When I installed and started the engine for the first time I saw that engine coolant leaked badly. Bill Sherlock (a really good aircraft engine mechanic with credentials in the UK), found that this was attributed to a warped block. Jan initially assured me the engine was tested fully and the problems were mine until Bill Sherlock demonstrated with pictures (below) that the block was bad. This means the engine was not pre-tested. Jan replaced the engine and I had to spent many days removing, sending back, and then reinstalling the new engine. He did not offer to refund the approximate $18,000 for the engine and all the accessory parts so I was stuck with the Viking engine.

The warped head (note space under ruler)

After only 64 hours (probably only about 50 in the air, the spider linkage on the gearbox parted (picture below) while flying over mountainous terrain near Boonville Airport sending parts flying through the cowling and causing me to make a power-off landing with my fiancé aboard.  Several parts in the plane, in addition to the cowling were damaged as a result of the metal that flew off the spider at a high speed.


Eggenfellner / Viking sent new parts at no charge claiming he mistakenly had failed to weld original pins, which were only pressed onto the spider. However, the damage did not appear to be associated with pressed-on pins. I was assured new parts would not fail. Bill Sherlock and I changed out damaged gearbox, linkage, aluminum coolant tubes, and geared flywheel (which had all been damaged. New plumbing of the gearbox did not fit in old damaged cowling and ken Robbers, a Viking contractor now living in Oregon, modified cowl at Viking’s expense.

Broken spider and damaged gearbox

After 276 hours, the flywheel sent by Viking earlier failed
. The spider was bolted to the flywheel in a way that allowed the spider to come loose form the flywheel. This bolted-together flywheel/spider is in my hanger for inspection There is about 1/” play between flywheel and spider. Jan refused to replace the flywheel without charging me even though it was defective. (I think it was $200 or $300 for a new one-piece spider and flywheel). Note that where were no instructions at the time regarding how to make this replacement. Partially due to this Bill Sherlock and I put the rubber linkage on backwards so that the gearbox was being pushed by the linkage rather than being pulled.  Eggenfellner blamed this for the next spider failure.



Unknown date and engine hours (this was not put in engine log)
My engine monitors showed I was getting no electric charge before takeoff so I looked at the engine and discovered that a free spinning pulley supporting the engine alternator belt fell off while still on the ground. This occurred because Eggenfellner initially user the wrong size bearing on the pulley.


Viking never notified us that there was a known defect and when I questioned him about it he told me to look at a very obscure note he had placed on his website. We should have been notified individually. Viking Aircraft Engine Forum and website lacks consistent useable TSO information or consistent installation instructions (it is primarily a sales tool and there are no written installation manuals). The parts were readily available at an auto supply store. I don’t think Jan keeps track of that upgrades he has sols to any of his customers.



For all 305 hours to-date, that this engine had been using excessive oil and Eggenfellner suggested we remove his very fancy “Viking” aluminum cylinder head cover and replace it with the standard Honda Fit plastic cover, requiring an added an oil vent hose, which I did at a cost of several hundred dollars.



4/1/17 - 4/20/17
After 397 hours, one of the three pins on the spider that connects the rubber linkage once again broke, this time it occurred on takeoff causing engine coolant tube failure and coolant leakage.

Pin recovered after it broke off the spider

I made an emergency engine-off landing at Petaluma while coolant was covering the cowling and windshield. Jan made jest of the fact on the internet, mentioning me by name, announcing that I had put the rubber linkage on backwards. Note that the YouTube video instructions regarding how to put these on was not available until months after he sold me his replacement (see 2/12/16 paragraph). 


I was charged $1585 by Viking to inspect the gearbox and replace the spider. When I asked Jan how to put it on he told me and Bill Sherlock to follow his video instructions. This is all he told us. We followed the video religiously. The video said to use ¼” washers to extend the gearbox forward since the spider was thicker than the previous one. We did this and when I test flew the plane rubber started pealing of the rubber linkages in flight, the smell of which again requiring me to make an emergency landing.  This resulted from Eggenfellner thickening the spider linkage still further without telling us or providing thicker washers.


Here is a photo of the damage that required me to purchase a new rubber linkage from Viking (~$100).

Rubber shearing off linkage

Here is the email I sent to Jan on 4/20/17:

Hi Jan,

I hate to say it, but after installing the new rubber linkages that you sent, it now seems apparent that the problems with the last installation was Vikings doing.  Please hear me out.

Before removing the damaged rubber linkages, we measured how well centered the spider you sent was mounted. Measuring all three extensions, the ASP who did the measuring with a feeler gauge said It was less than 3-thousants off. So he told me that the centering we did, based upon your video, was adequate! Nevertheless, we did it over again when installing the new linkages.

Next we measured the thickness of the base of the old spider (it is 7/16th-inch) compared to that of the new one which is 5/8th-inch thick. We were surprised to find that the base of the new spider you sent was 3/16ths thicker than the old one.  The 1/4th-inch washers you provided, less the removal of the old 1/8th-inch washers only extended the transmission out 1/8th-inch. This meant that the space for rubber linkages was compressed 1/8th-inch. This compression caused the rubber linkages to disintegrate. We fixed it my adding back the original 1/8” thick washers to the 1/4th inch washers. This was not what you described in your video or in any of our communications.

I ran the engine for 15-minutes yesterday without any rubber shredding issues, but need to know if you think that the compression while running the engine for ½ hour while the rubber disintegrated last week caused any damage to the transmission.

I also think you should refund the charge for the second set of rubber linkages since you sent a spider that was 3/16ths-inches thicker that the last one while your video called for extending the transmission only 1/8th-inch to accommodate it without notifying me or modifying your installation procedures. (I’ll pay the $200 for the ASP).


On the phone call made to Jan around the 21th, Jan said gruffly that: ”… this is an experimental and I told you to check clearances” and would not respond to the issue regarding damage to the gearbox. I told him that he never asked us to check clearances, but he did tell me several times to follow the video, which was incorrect given the greater thickness of the spider. To me this sounds like failure to accept responsibility and disregard for the wellbeing of his customers.




With 417 hours on engine the linkage between the gear box and flywheel again failed (less than 20 hours since being replaced). This time it occurred over vineyards, with no safe place to land so the plane was destroyed. Attached find picture of the failed part, which caused a coolant line failure, which stopped the engine. Note the similarity to the failure that occurred in September 2014, which we were told had been addressed by Viking.

Base of spider spit and pins holding rubber linkage missing

Destroyed N422ES Zenith CH 701 upon rolling into a ditch after touchdown

Destroyed N422ES Zenith CH 701 upon rolling into a ditch after touchdown

I don’t think I need to say more about the lack of QC and engineering capability demonstrated by Viking here.