7050 rivets are the modern replacement for "ice box" rivets. I have specified this rivet type many times where the strength of AD rivets was not quite enough. They are a little harder to drive, and less tolerant of excessive hits with the rivet gun; i.e., the buck tails will split more readily than other aluminum rivet types. They probably should recieve more attention to corrosion control - installing wet with sealant or primer is a good practice.
why wouldn't you use DD's? We have heard from other sources that the KE (7050-T73) rivets are difficult to use and nobody likes them. What kind of acft do you work on?
I am re-building two Navy N3N bi-planes that were assembled with "ice box" rivets, (2017-T4). I have a supply of these rivets, but I don't know how old they are. Are they still usable after being at ambient temp. for years? Where can I find specs and proceddures? What alternative rivet should I use?
Would you mind letting me know the shear strength of the 7050-T73 rivets (please include the source of information:author, title, page, table, fig., etc.) Thank you for your help !
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.
I was going to say that wet installation of rivets was a hot topic around our shop for awhile. But rivet installation with primer or sealant is actually recommended in some manuals (eg: military standard tech orders). We've been using it for repairs to external surfaces.
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.
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.
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.
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?
