Speed Brake O/H

[seebruce]

Has anyone sent their speed brakes back to Precise Flight for overhaul? They tell me that there is a 1,000 hr. limit on the clutches.

[Piloto]

Only the electric ones have clutches. The first ones (1980 -1990) were pneumatic, they do not have clutches. If you can deploy the brakes with the engine off but master on you have the electric ones. The pneumatic type needs the vacuum pump runing for deployment.

José

 

[seebruce]

I do have the electric.

[Ron McBride]

1,000 hrs of airframe time, or 1,000 hrs of use?   In a 100 hours of airframe time, do you have 2 hours of Speed Brake use?

 

Ron

[seebruce]

Airframe time.

[fantom]

My electric SB are 16 years old, way over 1,000 hours, don't get used often, and are (knoeck wood) going strong.

IIRC, the only PM needed on them is some spring replacement.

 

[Piloto]

I don't think it is flight critical if you wait until they malfunction. After all they are mostly used in the retracted mode. Beware that deployment in icing condtions can inhibit them from retracting.

José 

[seebruce]

It could be a safety issue. They are suppose to retract automatically if there is a loss of electrical power. The thinking is that it could be possible to have an engine failure at the same time and in which case you wouldn't want the brakes sticking out. The problem is that apparently the clutches start to hang up as the brakes get old and wouldn't allow them to retract without power as designed. If you extend them and switch off the master and they slam down then yours are working correctly.

[Kwixdraw]

I could see things getting pretty hairy if you had sort of a split speed brake situation with one deployed and one retracted. Or is it no big deal?

[jlunseth]

The brakes are designed to detect differential deployment rates, and the default is to auto-close if there is a problem.

[Kwixdraw]

OK thanks. I have no experience with them so I had to ask.

[RJBrown]

There is no way (for the plane) to detect if only one brake is deployed. Part of the certification process was to show that if only one were deployed that the plane remained controllable. If you turn off the master switch before the brakes are retracted they "slam" down.  I had one that would stick, I sent it in for repair. Easy to install and remove. They are more effective the faster you go. At high speed with only one deployed there is a mild yawing moment. In the pattern with only one up you can barely notice it.

[Butch]

Working on an M20K with the old style (pnuematic) speedbrakes. The actuator cable outer covering needs replacing. The PF people said you may be able to cut the inner cable and slide the new sheathing over it without pulling the seat, etc. Has anyone done this and could you please pass along any tips?

[N513ZM]

I have the earlier style of electric speedbrakes (2000 Ovation) - not the more complicated/sophisticated latest version. I have had asymmetric deployment twice - it's no big deal - the airplane is controllable. The failure mode is that one will deploy and one won't and in this instance both will stow when commanded - not that they one or both stick up. I have had mine rebuilt 3x in 4 years, however - although the factory has been very helpful they do seem to keep breaking - I have wondered if it's the TKS contributing to this.

[jlunseth]

I had my speedbrakes sent back to Precise Flight, they do need to be reworked every 1000 hrs.  There appears to be a continuing issue after the rework, probably in the control box.  The problem I had before the rework was that the brakes would deploy at different rates, detect the discrepancy, and then autoretract.  This produced a very short and minor snap roll.  The problem now is that only one brake will deploy, and it stays deployed.  You can feel a "drag" on one side, but it is easily compensated for and just not a problem.  I tend not to use them anyway for most flights.  If you plan your descent well enough there is no need to deploy the brakes.  If ATC wants you down now, or if they can't allow the start of descent far enough out, then they are useful.  I have not tried them during landings yet, but will probably do that as soon as they get repaired and are functioning properly.

[N513ZM]

@JimR - how very true!

@jlunseth - if you have not tried them during landings you have missed out on the fun! They are magic! I use mine all the time and currently am using them to keep the power up while I descend as I'm still breaking in my newly overhauled jugs. Since I fly in the NE I am slam dunked all the time by NY and Boston Center. On the occasions when I have had the boards out for repair it has been a real PITA.

To Precise FLight's credit although they have been repaired 3x the repair has only been paid for once. They have been excellent to deal with. 

[Earl]

Quote: Kwixdraw

I could see things getting pretty hairy if you had sort of a split speed brake situation with one deployed and one retracted. Or is it no big deal?

[jlunseth]

Quote: N513ZM

@jlunseth - if you have not tried them during landings you have missed out on the fun! They are magic! I use mine all the time and currently am using them to keep the power up while I descend as I'm still breaking in my newly overhauled jugs. Since I fly in the NE I am slam dunked all the time by NY and Boston Center. On the occasions when I have had the boards out for repair it has been a real PITA.

[Piloto]

Just make sure you do not deploy the speed brakes during icing conditions. I had them accidentally stuck up with ice when I depressed by mistake the speed brakes button instead of the mike button on the yoke. This happened over the North Atlantic on my way back to St. John's New Foundland at night. Soon I was computing fuel range with them deployed. I went from FL 180 to FL 060 for warmer air to melt the ice. Since then I always pull the speed brakes CB when in icing conditions.

José

 

[LFOD]

I couldnt deploy the brakes after getting iced up once, but it is a much less significant emotional event then if they had been deployed. Don't touch that button if you are watching the ice build on your leading edges. 

[HopePilot]

How much does the overhaul cost (I just placed an order for speed brakes today)?

[AustinKalb]

Can anyone tell me how the stall speed changes with SB deployed with and without landing flaps. I have an Ovation 2GX. Also, I presume the stall warning is "off" speed with them deployed.

[MooneyMitch]

Hi Austin.

We have a full thread on this topic, including input from Don Kaye, a very experienced Mooney instructor.

Search the forum for the following thread:

Speed Brakes (How To Use?)

Maybe we'll see you at the Summit!

[BnB]

HI AUSTIN,

SPEEDBRAKES WILL HAVE NO EFFECT ON LANDING.  SHOULD BE USED AS OTHERS COMMENTED FOR SLOWING FOR TURBULENCE OR FASTER DESCENTS TO STAY OUT OF THE YELLOW.  MINE HAVE BEEN OVERHAULED RECENTLY AND NOW THEY ARE NOT WORKING AGAIN.  NOT PLEASED, HOWEVER I SELDOM USE THEM UNLESS I NEED TO SLOW DURING DESCENT OR BECAUSE IT HAS BECOME BUMPY ON THE RIDE DOWN IE FOR PASSENGER COMFORT.

[HopePilot]

Hey Austin, we met at the Tehachapi Fly-in, still hoping to go camping there in the future, but...my plane is in the shop because of the speedbrakes!  Yup, they lasted about four months before breaking.  That said, I still think they're magical.  I've used them twice recently to maintain altitude, on short final, at airports that have a hill.  Without them I'd have to put the nose down and dive.  They are an amazing safety feature to use over obstacles and maintain a stabilized approach.