MOSAIC NPRM

[gyoung]

The ASTM consensus standards are the heart of the current LSA regs and MOSAIC just expands their application. They are far simpler for a manufacturer to deal with than FAR Part 23. This only applies to getting a new model certified. A manufacturer that wants to certify a new aircraft that fits in the expanded LSA rule could still choose to certify it using Part 23 but I can't imagine any doing so. ASTM is still a ponderous bureaucracy but is much more adaptable to the real world unlike FAA. It is a good thing for us. MOSAIC also expands which existing aircraft can be flown by Sport Pilots. Something like a C-172 that was certified under Part 23 or CAR 3/4 does not change its certification.

 

[talon167]

ASTM

The ASTM is an FAA accepted industry consensus standards. Basically FAA provides input and must approve changes.

The FAA does not evaluate or approve LSA manufacturer's kits.

A special airworthiness certificate in the light-sport category is issued to an aircraft that meets the definition of light-sport aircraft (LSA), is manufactured to the applicable FAA accepted consensus standards.

ASTM SLSA are not manufactured under a production certificate (PC) issued by or monitored by the FAA (no FAA review or oversight of QA).

Source:
https://www.faa.gov/sites/faa.gov/files/aircraft/gen_av/light_sport/LSA_Buyers_Guide_2019.pdf

Expansion Comment
But with the ASTM standards, the investments should be lower, the developmental times faster, capabilities higher and sticker prices lower.
Source: https://www.avweb.com/insider/light-sport-rule-v-2-0-a-qualified-step-forward/

Current chart of FAA accepted ASTM consensus standards for LSA
https://www.faa.gov/aircraft/gen_av/light_sport/StandardsChart

 

[Warp10]

Right from the preamble of the NPRM (emphasis mine):



And, this is how the rules already operate. Any aircraft meeting the performance requirements for an LSA can be flown by a sport pilot, or a "regular" pilot sans medical. The aircraft certification drives how it can be built, maintained, and used, not who can fly it.

Ok .. so the Sport Pilot rules now apply ( drivers license Med) to any AIRCRAFT that meats the MOSAIC definition of Light sport. Got that.

Lets discuss a real world example... Take a RV7A that has stall strips attached has demonstrated during Phase 1 that it stalls below 54K with flaps retracted...

This AIRCRAFT meets the Mosaic LSA rule.. but does AIRCRAFT really mean MODLE not an individual aircraft?

 

[FL Flier]

Ok .. so the Sport Pilot rules now apply ( drivers license Med) to any AIRCRAFT that meats the MOSAIC definition of Light sport. Got that.

Lets discuss a real world example... Take a RV7A that has stall strips attached has demonstrated during Phase 1 that it stalls below 54K with flaps retracted...

This AIRCRAFT meets the Mosaic LSA rule.. but does AIRCRAFT really mean MODLE not an individual aircraft?

Since each E-AB aircraft is unique, it shouldn’t be a problem. Although they probably followed the plans, it’s a given that a Joe Smith RV-7 and a Bob Jones RV-7 are not 100% identical. Heck, you could even follow the plans for an RV-7 exactly but call your plane a Skywolf Special.

 

[Jslow2]

What experimental has actual calibrated stall speeds?

 

[lr172]

Ok .. so the Sport Pilot rules now apply ( drivers license Med) to any AIRCRAFT that meats the MOSAIC definition of Light sport. Got that.

Lets discuss a real world example... Take a RV7A that has stall strips attached has demonstrated during Phase 1 that it stalls below 54K with flaps retracted...

This AIRCRAFT meets the Mosaic LSA rule.. but does AIRCRAFT really mean MODLE not an individual aircraft?

I think that is the big question. I don't think we will have an answer until we see a final rule and even then it still may be ambiguous. If that is the case, I would expect the EAA to leverage their relationship to get a formal clarification from the FAA. I would expect the FAA to want to use the kit mfr speed, but that breaks so many of their EAB rules that it doesn't seem realistic. Right now, the builder is considered the manufacturer and sets the speeds. That seems VERY clear. Question is do they tweak the current language to be something else to avoid builders from fudging the numbers to achieve a goal. Not hard to do; Just move the static port around until the airspeed reads low enough. I put some fences around my static port to get the airspeed to read correctly on my 6A at high speed and it changed my stall speeds.

 

[lr172]

What experimental has actual calibrated stall speeds?

I can't see any EAB builder buying or renting the equipment necessary to determine "actual" stall speeds, at least beyond Mike Vaccaro. I expect that 99.9% of all EABs have stall speed set as indicated. I just had to go through this with my son's DPE for his PPL. Guy wanted the CAS for my 6A and I had to explain why they don't exist in EAB.

 

[Warp10]

I think that is the big question. I don't think we will have an answer until we see a final rule and even then it still may be ambiguous. If that is the case, I would expect the EAA to leverage their relationship to get a formal clarification from the FAA. I would expect the FAA to want to use the kit mfr speed, but that breaks so many of their EAB rules that it doesn't seem realistic. Right now, the builder is considered the manufacturer and sets the speeds. That seems VERY clear. Question is do they tweak the current language to be something else to avoid builders from fudging the numbers to achieve a goal. Not hard to do; Just move the static port around until the airspeed reads low enough. I put some fences around my static port to get the airspeed to read correctly on my 6A at high speed and it changed my stall speeds.

I suspect I know the answer to this question, but here goes... The V1s speed is what the MOSAIC Light Spot aircraft is using. Does not seem to me that we have lots of crashes during level flight???? I would think that V speed in landing config would be more realistic? I think the answer is , that is what is in todays LSA aircraft.

 

[Ironflight]

I suspect I know the answer to this question, but here goes... The V1s speed is what the MOSAIC Light Spot aircraft is using. Does not seem to me that we have lots of crashes during level flight???? I would think that V speed in landing config would be more realistic? I think the answer is , that is what is in todays LSA aircraft.

Hate to tell you, but something like 30% of LOC accidents occurs during take-off, twice as many as during landing…..

 

[Warp10]

Hate to tell you, but something like 30% of LOC accidents occurs during take-off, twice as many as during landing…..

Ok.. makes sense ....Thanks...
I have sent a Comment to the FAA on Mosaic asking if vortex generators can be used to lower the clean stall speed so more aircraft can fit into the 54Kt clean stall. Seems to me that "No stall reduction devices allowed" should be modified. Any stall reduction device that is not adjustable by the pilot should be allowed.

 

[Warp10]

I can't see any EAB builder buying or renting the equipment necessary to determine "actual" stall speeds, at least beyond Mike Vaccaro. I expect that 99.9% of all EABs have stall speed set as indicated. I just had to go through this with my son's DPE for his PPL. Guy wanted the CAS for my 6A and I had to explain why they don't exist in EAB.

Huum CAS is IAS corrected for installation error ( of many airspeed sensing equipment???) and instrument error. How does one go about to find CAS?

 

[plehrke]

Huum CAS is IAS corrected for installation error ( of many airspeed sensing equipment???) and instrument error. How does one go about to find CAS?

You should have a curve created during phase 1 flight test that has calibrated airspeed as a function of indicated airspeed. It should look like attached.

To do it with a gps, fly 3 or 4 (depending on equation you use) headings at least 90 degrees apart and write down heading, indicated airspeed, indicated altitude, altimeter setting and OAT. Use equations to get true airspeed, use this website (or similar ) to get calibrated airspeed from true airspeed. Substract this calculated calibrated airspeed from the indicated airspeed to find error. Make plot of calibrated vs indicated.

 

[j4cbo]

Huum CAS is IAS corrected for installation error ( of many airspeed sensing equipment???) and instrument error. How does one go about to find CAS?

You can get CAS by going backwards from TAS. The "equivalent airspeed" is the middle step, and that's defined two ways: EAS is CAS corrected for compressibility (which is negligible at our far-subsonic speeds), but EAS is also TAS corrected for air density.

In other words, the translation layers are:

TAS <-(air density)-> EAS <-(compressibility)-> CAS <-(instrument error and installation error)-> IAS

I've always thought the "CAS is IAS corrected for installation error" definition, although standard, is silly. IAS is the literal number on the dial or screen, CAS is the value that the airspeed indicator is "trying to" measure. So instead of saying "CAS = IAS - error", I think it makes a lot more sense to say "IAS = CAS + error"...

 

[8s_Great]

Thoughts?

https://youtu.be/sveMP-yCrtI?feature=shared

These guys are the LSRM experts and I think involved in MOSAIC

 

[jrtens]

One data point - I would not have bought a Vans RV-12iS SLSA if the 15 day LSRM course was not available and I'm sure I'm not the only one.

Bottom line - if they mess with that course, SLSAs sales will go down.

 

[Warp10]

You should have a curve created during phase 1 flight test that has calibrated airspeed as a function of indicated airspeed. It should look like attached.

To do it with a gps, fly 3 or 4 (depending on equation you use) headings at least 90 degrees apart and write down heading, indicated airspeed, indicated altitude, altimeter setting and OAT. Use equations to get true airspeed, use this website (or similar ) to get calibrated airspeed from true airspeed. Substract this calculated calibrated airspeed from the indicated airspeed to find error. Make plot of calibrated vs indicated.

Yes .. To me this flying method seems to factor in the equipment errors in the system. I did this in Phase 1 and the CAS and IAS at or near clean stall was not and much different... At or around 5kts above stall, my RV7A would shudder and IAS bounced (so did altitude) so data was useless. My curve is not a straight line, unless I eyeball a straight line using best fit thru the points... Extending the straight line down from 65Kts down to 0 seems to be less than 1 Kt at the 50 to 60kts range.
I didn't do every 10kts, more like 20kts.. Use auto pilot with alt hold knob. My Static pitot system, has been tested every two years and has almost 0 leak down in 15mins every time.

Maybe my scatter plot needs some Statistical Analysis software to get a more accurate fit of my eyeball fit line. But Even with that .. I bet the difference between IAS and CAS will be very small around the 50 to 60 kt range.

 

[plehrke]

Maybe my scatter plot needs some Statistical Analysis software to get a more accurate fit of my eyeball fit line. But Even with that .. I bet the difference between IAS and CAS will be very small around the 50 to 60 kt range.

My flight data showed that I had only about 1 kt error at stall but about 10 kts at cruise. Here is my plot and I did fit a curve through my data.

 

[Warp10]

My flight data showed that I had only about 1 kt error at stall but about 10 kts at cruise. Here is my plot and I did fit a curve through my data.

It seems that the Vans Pitot tube and Static port is where the "Installation Error" would come from. At high angle of attack the airflow into the pitot is not parallel to the on coming airflow, causing a drop in Pitot pressure. Also turbulent air is now flowing over the static port too. Not having access to any of the CFD data I can only speculate is this will change the pressure at the Static Port also?????

To get a better picture of the real speed the aircraft just before stall I can think one experiment that my help find a major portion of the "installation Error" would be to design a Pitot tube that will be orientated so that at the stall angle of attack, the P tube normal to the airflow. This assumes that the static is unaffected by the turbulent air passing by it????

 

[rocketman1988]

Honestly

I honestly think that, for our aircraft, there is a bit of overthinking going on…

There is no perfect system; there will always be errors.

 

[plehrke]

CAS advantage

Getting back on topic to the NPRM, since it currently states stall speed as CAS, that may make a few more types meet the stall speed requirement since in my experience CAS is typically lower than IAS.

 

[grubbat]

Speed

It seems to me that once you get over 45 mph, it’s a moot point. Trying to decide whether it’s 50kts vs 54kts seems fruitless. If it based on some sort of safety window, then it’s got to be below 55mph. Otherwise there really shouldn’t be a limit. A stall at 90mph and one at 60mph will have similar outcomes. Heck, people are still stalling cubs and perishing. I never understood the speed thing in this deal.

 

[plehrke]

It seems to me that once you get over 45 mph, it’s a moot point. Trying to decide whether it’s 50kts vs 54kts seems fruitless. If it based on some sort of safety window, then it’s got to be below 55mph. Otherwise there really shouldn’t be a limit. A stall at 90mph and one at 60mph will have similar outcomes. Heck, people are still stalling cubs and perishing. I never understood the speed thing in this deal.

I agree and have tried to think of an alternative. I guess the overall goal is survivability of an incident on take-off and landing but that is really subjective and not measurable as it is a function of lots of stuff like low speed controllability, structural crash worthiness, terrain, pilot ability, winds/weather, etc. Maybe use wing loading or something else measurable but that also can not really correlate to survivability. Stall speed is defined and measurable.
The really problem comes from no matter what is used there will be a cut off number and unfortunately there is such a continuum of airplanes in that range of performance that inevitably you will cut off aircraft types that just miss the number but really are not all that different in characteristics.

 

[8s_Great]

Hopefully they don't can the LSRM program or make it unnecessarily more difficult as it seems one of the two things is currently where the NPRM is pointing already. I hope they understand we need more mechanics not less.

 

[warmi]

It seems to me that once you get over 45 mph, it’s a moot point. Trying to decide whether it’s 50kts vs 54kts seems fruitless. If it based on some sort of safety window, then it’s got to be below 55mph. Otherwise there really shouldn’t be a limit. A stall at 90mph and one at 60mph will have similar outcomes. Heck, people are still stalling cubs and perishing. I never understood the speed thing in this deal.

Well, I mean the faster you land the more energy you gonna have to dissipate and more likely end up having a bad outcome in case of some kind of emergency landing - I guess that’s the rationale here.

 

[Mel]

Hopefully they don't can the LSRM program or make it unnecessarily more difficult as it seems one of the two things is currently where the NPRM is pointing already. I hope they understand we need more mechanics not less.

Did I miss something? I didn't see anything in the NPRM relating to the LSRM program. Why wold you think they would "can" it?

 

[BobTurner]

Getting back on topic to the NPRM, since it currently states stall speed as CAS, that may make a few more types meet the stall speed requirement since in my experience CAS is typically lower than IAS.

My experience is exactly the opposite, mostly due to the non-zero angle of attack of the pitot tube at low speed.

 

[BobTurner]

It seems to me that once you get over 45 mph, it’s a moot point. Trying to decide whether it’s 50kts vs 54kts seems fruitless. If it based on some sort of safety window, then it’s got to be below 55mph. Otherwise there really shouldn’t be a limit. A stall at 90mph and one at 60mph will have similar outcomes. Heck, people are still stalling cubs and perishing. I never understood the speed thing in this deal.

Stall speed is a good indicator of touch down speed. If you had to land in a rough pasture, would you rather touch down at 92 or 57 mph?

 

[8s_Great]

Did I miss something? I didn't see anything in the NPRM relating to the LSRM program. Why wold you think they would "can" it?

Check out Rainbow Aviation's take n the NPRM. They are anti ASTM taking over because you don't have access to see what the standards are and they can change without Fed input.

Also, 147 schools are pushing for LSRM to change. Check out their videos. They have made 2 on the NPRM so far. They are trustworthy people and made a large majority of the LSRMs. Bias? Sure. But they go about why it's in aviations interest not to make it harder to get your airplane worked on or become a mechanic.

https://youtu.be/GYvqGyp1sEM

 

[HS2020]

Check out Rainbow Aviation's take n the NPRM. They are anti ASTM taking over because you don't have access to see what the standards are and they can change without Fed input.

Also, 147 schools are pushing for LSRM to change. Check out their videos. They have made 2 on the NPRM so far. They are trustworthy people and made a large majority of the LSRMs. Bias? Sure. But they go about why it's in aviations interest not to make it harder to get your airplane worked on or become a mechanic.

https://youtu.be/GYvqGyp1sEM

Bias is an understatement, these people make a living peddling access to the LSRM/LSRI niche. To wit, do you agree with their assertion the EAB "safety record" is "significant"? (is the word she used).

She minced no words when it came to the statsitical majority who resembles the remark, aka non-builder owners of EAB. The blurb about the FAA flirting with the idea of forcing EAB owners into LSRM also did not escape me.

 

[N8DAV8R]

She minced no words when it came to the statsitical majority who resembles the remark, aka non-builder owners of EAB. The blurb about the FAA flirting with the idea of forcing EAB owners into LSRM also did not escape me.

I don't think that their suggestion to give non-builder owners an avenue to control maintenance and inspections (via a similar LSRM/I path)was intended to take away anything from those that want to go the A&P route.