Weak brakes in my S-LSA

I am used to better brakes than the ones I have in my new S-LSA. They take a LOT or pressure to keep the bird from creeping during run up etc. The brakes in my old and beloved Bonanza were much better.

Do you know if there is an effective and legal (for an S-LSA) adjustment for them?
Thanks,
EBB

EBB,

Last 2 flights on my SLSA I noticed weaker brakes and saw air bubbles in the lines. Going to get them bled tomorrow.
I also ordered a new set of brakes from Matco. My brake wear indicators show about 2/3 wear in 52 hours which I put down to being a newbie and that using differential brakes for steering will cause increased wear.

Weak brakes can stem from a couple of things.

Improperly breaking in the brake pads. Failure to do this can result in as much as a 50% loss of braking power.
Air bubbles in the system from poor bleeding technique.
Over heating the brake pads and glazing them and or warping the disc.
A drop or two of brake fluid that has leaked on a pad.
Brake fluid level too low.
master cylinder in need of a rebuild kit.
The wrong type brake fluid in the system (Dot 4 verses 5606)

Thanks Roger.

My ace mechanic is going to bleed them tomorrow! Will also look at the pads and their condition.

Top Cat:
Please tell us what you and your Ace Mech find. I can't imagine that the pads should be 2/3 used up in 50 hours or that the brakes were not properly broken in -- Van's flew the birds for the first ten hours or so and I think the know what they are doing.

I'm interested too if the bubbles in the line reflect a leak that we should look for.

Thanks,
EBB

roger lee said:

The wrong type brake fluid in the system (Dot 4 verses 5606)

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Please don't tell my brakes that there's Mobil synthetic ATF fluid in the lines!!!

EBB, the brakes are going to require more pressure than you are used too because they are smaller. As long as the brakes will hold during a full static run up, they are good enough to go. That's not to say yours might not have a problem, just say'n what's needed to go flying.

Top Cat said:

EBB,

Last 2 flights on my SLSA I noticed weaker brakes and saw air bubbles in the lines. Going to get them bled tomorrow.
I also ordered a new set of brakes from Matco. My brake wear indicators show about 2/3 wear in 52 hours which I put down to being a newbie and that using differential brakes for steering will cause increased wear.

Click to expand...

I am a little surprised about your brake wear. In my CT (912ULS) I like to taxi with no less than 1800 RPM, usually 2000 RPM. This means constantly using the brakes to keep my taxi speed down. I figured this practice would wear my pads quickly so ordered a new set to have on hand.

After 210 hours I have yet to need the new pads.

Hi John,

I had 900 hours on my original Matco brakes before a pad change.

Roger - OK. One set of new Matco pads for sale cheap.

Just joking

Hi John,

Why aren't you coming to the Page, AZ Fly-In?

Okay, here's what happened with my RV-12 SLSA brakes today.

My mechanic (Rotax qualified, and Light Sport qualified as well as A/P) replaced the brakes with a new set I got from MATCO.
No fluid leaks noted, multiple air bubbles in lines, and he called the removed pads' condition as 'weird, sort of spongy'. He gave me a worn set from a Sport Cruiser for comparison and they were 'harder' and drier. The edges of my pads instead of brake dust were greasy-like, although again, we found nothing appearing to contaminate them.
They were actually worn about ½ and the plane arrived with 53 hours total time.
He suggested calling George at MATCO and reviewing the removed brakes with him. As per MATCO I'll return the brakes to them for resurfacing.
He also asked if I'd done any wearing in. The new pads had a note with a procedure to help set the surface of the brakes which involved a few high speed runs and then braking till about 5 knots and then allowing to cool. I followed this to the letter with the new pads. Vans never mentioned any of this when I took delivery of the plane.

The brakes worked very well and steering and braking was excellent. We discussed my being a newbie to differential braking and being more efficient with them as I get used to the airplane.
I checked the brake lines when I got home and did find a couple of bubbles, one about 3-4 inches and a smaller on about 1 inch. Not sure if /how air is getting in but I'll monitor the brakes and we'll adjust again at the next oil change unless we need to do it before-hand.

I did have a couple of other issue that I talked to the mechanic about. I'll post them in another topic thread…titled "Fuel smell and transponder failure caution".

I'd appreciate any comments!

Top Cat said:

The new pads had a note with a procedure to help set the surface of the brakes which involved a few high speed runs and then braking till about 5 its and then allowing to cool. I followed this to the letter. Vans never mentioned any of this when I took delivery of the plane.

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The wear in procedure for the brake pads has to be done at first use, so it gets done before the initial test flying even gets started.

rvbuilder2002 said:

The wear in procedure for the brake pads has to be done at first use, so it gets done before the initial test flying even gets started.

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Good point, but then Vans never mentioned it either. Come to think of it, Vans didn't say much of anything other than hand me the keys.

I wish I'd known. Anyway, the set the plane with don't seem quite right so I'll be per suing it with MATCO to see what the issue might be. They appear to be a really good company to work with and have been very informative.

Top Cat said:

Good point, but then Vans never mentioned it either. Come to think of it, Vans didn't say much of anything other than hand me the keys.

I wish I'd known.

Click to expand...

Any aircraft that uses typical aircraft brakes ( cirrus, cessna, piper, etc.) has to have the brakes worn in properly when they are first used.
No one that purchases any of these aircraft new would be told about it either. It has already been done as part of the initial testing process.

It is something that mechanics do when they replace brakes as a maint. process.

From the way you described the pads your mechanic removed, it sounds to me like your pads got contaminated some how.

I agree, and we made sure today that we did the right thing with the new pads.

You're right it does sound like some form of contamination on the pads. I'll speak to MATCO about it and get their take on it.

Thanks.

RV12 brakes vs Bonanza brakes

The brakes on my S-LSA are a lot softer than they were on the Bonanza and the difference is stark; they don't stop the bird as well and the pressure on the brake peddle to achieve a non creep run up and stooping on landing is a lot more.

Obviously, the RV12 brakes are smaller because it's 1/3 the size/weight of my Bonanza. But the difference in performance has nothing to do with size or weight IMHO.....I think the RV12 brakes are simply not as good as the Clevelands. This is true on my bird but it may not be true on other RV12s.

I'm going to investigate the stuff that Top Cat has found in his S-LSA which left the factory about the same time as mine.

EBB

EBB,

I talked with George at Matco brakes today regarding what we found with mine.
Mine were ? worn and instead of brake dust the dust was like a paste, greasy like.

George suggested some kind of contamination although we found no source. No grease or leaking brake fluid and it was on both sides. I told him the pads were more pliable and at the rear of the right side the pads were starting to curl around behind the rotor. The edges of the pads had a ragged appearance with the 'dust paste' sticking to the edge.

He made notes and I'll put my pads in the mail to them and get a relined set in return.

At this point I don't think it's anything I've done and I'm more used to taxiing the airplane now. After 52 hours even a ham-fisted operator/newbie should have gotten better life.
I don't think it's the pads either as the new ones I got are good quality and Matco are very conscientious about their product.

I'll follow up with Vans and see if something happened maybe when the reassembled the plane after the airworthiness inspection the day before delivery. George indicated that they tested their pads with various contaminants and found that once a pad has soaked up something like oil, grease etc it stays in and can cause the pad the deteriorate.

Blimey, using the brakes on landing? How short are your runways?

I thought it was us in the UK that had short runways and we don't need to use the brakes on landing...!

As for taxying, the rudder helps turn the nose - it doesn't all have to be done on the brakes and keeping a little bit of inertia up on the taxy helps with the ease of taxying.

No need for 75% power to taxy like most Cirrus pilots use - not that the Cirrus actually needs it...

Jerry,

Born and bred in the UK actually!

Not saying I DO use the brakes excessively on landing or even taxiing. However, when you NEED brakes you NEED them to be effective. In my case it was more that the brakes needed bleeding but we ordered a net set of pads just in case.
Turns out the brakes are soft and contaminated with something, not quite sure, but the manufacturer wants to see them and my mechanic suggested a change.

All my flying life I got my knuckles rapped if I rode the brakes, now I have an airplane that requires, if not riding them, differential braking for steering, so I use them much more. At first I think I was clumsy rather than deft. I've since learned the art of 'dancing on the brakes' and I'm sure my next set will last much longer.
It has been disconcerting the last few hours when brakes were slow to engage and sluggish when trying to turn. Sometimes there just isn't a way to use more power close to other airplanes etc.

We think the nose wheel also needs some attention as it seems a bit difficult to turn at times.

Enjoying the 85F sunny skies and perfect flying weather in the SOUTH. We just returned from a stay in the UK and?.well, it's getting colder colder and wetter every day!

Hi Topcat,

Maybe you picked something up from a taxiway or runway from someone else's leak.

It's possible Roger, but what could I have picked up that would have soaked into the pads on both sides?

I'm sure I would remember going over something like that. It'll be interesting to see what Matco says once they've received the old pads.

Seems like only brake fluid or axle grease could be the culprits. Both would be very visible.

Top Cat said:

Jerry,

Born and bred in the UK actually!

Not saying I DO use the brakes excessively on landing or even taxiing. However, when you NEED brakes you NEED them to be effective. In my case it was more that the brakes needed bleeding but we ordered a net set of pads just in case.
Turns out the brakes are soft and contaminated with something, not quite sure, but the manufacturer wants to see them and my mechanic suggested a change.

All my flying life I got my knuckles rapped if I rode the brakes, now I have an airplane that requires, if not riding them, differential braking for steering, so I use them much more. At first I think I was clumsy rather than deft. I've since learned the art of 'dancing on the brakes' and I'm sure my next set will last much longer.
It has been disconcerting the last few hours when brakes were slow to engage and sluggish when trying to turn. Sometimes there just isn't a way to use more power close to other airplanes etc.

We think the nose wheel also needs some attention as it seems a bit difficult to turn at times.

Enjoying the 85F sunny skies and perfect flying weather in the SOUTH. We just returned from a stay in the UK and?.well, it's getting colder colder and wetter every day!

Click to expand...

TC, fear not I didn't mean your technique - rather that described by the former Bonanza driver!

And yes, it is getting colder and wetter as the days pass by here in dear old Blighty. Me, jealous? Yup....

RFSchaller said:

Seems like only brake fluid or axle grease could be the culprits. Both would be very visible.

Click to expand...

Just spoke with Matco tech today. They were surprised at the condition of the pads I returned to them.

At 52 hours they were half worn and the dust was turned to a pasty/greasy consistency.
They suggested a tire polish fluid, Armourall or similar, or grease from the backside bearing.
I haven't washed the airplane but once, using soap and water per the paint 'warranty' (SLSA) and I don't use tire shiners or similar. There is no evidence of leaking brake fluid or grease around the brakes and no sign of anything on the ground. The fairings were clean on the inside.

It's kind of strange but I'm thinking something got into the pads maybe at Vans.
I got the plane with 5 hours on it. Did 28 hours flying home from OR. Did the first oil change (for Rotax) at 35 hours, and the rest of the time has been local flying, up to 2 hour legs, and never landed or taxied over grease or similar.

Brakes needed bleeding a lot and Matco suggested the more rapid brake wear from the softer pads could have introduced more air to replace the fluid adapting to the pad wear.