Are the M20C/D's legal to fly under MOSAIC

[ptwffz]

Looking for advise since AOPA brushed me off due to legal concerns. I own a 1946 M20D Master that was converted to retractable gear and constant speed prop (making it basically a "C").

MOSAIC says the aircraft must have a clean stall speed (VS1) no greater than 59 KCAS. My POH only lists IAS and shows a clean stall speed of 67 MPH IAS. That converts to 58 KIAS putting it just under the 59 knot stall requirement. The problem is that's not calibrated. How do I find out what the calibrated stall speed is when there's no calibrated info in my POH? The guy who took my call at AOPA said it's a gray area and maybe it's best to be gray but I wanna be legal. Any thoughts or solutions? Please no "why not get Basic Med." That's not a solution at the moment. Thanks.

[hammdo]

You probably mean 1966. Was the person at AOPA an aviation lawyer? My guess is few if anyone here can give you a ‘legal’ interpretation better than AOPA laywers. Since they stated it’s a gray area, someone would need to ‘try’ MOSAIC with the C and see how it goes. Then, the FAA lawyers would probably come out with an interpretation to clarify.

-Don

 

[ptwffz]

My bad. It's a 1964 M20D.  Thanks for the reply. So test the waters and seek legal representation when the hammer comes down. lol. Does your manual mention calibrated anywhere? I saw a chart where a J model had lower CAS than IAS. Strange.

 

Joe

[hammdo]

No hammer really, but the FAA would evaluate if that is a valid use of the MOSAIC law - if an issue came up. My op manual is more marketing material - probably like your 64’s with no calibrated correction  speeds…

-Don

[Hank]

@ptwffz, I've attached the relevant page from the Owners Manual for myn1970 C, but there were many changes made from 1964-1970. Do you have a similar page?

There are additional Owners Manuals available in the Downloads section, you maynfindnine for a C with this information from a year closer to yours; I think I've seen a 1965 book there.

P.S.--Pay attention to the offset note under the Airspeed Corrections table.

[hammdo]

Here is my 66’s - TAS and calibrated tables - no correction tables. My calibrated stall is ~53 knots

 

[hammdo]

AFM-2, for my 66 shows these numbers (these are in the MAPA training material below) but does not state calibrated that I can find: - note the weight!

 

[ptwffz]

Thanks for the charts Hank and Hammdo. Hank, I do not have that page in my POH. I do have Hammdo's page. I guess I'll have to interpolate the numbers to see if there's any hope. My POH shows stall speed clean at 67 mph IAS and bottom of the green arc at 70 mph CAS. It's interesting that 70 IAS MPH (bottom of green arc) translates to 67 CAS MPH with power on with your chart Hank. That would take me at 58 KCAS bringing me just below the 59 KCAS or lower requirement. But it's with power on and I don't see MOSAIC specifying power on or off speeds. Loophole? Who knows.  

[ptwffz]

62 mph brings me way below the threshold even after it would be converted to calibrated. I can't imagine adding the extra 125 lbs to bring the weight up to max (2575) would change the stall speed that much. I'm no engineer. I'll need to find a copy of that POH. Thanks.

[hammdo]

The ‘important speeds’ are from the MAPA Safety Foundation training guide — pretty good authority for Mooney Training, recognized by Insurance Company’s, and FAA wings credit too…

-Don

[ptwffz]

45 minutes ago, hammdo said:

The ‘important speeds’ are from the MAPA Safety Foundation training guide — pretty good authority for Mooney Training, recognized by Insurance Company’s, and FAA wings credit too…

-Don

Ok. Thanks Don. I'll check it out. I used to be a member.

[hammdo]

https://www.mooneysafety.com/
 

May no long be associated to MAPA…

-Don

[ptwffz]

1 hour ago, hammdo said:

https://www.mooneysafety.com/
 

May no long be associated to MAPA…

-Don

Thanks.

[PT20J]

This should really be pretty simple. The Mooney website lists the current revision of the manuals for each airplane. https://mooney.com/wp-content/uploads/2023/04/Mooney-Technical-Publications-1.pdf

I would get the version for my airplane and use that. If only IAS values are published, I'd just go with that because there is no other information available from the type certificate holder. If it's close, I would find the closest manual from Mooney that has CAS stall speeds and use that for backup. In the case of a D converted to a C, I would expect that the conversion had some documentation with it, but if not, I would check with the factory for guidance. As long as Mooney backs you up, the FAA won't argue with it. Using other non-certified sources is questionable. The data has to be directly traceable back to Mooney.

 

[cliffy]

There was a notation in an AOPA article (2 articles)  this month (Nov) that delt with this very issue. It seems there is guidance from the FAA on how to determine CAS from IAS in those airplanes without CAS references.  It is AC  90-89C 

MUST be  Originally Certified with a Stall speed clean at max gross weight -- 59  KTS CAS max and meeting the rest of 61.316     

 A practical test meeting  61.307b is required ------

Along with training and sign off if night flying is needed.   

Training and endorsements for controllable props and suckum up gear is also required  per 61.331

Can't fly on driver's license medical IF one has applied and failed a real 3rd class or Basic Med exam. 

AND   No more than two persons (pilot and passenger) in a 4 place airplane if flying as a Sport Pilot.

Hope this helps

[ptwffz]

3 hours ago, PT20J said:

This should really be pretty simple. The Mooney website lists the current revision of the manuals for each airplane. https://mooney.com/wp-content/uploads/2023/04/Mooney-Technical-Publications-1.pdf

I would get the version for my airplane and use that. If only IAS values are published, I'd just go with that because there is no other information available from the type certificate holder. If it's close, I would find the closest manual from Mooney that has CAS stall speeds and use that for backup. In the case of a D converted to a C, I would expect that the conversion had some documentation with it, but if not, I would check with the factory for guidance. As long as Mooney backs you up, the FAA won't argue with it. Using other non-certified sources is questionable. The data has to be directly traceable back to Mooney.

 

Thanks. I'll look for the most current revision.

[ptwffz]

1 hour ago, cliffy said:

There was a notation in an AOPA article (2 articles)  this month (Nov) that delt with this very issue. It seems there is guidance from the FAA on how to determine CAS from IAS in those airplanes without CAS references.  It is AC  90-89C 

MUST be  Originally Certified with a Stall speed clean at max gross weight -- 59  KTS CAS max and meeting the rest of 61.316     

 A practical test meeting  61.307b is required ------

Along with training and sign off if night flying is needed.   

Training and endorsements for controllable props and suckum up gear is also required  per 61.331

Can't fly on driver's license medical IF one has applied and failed a real 3rd class or Basic Med exam. 

AND   No more than two persons (pilot and passenger) in a 4 place airplane if flying as a Sport Pilot.

Hope this helps

AC 90-89C wasn't much help since it requires me to fly the plane to calculate CAS. It's been a paperweight for years. Need to know if it's legal or not before sinking thousands into her. I have over 2,000 hrs in my M20 and hold an ATP. Circumstances have forced me into this direction. 

[cliffy]

It seems that the FAA has put us in a box with only one way out   --   CAS    If the airplane in question was not certified using CAS then right now 

the only option according to them is the AC.  It probably remains a paper weight for this discussion

[ptwffz]

But it's a pretty one!

[Jackk]

My AI buddy says 

 

“58 KCAS

(67 MPH × 0.868976 = 58.22 knots; IAS ≈ CAS at low speeds, rounded to whole knot per aviation convention”

 

Edited 6 hours ago by Jackk

[Hank]

I agree with @Jackk's AI's invisible comments . . . .

[ptwffz]

???

[ptwffz]

I won't continue to harp on this subject. One last thing. My Owners Manual says bottom of green arc is 70 mph calibrated and my stall speed is 67 mph IAS. If true, then there must be a 3 mph increase from IAS to CAS. Hank shows a chart showing a 70 mph IAS corrected to 67 mph CAS with his 1970 C.  How is it that possible? One increasing by 3 mph and the other decreasing by 3 mph. Can the installation error be that far off?

[Jackk]

1 hour ago, Hank said:

I agree with @Jackk's AI's invisible comments . . . .

my copy paste not work?

[Hank]

57 minutes ago, ptwffz said:

???

To read what he wrote, I have to select a random spot and click on "Select all". Otherwise it's just invisible writing.