speed brakes

[Duane Baker]

I understand but they also want $1700/2500 to replace a $64 part. sooo

[ArtVandelay]

The rest of the story, there are two cams with micro switches that control the power and witch way they go. One of the cams came loose and moved, this let the geared motor keep running and destroyed the gear inside the motor. Lubing the external gears would not have helped avoid this. My AP/IA found the motor $64, retimed the cams and we are back to normal and they work fine. After getting inside the speed brake and seeing how they work I'm going to start covering them when I wash the plane to help protect them and a little corrosion-X to lube them up.

For future reference do you have the motor model number and where you found it?


Tom

[LANCECASPER]

11 minutes ago, Duane Baker said:

I understand but they also want $1700/2500 to replace a $64 part. sooo

But what does that have to do with using Aeroshell 22  rather than Corrosion X?  You're confusing scheduled maintenance with Repairs and Overhauls.

I'll stick with the most current (Revision D) Instructions for Continued Airworthiness in Section 4 of the Manual. 

The Airworthiness Limitations section (Section 4.0) is FAA Approved and specifies maintenance required under Sections 43.16 and 91.403 of the Federal Aviation Regulations unless an alternative program has been FAA approved

[carusoam]

@Ftlausa see if there is anything here that helps explain your speed brake challenge...

Best regards,

-a-

[M016576]

On 10/21/2019 at 2:17 PM, Mark89114 said:

...I think it is running about $1000 for "overhaul", which I think I think is sinfully outrageous for a mechanism that gets used a total of maybe 10 hours in use before recommended OH or outright failure. 

Caveat emptor.

is the “overhauling” a speed brake difficult or requiring of a unique skill set?  Is it worth ones time to do it themselves?  Is it legal?

people pay over $1000 for 2 seatbelts that are not functionally different than $50 automotive seatbelts... other than they are less comfortable in the mooney application... but those belts aren’t stamped “TSO’d”.  
 

not saying that one should try to overhaul their own speed brake... just saying that’s the cost of entry to play in the theme park known as general aviation.

 

[Guest]

What’s wrong with removing the defective speed brake and repairing it?  If your maintainer can overhaul your engine surely he can fix your speed brake. If not you’ll have to send them back to the manufacturer.

Clarence

[Duane Baker]

For any body interested the PF SB motor is a Pittman #GM8712-21, call 866-287-3786 I think his name was Denis.  Specs 19.5:1 ratio/19.1 volts, you will have to reuse the mounting bracket from the old motor, getting the old gear off is tough the set screw may have to be drilled and taped. That's the hard part, the rest is easy. seeya Duane

[Will.iam]

On 11/6/2019 at 12:14 PM, LANCECASPER said:

I just serviced mine this morning. Removing them is very easy (I have the electric type)... ...After generously applying Aeroshell 22 grease I put it on a stool under the airplane (with the master on and the speed brake switch on). Every time I plugged in the connection it would activate. After a few cycles it was noticeably quieter and faster to deploy. 

Great tip! Does your speedbrakes have the sympathetic retract when one side doesn’t deploy the other side drops too? Just wondering as mine does and i could see once i unplug the right the left would drop and then i would have to plug back in the right and go recycle the speedbrake switch. Not a big deal just curious. The right side was so easy I’m going to do the left as well. Also do you put grease anywhere else besides the worm gear? Say like the return spring roller? Pic attached with blue circles around what I’m asking should also be greased besides the worm gear. And is the clutch the circular housing with the gear on the outside where the worm drive attaches?

[milotron]

On 1/20/2020 at 12:38 PM, Duane Baker said:

For any body interested the PF SB motor is a Pittman #GM8712-21, call 866-287-3786 I think his name was Denis.  Specs 19.5:1 ratio/19.1 volts, you will have to reuse the mounting bracket from the old motor, getting the old gear off is tough the set screw may have to be drilled and taped. That's the hard part, the rest is easy. seeya Duane

Anybody happen to know the part number for the 14V model? I think it is 7.5VDC on the motor itself. 

 

[carusoam]

My ‘94 doesn’t know what the other side is doing...

They are activated by the same button push, but have no idea if the other side deployed or not...

Having one deploy, would be better than none... if you are trying to lose altitude... and one fails...

I only have a single light for the status...

I have not tried deploying a single speed brake anywhere near Vne... just sayin’....

Nice pics Will!

 

PP thoughts only, not a mechanic or CFI...

Best regards,

-a-

[LANCECASPER]

14 hours ago, Will.iam said:

Great tip! Does your speedbrakes have the sympathetic retract when one side doesn’t deploy the other side drops too? Just wondering as mine does and i could see once i unplug the right the left would drop and then i would have to plug back in the right and go recycle the speedbrake switch. Not a big deal just curious. The right side was so easy I’m going to do the left as well. Also do you put grease anywhere else besides the worm gear? Say like the return spring roller? Pic attached with blue circles around what I’m asking should also be greased besides the worm gear. And is the clutch the circular housing with the gear on the outside where the worm drive attaches?

 

 

I've only ever greased the worm gear.  Just make sure that you only use Aeroshell 22.

 

[buddy]

On my ‘05 if one of the speed brakes doesn’t deploy the other side will go up and retract immediately.

[PT20J]

16 hours ago, Will.iam said:

Also do you put grease anywhere else besides the worm gear? Say like the return spring roller? Pic attached with blue circles around what I’m asking should also be greased besides the worm gear.

[tls pilot]

Here is the speed brake diagram

 

[PT20J]

Nice drawing but the gears are labelled incorrectly.

A worm gear set is actually a spiral gear called a worm that mates with a round gear sometimes called a worm wheel. So the gear labelled pinion is a worm and the gear labelled worm is a worm wheel. Probably no one cares, but these things bug me. 

https://www.motioncontroltips.com/worm-gears-what-are-they-and-where-are-they-used/

Skip

[cbogie]

The resources in this group are remarkable. Above Duane Baker supplied the part number and phone number for the precise flight speed brake electric motor. Mine failed a few days ago. The person answering the phone is still Dennis as quoted above. The price is $87 plus shipping. Do not supply the part number that is on the electric motor in the speed brake. The one that is printed on the speed brake is the OEM part number and they will not sell it to you. The updated part number is GM8212–12. The only difference is 12 inch electrical leads on the electric motor rather than solder terminals.