Builder's Fatal Mistakes

[Bill Greenwood]

People often do a homebuilt to save money, but also to have something they made and often the creative side wants to customize or personalize a plane.
But CAUTION, any changes from a proven and tested design, can be dangerous.
Here are two cases.
I was minor partner in building a Starlite, the single seat predecessor of the Pulsar. It was a cool little design, single seat, low wing, glass fuselage, mostly wood wings, Rotax 2 stroke engine, bubble canopy, and sleek look, and 254 lbs and 130 mph speed.

There were fatal accidents, both caused by builder mistakes.

When the NTSB called Mark, the designer, he could scarcely believe what they found. The wing spar is a beautiful piece of spruce or fir, about 1 in by 4 in, several feet long, knot free and very strong, in one direction. It goes in the wing on edge so the main strength is to resist the bending stresses up and down, thus the full widest part is taking most of the stress. To bolt the wing onto the fuselage there is a bushing about an inch in diameter that is inserted in the spar near the inner end, and the attaching bolt goes through this bushing. Now, the hole in the spar for this bushing would weaken the spar somewhat,so the correct method is to wrap the inner end of the spar in 6 layers of fiberglass and epoxy around the spar and the result is very strong, and keepS the spar intact.

Mark could not imagine until he actually saw the wreckage, but the builder had not put ANY wrap on the spar at all. The plane flew ok for a few hours, but the bushing was working in the hole in the spar, and soon caused the spar to split and fail and of course the wing to come off.
WHAT DO YOU THINK THE DESIGNER WOULD HAVE TOLD THE BUILDER IF HE HAD ONLY ASKED? What the builder completely left out was one of the most critical steps of the job. He did not not survive so couldn't be asked what he was thinking.

Next the horizontal stabilizer sllides through a slot into the fuselage. It also has some epoxy or a wrap or some type of reinforcement, ( I can't recall for sure). The problem is that the fit is snug,and you have to get the stab all the way in in order to hook up the controls; so that each time you slide in some of the epoxy is squeegeed off when you slide the part into the fuselage slot. The builder put some epoxy on the part, but then slid it in and out several times to get it to fit so that the epoxy was mostly wiped off the part and did not do it's job, and the horizontal tail was not secure in the fuselage. This error is a little less glaring than that above and not as easily seen as the wing wrap.

The designer was actually test flying one plane for the owner, ( may have been this one) at Sun N Fun when it failed, and he was saved by his parachute.

So if you want to make any changes in a kit or plans, ASK THE DESIGNER. He may say no to cover his potential liability, or he may say yes or maybe, but you may avoid a serious mistake, and as least understand what you are getting into.

[1600vw]

When did these accidents happen?

May I ask why keep the weight to 254 lbs but have a speed of 130 mph? You are outside of the Far 103 rule with the speed so why not up the weight?

Tony

[martymayes]

When did these accidents happen?

1980's.

May I ask why keep the weight to 254 lbs but have a speed of 130 mph? You are outside of the Far 103 rule with the speed so why not up the weight?

In airplane design, indiscriminate adding of weight can have adverse effects due to the various flight and ground loads on the vehicle. So while one may think they are making it stronger, it may actually be weaker.

The Starlite was essentially an LSA, decades ahead of the regulations. When properly built, it was tested and shown to have adequate strength. There have been many similar accidents from what Bill described, in most cases it's hard to say if the builder didn't understand the instructions, committed an error of omission, or purposely redesigned the structure, because they are no longer available for questioning.

[Bill Greenwood]

Tony, the Starlite was a design by Mark Brown in 1986. It was on the cover of KITPLANES magazine back then and maybe SPORT AVIATION. It was awarded best new design by EAA back then, late 80s I think, won EAA best kit or new design or whatever the title was.

It was and is a cool looking plane, a low wing monoplane.. It was a departure from some the basic low end designs of the past. With a small 2 cylinder Rotax 2 stroke, I think it had 40 hp.it was sort of a putt-putt power wise. but unlike something like a Pitenpol, it was very streamlined and fast looking. Look up the photos on Google. And it was fast, it would run off from a C150 or 172, It may have only had 40 hp, but it was so light and so streamlined that it would take off in a few hundred feet even here at 8000 ft elevation in Aspen. I think it weighed about 254, can't recall exactly. This was long before any LSA regs or specs. It seems to me that originally VNE was set at 150 mph and wide open I got close to that figure. I have no doubt that in a dive it could easily exceed that. After an accident or 2, the designer said that VNE should be lowered to, I think 120 moh, and that was not a problem for me in cruise as that is indicated airspeed rather than true airspeed and flying here at 9000 feet indicated will be perhaps 20 mph lower than true. That little thing could move, had no trouble topping 120 true when run wide open.

It is small, I was 5'10", in ski racer shape, Mark was smaller. I guess he fit in it ok, but it was tight for me. I hadn't thought about having space for a parachute when we first started building it, and when I got ready to test fly it, I had to find a really small Nat 360 chute and it still was very tight. I wouldn't fly it without a chute. It had a side stick which I don't like since just like a Cirrus one doesn't immediately know where neutral is with a side stick, but it flew just fine. The 2 stroke engine worried us with the rattling noise at low speed but ran ok once you gave it the throttle. It did rev pretty high cruising up around 4000 or 5000 rpm , much different than a normal aircraft engine, cruising anywhere from 1800 to 2500. It was touchy on ground handling at slow taxi speeds with the tiny tailiwheel but when you gave it power it was off the ground so quick that this was no problem.
The last I read ours was in Michigan, I'd hope it is still flying and safely. My partner, the late Major Warner Giles built most of it, and was a great guy, and avid EAA member, who flew with me to a number of EAA events.