Cherrymax for seat rails YES or NO?

Cherrymax for seat rails YES or NO?

Can someone give me regulatory chapter & verse on why cherrymax installations are, or are NOT approved for seat track replacement. The 182 SRM states:( while not speaking directly to the rail installation) "blind rivets are used", in the rivet description paragraph. A call to Cessna's help desk while not being able to give me "anything in writing" stated that rails installed with cherrymax rivets cause the aircraft to "not meet the type certificate". He offered to talk to the present owner, if they would call. A call to McFarland's engineer showed numerous hand written notes on his PMA drawings saying "no blind rivets!!" But again, no regulatory references.

My problem, is that I am in the process of annualing an aircraft that has one previously installed ( with cherrymax fasteners) seat rail. I can find no entry in the records. This aircraft has been maintained for several years at a quality shop, ( Central flying service, LTR ) and they seemed to be OK with it. After all these years, surely there's something on paper? I don't feel confortable releasing the aircraft, & the current owner soesn't want to spend money unnecessarily.

Anyone?

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Steve
There is an SAIB (Special Airworthiness Information Bulletin) # CE-90-03R2. This bulletin authorizes the use of screws as a substitute for rivets. The screws listed in this SAIB must have a tensile strength exceeding 50 ksi. As far as cherrymax rivets are concerned, The minimum tensile/shear strength of a Cherrymax rivet ranges between 50 and 75 ksi. I have installed more seat rails that I care to count and I have always used CM rivets in tight places, I would ensure, by inspection, the the rivets are properly installed via grip length. I also believe that CM rivets are structural rivets, I have installed numerous structural STC's that utilize CM rivets and the STC's are FAA approved.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Steve, I have seen CM rivets used for Cessna seat rails also.  I have no problem with the CM rivets as long as they are gripping good as Tom mentioned.  If you decide to use screws as mentioned in the SAIB the seat rail is supposed to be spot faced.  But from what you described I would leave the rail installed as is and press on.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

I did finally find the information I needed. In the application literature for Cherrymax rivits, there is a disclaimer saying,and I'm paraphrasing here, " Unless the aircraft manufacturer specifically approves cherrymax rivets for part replacement, they are not to be used."

I was also referred to the FAA's "Inspector's Handbook" which has similar language.

Remember, this is a parts replacement.Not a 'repair' or 'alteration'. If you shoot the rail in with blind rivets, it BECOMES an alteration, and must go through the field approval process. You are unlikely to get an easy approval without a DER & physical testing of the installation.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Based on the above "Unless the aircraft manufacturer specifically approves cherrymax rivets for part replacement, they are not to be used." Does Cessna or Piper approve cherry max rivets?

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Appearently cherrymax rivets have greater shear strength than an rivets and less tension strength.  Therefore the installation of cherrymax rivets are not accetpable except in hard places.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Remember, this is a parts replacement.Not a 'repair' or 'alteration'. If you shoot the rail in with blind rivets, it BECOMES an alteration, and must go through the field approval process. You are unlikely to get an easy approval without a DER & physical testing of the installation.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

I would consider this a minor alteration which requires a simple log book entry

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Cessna is a little vague about many things. If they have a list of fastner substitutions ,and Cm,s are listed as a replacement for 470,s in all cases and not forbiden in special instalations such as seat tracks then they could be used. I would check with Cessna Engineering to cover my self.Unfortunatly they don't seem as serious as someone like Boeing when it coms to a structural repair manual.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

Since I originally posted this, I did what I have only done twice before in a 38 year career,I signed the aircraft off as unairworthy, with discrepancies noted, & given to the owner. I simply didn't feel this aircraft met it's type certificate with the cherrymax installation. We settled up, no hard feelings, ect, & of course he found a guy, two years out of school, who was willing to 'say grace' over the installation & release it. No problems from me, ( after all I was not that darn confident Or I wouldn't have queried the group here ) and the owner was surely happy. Anyway some time later, at the local EAA meeting, he was 'holding forth' maybe a little to loudly about the project, & how he "handled it" and guess who was standing by the coffee pot at the time? Yeah, FSDO inspector, in town just to show the flag, press the flesh, "help us out", you know the drill. I think you can guess how this progressed; he tagged the aircraft, and the work had to be done anyway. The kid got away with a warning, nothing in his "jacket". You might have gotton another result from another inspector, or another fsdo, but I bet he would have hung me, thinking "I should have known better"

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

You are kidding me, using C/M's in a seat rail. anytime. I would never flag a jet over something that trivial.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Re: Cherrymax for seat rails YES or NO?

No, I am not kidding


http://www.ntsb.gov/recs/letters/2000/A00_46_50.pdf

and scroll down to page 7:
http://www.peerlessaerospace.com/pub/Pr … RRYMAX.pdf

The longitudinal seat tracks on a single engine Cessna are primary structure.Don't take my word for it, ask Cessna.

Here is a revision to Ac43-1B
scroll down to pg 2; 4-19  4-57f, read the "caution"

it requires permission from the manufacturer or an FAA representative.
There goes the 'acceptable data' gray area.

http://www.ercoupeparts.com/ac43.13_1b_update.pdf

You can buy if off if you like, but your hanging yourself outthere.

Guest
Guest
useravatar
Offline
Posts
User info in posts
Only registered users or members can reply or post

Board Info

Board Stats:
 
Total Topics:
6026
Total Polls:
1
Total Posts:
16346
Posts this week:
1
User Info:
 
Total Users:
2410
Newest User:
YingqianB2
Members Online:
1
Guests Online:
2019

Online: 
Bob H

Forum Legend:

 Topic
 New
 Locked
 Sticky
 Active
 New/Active
 New/Locked
 New Sticky
 Locked/Active
 Active/Sticky
 Sticky/Locked
 Sticky/Active/Locked

ankara escort ankara rus escort ankara escort bayan ankara bayan partner ankara escort kizlar escort ankara ankara escort ankara eskort ankara escort bayan ankara bayan partner ankara escort kizlar escort ankara