2024 vs 7075

huangyhg

2024 vs 7075
i am a contract liaison engineer (19 yrs exp) currently working on the sikorsky ch60 program....my last (2) positions were for bell and boeing on the huey/cobra and apache upgrades....question, sikorsky's srm repair things very different than what i'm used to (i've seen and done repairs here that would have gotten me fired at either boeing or bell).....are these craz repair becaues the blackhawk is basically 7075, whereas the apache, huey and cobra are 2024?
what kind of repairs? can you describe the procedures you refer to?
what heat treatment is specified?  what coatings are specified?
israelkk:  we're not allowed to do primary structural repairs without running them by sikorsky structures dept. and our sheetmetal repairs have to go thru d.c.m.a. of course, so i would say most of our work deals with sheetmetal and machined fittings under .070 thick.
one crazy procedure i refer to is they are allowed to fill a hole, sandwiched between (2) pieces, with sealant-allow it to fully cure-then drill thru the entire assembly and install the repair fastener.
tvp:  t6 for the most part, unless we have to do a pretty tight bend radius of course.  a typical finish statement would read "use 7075-t6 aluminum anodized shim stock or chromic acid anodize with dichromate seal per ss8483 or phosphoric acid anodize per ss8482.  apply (1) coat of primer mil-p-85582 per ss8555 except on faying/bonding surface".
agree, sounds pretty flakey ... why wouldn't you bush the hole "properly"
i guess the "only" thing that can be said in its favour is that (as much as we know) there are no smoking holes in the ground because of these repairs ...