Sheared Rivits in both Main Gear Boxes

[mschwab]

Dear George, Bruce and Gang;
With my project N5567C...Ser. 19620 (A model) I have run into a problem regarding both main gear boxes. It concerns the Angle
-Landing Gear Support-Lower Outboard (PN 0511495-5) Figure 20-Bulkhead Assembly #20-39 and #22-55. The rivit heads are sheered off-totally on starboard and three on the port side. I see no way of bucking these rivits because of limited space. Is there an equivilent hardware I could use in the place of rivits? I have pictures of such but am not sure how to add it to this message.

Thank You for your consideration and any suggestions you may have.

Sincerely
Mike Schwab

Mod Bruce- I added this detail to help others find the correct part

[Bruce Fenstermacher]

Mike, see this link for instructions how to add photos. http://www.cessna170.org/forums/viewtop ... =12&t=8777

[mschwab]

Thank you sir..will do!

[mschwab]

Starboard I removed some rivits

Starboard I removed some rivits

ce170.jpg[/attachment]

[ghostflyer]

Seeing this ,I would be doing a very intense and through inspection of all areas and checking each rivet for security and corrosion. If the rivets have sheared due to large forces ,I would be inspecting all attach points and checking alignments of the rest of the airframe .
If you can't buck the rivets ,use huck bolts or MS nuts and bolts . Do a through inspection between the plates because corrosion will be present .have a talk with cessna techanical lads and explain what you have found. I have had a number of discussions with these people over the phone and found them to be very good. Also have a talk with Harry Delicker or Chris at Porter ville in Calf.

[c170b53]

Hi-lok's work well in small spots but from the pics if the space is limited on the O/B side then maybe rivets are the answer. likely a good Tin man would make a bar to fit and will be able to affect a repair. Good news is that you found them before they could cause big trouble.

[blueldr]

The problem here as I see it is that RIVITS, which are reported to be non structural, were apparently used in place of RIVETS which are the standard of the industry.

[mschwab]

Ghostflyer;

Thankyou for the consideration and information. If it would not be too much trouble would you let me know how to contact Cessna and who or what dept should I contact? Thank you. Also I will remove part to deal with any corrosion. I will rivet to skin and use the hardware for the gear box. Am I on the right track?

Thanks
mike

PS Logs were lost in 1956 in a fire. I bought with no damage history but she has obviously been ground looped. The doors don't line up quite right a a little wrinkle by door. On the last Pair of new Condor tires they wore perfectly with over 600 landings . Im almost afraid to check too close but I definitely want to be safe!!

[Bruce Fenstermacher]

Mike, you might note that Ghostflyer is located in Australia. I'm not saying his advice to use MS hardware rather than the rivets (BL are you happy now) is bad and that is the path I'd explore, I just can't find a reference in 43.13 that would allow it. I've often heard it quoted from A&Ps that appropriate screws and or bolts can replace rivets, I'd want a reference before I did it.

Maybe one of the A&Ps can chime in with a reference.

[mschwab]

Bruce;
I couldn't find anything in 43.13 either or any equivalency charts. I was sure hoping I could use nuts n bolts.

[T. C. Downey]

Maybe one of the A&Ps can chime in with a reference.

This is a quote from the Cesna 100 service manual

REPLACEMENT OF HI-SHEAR RIVETS.
Replacement of Hi-shear rivets with close tolerance bolts or other commercial fasteners of equivalent strength properties is permissible. Holes should not be elongated, and the Hi-shear substitute should be a smooth push fit. Forgings may be spot-faced the least amount necessary for proper seating of fasteners.

It's also in the structural repair manual.

[ghostflyer]

Well done T.C. Downey on the reference for the replacement of rivets with MS bolts and screws.I am not at the office these days and do not have all my resources at hand. I wasnt surprised to learn that the fuselarge had aligment issues .When rivets are sheared the aircraft has had a big hit. please note when the aircraft is in this state of undress its a good time to start the SIDS program. Its not a big issue with this aircraft. Cessna has released all of the extra inspections and corrosion inspection details. Another reason why I think this one of the best aircraft ever built.

[n2582d]

Tom, That forging is attached with several Hi-Shear rivets but they are not the ones that have "popped". The Cessna Service manual does not apply in this case. In the IPC the Hi-Shear rivets are #83.

AC 43.13-1B table 4-9, 4-10, and 4-11 tell how many AN 3-3 bolts to use for various types of repairs and aluminum alloys. The way I read it one would need at least 12 bolts in a six inch section -- serious overkill. Someone correct me, I'm probably reading it wrong.

If you can't get a double offset rivet set

1470-x.jpg (8.07 KiB) Viewed 6355 times

in there to drive these rivets in "backwards" I think you might be looking at removing the entire forging and do like Cessna did when they built it and drive those rivets before installing the assemblies (#34 and #50) to the aircraft.

The place to get good advice on this repair would be P Ponk.

[T. C. Downey]

Were I doing the repair, I'd pull the entire belly skin. inspect as required and remove and replace the rivets with new.

The 100 service manual will always be excepted reference for repairs on a 170, that is why Cessna titled the manual the way they did, a 170 is still a 100 series, even though it was built prior to the manual being written.

Plus the Cessna structural repair manual will give the proper procedures for the repair.

I'd not use the AN common hardware to replace the rivets. I know it is a common practice but I don't like it. but that is just me.

[GAHorn]

Cessna's manual refers to replacement of Hi-Shear rivets with AN bolts...not common AN420's, etc..

An excellent example of such an approved replacement can be found on the wing-strut attachments to their end-forgings. (In fact, Cessna did just that in about 12 newly-mfr'd airplanes in late '52 while they had rivets on back-order. Ultimately they abandoned Hi-shears and went with 420's.)

BUT.... anytime threaded fasteners are used to replace rivets... one should consider that only reamed-holes will equally share the load with bolts (which should be close-tolerance bolts in the case mentioned by Tom.) Otherwise, only one bolt in a set might be carrying the entire load.