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 > Safety
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-25-2012, 12:36 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,841
Exclamation Injector Line Failure In Flight

Took a very short hop this am with my bride to check out the results of a small local brushfire. Cruising sedately along at 22 squared and lean we approached our airport for landing. Still out about 2 miles, the engine went rough and #4 EGT dropped out on the way to ambient temp. In light of the recent ignition issues I have been though, that was my first thought. Quick mag check showed exactly the same behavior on both ignitions, so that ruled out spark as the issue. That only leaves fuel and air... Since the other cylinders are still going strong, "air" seems unlikely as a cause. So that leaves fuel. With fuel injection and all other indications normal, a blocked nozzle pops into my mind - not a huge deal...

...Then I smell the raw fuel! I'm suddenly not interested in troubleshooting any more and just want on the ground ASAP. Fortunately, I'm on top of the pattern and simply chop the power, bleed off some speed with some s turns and set myself up for an uneventful landing.

Minutes later I have the cowl off and sure enough, #4 injector line is broken right at the nozzle and dumping fuel right on cylinder head near the spark plug boot. Good thing I didn't go full rich! Anyway, it's an odd failure in the respect that the line broke INSIDE the nozzle ferrule and the silver solder separated cleanly at the joint. Hard to inspect for THAT failure mode!

All in all it was a non event, but I thank God this this didn't happen at 8500 feet over the open desert!

__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C

Last edited by Toobuilder : 11-25-2012 at 12:45 PM.
Reply With Quote
  #2  
Old 11-25-2012, 12:39 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,968
Default Yikes!

Amazing that you didn't get a fire!
I did a repair on a line like this for a Maule one time.

It was clear to me that the silver-braze job was not done right. Lots of folks don't know how to braze stainless steel properly.

I used to build custom bike frames, so I'm pretty good at silver brazing
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 700
also
1/4 share in 1959 C-182B (tow plane)
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2020
Reply With Quote
  #3  
Old 11-25-2012, 12:47 PM
Walt's Avatar
Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 6,339
Default

You may also want to have a look at Lycoming SB342F
__________________
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, 2000+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
Reply With Quote
  #4  
Old 11-25-2012, 01:24 PM
Don at Airflow Don at Airflow is offline
 
Join Date: Jun 2006
Posts: 316
Default Inspect those injector nozzle lines!

Actually we see this type of pending failure a lot. Most people and mechanics kind of forget about the nozzle lines. But being that these systems have thousands of hours on them most people don?t think about replacing the nozzle lines on their engines at the time of the overhaul of the components. Even if installed correctly the metal will work harden at the radius going down to the nozzle line cone (ferrule). If you inspect this area around the braze joint (use a 5X to 10X magnification glass) and you find cracking of the braze material next to the nozzle line material, it?s time to replace the lines. Personally I would replace the lines at engine overhaul (2000 hours), for what it costs (around $110 for a four cylinder engine) it?s cheap insurance. Another issue with old lines is the coking up of the interior of the line with fuel dye. After repeated heat cycling of the lines on top of the engine, the fuel dye will no longer dissolve and will build up on the inside of the nozzle line. This debris then breaks off and can clog the injector nozzle. The material will look like black hard substance that will crumble if you can get a piece of it. Again, this doesn?t happen until the lines have thousands of hours on them. But you would be surprised how many of these we see that are probably from the 1960?s.

So next oil change, check you injector nozzle lines and the clamps for proper installation and condition of the rubber on the clamps (it?s good practice to do it every oil change or at condition inspection). We make nozzle lines and can supply the clamp kits that comply with the Lycoming Service Bulletin.

Don
Reply With Quote
  #5  
Old 11-25-2012, 01:40 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,841
Default

These certainly look to be OEM lines, and though appear to be in good overall condition, are likely to be as old as the basic engine.

Don, I'll be contacting you soon.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
Reply With Quote
  #6  
Old 11-25-2012, 03:39 PM
aerhed aerhed is offline
 
Join Date: Dec 2008
Location: Big Sandy, WY
Posts: 2,567
Default

Quote:
Amazing that you didn't get a fire!
That's what I used to/still sorta think. But, after finding a half dozen of these broken here and there, and worse yet seeing a couple engines encased in blue paste from long term leaks I'm stumped. I'm stumped as to why they don't all ignite, they don't though.
__________________
Actual repeat offender.
Reply With Quote
  #7  
Old 11-25-2012, 06:23 PM
Wesael's Avatar
Wesael Wesael is offline
 
Join Date: Feb 2009
Location: Brooksville
Posts: 282
Default Auto Ignition

Quote:
Originally Posted by aerhed View Post
That's what I used to/still sorta think. But, after finding a half dozen of these broken here and there, and worse yet seeing a couple engines encased in blue paste from long term leaks I'm stumped. I'm stumped as to why they don't all ignite, they don't though.
You need about 475 deg F. to auto ignite gas so the cyl-heads will not be enough alone to get it started.

The Exhaust temp. is enough though If you spray gas straight onto the exhaust riser you WILL have a fire.
__________________
Weasel
RV-4 715hr Sold
RV-10 "School Bus"
I have changed my User Name to the correct spelling as it became availible. Please direct all correspondence to Weasel
Reply With Quote
  #8  
Old 11-25-2012, 06:54 PM
Wayne Gillispie Wayne Gillispie is offline
 
Join Date: Apr 2009
Location: USA
Posts: 1,499
Default

I am guessing with 200-350F cylinder heads and all of that dilution air, any liquid has turned to vapor and too lean to ignite by the time it reaches the hot exhaust pipes. It amazes me too.

Glad all worked out for you guys.
__________________
Good judgment comes from experience, and a lot of that comes from bad judgment.
Reply With Quote
  #9  
Old 11-25-2012, 07:46 PM
g zero g zero is offline
 
Join Date: Jun 2007
Location: palm coast fl.
Posts: 997
Default Fuel lines

Aeroinstock sells experimental fuel lines , much savings over factory .
Tom
Reply With Quote
  #10  
Old 11-25-2012, 08:42 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,308
Default

That line looks like it had been under a fair amount of stress.

Shaping them so they sit in position might help.

Maybe Don can expand on that.
__________________
______________________________

David Brown

DYNON Authorised Dealer and Installer


The two best investments you can make, by any financial test, an EMS and APS!
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 05:12 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.