7050-T73 aluminum rivets
7050-T73 aluminum rivets
(OP)
Has anyone experienced problems with rivets made from 7050-T73, eg: corrosion?
thanks
thanks
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RE: 7050-T73 aluminum rivets
A very common rivet in the aero industry.
RE: 7050-T73 aluminum rivets
thanks
RE: 7050-T73 aluminum rivets
RE: 7050-T73 aluminum rivets
RE: 7050-T73 aluminum rivets
RE: 7050-T73 aluminum rivets
Do not install rivets wet...they need to be installed dry.
The problem arises that the rivet may not fill the hole properly.
Installing non-aluminum fasteners in aircraft structure is fine...but NOT RIVETS!
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Nert
RE: 7050-T73 aluminum rivets
Should have said "installing non-aluminum fasteners wet" is fine...
but rivets NO!
-----
Nert
RE: 7050-T73 aluminum rivets
1. The D rivets can be made useable again if re-heat treated and "frozen" [-60F to -100F within a few minutes after heat treatment (heat/quench/freeze)]. NOTE: absolutely NO corrosion or discoloring, nor any grime or other coatings should be visible prior to heat-treatment... if so the rivets should NOT be used... or used after CAREFUL cleaning and reclamation. D rivets properly heat-treated are very soft and driveable... even in the largest diameters. They may be restruck as needed within a "few" minutes of driving.
2. DD rivets are a direct replacement for D rivets... even though they are less forgiving when driven [harder to drive and should not be re-struck after 5 seconds of original hit due to work hardening. Stength and alloy similarities make them great for use in 2XXX series aluminum alloys.
3. E and KE [7050] rivets are BEST used in 7XXX series aluminum alloys due to stength and alloy similarities. If used in 2XXX seies alloys dissimilar material corrosion is a REAL threat. These rivets should not be re-struck for the same reason as DD rivets.
4. Both D and E/KE rivets drive very "hard"... and as such should be driven agressively. Some testing indicates a potential fatigue problem with these rivets: they use more energy to swell and deform the rivet and have less energy available to radially pre-stress the hole. These rivets have more "statistical variance" [strength and durability] when driven by hand.
5. All aluminum rivets CAN be driven "wet" with primer successfully... and there will be no substantial statistical variance in strength or durability. Low viscosity primer squishes out of the way before driving... if proper techniques are used [good-techniques can always be ignored by "Murphy"]. Caution: primer is NOT good for fuel sealing structure... and could have problems in other areas.
6. Some rivets [NAS1097 100-deg shear-head] can be driven "wet" with sealant if properly seated before driving. The statistical variance in strength and durability changes significantly for all Briles-Flush [120-Deg head] rivets... and most 100-deg flush-tension and protruding-head rivets. This problem occurs due to the hydrostatic un-seating of the head due to entrapped "wet" sealant under the rivet-head.
7. Blind-rivets/bolts, Bolts and Hi-Loks are NOT immune to variance when installed "wet". Primer is generally OK for all fasteners... but sealant interferes due to entrapment. Use lots of temporary fasteners [power or wing-nut CLECOS] to pull the structure tightly together and install fasteners using a CROSS-PATTERN installation-sequence. Threaded fasteners Should have a STAGED TORQUE-UP [25%, 50%, 75%, 100%, X-pattern] for best possible mechanical joint strength and durability.
Regards, Wil Taylor
RE: 7050-T73 aluminum rivets
The only reference that I could find on this topic is Boeing service letter 727-SL-51-29 dated 29 Jan 92, which does not recommend installing rivets wet. However, the practice is still found in recent revision of the 727 structural repair manual.
comments?
RE: 7050-T73 aluminum rivets
I work at Boeing and have my feet in the military side. This was a BIG topic of debate... because the commercial folks summarily elliminated all "wet sealant" driven rivets primarily due to manufacturing and field-repair issues... and us in the Military side reluctantly came along. NOTE: "we" need improved corrosion protection... especially with the older aluminum alloys and the mission of the aircraft!
I have much more that can be said about the subject... but I kida feel I would be relaying US military and Boeing-Proprietary information... so I have to stop.
Regards, Wil Taylor
RE: 7050-T73 aluminum rivets
I work at Boeing and have my feet in the military side. This was a BIG topic of debate... because the commercial folks summarily elliminated all "wet sealant" driven rivets primarily due to manufacturing and field-repair issues... and us in the Military side reluctantly came along. NOTE: "we" in the military side see a need for all the corrosion protection we can get... especially with the older aluminum alloys and the mission of the aircraft!
I have much more that can be said about the subject... but I kida feel I would be relaying US military and Boeing-Proprietary information... so I have to stop.
Regards, Wil Taylor
RE: 7050-T73 aluminum rivets
RE: 7050-T73 aluminum rivets
The discussions on fasteners in the past few months have been extremely interesting and insightful, coming from persons with practical experience in the field.
The whole subject of fasteners gets so little attention in engineering courses at college yet is so important.
What about a practical book on the subject? I think there is really opportunity here. How about it Wil Taylor?
Regards
Andries