Avid / Kitfox Accident Causes and Rates

[dholly 718]

Very interesting article if you get a chance to read it. Although, because of registration methodology, the author admits there really is no way of breaking down each manufacturer's planes into specific model groups (ie., impossible to know how many "Kitfox" accidents are Model II, II whatever).

A few of takeaways...

...in the 'Relative Occurrence Rate of Accidents Not Involving Pilot Miscontrol' category, the highest accident cause rates were Engine Mechanical Failure (Avid) and Fuel System Failure (Kitfox).

...in the '2-stroke Engine Mechanical Failure' category, the internal engine failure rate for the Avid is almost 3x higher than for the Kitfox. Of course, it has long been speculated this is due to the inverted engine mounting in the Avid. Giving some credence to the theory is that when comparing 4-stroke engine mechanical failure accident rates, the difference disappears.

...in the comparisons of both 'Annual Accident Rates' and 'Fatal Accident Rates', Avid and Kitfox are well below the average for both aircraft types.

...the FAA database for Jan 2010 shows about 650 Avids and 1300 Kitfoxes registered.

[akflyer 1427]

well I would take a shot in the dark on this one.. When Avids were first introduces, they used the 430 Cayuna.. a better boat anchor than an engine. That would probably account for a huge percentage of the failures. Kitfoxes came later after the 582 was the engine of choice. I would like to see it broken down to rotax versus other engines. I would also take a stab at it and say that probably 70% of the engine failures are caused by pilots who do not understand how to operate a 2 stroke... But that is just my biased opinion

[Av8r3400 1177]

Just logged on after reading that article. A very good read.

I think you are probably partially correct, Leni, in your evaluation of 2-stroke operations and operators. That may be a huge factor.

The gist I took from the article is still that the basic design, Avid or Kitfox is still one of the safer designs flying.

[akflyer 1427]

Hey Doug, just caught your subject line... how the hell did you get a sneak peak at the September 2010 issue

[dholly 718]

Hey Doug, just caught your subject line... how the hell did you get a sneak peak at the September 2010 issue

I guess they figure if they send the issues out a month or two early they can justify sending their subscription renewals 6 months early too.

BTW, the same issue has a good run down of current EFIS offerings that might be helpful for anyone interested.

[akflyer 1427]

I guess they figure if they send the issues out a month or two early they can justify sending their subscription renewals 6 months early too.

BTW, the same issue has a good run down of current EFIS offerings that might be helpful for anyone interested.

Maybe I should have mine delivered to work instead of the house. That way I get to see the damn thing before my kid carts it off to go only knows where.. hell when I was his age I was using um, different mags, not airplane rags for props

[skypics 89]

FYI

 

I had 4283 hours on my Jabiru 2200 at the time of my recent crash...not an engine issue.

 

I have had 5 engines on my Avid B STOL since 1990.

 

It had a 532 rope start when I bought it. Then 2 each 582s which I had on it for 2400 hours with no major issues. Finally I got tired of the 2-stroke sound, water plumbing and fuel burn and went to a Jabiru 2200. 

 

The Jab had to have the valve guides replaced on warranty at 200 hours. Then at 585 hours it sucked an exhaust valve and I dead sticked back to the airport. This was a bad design issue when Jabiru went from straight lifter to hyd lifters.

 

NOTE: On 4 strokes, if you have badly worn guides replace the valves also, not just the guides.

 

The replacement Jabiru had all the upgrades to address the hyd lifter change and the engine had 1030 hours on it when I totaled the aircraft.

 

My friends all have Rotax 912s and all have had issues as well. One of the biggest differences is the cost of replacement parts for Rotax vs Jabiru with Rotax part running 3-4 times more expensive.

 

That said there are different benefits in the Rotax and Jab.

 

ROTAX: You can run a longer prop for better climb. They use less oil although you can't use common aircraft oil. The can and do run high EGTs with no issue because the water keeps the heads cooler. Recommended TBO runs 1500 hours, but they typically go over that time.  You have to "burp: the engine to check the oil.

 

Jabiru: Lighter weight. Less complicated using mostly off-the-shelf items like distributors and rotors that can be purchased from NAPA. The use regular aircraft oil. Cruise at 2800-3000 RPM as opposed to 5400-5600 RPM so sounds more mellow. Parts are based on the Aussie dollar as opposed to the Euro. Easy to work on and less complicated with no water hoses, radiators, over flow bottles, etc. Direct drive so no gear box or Spraug clutches. Fewer moving parts. Recommented top ovehaul is 1000 hours.

 

That said, all brands of engines have failed, including jet engines. Conts and Lycs have over 70 years of issues and engineering improvement. Rotaxes and Jabs will go through some engineering iterations and over time become more robust.

 

My friends like their engines and I like mine although we do have some healthy discussions on which is the best.

 

Religion, politics and aircraft engines.

 

John M

Edited 17 Oct 2014 by skypics

[EDMO 1078]

Nice Post John,

         However, you left out the reason you totaled the Avid.

Thanks,

EDMO

[1avidflyer 1983]

Wow John,  so sorry to hear your plane got wrecked.  It probably had more hours on it than any other Avid.  Hope you had good insurance.   It can't replace your baby, but might help you get something to take it's place.  Jim Chuk

[wolves200 31]

man! that sucks, even the most experienced pilots --- sorry to hear that John, but I think like the rest of us I Would like to hear more about your accident!!

[allonsye 85]

FYI

 

My friends like their engines and I like mine although we do have some healthy discussions on which is the best.

 

Religion, politics and aircraft engines.

 

John M

John - appears that the worst issue for the 582 for you was the sound. Otherwise appears it more reliable than the 4strokes you operated. Thanks for sharing...........btw, sorry about your accident. Please do tell for teachable moment sake.

P.

[herman pahls 9]

Is this the time to confess regarding when the fan stops.

 

37 years flying Lycoming and Continentals;  no dead stick landings.

13 years flying Rotax 532 converted to snowmobile ignition;  no dead stick landings.

3 years flying Rotax 582; no dead stick landings and still flying the engine.

2 years flying Jabiru 80HP; one successful dead stick landing.

6 months flying Rotax 912ULS; one successful dead stick landing and still flying the engine

 

The Jabiru would not restart while I was a glider but started right up an hour later after the authorities made their reports.

I had just circled down from 9000 feet to sea level at idle with some occasional bursts of throttle to make sure it  was still running well and it quit when I leveled out  to enter the traffic  pattern.

I either had carb ice or a fuel tank venting problem.

I changed the tank venting and flew it 2 years but never descended for any length of time at idle after that.

I got rid of the engine because it would only climb to 9000 feet but otherwise enjoyed all the simplicity of the Jabiru that John M. referred to.

It would have performed much better at altitude if it were the newer 85HP version like John M. had.

 

The 912ULS refused to restart even with plenty of fuel in the left tank.

I found out that a Model 4 Kitfox is a decent glider.

Turns out the 5/16" Tygon tubing that came with the Kitfox I had recently purchased had collapsed where it gets flexed the most when the wings are folded (it was not pinched between the wing and fuselage butt ribs) .

I feel that even new 5/16" tygon tubing has too thin of wall thickness and easily collapses when bent.

I replaced it with heavy wall 5/16" rubber fuel line from Napa that you can almost tie it in a knot and it will resist collapsing.

I suggest you test the fuel line you use for how much it will bend before it starts to collapse.

I am tempted to remove some of the covering material and some rib material on my butt rib so I can monitor all of the  wing tank fuel line and could have reached up and prevented my dead stick landing by pinching the tygon so it would flow fuel.

 

I appreciate Doug bringing up the subject and hope that my experiences can prevent a possible tragedy.

We had an Avid go down here a year ago due to fuel tank venting issues and it will never fly again so I feel lucky and blessed with my 2 dead sticks.

 

Herman

[Guest]

I believe the reason for the high Avid 582 failure rate is that Avid ran the engine inverted whereas kitfox did not. Since oil and gas are mixed in two strokes it makes sense that they can be operated in any position. However, I discovered when tearing apart my 582's that there is an oil collection "funnel" built into the block that feeds the bearings when the engine is operated right side up. This collection funnel does not function with the engine operated inverted. If it wasn't necessary, or at least a good idea, I doubt Rotax would have built it into the engine. That said, I flew 1250 hours behind 582's in my MKIV and never had a bearing failure lead to a forced landing. However at around 660 hours on one engine I was doing a preflight and while pulling the prop through, I heard a funny rattle. I was nervous so took the engine out and tore it down. On the end of the crank with two bearings, one of the bearing's plastic ball retainer had broken apart and become all balled up between the two bearings. This left all of the balls in one of the bearings bunched together in the bottom of the bearing. When I hand turned the prop some of the balls had rolled up over the top and clinked down to hit the others. That was the noise I had heard. Once I made the discovery, I looked back and had thought the engine was making just a bit more noise recently, but wasn't sure. The balls in the bearing with the failed retainer still looked perfect, so I had caught it early. I think I was very lucky that time. Since there was a second bearing and the balls in the one without the retainer probably evened out at high speed, it might have run for a while or it may have grenaded on the next flight. 

[Guest]

Here's my engine outs.

 

 First engine out was in my MKIV. Was just finishing up after a maintenance engine swap. I had two 582's and would just swap when heavy maintenance was scheduled. A pilot friend came over and asked if he could help. I asked him to finish up the plugs and safety wire the caps. He did a great job safety wiring the caps on while I finished up other stuff on the plane. I took it out for the first flight with the newly maintained engine. I landed at a favorite secret spot and was relishing in flying again. When I took off to head home, the engine got super noisy like a big fart and lost all power. I was 10 feet off the road I had taken off from. Fortunately it was long and straight and I uneventfully landed straight ahead. When I removed the cowl one of the plugs was hanging by the safety wire. It had come unscrewed. My friend had not tightened the plugs I had hand threaded in! Lesson: make sure tasks are CLEARLY communicated. I carry a small tool kit and was able to reinstall the blown plug, tighten all the others and fly home without further incident.

 

Second engine out was in my Magnum. I had about 50 total hours on it, had just completed the FAA fly off period and had  a very successful flight to the Arlington Fly-in. I had developed enough confidence to take it on it's first water crossing. I flew from Tri Cities to Seattle in beautiful conditions and had just crossed between Paine Field and Whidbey  Island on my way to celebrate my then girlfriend's birthday at a music festival in Port Townsend. I had a GPS waypoint on the small grass airstrip on the south of Whidbey on my way to my destination at Port Townsend. My girlfriend at the time saw the little airstrip strip so I headed towards the next water crossing and Port Townsend. Just then the engine quit. I was at about 4500 feet. I remembered the airstrip and turned to spot it and began slowly circling down. Went through as much trouble shooting as I could while circling down, but could never get the engine to run above an idle and even then it would quit then start from prop turn, then quit, then start etc. Fortunately the grass airstrip was almost directly underneath when the engine quit and other than soiled pants, that landing too was uneventful. However my girlfriend eventually broke up with me as a result. The builder of my Magnum had installed fuel filters right at the tank outlets which I now know should NEVER be done under any circumstances because there is no pressure head to push fuel through and even a mildly clogged filter. Especially on a gravity fed system like the Magnum! I removed the filters and all was fine. The plane still had the header tanks and gascolator with screen which is all that is needed. I consider myself EXTREMELY lucky to have walked away from that one because Whidbey Island is all trees and is surrounded by water. I still marvel at that. I were a more religious manI would say God had a big hand in it!

 

Those are the two engine outs I have had in 1750 hours of flying experimental planes. I wish it had been none. The Whidbey Island one in particular had the most profound effect on me of anything in my flying career including wrecking my Magnum in a bad landing. If you're already on the ground and in trouble chances are you will survive. If I had been one or two miles either side of that little airstrip when the engine quit in my Magnum. I might very well not be alive and would have taken someone with me. Very sobering.

 

Chris