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.


Go Back   VAF Forums > Main > RV General Discussion/News
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 03-12-2021, 03:57 PM
jcarne's Avatar
jcarne jcarne is online now
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,635
Default Is this bottom skin heat/discoloration normal?

Hello everyone, fresh 4.3 hours on the aircraft and today I noticed the bottom skin has some discoloring from heat of the exhaust/exit cooling. I would think it would have to get pretty hot to discolor the aluminum like that. Is this normal? Anything I should do to try and make it better?

CHTs have been around 350-380 and I have been keeping the EGTs around 1300.

Capture by Jereme Carne, on Flickr

Thanks for the feedback!
__________________
Jereme Carne
PPL
RV-7A Flying as of 03/2021
Exempt but gladly paying!
Reply With Quote
  #2  
Old 03-12-2021, 04:09 PM
Jpm757's Avatar
Jpm757 Jpm757 is offline
 
Join Date: May 2013
Location: Sherman, CT
Posts: 940
Default

I doubt the discoloration is from heat, especially that far aft. Looks more like a chemical reaction between the aluminum and some chemical. Possibly a detergent of some type that was not rinsed off thoroughly.
__________________
Jake
RV6 #20477 completed 1991 sold.
RV7 #72018 N767T first flight 11/21/2017
(KOXC)Oxford, CT, (0NY0)North Creek, NY.
1941 J3 Cub skis, floats.
Building Javron Super Cub.
2020 dues gladly paid.
Reply With Quote
  #3  
Old 03-12-2021, 04:30 PM
rv8or rv8or is offline
 
Join Date: Oct 2007
Location: Norwich England
Posts: 162
Default My guess

Burnt oil residue from combustion is my guess

Rob
Reply With Quote
  #4  
Old 03-12-2021, 05:43 PM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,107
Default

normal. it's doesn't get hot back there.
__________________
Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
Reply With Quote
  #5  
Old 03-12-2021, 07:33 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,407
Default Breakin oil

During break in you are burning a lot of oil. If it is hitting the exhaust pipe, it is probably smoking a little bit. You might be even leaving a trail??
__________________
John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2021, worth every penny

RV9A- Status:
Tail 98% done
Wings 98% done
Fuselage Kit 98% done
Finishing Kit 35% canopy done for now
Electrical 85% in work
Firewall Forward 5% in work
Fiberglass 0%, thought i was building in metal?
www.pilotjohnsrv9.blogspot.com
Reply With Quote
  #6  
Old 03-12-2021, 09:57 PM
jcarne's Avatar
jcarne jcarne is online now
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,635
Default

Thanks for the replies everyone, I went back out to the airport and did some more rubbing and it is definitely burned oil/combustion product. I guess I didn't rub hard enough the first time but it easily comes off.

Now the hard part of knowing when my engine is broken in... I have only burned 0.75 qts in those 4.3 hours. That also could have been the engine dropping some to get down to it's happy spot. Time will tell I guess.
__________________
Jereme Carne
PPL
RV-7A Flying as of 03/2021
Exempt but gladly paying!
Reply With Quote
  #7  
Old 03-13-2021, 12:19 AM
KayS KayS is offline
 
Join Date: Jul 2009
Location: lake constance
Posts: 355
Default

the belly of my 7 looks the same, nothing to worry. your oil consumption seems to be normal for break in. my engine with nickel cylinders had used around 1 qt per 1 hour at the beginning. now it stabilized at 1 qt for 7 hours.

just keep track of your oil usage over engine/flight time, if it doesn't change anymore your're done.

btw... Congratulations to your First Flight!!!!!!!! i love the paint scheme of your wings. mine is the same. :-)

Last edited by KayS : 03-13-2021 at 12:24 AM.
Reply With Quote
  #8  
Old 03-13-2021, 07:35 AM
jcarne's Avatar
jcarne jcarne is online now
 
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,635
Default

Quote:
Originally Posted by KayS View Post
the belly of my 7 looks the same, nothing to worry. your oil consumption seems to be normal for break in. my engine with nickel cylinders had used around 1 qt per 1 hour at the beginning. now it stabilized at 1 qt for 7 hours.

just keep track of your oil usage over engine/flight time, if it doesn't change anymore your're done.

btw... Congratulations to your First Flight!!!!!!!! i love the paint scheme of your wings. mine is the same. :-)
Haha thanks! Glad I'm not the only one that found flying more important than wiping that stuff off. lol
__________________
Jereme Carne
PPL
RV-7A Flying as of 03/2021
Exempt but gladly paying!
Reply With Quote
  #9  
Old 03-13-2021, 09:17 AM
flyvans.com flyvans.com is offline
 
Join Date: Feb 2005
Location: Zurich, Switzerland
Posts: 479
Default

looks normal/accetable to me.
interesting that the "stain" is so far back... residues are either close to the exhaust or then tend to spread evenly in the very aft area.
by the way, we clean the exhaust stains with WD40, which seems a bit counter intuitive but works really well.
__________________
++++++++++++++++++++++++++++++++
Bernie Daenzer, Alex Lichtensteiger
www.flyvans.com
RV-7A
S/N 72072, Flying!
HB-YMT (Switzerland)
Reply With Quote
  #10  
Old 03-13-2021, 09:45 AM
RV10Pilot RV10Pilot is offline
 
Join Date: Jan 2005
Location: Medford, NJ USA
Posts: 378
Default

Quote:
Originally Posted by jcarne View Post
Now the hard part of knowing when my engine is broken in...
It should be easy to know when the engine is broken in. You will see a dramatic change in CHTs, especially when climbing out.
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 07:53 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.