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Brake check?

N941WR

N941WR

Legacy Member
One of my neighbors who happens to be an IA lost his left brake on his 310 during rollout and went off the runway. The result was that he ripped the left wing off, just outboard of the left engine, when he used a tree for a parking brake.

The plane had just come out of annual and he said the brakes were fine and that he had put new linings in them.

My questions to this group are:

1. How can you inspect the caliper?
2. Should the calipers be rebuilt at a set interval?

(No one was hurt in his incident, only tree was harmed in the making of this story.)
 
Reinsalling the brake pucks

I don't know if his brakes are like ours but if they are he more than likely installed the puck backward with the o-ring facing out. if he did then the o-ring came out too far when the brakes were applied and he lost his hydraulic fluid and the brake no longer worked.

Read about it and see the pictures here:
http://home.newwavecomm.net/bobbyhester/2012Flying.htm

I have a friend that ran his plane into the large metal post in front of a fuel pump, prop first because of this :-(
 
bhester said:
I don't know if his brakes are like ours but if they are he more than likely installed the puck backward with the o-ring facing out. if he did then the o-ring came out too far when the brakes were applied and he lost his hydraulic fluid and the brake no longer worked...
Click to expand...

Nope, they were installed correctly. Good thought though. It appears they "just" failed.
 
HUM---so what was the failure---hydraulics, or lack of, or lining failure?
Mastercylinder, brake hose, aluminum line, lining departed from rivets, etc?

No flame war here Bill, just interested in the cause of the failure.
Kinda like the 'hatch just blew. It was a technical malfunction'.

Inquiring minds may want to know.
Tom
 
They don't just fail. Something was wrong. Those linings aren't riveted, they clip over stud rivets on the plates and if the studs aren't great the linings can slip off. There are also more parts to get wrong like brake shims and piston insulators. Good lesson here. Always stand on brakes and give them a torture test after reassembly. After dropping the gear ALWAYS do a brake check BEFORE landing.
 
TS Flightlines said:
HUM---so what was the failure---hydraulics, or lack of, or lining failure?
Mastercylinder, brake hose, aluminum line, lining departed from rivets, etc?

No flame war here Bill, just interested in the cause of the failure.
Kinda like the 'hatch just blew. It was a technical malfunction'.

Inquiring minds may want to know.
Tom
Click to expand...

No flame here either but the question is, how do we inspect our brakes properly? Inspecting and replacing our linings is easy but how do I know if the puck and O-rinngs are in good shape? Should we rebuild ours every X hours or Y years?


(His O-ring split.)
 
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Split o rings can happen at caliper overhaul, or from age. Either way, its a bad feeling when they dont work.
Explains the technical malfunction. Fluid loss, equals no hydraulics.
Tom
 
TS Flightlines said:
Split o rings can happen at caliper overhaul, or from age. Either way, its a bad feeling when they dont work.
Explains the technical malfunction. Fluid loss, equals no hydraulics.
Tom
Click to expand...

Yep, major bummer as it tore up a nice airplane!

So... how long should we wait to change our O-rongs?
 
Brakes

Did that happen at SC86??
With a reasonably wide runway there is no need to go off the runway if you lose the brake in ANY Twin Cessna. I have had brake failures in the 414 and Piper Navajo, reasonably long runways, no problem either time.
Flying a 310 out of a runway like SC86 is just asking for trouble. WAY too high risk.
 
Bill---I dont think you can put a time on it. Some guys are harder on brakes than others. High heat will transfer to the caliper, including the piston and o'ring. So the heat cycles will have an effect on the o'ring, causing issues. How long, is anyone's guess, but I'd have to say 250 hours (?).
maybe Grove, Matco, or Cleveland has a 'recommendation'.

Tom
 
TS Flightlines said:
Bill---I dont think you can put a time on it. Some guys are harder on brakes than others. High heat will transfer to the caliper, including the piston and o'ring. So the heat cycles will have an effect on the o'ring, causing issues. How long, is anyone's guess, but I'd have to say 250 hours (?).
maybe Grove, Matco, or Cleveland has a 'recommendation'.

Tom
Click to expand...

Probably more appropriate to go by the number of landings versus flying hours. Unfortunately, our aircraft logbooks, unlike military types, don't track landings; it is retained in the pilot logbook.
 
TS Flightlines said:
Bill---I dont think you can put a time on it. Some guys are harder on brakes than others. High heat will transfer to the caliper, including the piston and o'ring. So the heat cycles will have an effect on the o'ring, causing issues. How long, is anyone's guess, but I'd have to say 250 hours (?).
maybe Grove, Matco, or Cleveland has a 'recommendation'.

Tom
Click to expand...
I have almost 700 hours on mine. Sounds like they should be rebuilt?

Raymo said:
Probably more appropriate to go by the number of landings versus flying hours. Unfortunately, our aircraft logbooks, unlike military types, don't track landings; it is retained in the pilot logbook.
Click to expand...
I keep my logbook in Excel and since I'm the only one who flies it, I can tell you exactly how many landings I have on it. What I can't tell you is how many of those lands the brakes have been used.
 
I went to the source

I called Cleveland AKA Parker Hannifin and was told to replace the O-rings in the master cylinders every 10 years. The O-rings in the calipers should be replaced every year, every two years at the most. The reason, I was told, is because of the heat build up in our small brakes can cause the O-rings to fail.

He mentioned that they consider 50 to 100 hours a year normal.
 
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makes good sense

N941WR said:
I called Cleveland AKA Parker Hannifin and was told to replace the O-rings in the master cylinders every 10 years. The O-rings in the calipers should be replaced every year, every two years at the most. The reason, I was told, is because of the heat build up in our small brakes can cause the O-rings to fail.

He mentioned that they consider 50 to 100 hours a year normal.
Click to expand...

We have a lot riding on those little o-rings. As I recall there is only one of them on each side. Thanks for the excellent post Bill.
 
Carpet

I know a feller who had an rv6a which had nice dark carpet. It was so dark, that he never noticed the sloooow brake fluid leak until one day, before he took off, brakes felt kinda mushy but nothing to write home about. Upon landing at long runway, right brake was unresponsive so long rollout was in order but no right turns. He got to walk his fine plane to the tiedown area. Carpet was completely saturated with brake fluid. Carpet went to the trash. Brakes needed new o-rings and was returned to service. Pilot was re-educated on pre-flight stuff and he too was returned to service. He said the -A model is no fun without brakes.
 
50-100 hours? HUM---well seems kinda often to me, but if thats what they recommend. YMMV of course. I guess we'll be keeping several set of o'rings handy, as well as our pressure bleeder.

Tom
 
non-mechanic question.....

just some questions to learn from, no accusing here....

after a brake rebuild, do you have to break the pads in with long taxi's, or hard braking on a couple of landings? I would hope deficiencies would show up there.

what would show up at run-up when holding brakes for only a few seconds at high thrust? could you miss a slow leak?

Pistons/o-rings, just how much degradation can happen in a year or two? obviously more potential in hot/cold, dusty, seawater etc. or commercial use, but the Waddington effect of fully rebuilding my brakes every year after 25-50 landings seems counter intuitive.

what if you are using viton o-rings and synthetic fluid?
 
Happens

When mine failed, it was just after the engine sputtered on climb out. Later found rain water in the tank. Rode the brakes hard to get stopped before the runway ended. Brakes got very hot... then the puck blew the o-ring. Smoke coming out and a power screw driver is just not fast enough to get a wheel pant off! Found that someone had put one puck in backwards. Very little clearance under hard braking for the o-ring. I wish the puck was like the Claymore back in the day. At least it told which way to face it !
 
I'm still baffled with the left brake failure and left wing impact/damage. No flame here either, but having a hard time drafting it in my mind.
 
Infidel said:
I'm still baffled with the left brake failure and left wing impact/damage. No flame here either, but having a hard time drafting it in my mind.
Click to expand...

Lesson learned, never include the background that prompted the question, it causes way too much thread drift!
 
N941WR said:
I called Cleveland AKA Parker Hannifin and was told to replace the O-rings in the master cylinders every 10 years. The O-rings in the calipers should be replaced every year, every two years at the most. The reason, I was told, is because of the heat build up in our small brakes can cause the O-rings to fail.

He mentioned that they consider 50 to 100 hours a year normal.
Click to expand...

From my experience, O rings will start to seep/leak when they get old/hard from heat or age. They don't generally just "fail". Replacing them on a hourly or yearly basis seems like way overkill to me unless there are signs of leakage.
Every 5 years I might agree, but every year, I don't think so.

Some quotes from the Cleveland Maintenance Manual: (maybe the guy you talked to hasn't read their owm CMM)

Remove o-rings (8) from either pistons or cylinder. It is recommended that o-rings be
replaced at reassembly. However, if necessary, o-rings may be reused if not damaged,
cut, or deteriorated.

Replace o-rings with o-rings of corresponding part numbers. If necessary, o-rings may be
reused in the same position from which they were removed if not damaged. Inspect o-rings
for cuts, nicks, distortion, or excessive wear. Check to be sure o-ring has not become brittle.
Refer to o-ring removal procedure in paragraph 2B (1)(h).
 
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flyboy1963 said:
after a brake rebuild, do you have to break the pads in with long taxi's, or hard braking on a couple of landings? I would hope deficiencies would show up there.
Click to expand...

I would do a few hard-ish stops either while taxiing or landing to promote some pad material transferring to the rotor surface. You don't want to overdo it, because as stated earlier, we have tiny brakes and not a ton of cooling airflow if the wheel pants are fitted.

Good stuff on bedding, transfer layer, etc. here from StopTech:

http://stoptech.com/technical-suppo...y-definitions-and-procedures/brake-pad-bed-in
 
Walt said:
From my experience, O rings will start to seep/leak when they get old/hard from heat or age. They don't generally just "fail". Replaceing them on a hourly or yearly basis seems like way overkill to me unless there are signs of leakage.
Every 5 years I might agree, but every year, I don't think so.
Click to expand...

Ditto. My experience is that the pads wear out well before the o-rings are close to failing, and that's a good time to check the system and replace things that need it.

On a time basis, o-rings seem to last considerably more than five years, even with heavy landing usage.

Dave
 
Leaking Brake

Well I'm glad this thread is been discussed as I've had a few issues lately with my brakes on my RV-4.

Will anybody know the Part number for the Piston O'Ring ( Cleveland ) for an RV-4..I looked everywhere but can't find it :eek:

Also are some better than others??

Thanks

Bruno
[email protected]
 
N941WR said:
No flame here either but the question is, how do we inspect our brakes properly? Inspecting and replacing our linings is easy but how do I know if the puck and O-rinngs are in good shape? Should we rebuild ours every X hours or Y years?


(His O-ring split.)
Click to expand...

I have seen leaks start where you can see brake fluid around the calipers leaking past the O-Ring seal.

IMHO, they should be replaced every 5-years or 1,000 hours. I have seen several fail from age and also from time in service.

Just my experience and others may vary.

My RV-6 will have been flying for 18-years and 3,010+ hours next month.
 
RV-4 said:
Well I'm glad this thread is been discussed as I've had a few issues lately with my brakes on my RV-4.

Will anybody know the Part number for the Piston O'Ring ( Cleveland ) for an RV-4..I looked everywhere but can't find it :eek:

Also are some better than others??

Thanks

Bruno
[email protected]
Click to expand...

Info on the brake o-ring can be found here.
 
N941WR said:
No flame here either but the question is, how do we inspect our brakes properly? Inspecting and replacing our linings is easy but how do I know if the puck and O-rinngs are in good shape? Should we rebuild ours every X hours or Y years?


(His O-ring split.)
Click to expand...

These O rings are cheap... I keep 2 new ones in my hanger all the time. I replace them at least once every year. A little of my time and and a few bucks.... Truth be told, when I moved over to my -7, I had never flown tail draggers in my life. Ironically I flew a 310 for 13 years.... and when I was training and learning (still learning) to fly, land and taxi a tail dragger, I was dragging my feet on one of the brakes and one of the o-rings got too hot and leaked out all the fluid. Luckily for me it was after I put the plane up in the hanger. After taking the puck out to inspect it I found a nice FLAT O-Ring around the puck.
I can laugh at myself now but I learned a couple of things from that experience:
1. The O-ring is cheap and easy to replace.
2. It is one of those CRITICAL items that costs nothing compare to what's it's job is.
3. When it fails, I'm having a bad day.
4. And oh yeah, place my feet on the outer frame of the pedals while taxing.

Moral of the story: May not be something that you check often right now, but it is a critical item that costs very little and gives you a piece of mind.
 
Very timely for me. I took my plane to it's first condition inspection yesterday and when I pulled the wheel pants, there was brake fluid on the inside of the passenger side one, on the brake side of the wheel. No signs of drips or fluid on the tire and no change in funtionality. Sounds like I was about to have a bigger problem. Great discussion.

PS. I ordered a half a dozen o-rings this morning.
 
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Caliper O-ring failure

Symptoms of o-ring failure I've seen

None but obvious- brakes dragged on extended taxi in at S&F, smoke billowing out tight wheel pants after parking. Both o-rings failed, spilling fluid caught fire, lucky ground staff had extinguisher available. RV10 60hrs

Obvious- puddle under tire, owner mentioned he always had to add fluid every annual, dirty stain on Caliper but not wet... RV7A 600hrs

None- one brake failed under hard braking followed by a very abrupt 360 on the runway, followed by angry comments from the controller.(in Mexico) When mechanic removed piston o-ring was hard & deformed square. They found a right sized o-ring in their tool kit, filled & bleed the system and sent the owner on his way. RV7A 1300hrs. On return from his trip, I replaced both Caliper o-rings with proper MS spec o-rings & fluid as we weren't sure if the 'fix' was with natural rubber (hardware store) o-rings or not.

Following this last incident I have been advising my guys to replace these o-rings at least every 500hrs.
 
Pad break in

Cleveland has published procedure for pad break-in in their Component Maintenance Manual area.

Product Reference Memo PRM-14A describes using hard braking to break in METALIC brake pads.

Product Reference Memo PRM-13A describes using a process of taxiing for 1500ft at 1700rpm and applying enough braking force to maintain 5 to 10mph, followed by a 15min cool down for ORGANIC pads - which most of us have on our planes (unless you upgraded to Metalic)
 
Some of the most common causes of brake caliper failure are excessively worn caliper bores and excessive braking. I have seen many older aircraft, especially twins, that have brake calipers leaking / failing due to the bores in the calipers being out of spec, either due to wear or corrosion. The piston / o-ring / bore fit degrades over time due to the bore getting a tapered wear pattern. As the brake pads wear, the piston moves more and more out of the bore and can't seal as well in the worn areas, thus loss of sealing. Pilots of twin engine aircraft tend use their brakes more due to the need to augment steering via differential braking or landing too fast and trying to make the first taxi way. Some twins don't steer well without using differential braking, that combined with more power and weight, usually means excessive brake wear. I have seen many brake failures on twins due to all the above. At annual the owner says the brakes are leaking, so after you point out the caliper bores are worn beyond spec and cost $1500 a piece, you end up with the owner going cheap and just putting new O-rings in, along with new pads, which solves the problem for about 10 hrs. The other cause of brake failure is the excessive use of brakes, which heats up the fluid and it expands to the point where it forces its way out of the path of least resistance, the o-ring. The RV series, both A and TW models use differential braking to augment steering, so lesson learned, don't over heat the brakes and periodically inspect the brake caliper bores / o rings / pads.
 
Brake Leaks

Thank you Gary, much appreciated.

I will go with the Viton O'Rings if I can get them from Spruce or Aviall ( Suppliers are far apart around here)

Cheers

Bruno

Edit: Gary, I just re-read your post and regarding the fuel caps O'Ring ...Are they the same as the brake piston O'Rings if so I got some here????
 
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Infidel said:
I'm still baffled with the left brake failure and left wing impact/damage. No flame here either, but having a hard time drafting it in my mind.
Click to expand...

Picture this, you need to brake for what ever reason and then there is only right brake which will pulls you hard to the right and off the runway. Now as bad luck has it, there is a tree just to the left of you. Or possibly that you have some control but not enough to stop, so you aim for the tree with the wing in order to save yourself (cabin)

This is of course one of the many possible way that could have happened.

My question is that why so brake failure on the roll out.
 
Even though Viton seals are better than Buna N at high temps they will become quite stiff at colder temps, I suggest you do some research before you switch especially if you live in or visit cold climates or high altititudes.
Most brakes systems use MS28775 (NBR/Buna N) as standard, I suspect manufacturers have a pretty good reason for using these over viton but I'm not an expert on O rings.
 
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Brake leaks

Walt

Good thinking about the Vitons becoming more stiff in cold temperature ( Which happen sometimes up north )..I know the fuel caps one are getting stiffer with colder weather..
I couldn't find them ( Using the # Gary published on his page ) on the Spruce web site so I went with the standard Buna N O'Rings.

I also bought the Bleeder Tank, hopefully it will help in preventing the typical Hydraulic oïl mess..

Should get the parts tomorrow or Monday..

Thank you all

Bruno
[email protected]
 
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