Minimal damage after I crashed my kitfox. I got it on video!

[JonasM]

Hey guys,

If you haven't seen the video of me crashing my kitfox here it is!

If you are flying a rotax. be careful of vapor lock issues.

https://www.youtube.com/watch?v=FQ3WByjahOc&t=145s

[Shadowrider]

Do you have a fuel pump, or are you going to add one to help?

[JonasM]

Do you have a fuel pump, or are you going to add one to help?

I changed the gold rotax fuel pump to the new silver one and did the bypass.

i haven't had any issues so far.

[Av8r3400]

So the plane is repaired and flying again? How long ago was the incident?

[Guy Buchanan]

First, well done video. Second, good job on the crash. No injuries, minimal damage, what more could you ask for? (Yeah, I know...)


I worked hard on my build to minimize the vapor lock possibility. I re-routed my fuel line away from heat sources and fire shielded all the lines. Of course, I also had a round cowl, which ventilates much better than the tight 7 cowl. Take a look at your installation. See if you're getting any heat from the exhaust system or other high heat sources.


Good luck!

[Jerrytex]

Glad your ok. Curious to know, how long from the time you started up until take off? As in, did you fire it up, and immediately take off or did you sit there idling for “x” amount of time?

[Dave S]

Curious how you were able to determine the issue was vapor lock?



The classical Rotax vapor lock issue is a hot soak situation following shutdown on a hot day and attempting to restart 5-10 minutes later where the bleed line is not installed.


Any feedback on the type of fuel that was being used at the time?

[airlina]

Also be aware that even though the prop was not turning ,this is still considered by rotax's definition as a prop strike and their maintenance manual should be consulted on what is required. From the manual-3.2.2) Propeller strike
A propeller strike can be defined as follows:
1.Any cases in which the engine is operating and the propeller impacts an object which causes
a
considerable drop in engine RPM
.
Propeller strikes on ground or contact with various objects can result in engine and/or compo-
nent damage even if the propeller may continue to rotate. Such damage may progress to engine
failure.
2.Any incident, whether or not the engine is operating (e.g. damage due to contact with foreign
objects, landing gear failure etc.), that requires a removal of the propeller for repair. Also if a
propeller governor is installed, it must be the inspected and repaired in accordance with the
propeller governor manufacturer ́s published instructions.
3.Any incident with a sudden RPM drop while impacting water, tall grass, or other similar medium
where damage on the propeller structure is not incurred.

[Slyfox]

ok, I'll add my thoughts. how's the tail. A quick visual is NOT going to work. seems it hit real hard on roll over. My thought is, you have to remove all the fabric on the back vertical on down into the fuse and inspect for cracks and repair as per needed. someday it could snap and you will be in for a, how do you say it, not so fun ride.

[Slyfox]

one more thing, the engine, ya it was not turning. I guess the engine might be ok. but I would tear the gear box off and do a runout check on the crank and gear box. the prop, no way, new one. you could have a slight crack or weakness and not know it and someday, POW! again, you will have one of those, oh crap moments.

[Hockeystud87]

For a vapor lock issue would a longer run up prevent any issues with this?

What are ways to 100% avoid/prevent vapor lock?

[kmach]

You can reduce the chance of having vapor lock by;


Have a restricted fuel return line to your header or wingtank.
Having your fuel lines in heat sleeve.
Parking facing into the wind. Opening your oil tank access lid after shut down to let hot air out.
Running your engine for a reasonable amount of time to do your checks before takeoff.

[rogerh12]

Five words: Backup Flow-thru Boost Pump

[Floog]

Also, MOGAS (which is what I use) is more susceptible to vapor lock than 100LL due to lower boiling point.

At 1,400 hrs. the only 'engine failure' I've had was similar to Jonas': it quit on rotation on a gravel bar on April Fool's Day! Fortunately, the wheels were still on the ground with plenty of overrun left.

After that trip, I took apart the return line and inspected the orifice, check valve, and the entire fuel system. All AOK. I ass-umed vapor lock...

Thanks to all for the ways to inhibit vapor lock!

[jiott]

I also had what I am fairly sure was vapor lock after landing on a gravel bar on a hot summer day. After about a 10 minute shutdown I fired up and on the T/O roll it started to stumble badly. Fortunately, like Floog, there was plenty of room to get stopped. I let the engine run a while and ran it up to hi rpms and it soon smoothed out and ran fine with no more problem. I do have a return line to the header tank (factory kit) and fuel lines in firesleeve.

Lessons learned:
- You can have vapor lock even with a return line, but I believe it is not as severe and clears itself more rapidly.
- Gravel bars are especially bad places.:D
- On a hot day after a short shutdown, ALWAYS run the engine and do a hi rpm runup before T/O.
- I have been trying to train myself to open the oil door after a hot shutdown. Not only is it good to prevent vapor lock, but it also will extend the life of your ignition modules I have heard.

[Dusty]

The heat buildup after shutdown is surprisingly high.I run a temp probe near one of my carbs,15-20c on cruise 45- 50c after shutdown.this is on a round cowl,I would guess the smooth cowl temps may be higher.opening the oil hatch sounds like a good idea!

[HighWing]

I find this discussion fascinating. Along the way, I am constantly recalling my experiences with the numerous cross country and back country trips we took as a flight of six or so. All Kitfoxes except the two Rans - S6 and 7. Thinking about it, it is likely the shortest times on the ground were fuel stops but with six or more airplanes it likely took close to an hour or so total. Then all were TD's except the S7 with ample air flow up through the bottom cowl exit through the sizable air outlet at the high end - at least while on the ground. Vapor lock was never ever an issue. I am extremely curious what it is that has triggered the problem. The Avgas vs. Mogas might be part of it but back then we often found mogas at some airports.

The picture is at Rome Station, Oregon - a restaurant and gas station on Highway 95 with a dirt strip out back - I guess we cheated.

[Pilotharry]

Hello Guys,
Been following this group for the longest time and have used tons of knowledge from here. I though I will share my 2 cents of experience and knowledge on this subject. I had 6 "vapour lock' indents with 912 in a Zenith 601....right after I followed the mendatory AD from Rotax to replace old 'Piersburg' pump with new style pump (BCD/corona). I was lucky on incidents every time, either there was enough landing option available or enough altitude available to pull throttle back to about 30% and get the fuel flowing again. Yes, I have extra Facet pump to help but major issue is that when this happens on new style pumps, it even restricts the pressurised flow from auxiliary pump to flow thru.

Having said this and long story short, experience dealing with Rotax on the incidents was not pleasant and in spite of following everything they advised including installing the return line to main tank. It kept happening on moderate warm days....till I switched back to my original fuel pump and already have over 100 hours on the setup after that without missing a beat.

Food for thought is that everything is kept the same in terms of air flows, exhaust setup, fuel lines and insulation on them type of fuel (MOGAS) and even to a point that return line was also temporarily blocked with no issues. The new style 'Corona' (BCD) pumps seems to have a bad design and enough void volume to create this problem. I have also ended up switching a new style fuel pump on one of my friends 'Skyboy' with duel facet pumps in a redundant setup with pressure sensor after he had long frustrating episodes of rough running and vapour lock issues. Yes, now he is dependent on voltage for flying but its better than having unforeseen sudden engine out or nasty vibrations.

[Squelch]

I curious about what you had to do to get the airplane home.

[Esser]

His next video is gong to be all a out that.