Jan. 10, 2016
Shortly after takeoff on its first flight, the airplane’s engine experienced a total power loss and the pilot initiated a descending left turn in order to avoid an airport fence. Subsequently, the airplane impacted terrain in a nose-down attitude with the left wing low.
An examination of the engine revealed that the “Force One Main Bearing” seized to the crankshaft. Further, there were multiple circular impressions on the bearing surface. Based on this evidence, it is likely that while building the experimental engine, the pilot did not properly align the Force One main bearing, and the oil feed hole was inadvertently used as the dowel pin hole. This mistake resulted in a blockage of the oil transfer hole, preventing oil from entering the bearing, which led to the engine seizure and total power loss.
Was this engine not built by a certified engine shop? Was it not tested on a dynamometer prior to installation? Why wasn’t the overheating due to failure of the bearings not being lubricated discovered on fast taxi testing?
This accident would never have happened, had any of the above procedures been properly performed.
The VW-conversion engine was likely built from a kit by the homebuilder. Some of these engines come with instructions to avoid “excessive” ground running because people have overheated and damaged these engines trying to perfectly tune them with the airplane tied down (leading to insufficient cooling). It is possible that this builder took such advice to an unhealthy extreme; or its possible that the engine survived some short ground-runs without obvious signs of the damage that was occurring.
[Note that this also occurred a decade ago]
In the spirit of EAA, I built my IO-390 clone in an engine shop builder assist facility, so that I could thoroughly understand and be able to maintain it. After assembly, it was run on a dynamometer for three hours before mounting it to the airplane. I wish everyone had that opportunity.
That seems a pretty high-strung setup, if you can’t ground run the engine lest you overheat it!
Andrew – many aircraft have this issue. If you tie them down on the ramp and try to run the engine at high power settings for more than a few moments, they will overheat.
IMHO, asking an ‘amateur’ to build both the airframe and the engine (which I myself did with my Sonex) is asking a lot for a first-time builder. Even if they do a good job, you can expect the builder to be nervous and want to thoroughly check/verify things – like tuning the carb and tweaking the timing and checking fuel flow and such. Its easy for someone to obsess over those things and overdo it on the ground.
Sadly, as this accident may prove, its also possible to *under-do* it on the ground. As with so many things, a balanced approach is key!
Doesn’t look like the engine was too high strung then. Run it on the ground for a while but not at high power. Tuning the engine will require high power, so just don’t tune it. Fast taxis is still a ground run. Maybe the pilot did do a lot of fast taxis and was just unlucky. I know it looks like they didn’t do much fast taxying, but maybe they did.
Seems a poor design of the bearing that the dowel fits into the oil hole.
This is very true. A so-called latent error.