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RV horizontal stab crack reporting thread

RV3b cracks

RV3 two cracks, port side (left) one each, bottom rivet holes. No cracks starboard side. Shop head forward side of spar. Airframe 962 hours. I'm anxiously awaiting Vans approved fix.
 
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RV-8
80 hours
NO cracks
Manufactured rivet heads: forward

FWIW
~200 hp
Prop: Not Dynamically balanced (yet)
 
1 RV-8, 400 hours, shop head on fwd side - no cracks
1 RV-8, 210 hours, shop head on fwd side - no cracks
1 RV-10, 401 hours, shop head on fwd side - no cracks
 
Cracks, RV8

Cracks found RV8 SN 80209

Total Hours: 3382

Cracks found:
Tiny cracks on port side top two rivets nearest rod end projecting horizontally.
1/4" cracks on starboard top two rivets nearest rod end projecting horizontally.
Pictures of cracks sent to Vans.

Acrobatics: yes full range, 4.5 G max. Stopped doing spins because of tail buffeting, documented by Go-Pro. Did a few snap rolls, but stopped as they were simply not satisfying.
 
RV8 serial number 83830 150 hours light acro 3.5 G max, shop heads forward, prop dynamically balanced. No cracks.
 
Spar update

1050 hr
RV6A
Nosewheel
No cracks
Rivet factory head aft. (Shop head forward)
__________________
 
RV-4
750 hrs
Shop heads forward
Gentleman's acro
Prop spent most of its life unbalanced (wood prop) but was balanced 50hrs ago when upgrading to GA Sensenich
Infrequent grass/rough strips
Fifth rivet in middle of bracket
No cracks on spar
Note -- I did find one of my brackets cracked! And am grounded awaiting the revised SB parts for replacement
 
RV6A

2000 RV6A with RV8 tail.
O 360 A1A with C/S prop.
No cracks 2200hrs.
Shop head FWD.
 
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cheeselion said:
RV-4
No cracks on spar
Note -- I did find one of my brackets cracked! And am grounded awaiting the revised SB parts for replacement
Click to expand...
The mothership may want to know more details about the cracked bracket, and so would I. Out of 83 reports (including yours), that's the first I've heard of a cracked hinge bracket.

For now, I'm just keeping track of cracked spars.
 
RV6 Before Pre-Punched Kits
IO-360/Constant Speed Prop
1500 hrs.
Light Gentleman Aerobatics
Shop Head Front Side of Spar
No Cracks

Jim Baker
 
greghughespdx said:
Was the bracket itself cracked, or was the crack in the HS the rear spar?
Click to expand...

The bracket itself. No cracks in the spar that we can see.

I've only owned the plane for the last 100hrs, so not sure of the history beyond what's in the logs but there are no sign of other issues, it feels more like a coincidence. The other brackets are all fine.

Bracket pic attached.
 

Attachments

  • RV4 Right Outboard Elevator Hinge Cracking - Vans SB 00036-Rev1.jpg
    RV4 Right Outboard Elevator Hinge Cracking - Vans SB 00036-Rev1.jpg
    1 MB · Views: 545
RV-6A
1050 hours
no cracks
Shop head side is not statistically relevant based on engineering assessment
 
RV-8 80331
1700 hours
shop head forward
prop balanced
IAC Sporstman aerobatics (41/2, occasionali 5G)
Several very small cracks, one larger (1/2"). All on top rivets.

Scott A. Jordan
N733JJ
 
N76KL RV-10 No Cracks

Inspected N76KL (serial # 41678) with 65 flight hours, no cracks found.
 
cheeselion said:
The bracket itself. No cracks in the spar that we can see.

I've only owned the plane for the last 100hrs, so not sure of the history beyond what's in the logs but there are no sign of other issues, it feels more like a coincidence. The other brackets are all fine.

Bracket pic attached.
Click to expand...

Just a hunch, but I suspect that this crack is just in the powder coating and not actually in the steel bracket.

Skylor
 
plehrke said:
RV-6A
1050 hours
no cracks
Shop head side is not statistically relevant based on engineering assessment
Click to expand...

I'm inclined to disagree with this. The rivet-setting process introduces significant hoop stress around the hole in the area of the shop head as the rivet swells. Less so at the manufactured head end. Depending on how thick the whole stack of parts is that the rivet is swelling into, the added hoop stress may be much more of an issue on the shop head side. It makes sense to me to put the shop head on the steel part, and the manufactured head on the aluminum part.

If the area is prone to fatigue, it may be a factor of two or more in hours on average between cracking at the shop head or the manufactured head. - Just speculating with that -- but if it made the difference between 2000 hrs and 4000 hrs, it would be a statistically significant result for the fleet.
 
Horizontal spar cracks

1992 RV-4
900hrs ( same owner since new)
Very light very limited Acro
Shop head forward
No cracks

Thank you for the thread info.
 
RV-7

2008, 680 hours, gentlemen's aerobatics, manufactured head forward, no cracks. Landoll ring and catto prop.
 
RV-9A, 2011, 420 tach hours, no aerobatics, round heads aft side of spar, composite (MT) CS prop.

easily inspected with just a flashlight, actually part of pre-flight inspection now

no cracks
 
Google Forms crack report

I created a short form on Google Forms to collect crack reports. (As you can see, I'm not an early adopter, because this comes after collecting reports on about 90 airplanes.)

The form is at this link.

If you want to report on multiple airplanes, you'll need to submit one form per airplane. Each time you submit a form, it fills in one line in a table, which I'll have to copy and paste to my spreadsheet.

Please submit only one response for each airplane.

I'd prefer you use the form, to save me some typing, but you can still respond in this thread.
 
my results

2007 RV7a, 2175 hours, shop head forward, Hartzell prop balanced once, no cracks, little acro
 
my results

N625DK, 2007, RV-9A
O-320 160hp
shop heads aft
860 hrs., no acro.
sensenich wood prop not balanced

no cracks
 
2010 RV-7, 660 hrs, IO-360, Hartzell not balanced, shop head forward, light acro.

One small crack, left side. :(
 
Report on RV HZ stab hinge bracket spar cracks.

1994 RV6
868 hours
Very light aero.
Bucked rivets on bracket side.
Prop Dynamically balanced.
No cracks.
 
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Report on HZ Stab spar cracks.

1995 RV4
1,995 hours.
Lots of aerobatics.
5 rivet pattern on both sides of bracket.
Bucked rivets on front of spar.
Prop dynamically balanced.
No cracks.
 
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Report on RV HZ stab hinge bracket spar cracks.

2001 RV6A
2,000 hours.
Only aileron rolls.
Rivets bucked on bracket side.
Prop never dynamically balanced.
No cracks.
 
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Report on RV HZ stab hinge bracket spar cracks.

2005 RV8
1,700 hours
Lots of coordinated medium aerobatics.
Bucked rivets on bracket side.
Prop dynamically balanced.
No cracks.
 
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Report on HZ Stab spar cracks

2018 RV-8
No cracks

~ 330 hours, WW200RV prop dynamically balanced, aerobatics to +3.8g/-1g, rivet shop heads facing aft
 
“Shop head side not relevant”

scsmith said:
I'm inclined to disagree with this. The rivet-setting process introduces significant hoop stress around the hole in the area of the shop head as the rivet swells. Less so at the manufactured head end. Depending on how thick the whole stack of parts is that the rivet is swelling into, the added hoop stress may be much more of an issue on the shop head side. It makes sense to me to put the shop head on the steel part, and the manufactured head on the aluminum part.

If the area is prone to fatigue, it may be a factor of two or more in hours on average between cracking at the shop head or the manufactured head. - Just speculating with that -- but if it made the difference between 2000 hrs and 4000 hrs, it would be a statistically significant result for the fleet.
Click to expand...

Steve,
I happen to agree with your opinion. And may also be in part on how smooth the holes in the spar were de-burred.
 
2005 RV8
1,100 hours
Lots of formation & light aerobatics.
Bucked rivets on spar side, not very pretty. (I didn't build it!)
Prop dynamically balanced.
Small cracks (7-9 mm?) at 1 outboard rivet on each side.
Argh!
 
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