VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.






VAF on Twitter:
@VansAirForceNet


Go Back   VAF Forums > Main > Safety
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 08-16-2022, 06:13 PM
RV8JD's Avatar
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 744
Default RV-7/7A In-Flight Breakup Accident Information

There was some interest in a previous thread regarding the status of the investigations into the RV-7/7A in-flight breakup accidents that have occurred.

I put together the attached spreadsheet documenting the accidents I am aware of. The spreadsheet has embedded links to the respective national safety board's investigation reports, links to the dockets where available, and links to some references.

I plan to update this spreadsheet as necessary. If there are any accidents I missed, please let me know.

Clicking on the image below will take you to the spreadsheet.



Fly safe!
__________________
Carl N.
RV-8
KAWO

Last edited by RV8JD : 11-09-2022 at 08:08 PM. Reason: Added link to Final Report for RV-7A VH-XWI.
Reply With Quote
  #2  
Old 08-16-2022, 06:55 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 1,449
Default

What are you finding to be a common link? Is it the ripper rudder coming apart from possible over speeds?
__________________
Tom
Las Vegas
RV-4 flying…
RV-8 empenage finished 10-2020

Wings Started.. 11-2020
Reply With Quote
  #3  
Old 08-17-2022, 12:14 AM
swift12 swift12 is offline
 
Join Date: May 2021
Location: Palmerston North
Posts: 207
Default

"Aircraft pitch is approximately 30° nose-down, wings almost level. The
IAS is recorded at 244kts"

ZK DVS....it appears commonality among some accidents is overspeed. slippery aircraft flying close to VNE pointing downwards not a good mix. I flew a lancair many years ago and came to the conclusion it was awesome to roll and a lawn dart pointing downhill...its ok...but not if you screw it up. I went over VNE pulling out and eased off...luckily the surfaces did not flutter. Id like to see the rudder have a 50% margin on the speed before breakup...maybe 300 knots but perhaps thats unrealistic.

I do wonder if the "8" rudder is better in this respect being a folded trailing edge? seeing these rudders fold in the wind is a little worrying.

In this case rudder flutter caused the vertical stab to separate and one wonders if the surface was balanced well....

quote..."Van’s Aircraft has conducted stick raps and rudder pedal kicks testing to 220kts, 8 with no indication of flutter up to this airspeed. Flight at any airspeed over Vne, however, exposes the aircraft to the possibility of flutter"

I tend to think that there is somewhat of a variance in what might be experienced between different aircraft and balance of the flight controls should be of paramount importance especially after painting. You simply cannot take flutter with a grain of salt...it destroys aircraft.

So in that case..no doubt vans has done extensive testing and in the normal envelope with balanced controls we have nothing to worry about...but overspeed or overload and add flutter.....mmmm.....poor buggers.

Its a timely reminder to do two things...
1. balance your controls
2. don't fly outside the manoeuvring speeds or g loading. if you do...carefully recover....
__________________
2022 dues paid gratefully. great site for help and info.
Reply With Quote
  #4  
Old 08-17-2022, 06:34 AM
AndrewR AndrewR is offline
 
Join Date: Jun 2017
Location: Ballarat, VIC
Posts: 71
Default

I wonder how much difference builder to builder variations in the training edge make?

It would be interesting to compare differences in the stiffness of rudders on different aircraft. It might not require much shear movement in the trailing edge before balancing becomes ineffective because the top and bottom flutter independently.

A folded trailing edge seems like it would be much stiffer.
Reply With Quote
  #5  
Old 08-17-2022, 06:50 AM
plehrke's Avatar
plehrke plehrke is online now
 
Join Date: Sep 2006
Location: Defiance, MO
Posts: 2,047
Default

Quote:
Originally Posted by AndrewR View Post

A folded trailing edge seems like it would be much stiffer.
Remember that folded rudders also tend to have a dab of RTV or proseal at the end of each stiffener to help prevent skin cracking. That will tie skin and stiffeners all together making a much more robust trailing edge.
__________________
Philip
RV-6A - flying 1000+ hours
Donated to VAF yearly since 2007. Why? Because it is worth every penny and more.

There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact. —MARK TWAIN
Reply With Quote
  #6  
Old 08-17-2022, 08:37 AM
Snowflake's Avatar
Snowflake Snowflake is offline
 
Join Date: Oct 2009
Location: Sidney, BC, Canada
Posts: 4,413
Default

I have the full report on C-GNDY from the TSB. In addition to the overspeed in flight (also over 240 kt if I recall) the conclusion was that the rudder was severely unbalanced. It had been inspected in an unpainted condition, and afterwards it was painted and that included some significant (up to 1/8" thick) filler used smooth the rudder and elevator surfaces. There was no evidence that the surfaces were re-balanced after the paint job.

So in addition to keeping speeds under Vne, keep your control surfaces balanced.
__________________
Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 06:17 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.