SWAPPING VACUUM-DRIVEN SPEED BRAKES FOR ELECTRIC ONES IN M20K

[glbtrottr]

A friend here in California with a G model needed the clutch in his speed brakes replaced. - he’s an aerospace engineer and IA.

Precise doesn’t sell parts anymore, opting only for $4000 as a flat overhaul fee. Need the little spring? $4000. For that much cash, it’s better spent learning alternate methods of speed management. I am all about supporting vendors, but seriously? No.


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[DanM]

When Mooney shopping, is there an easy way to determine if the speed brakes are pneumatic or electric?  Would the presence of a dedicated circuit breaker for the speed brakes indicate they are electrically powered?  (Pneumatic brakes probably need power for the switch but maybe not enough for a dedicated breaker?).

Thanks.

[LANCECASPER]

1 hour ago, DanM said:

When Mooney shopping, is there an easy way to determine if the speed brakes are pneumatic or electric?  Would the presence of a dedicated circuit breaker for the speed brakes indicate they are electrically powered?  (Pneumatic brakes probably need power for the switch but maybe not enough for a dedicated breaker?).

Thanks.

What year is the one you are looking at?

[231LV]

7 hours ago, DanM said:

When Mooney shopping, is there an easy way to determine if the speed brakes are pneumatic or electric?  Would the presence of a dedicated circuit breaker for the speed brakes indicate they are electrically powered?  (Pneumatic brakes probably need power for the switch but maybe not enough for a dedicated breaker?).

Thanks.

turn on the Master and throw the speed brake switch....if they work, they are electric, if not, vacuum-driven

[kortopates]

Even easier to just ask the owner!


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[natdm]

On 9/26/2023 at 5:22 PM, 231LV said:

turn on the Master and throw the speed brake switch....if they work, they are electric, if not, vacuum-driven

 

25 minutes ago, kortopates said:

Even easier to just ask the owner!


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Even easier than that, electric ones have a placard below the speed brakes stating they are in fact electric.

Page 21: https://drive.google.com/file/d/1BjCg2ZTXPlRzAYdYzkFdc2Sa4uxqtdvz/view?usp=sharing from Precise Flight Speed Brake install guide (Mooney)

[Rick Junkin]

45 minutes ago, natdm said:

Even easier than that, electric ones have a placard below the speed brakes stating they are in fact electric.

Careful with that one.

My brakes are vacuum operated and when the airplane was repainted by the previous owner that placard was mistakenly put on the wings. This caused some confusion for my installer during my panel replacement as to whether the vacuum system should be removed.

I'm casually working on sourcing a diaphram replacement as I'm sure I will need one at some point, but the brakes still work work great!

Cheers,
Rick

 

[natdm]

1 hour ago, Rick Junkin said:

Careful with that one.

My brakes are vacuum operated and when the airplane was repainted by the previous owner that placard was mistakenly put on the wings. This caused some confusion for my installer during my panel replacement as to whether the vacuum system should be removed.

I'm casually working on sourcing a diaphram replacement as I'm sure I will need one at some point, but the brakes still work work great!

Cheers,
Rick

 

That seems crazy.

[ArtVandelay]

Even easier than that, electric ones have a placard below the speed brakes stating they are in fact electric.

Js don’t have placard probably because they only came with electric (they were an option in the later years).

[Fly Boomer]

5 hours ago, kortopates said:

Even easier to just ask the owner!

Maybe.

[LANCECASPER]

5 minutes ago, ArtVandelay said:

Js don’t have placard probably because they only came with electric (they were an option in the later years).

Precise Flight Speed brakes first became a factory-installed option on the J and K (the last year of the 231 K)  Mooneys in 1985. These were vacuum operated and in 1988 were available on the L model (Porsche) and in 1989 and 1990 (and early 1991 if I remember correctly) they were standard on the M.

The electric speed brakes didn't get STC'd for Mooney until 1991.