fin attachment inspection info

scsmith · #1 12-16-2015, 07:56 PM

Back in 2012 there was a discussion thread that resulted from two cases of finding cracks in the forward fin attachment bracket.

There was some indication that those particular parts might have been assembled so that the forward fin spar edge was impinging on the bend radius of the attachment bracket, rather than nesting properly. There was also discussion about possible pre-load in the bracket from improper shimming of any gap in the parts as they were assembled.

This thread elevated awareness of this area as one that should be carefully inspected during condition inspections.
Additionally, there is now a service bulletin calling for inspection of the horizontal tail forward spar in this same general area. So, for some time now, there have been a lot of eyes looking at this area.

What I would like to know, now, is:

Beyond the two cases that were reported previously of cracks in the forward fin attach bracket, F-681, F-781, F-981 as the case may be, are there any additional cases that have been discovered/reported?

scsmith · #2 12-17-2015, 02:44 PM

I'd like to keep this fairly visible for a few days to improve the chance that anyone that had an issue will see it,
Also improved the title a bit, but the revised title doesn't seem to appear on the forum thread listing
Thanks,

scsmith · #3 12-17-2015, 09:53 PM

another bump to the top. 234 views so far. Hoping for more.

scsmith · #4 12-18-2015, 01:05 PM

One more bump to the top. 357 reads so far.

mdevans9 · #5 12-18-2015, 04:17 PM

Steve,

Will you please post the Thread you are referring to. I searched, but ...

Due to several (I'd say, four) accidents that seem to begin the sequence with the vertical fin attachment failing (my take), I am very interested in understanding what is going on here.

Thanks,

Merrill

scsmith · #6 12-18-2015, 07:38 PM

Merrill,
Please check your PM's

Quote:

Originally Posted by mdevans9

Steve,

Will you please post the Thread you are referring to. I searched, but ...

Due to several (I'd say, four) accidents that seem to begin the sequence with the vertical fin attachment failing (my take), I am very interested in understanding what is going on here.

Thanks,

Merrill

Lynnv · #7 12-18-2015, 09:50 PM

Steve, +1 on the thread for me too. After reading the NTSB preliminary report on last week's RV 7 accident, I want to get every piece of information about the tail section that is available.

grubbat · #8 12-19-2015, 07:56 AM

Steve,
Thanks for the post. This is definitely high on my list right now for. I found an old thread in the -9 forum about a horizontal crack issue in the oblong hole where some used a larger washer to spread the load somewhat. Here is link I found:

http://www.vansairforce.com/communit...ferrerid=15798

Is this the general area?
Cj

scsmith · #9 12-19-2015, 04:24 PM

search for F-981 and it will come up.

grubbat · #10 12-22-2015, 01:42 PM

Visiting a friend and saw an RV-8 today with the cracked Horizontal spar. I'll be helping fix this one as I haven't see this type of crack before in person, only read about it here. Approximately 150hr on airframe since new.

Will follow Service Bulletin 14-01-31 on this repair.
cj