The designer during the design and structural analysis process considers the holes, both locations and diameters, and load being applied to determine the final size requirements. This is normally an iterative process to ensure a strong part that meets the design requirements. If it exceeds the design structural requirements it will be too heavy as well as too strong, and increase cost to produce.
To continue the design process of the spars, the designer determines the landing gear strut load conditions. These load conditions are converted to forces (quantity and direction) that the landing gear attachment must transfer to the spar caps. The end result is a specific size and location of the landing gear strut with a defined attachment method and bolt pattern to meet the aircraft design requirements. The designer considers the bolt sizes (smaller bolts are less expensive and reduce weight), hole diameters, and locations within the spar geometry. We will ignore part commonality, reducibility and maintainability. To relocate the holes from the original pattern to a pattern that has them closer together and located in the risers will increase the loads on the spar webs, landing gear strut, and the bolts. Have a really good stress engineer evaluate what you want to do. Follow the drawings and you cannot go wrong. If you ensure hole locations and misdrill a hole slightly I doubt you will scrap the spar. I would think some have been misdrilled and are flying today after a minor repair. Bob Morrissey cam...@earthlink.net ----- Original Message ----- From: "Glynnis Young" <gyoungtra...@yahoo.co.uk> To: "KRnet" <kr...@mylist.net> Sent: Friday, December 03, 2004 11:46 PM Subject: RE: KR> spars > It is not so much the strength of the WAF's that concerns me, it is > drilling all those holes in the spar (cap). Even the landing gear > mounts require holes drilled in the upper and lower spar cap ....... >> G > > >
