Originally Posted by
mayam13
Hi Tech,
Thanks for bringing out bringing out safety points. The differential pressure in Fan cowling is a good point. I suggest the cowling be made of Titanium:
1) With titanium protracted turn around inspection is not required
2) Engineers can stand on the cowling.
3) Engine aerodynamic profile will be less bulky.Less drag is created eventual fuel efficiency improvements
4) When sheet metal is bent it improves stress, whereas Composites weakens.
5) It is alarmng to hear this has occured before on other engine.
6) By employing Composites on fan cowling, a few kilograms of weight may be saved, but using Titanium, passenger lives can be saved.
7) I guess FAA is listening
With all due respect, and I am
not being critical or disparaging you, I would suggest you read this article please.
https://www.premix.com/why-composite...composites.php
Both Riverman and Hi Tech summate the engineering / maintenance aspects very well, and certainly with regard to
possible causes of damage to composites with delamination being the hidden from routine inspections source. By the time you get to see de-lam, it's too late and the damage is done.
Likewise an innocuous dent ( Visible impact damage ) on the surface, but underneath, and invisible until a detailed inspection is carried out using NDT, the damage may be catastrophic.
Titanium is impractical for use in an intake, Kevlar however is, and it's also a time consuming nightmare to work with as any engineer who has been involved with the material will testify.
As for bending metal, no matter how much effort is applied to alleviate the problem, stress corrosion will be induced from the onset of the manufacturing process.
I formerly trained engineers in corrosion inspections and rectification techniques, both metal and composites, so my reply to you is not purely theory based and is intended to help remedy the misunderstanding within your summary.