"Failing" an airworthiness inspection...

[Frank Giger]

I'm involved in a long thread on another forum about what to expect when one's project is about to be signed off as an airplane - a fellow has a gorgeous aircraft that is simply a work of art, with loads of attention to detail and strict adherence to "best practices" and is a bit nervous about it.

I reminded him that the inspection is one focused on completeness and administrative compliance rather than "airworthiness," and he had nothing to worry about, along with some common sense advice (have all the paperwork pre-screened for completeness, have everything laid out for inspection, don't volunteer information, and don't argue!).

In my case, the FAA inspector wanted me to put slip marks on the case nuts on the VW. I didn't argue, I just did it on the spot to make him happy.

Anyhow, I made the remark on how I don't see how anyone could be refused to be signed off, only to be told it happens more often than one realizes, and it's made me curious.

So can y'all give me examples of a project remaining a project after inspection, and why?

[rwanttaja]

I wasn't given any specifics about it, but I met an FAA guy at Oshkosh two weeks ago that told me there was a builder at his location who has been repeatedly turned down during his inspection. The guy has gone through all the local DARs, who refuse to meet with him any more, and now regularly schedules the FAA guys to come by....who also won't accept the airplane. No details, but it sounded like a "Home Depot Airplane" sort of thing.

So the FAA *does* reject airplanes, on occasion.

Ron Wanttaja

[Mel]

An amateur-built aircraft may be declined for airworthiness certificate if the aircraft does not meet the requirements of part 21.191(g), or anything the inspector feels is an unsafe condition. It's fairly rare, but it does happen. Since 1999, I've done over 900 certification inspections and have denied only 2. In one case, the builder had redesigned the door on a pressurized aircraft and I was not comfortable with his latching system. I denied the A/W. Months later another DAR signed off on it. A few months after that, the door came off in flight.
In most cases the inspector will give the applicant a discrepancy list and come back when it is corrected.

[Airmutt]

How does 21.191(g) effect airworthiness determination by a DAR? Doesn’t subject paragraph simply state one can apply for an experimental certificate if built for educational or recreational purposes? Not being a DAR, how do DARs make engineering/design evaluations on whether a design is airworthy or unsafe?
For example, if I build an aircraft out of carbon reinforced bubble gum, does the DAR have the right to demand stress and load calculations?? Always thought the DAR responsibility was to inspect fabrication not make design evaluations.

[rwanttaja]

How does 21.191(g) effect airworthiness determination by a DAR? Doesn’t subject paragraph simply state one can apply for an experimental certificate if built for educational or recreational purposes?
I think Mel was just saying that the aircraft can be denied an airworthiness certificate if it didn't meet the education/recreation aspect of (g), OR if he or she feels the aircraft is unsafe. Not that the Part 21 aspect was establishing whether the airplane was safe to fly.


Not being a DAR, how do DARs make engineering/design evaluations on whether a design is airworthy or unsafe?
For example, if I build an aircraft out of carbon reinforced bubble gum, does the DAR have the right to demand stress and load calculations?? Always thought the DAR responsibility was to inspect fabrication not make design evaluations.
I'd expect the DAR to question the builder closely if the plane has some unusual design features. They'd probably ask to see results of any static testing, and the reaction of the builder might indicate whether sufficient thought was put into design margins.

(e.g., "Yes, I loaded the wing with 20 sandbags...." vs. "What's a static test?")

If the response is the latter, I wouldn't be surprised if the DAR withheld approval....

Ron Wanttaja

[Mel]

How does 21.191(g) effect airworthiness determination by a DAR? Doesn’t subject paragraph simply state one can apply for an experimental certificate if built for educational or recreational purposes? Not being a DAR, how do DARs make engineering/design evaluations on whether a design is airworthy or unsafe?
For example, if I build an aircraft out of carbon reinforced bubble gum, does the DAR have the right to demand stress and load calculations?? Always thought the DAR responsibility was to inspect fabrication not make design evaluations.
21.191(g) stipulates that the aircraft is built for education or recreation. It also stipulates that the aircraft is 51% or greater amateur-built. If the applicant cannot answer specific questions about how a particular part of the aircraft was built, the inspector may suspicious of who really built the aircraft and were they paid to do so. 8130.2j specifically states that the inspector will determine if amateur-built status is valid. It also states that that determination will not be based solely on the basis of the 8130-12.
If you built the aircraft out of carbon reinforced bubble gum and cannot show stress and load calculations, the inspector has every right to deny the airworthiness certificate.
If you are denied airworthiness certificate, you have every right to seek another inspector. But realize that the next inspector will have been notified of the denial and the reason for it.
I promise you that no inspector is going to deny A/W certificate unless there's a pretty good reason. Our goal is to get aircraft flying, not to deny them.

[Frank Giger]

I promise you that no inspector is going to deny A/W certificate unless there's a pretty good reason. Our goal is to get aircraft flying, not to deny them.

Thanks for validating what I "knew" about inspections!

I've read the phrase "Home Depot Airplane" a few times in different places but can't really imagine what that would mean, other than perhaps something that is grossly overweight and not really in the shape of a reasonable aircraft.

I'm betting that just about anyone who has built a working aircraft could use nothing but the items in a Home Depot and make a simple light aircraft that would fly safely.

[edit]

Maybe a bit of cheating by buying some ceconite. And a VW engine.

[rwanttaja]

Thanks for validating what I "knew" about inspections!

I've read the phrase "Home Depot Airplane" a few times in different places but can't really imagine what that would mean, other than perhaps something that is grossly overweight and not really in the shape of a reasonable aircraft.

I'm betting that just about anyone who has built a working aircraft could use nothing but the items in a Home Depot and make a simple light aircraft that would fly safely.
To me, the term implies a departure from aircraft building standards, and use of building practices that hold together at 1G with no clue as to the actual stresses the part may need to withstand. Leads to stuff like using sheet-metal screws instead of bolts.

And, as you say, making the plane grossly overweight by using, say, 3/4" plywood where 1/8" is adequate.

In any case, photoshop helps.....

https://cdn.instructables.com/F6O/UXM3/J839RIZ9/F6OUXM3J839RIZ9.LARGE.jpg

Ron Wanttaja

[Airmutt]

So DARs are also responsible to ensure the the EAB aircraft “complies with acceptable aeronautical standards and practices.” I always thought that applied more to the fabrication of the aircraft than the design of it.

Is it really in a DAR’s wheelhouse to evaluate the design? For example, a builder installs an autopilot.....Did the applicant establish any AP operating limits? If no, is it fair game to ask the applicant for the analysis demonstrating that the servo’s authority can not create a structural overload in the event of an autopilot hard over throughout the aircraft’s operating envelope? Based on comments in the thread then AW could be denied!?!?!

[Joda]

Is it really in a DAR’s wheelhouse to evaluate the design? For example, a builder installs an autopilot.....Did the applicant establish any AP operating limits? If no, is it fair game to ask the applicant for the analysis demonstrating that the servo’s authority can not create a structural overload in the event of an autopilot hard over throughout the aircraft’s operating envelope? Based on comments in the thread then AW could be denied!?!?!

I can only speak for myself and how my FAA office works. I am no aeronautical engineer or aircraft designer. I'm a mechanic and a pilot. I also have an extensive background in EAA and experimental aircraft. I understand that these aircraft are "experiments" and can sometimes diverge from what traditional mechanics may view as "standard aircraft practices". The key for me is that I never make a decision on denying a certificate in a vacuum. If I think something doesn't smell right, I will elevate the decision to my FAA advisor for guidance. I will make sure to have his guidance in writing as to how to proceed, and we will make the decision collaboratively. As has been said previously, our wish is to have more aircraft flying. We are not out looking for ways to deny certification.

[Airmutt]

Joe, not saying DARs look for a way to ground aircraft. And I truly respect that it’s a tough job to protect someone from themselves especially when a lot of time money and effort has been invested in a project.
However for new or highly modified designs, I think the FAA or EAA could establish guidelines as to what may be asked of them. I think this would benefit both the applicant & DAR communities and improve standardization in the process.
Just one guy’s opinion.

[Frank Giger]

Dave, I reckon that would be a very bad thing, as a set of concrete guidelines are the exact opposite of permissiveness.

I was reading about some of Glen Curtiss' aircraft, including the use of bamboo as longerons to hold the tail in a pusher design. Indeed, when the aircraft was replicated, the guy doing so cheated and put metal tubing inside of them for added strength, as he was a bit nervous about a proven design and material.

However, if one did that today - made a very lightweight aircraft and used bamboo for longerons - it would probably be signed off on. Maybe with some questions, but I don't see how it wouldn't be (especially since it's been done before).

I reckon the stuff that would get a no are things we can't really comprehend someone doing, such as securing said bamboo with cellophane tape to the rest of the fuselage, or securing the engine to the firewall with bailing wire.

However, looking at some oddly specific warnings on various products and places I don't put much past people.