Tool Tech: Does That Bolt Need a Washer?

Do all bolts need washers? Usually, only two factors are involved. Is the hole oversized, and is the bolt configured to work without the washer?

Turn the bolt over and look at the underside.

The first one on the left is simply flat. Number two is an AN bolt and has an area that acts as a washer. The third one has an enlarged surface, and the fourth has a separate, permanently attached washer. Only the first one must have a washer. The second one, does not require one, the third one has a washer built in, and that last one has a permanently attached washer.

Only the second one should be used on aircraft, though, as it’s the only one whose manufacture is fully pedigreed.

AC 43-13 section 7 allows you to skip the use of washer under an AN bolt. But a few AD's do, at times, require washers under both the bolt and the nut.

If you’d like to read further on this topic and don’t have a copy of AC 43-13 beside your bed, you can download it HERE.

Products: Castleberry Attitude Indicator

Aircraft Spruce & Specialty is now carrying the Castleberry Instruments & Avionics attitude indicator, which is an approved substitute for the previously mandated rate of turn indicators in Part 23 aircraft operating in Part 91 and less than 12,500 pounds. (This substitution is based upon the FAA Advisory Circular AC91-75, which promotes the installation of a backup attitude indicator.) But, even better, it's a suitable backup for Experimentals with glass panels.

The internally lighted electric attitude indicator replaces the turn and bank and is a straightforward installation in the same panel location, according to AC Spruce. It will fit a standard 3.125-inch instrument mount; the erecting knob passes through one of the mounting holes. The unit has a standard inclinometer and a failure warning flag to indicate loss of gyro rpm. When used with the Castleberry Emergency Power Unit (Model EPU 28-24RMT), this instrument offers a margin of insurance in case of an aircraft electrical power failure.

The Castleberry AI is available in either 14 volt (P/N 10-02823) or 28 volt (P/N 10-02824) and sells for $2095; the Emergency Power Supply (P/N 11-05822) is $1685. Both units may be purchased online at Aircraft Spruce & Specialty.

Commentary: Experimental "51%" solutions—is Primary Category the answer?

In February, when the FAA published the final report from the working group looking at “major portion” guidance, another proposal was floated to help manage what the feds believe is “excessive” use of commercial assistance in Experimental/Amateur-Built aircraft. That proposal centered on the Primary Category, a subset of certification rules introduced in the 1980s as a way to break an economic logjam in production aircraft.

In fact, the EAA and AOPA jointly proposed the category in 1984 because of two principal factors: Production aircraft were on the ropes, victims of an economic slowdown and ever tightening certification and production regulations, and kitbuilts were hot. Many people believed, at the time, that certified designs based on homebuilts could rid the land of boring Cessnas and pudgy Pipers, and all would be well. (Didn’t happen, but we’re getting ahead of the story.)

The Primary Category concept, much like what we have in Light Sport, was to reset certification and production approval standards in recognition of the fact that a simple, four-place airplane need not be certified to the same standard as transport aircraft. (This is, on the face of it, accepted among the more pragmatic builders and pilots I know, but is apparently difficult for regulators to grasp.)

As originally drafted, the Primary Category was limited to single-engine, non-pressurized aircraft weighing 2500 pounds or less with 200 or fewer horsepower. Your basic quasi Cessna 172, in other words, but not a 182. Or a Cirrus. Or, more central to our concerns, an RV-10.

But the EAA provided feedback and the FAA took the surprising step of reopening the comment period in 1991. Among the changes were to bump maximum weight to 2700 pounds and, to keep stall speeds in check, to specify a maximum landing-configuration stall of 61 knots, the same limit imposed on CAR3 and FAR Part 23 single-engine aircraft. Originally, the 2500-pound/200-hp limitation would take care of the whole wing-area argument. If you limited power, the designer would have to provide enough wing to have acceptable climb performance. The specter of mini wings and high stall speeds would remain locked in the basement.

Instead, industry managed to convince the FAA that an equivalent level of safety could be found by limiting stall speed, which returned the possibility of good performance using more than 200 hp. The other main limitations were that the engine not be turbo- or supercharged, nor could the cabin be pressurized.

By the time the rule was finally implemented in 1993—nearly a decade after the initial proposal—the industry was beginning to rebound and interest in alternative certification means was waning. Homebuilt Experimentals continued to grow, and the few companies with the wherewithal to pursue certification realized there wasn’t quite enough of a market there to justify the costs. Quicksilver certified the GT-500 as a Primary Category aircraft and sold almost none. At the time, the category was a bust.

But how about today? Could, as the Aviation Rulemaking Committee suggests, Primary Category be the bridge between super-fast-build Experimentals and the turnkey (but noncertified) aircraft the market seems to demand? Is the so-far good record of LSA enough to make it viable?

Dick VanGrunsven thinks so. “I think there’s a lot of merit here,” he says. “We would definitely look at the category.” According to the Van’s Aircraft founder, the certification process could be simplified to follow the ASTM-formed process that underpins Light Sport aircraft. “It would cost us money to prove our aircraft met the rules,” VanGrunsven says. “But we think we would make it back. We could develop new kinds of quickbuild kits. With Primary, the whole ‘major portion’ goes out the window. We could even produce airplanes ourselves.” Conspiracy theorists might note that the RV-10 seems to fit the category to a T: It’s right at the maximum weight, can make the stall speed requirement, and uses a normally aspirated engine. But there are many worthy designs that clear the limbo pole with headroom to spare; and they make up the bulk of the volume in our world, if not the majority of the money spent.

Sure, but what of the high-end pressurized turboprops that are also in demand? By the definition of Primary Category, they’d be out of luck, too big, too complex to be certified this way. Indeed, the only way for these aircraft to survive a comprehensive makeover of the “major portion” guidance would be to backtrack on what is provided in the kits—moving a significant portion of the work back to the builder—and, perhaps, to recast the way commercial builder assistance is applied to the project. (Meaning: You can actually take one home and build it.)

Where will this all land? That’s the question on the lips of many in the industry. The worry is that Primary Category is going to be used as the passageway for highly complete kits to be sold and built (and receive approval) while the screws are turned on both quickbuild kits and commercial assistance. A way, in essence, for the feds to say, “Look, we’re not putting you out of business,” while creating a huge gap: much less complete kits on one side and much more expensive quasi-production aircraft on the other. There’s great potential for the legitimate builder to get squeezed out of the middle as the FAA struggles to put clamps on the abusers.

—Marc Cook, editor in chief, KITPLANES

You Don’t Need a Weatherman to Know Which Way the Wind Blows

Yes, you do, if you’re going to fly safely. And while there are a lot of websites out there that give you all the information you need, some of them are buried in advertising or not reliably updated.

One that suffers neither of these flaws comes from our own gummint. Yes, the National Oceanographic and Atmospheric Administration have a wonderfully complete and up to date plethora of pages on the subject.

When you’re done here, browse over to and click on your area of interest on the map. Down the left you’ll find a matrix of times and weather parameters. You can easily kill an hour just watching the predicted changes. This series will become a favorite if you're headed out for lunch in that it shows ground conditions. If you're going further, you'll also find links to pages specifically for aviation. As for those other sites? This is where they get their data.

NOAA needs to work on the name though; "Administration" at the end of it implies control of said oceans and atmosphere and that’s a long way off.

News: On Changes to 51% Rule Guidance, VanGrunsven “Cautiously optimistic.”

Among the current kit manufacturers, Van’s Aircraft is indisputably the volume leader. Nearly 5600 RVs are flying, and like all other kit manufacturers, the company has a lot to lose if the guidance behind approval of kitbuilt airplanes becomes significantly stricter. But founder Dick VanGrunsven was, in an interview Friday, concerned but far from panicky. In fact, he is “cautiously optimistic” about the overall picture for homebuilts, which includes the potential for certification under the Primary category.

But for now, VanGrunsven is focusing on the short term, rallying builders and pilots of all Experimental/Amateur-Built aircraft to contact the FAA in support of the existing rule structure. “We need to get the word out,” he said, “so builders can write the FAA. We need to prove that what we have now [in quickbuild kits] is good and that builders benefit. Pilots and builders have a big part to play. Potentially, it’s the best thing we can do right now.”

He is concerned that changes to the rules “could be disastrous” if taken to the extreme. “We have had similar FAA meetings before, where little change resulted. And we thought this round was more about fine-tuning the certain regulations and directives. We spent a lot of time debating ‘shall’ or ‘must,’ but we were surprised where it went, regarding the compliance checklist.”

In the final report released on Feb 15, the FAA said that it was in agreement with several proposals offered by the Amateur-Built Aircraft Aviation Rulemaking Committee to reduce "excessive" commercial builder assistance, but could not reach consensus on ways to determine who gets credit for fabrication and assembly among the kit manufacturer, commercial assistance and the builder of record. In the report, the FAA gave little to no hint on how the new guidance would be written. “But indications are that the checklist [the 8000-38 form] will get tighter,” VanGrunsven said.

Considering the ways new rules might alter the makeup of quickbuild kits as we know them, VanGrunsven said, “The best case is that the quickbuild kits will become a bit more basic, maybe putting 10-20% back onto the builder. We could do that and still have a reasonably attractive product. Over the years, FAA-accepted rules interpretations have permitted quckbuild kits to evolve as they have, benefiting both builders and kit companies. Our job will be to convince the FAA that the way the industry has evolved [in terms of the quickbuild kits themselves] is generally favorable."

According to VanGrunsven, "Our objective was to stay as close as possible to the current rules. In our initial proposal, we wanted to look at a couple of current quickbuild kits and create a new checklist from that. Now it looks like the FAA is going to create the new checklist first and then see how it fits the actual kits."

In the meantime, as the industry waits for the FAA to publish a draft of the revised Advisory Circulars, builders can continue their work with a clear conscience. "If you're now building a 51% rule compliant kit, there's no problem. The old rules still apply," VanGrunsven confirmed.

One reason for VanGrunsven's moderated optimism is the hope that the Primary category could be used to alleviate the stress. "With Primary, all the rules change. The 'major portion' rule goes out the window. Getting the FAA to look at this as an alternative is a legitimate possibility," he said.

Check back this week for more analysis on the Primary category.

Update: Dan Parker's Altitude Attempt

KITPLANES readers will recall a recent article about Dan Parker and his High Flyer (January 2008 issue). He is in the process of designing and building an aircraft that he hopes will set a new world record of 31,051 feet for aircraft with a takeoff weight of less than 300kg.

Dan has informed us that he's made that milestone of attaching the wings and is hoping to fly it this Spring from an airport in Northern California. The requirement is that he has to take off with no external assistance such as a tow, and land with all the parts he had on take off, meaning he can’t drop the wheels or throw out oxygen bottles.

We’ll be watching this closely and reporting the flight. To see details of the aircraft go to Dan's website.