|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

09-21-2013, 01:07 PM
|
 |
|
|
Join Date: Jan 2005
Location: Ruston, Louisiana
Posts: 879
|
|
7A elevator spar crack
Due to the recent loss of a VAF'er I decided to inspect my empennage very carefully.
I found a crack in the right elevator spar at the outboard attach point.
This is how it looked upon inspection. Just a black line.
I wiped the black off the left side but you can still see the crack below.
And here it is after the dye penetrant test.
It's an RV7A serial number 72183 with 908 hours.
Everyone please check your elevators carefully before your next flight!
Mark
__________________
Mark Burns
Ruston, Louisiana
RV-7A N781CM 1,650+ hrs
FFI FL-24
A&P
|

09-21-2013, 01:11 PM
|
|
|
|
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
|
|
Good catch, Mark.
__________________
Kyle Boatright
Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
|

09-21-2013, 01:15 PM
|
 |
|
|
Join Date: Jan 2007
Location: Ontario Canada
Posts: 1,452
|
|
Interesting.
Thats a pretty signficant issue I would think. Will be interesting to see if a few of these show up, and how/why it would fracture there?
Not speculating on anything of course, but anything to do with spars gets my attention quick. Will inspect asap.
Thanks for the post.
__________________
Rick Woodall C-GSTT "ghost"
9a -TMX io-320, catto three blade, dual dynon hdx with a/p. 900+ hrs in 8 yrs flying.
Flew to Osh 11,12,15,17,19. SNF 2013. West to Cali /Washington/Vancouver/crossed the Rockies north to Red Deer east to Moosonee and over to maritimes. South to Jekyll Isl, cedar key, and Key West etc. 6 trips and 17 islands of the Bahamas. Flown turtles and dogs for Pilots n Paws too. Love our Rv's
|

09-21-2013, 04:56 PM
|
 |
|
|
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,686
|
|
A loose jam nut could be the cause of such a crack, if the jam nut is loose the nutplate and nutplate rivets are carrying the full load of the fitting.
FYI - I find loose jam nuts on elevators and rudders routinely
PS: good find, everyone should inspect this area at the earliest opportunity.
__________________
Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
Last edited by Walt : 09-21-2013 at 04:58 PM.
|

09-21-2013, 05:06 PM
|
 |
|
|
Join Date: Aug 2006
Location: Taylor Texas
Posts: 811
|
|
Whoa!
Hey Mark:
Assuming the rod end was tight, and the elev hinge line along the H stab rt side is razor straight, as is the elev hinge line, I would suspect a vibration mode of some sort here (elev counterweight involved) - I doubt you could do that with any sort of flying you would do in that plane - well - maybe 10 tail slides per day since the first flight? You're not doing that, are you?
I suspect a hinge line SNAFU, with the area of least strength (outboard hinge/smallest spar cross section)) giving up 1st. Get your dental floss and string-line bushings back out!
Could be that rivet was not driven correctly - the markings show it is a hard rivet...so that's not likely to be it.
What engine/prop combo are you running? Does it run smoothly in cruise? Did you do an engine run with the wings off way back when?? I'm digging pretty deep with that last one...
Carry on!
Mark
|

09-22-2013, 06:11 AM
|
|
|
|
Join Date: Jun 2007
Location: new iberia la
Posts: 768
|
|
Spar Crack
Mark: Good Job for paying attention and being proactive. No way to tell how long your crack has been there but looks like a few hours. This is a good illustration of how the parts of our "airworthiness system" work together. The airplane structure is designed to be tolerant of some level of damage or defect like this spar crack for a peroid of time until the inspection process comes around to catch it. Please keep us posted on what you find and how you resolve it.
Don Broussard
RV-9 Rebuild in Progress
|

09-22-2013, 06:35 AM
|
|
|
|
Join Date: Nov 2010
Location: Monroe, La
Posts: 39
|
|
Thanks for the info Mark !
Hope to see ya soon.
|

09-22-2013, 09:04 AM
|
|
|
|
Join Date: Jun 2007
Location: palm coast fl.
Posts: 945
|
|
Crack
My Cessna 120 had an AD to look for such a crack , along with the Rudder on an A36 Beech Bonanza , and the horizontal on a Rockwell 112 . I do believe the fix was either doublers or spar replacement .
As inexpensive as Vans parts go , I might opt to build a new one . A complete tail kit cost about the same as the cost to inspect the A36 or the Rockwell .
After the latest inflight breakup and another post about the length of rudder rod bearings we all need to take a realy good look at the tail components .
Remember tail kits are place that most every one learns on , most with NO construction experiance .
The latest 7 to come apart looks a lot like [ed. Wait for the investigators please. dr]. There are some other reports of RV7 flutter if you search the web.
Tom
__________________
Rv8
N 666 TA
First Flight 2-3-2015 🚀
2017 donation paid
Last edited by DeltaRomeo : 09-22-2013 at 09:10 AM.
|

09-22-2013, 11:45 AM
|
|
|
|
Join Date: Sep 2011
Location: AL
Posts: 69
|
|
Thanks
Mark, thanks for the post. I checked a friends RV-7 and found all 4 jam nuts loose on the elevator hinge rod-ends. No cracks though.
__________________
Bruce G.
RV-8
|

09-22-2013, 11:45 AM
|
|
|
|
Join Date: Feb 2011
Location: USA
Posts: 3,179
|
|
Mark - thanks for this thread.
On you're prompt, I just looked closer than usual at the lock nuts for both the rudder and elevator on my RV-8.
One of three on the rudder needed a wrench. One in four on the elevator needed a wrench.
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 01:25 AM.
|