FAR Part 23 Rewrite

[Tim M]

Now that spin recovery is no longer required under 14 CFR 23.2150 for airplanes such as the DA40, is there a way to get FAA approval to allow operating a DA40 with 50-gal tanks with a CG limit of 102.0"? Could a FSDO provide a field approval for an amendment to the operating limits in the AFM?

[CFIDave]

While the new Part 23 may no longer require demonstration of spin recovery, it includes 23.2150 that gives aircraft manufacturers the flexibility to create alternate means to prevent "departure from controlled flight."

A DA40 with extended range (50 gal.) tanks has the issue that it might not recover from a spin within only 1 turn (due to a higher polar moment of inertia, caused by more fuel weight out near the wingtips). So to meet the new 23.2150, the FAA might permit the airframe manufacturer to instead demonstrate some new capability (e.g., a stability augmentation system attached to the flight controls?) that keeps the plane from ever entering a spin in the first place. Aircraft manufacturers will still have to publish weight and balance limits in their aircraft flight manuals.

Bottom line: I doubt you could get FAA approval to simply ignore an aft CG limit that's there to help prevent "departure from controlled flight."

[Tim M]

Under 23.2150 the DA40 (all variants) would no longer have to demonstrate spin recovery. The new regulation only requires that the airplane be resistant to departure from controlled flight. Since the DA40s with 40-gal tanks have demonstrated that with a 102.0" aft CG limit, I'm thinking that the same flight test data could be used to show compliance with the new 23.2150 for those equipped with 50-gal tanks. I contacted our local FSDO with the question and they suggest that an STC would be the most efficient way to go.

I've sent the inquiry to Diamond Customer Service in the hope that it will eventually find its way up the DAI fod chain to engineering.

Next stop is the ACO that issued the Type Certificate (Kansas City).

[CFIDave]

Here's my understanding: The DA40-180 Type Certificate is currently held by Diamond Austria, which originally certified the plane with EASA. Because there's a reciprocal agreement between the FAA and EASA that each organization will generally recognize aircraft certification approved by the other, there are separate (but roughly equal) TCs for the DA40 issued by both EASA and the FAA. (The same is true for the DA42/DA62 models.)

There is also supposedly an effort right now to move DA40 TC ownership from Diamond Austria to Diamond Canada, since all DA40 production (including the NG) is being shifted to Canada. This will let Diamond Canada control the "destiny" of the DA40 going forward.

[Tim M]

Even though Diamond Austria is the TC owner, we could still get an STC from the FAA. The major hurdle would be obtaining the data from the original analytics and flight tests to show compliance with the new FAR 23.2150. If the factory is not interested in ownership of the STC, we could try to do it on our own and then try to recover the costs by selling it to anyone (including the factory for new production airplanes) who wants the 102.0" limit.

This whole TC and STC thing reminds me of the patent process, only with no expiration. Maybe instead of filing for patents all these years I should have been doing STCs .

[Tim M]

Talked to a program manager at the Ft-Worth ACO. If data exists from the original certification that would show compliance with FAR 23.2100 "Weight and center of gravity", the ACO would entertain the application.

[Antoine]

Don't give up Tim - great idea.

[TJS]

I would be interested in the outcome of your efforts. It would make a difference for me in my plane. I would like to know what the consensus is in this group on flying in the 102.0 envelope in the extended tank da40s. I personally have not tried as I have owned my plane for just a year now and only now getting quite comfortable in it . I only have 350 hrs with 4 years of experience and don't feel the need to "push my luck", but I would be interested in hearing other peoples thoughts. I know a lot of pilots are ok with flying over weight but not out of their envelope.
Let me know if there is anything I could do on the Canadian side that may help your cause. I will be at the factory in the next week or two.

[Tim M]

OK, here's what the FAA Aircraft Certification Office has to say:

If you feel that you can make a similarity argument with respect to the standard tank configuration, then this may be a fairly straight forward project.

What I would suggest is that you make application for an STC and provide a project specific certification plan (PSCP). I would include a rational argument as part of the PSCP to address how this can be done. We will probably require some flight testing and of course your argument will be helpful in making that determination.

Or, if Diamond will provide data and we agree with their data, this could be a very simple project. But, we may still require flight testing.

If you have any questions, feel free to call.