to interfacial disbonding. THIS HAS ABSOLUTELY NOTHING TO DO WITH EROSION OF THE PAINT!!!!!!!! There are documented cases of Rxx interfacial bond failures where the blades were never even fitted, and had zero hours flown, and therefore erosion can not be relevant in these cases. So if bond failures can occur without erosion and after no service at all, why is the theory of erosion the only cause of bond failure? Bovine excrement!
Regards
Blakmax
Last edited by blakmax; 20th Sep 2012 at 11:17.