Bullet Proof?

While chasing that philosopher's stone of general aviation, the "bullet proof" piston engine, I ran across this stimulating post on aircraft engine reliability.

Based on the data posted, I estimated the fleet-wide odds.  Over a 25 year period this is the rough-order-of-magnitude fraction of aircraft engines (including automobile engine conversions) that experienced catastrophic in-flight failure:

Lycoming:         1 in 1000
VW:                  1 in 120
Ford/Subaru:     1 in 30
Mazda:              2 out of 3
Chevy:              4 failures each

This is based on actual NTSB accident investigations back to 1985, compared to aircraft fleet sizes currently registered (as of 2009).

The truth is probably significantly worse for the Subaru/Mazda because there were very few flying before 15 years ago or so.  People have been flying behind Fords since the 1930s (Model A) and the VWs since the 1970s and maybe earlier.  Chevy enthusiasts have been trying to fly the "big block" engines but most have been using the Corvair.  I am disappointed the Mazda engines did so poorly here, because I had/have high hopes for the Wankel (rotary) engine.

The VW conversions actually come out looking pretty good.  The Aerovee slated for use in our Sonex probably does better than above because the data includes ALL Volkswagen derivatives.

The poor record of the Chevy conversions may be slightly overstated, but then again maybe not, because if the author's data is to be believed, apparently there are currently NONE registered (I cheated and divided by one).  The first thought that springs to mind is that they all must have crashed or scrapped!

As a postscript, I will add that the engines that I found most often mentioned as "bullet proof" are the Lycoming O-235 and O-360.  That's encouraging news for our Bearhawk, which sports the latter.

Bearhawk CD

Got a package from Russ Erb today.  Hopefully it's more than just the back issues of Trials & Tribulations.  Oops, I mean "Beartracks."

Bearhawk Discussion Group

While the Bearhawk might seem to be on the more experimental side of the experimental airplane spectrum, that's not always a bad thing.

Yahoo's aptly named Bearhawk support group is a great resource. I mean, where else can you find people telling you how to position your pitot tube, put skis on your plane, and land it? Yeah, I thought so. I've been getting the daily emails, but really need to delve into the old messages.

One of our concerns is the fact that we need to find out what revisions have been made between the time this plane was originally worked on, and now. The people in that group are really helpful and intelligent, which is what we'll need to have on our side in the coming months...

Torrance Fire Department

Should be satisified with our hangar's new fire extinguisher: 2A-10BC rated.  $30 at Lowe's.

Jig Planning

Took measurements today for the wing installation jigs.

Where to start?

It's taking a while to absorb everything about the Bearhawk. Up until a few months ago, the Sonex was at the forefront, so all of my focus was on learning about a small aluminum plane. Catching up on the Bearhawk has been quite the challenge, with so many sources of information (the fairly simple plans, actual manuals, magazines, forums, and so on...). There's a sort of DIY/Wild West mentality about the Bearhawk vs. the structured factory plans that come with the Sonex. I guess that embraces the experimental nature of this plane. And with the changes made by the original builder of this one, it makes it that much more...interesting.

A few observations from what I've looked at so far:

1) The mods we were planning on making are probably a great idea, because they will get us that much more insight into the current structure.

2) We'll need to do a lot of material inspection and measuring to ensure that this thing ends up solid but not overweight.

3) One mod we discussed (large access panel on the empennage) is in the builder's manual, so I don't feel so guilty about the damage I did to the fabric during the horizontal stabilizer removal. Knowing that, I probably could have removed the four final screws in something less than the four hours it actually took me while lying on the ground in -6 F winter weather.

Next up we'll come up with a good plan of attack, and then systematically improve and complete the plane.

Manuals are Here

Just downloaded Eric Newton's Bearhawk builder manuals.  I already had the Fuselage volume, but Don plumped for the Wings and Finishing volumes.

Naturally, I am starting with Finishing.

My end of the bargain is to order Russ Erb's Bearhawk data CD.  Lisa will do it for me, since she actually has a PayPal account.

Cabin Configuration

We're not planning on using these Cessna 152 seats, but they're kinda useful for trying out seating scenarios.

Hands Clean For Now

We are WAY ahead of where we ever thought we'd be with a Bearhawk by now.  So far ahead that we really don't know what to do next!  I have not been able to meet my goal of getting my hands dirty every day with AIRPLANE BUILD, because I simply don't know what to work on.

Hence, there will be a period of "hands clean" progress (studying, reading, learning new skills), but I will still try to get my hands dirty as often as I can.