CPSONE

CPSONE

Well Known Member
Not on an RV but worth sharing.
The left brake on my T-Seminole felt squishy for a lack of a better term. I've flown a lot of Pipers and the brake didn't feel right. My engineer bled the brake system twice per the service manual and it was still not feeling normal. My engineer got in and pushed real hard on the brakes and blew the left brake line spraying fluid all over the hangar floor. I'm replacing brake lines on both sides. He and I figure the soft brake was from the expanding line perhaps that was almost at the point of failure. Lesson learned for both of us. Squishy brake (s) with properly bled brake lines, keep looking for the problem!
 
Hangar floor

Ya, like that speckled red spotty floor look!
Kept telling my engineer, you know, it just doesn't feel right...
Extremely happy it didn't happen on the runway away from home somewhere.
 
Experimental Catagory RULES!

CPSONE said:
Not on an RV but worth sharing.
The left brake on my T-Seminole felt squishy for a lack of a better term. I've flown a lot of Pipers and the brake didn't feel right. My engineer bled the brake system twice per the service manual and it was still not feeling normal. My engineer got in and pushed real hard on the brakes and blew the left brake line spraying fluid all over the hangar floor. I'm replacing brake lines on both sides. He and I figure the soft brake was from the expanding line perhaps that was almost at the point of failure. Lesson learned for both of us. Squishy brake (s) with properly bled brake lines, keep looking for the problem!
Click to expand...

By your description, I'm assuming it was a flexible, rubber line that failed. It's also a common failure on automobiles/trucks. That is why race cars all use SS braided flex lines. The SS braided outer covering supports the rubber or Teflon inner jacket. You get a much firmer brake pedal that way, with a lower failure rate. If this was a home built, you could substitute a higher quality [SS over Teflon] hose.
Charlie
 
Brake line

I wish I could change it to a SS braided line on both sides. Yes it was rubber with that black woven material over it. Standard piper part 63901-17. Failed at around 1700 total time on the airframe. First brake line failure I've ever had in almost 30 years of flying. Crazy price for those brake lines at $95 each plus fedex.
Must get the -7 done!
 
A pretty good driver taught me to always give the brakes a good stab on final. That way you know what you got. None of my 20 some instructors ever came up with that.
 
Hose service life

gasman said:
Yes, but how old was the part? And what was it's service life?
Click to expand...

Very good question. I presume 1981. I'll look it up in the service manual to see if there is a service life on the brake hoses.
 
303 hose --

DOES have a service life----hum how many annuals has this plane had since 1981?? As a hose fabricator, makes me wonder who is actually looking at the hoses. Look at your log book---if you havent changed your hoses in 32 quarters of servive get them off of there. Brake hose failure in a hangar is a MINOR inconvience versus an oil cooler hose in flight. Think about it--its your plane.
Tom
 
CPSONE said:
I wish I could change it to a SS braided line on both sides. Yes it was rubber with that black woven material over it. Standard piper part 63901-17. Failed at around 1700 total time on the airframe. First brake line failure I've ever had in almost 30 years of flying. Crazy price for those brake lines at $95 each plus fedex.
Must get the -7 done!
Click to expand...

Mike,
That's not that far out of line with the cost of automotive flexible hoses. Remember, that the automotive units must be DOT [in the USA] approved. Tom gave you very good advice. The original hoses should have been removed long ago. Change them all. The cost of new rubber hoses is a LOT less than the expense of ground loop damage.
Charlie
 
hose change

I'm sure they've been changed along the way. I'll look through the logs.
I am putting a new hose on the other side too presuming they have the same service life and not taking any chances. 100 hour or annual inspection only calls for a visual check of hoses and clamps from what I've found so far.
The failed hose visually looked fine. It failed at the metal end fitting to rubber hose connection. I'll post a pic of it when It gets taken off and see why it failed.
 
Not to belabor the point--

But you can's see the hose liner. The outer cover 'may' look just fine, but the liner of the reinforcement could be deteriorated. Flex them. If they sound like Rice Krispies---get them off. You might be amazed what you will find.
Tom
 
CPSONE said:
snipped The failed hose visually looked fine. It failed at the metal end fitting to rubber hose connection. I'll post a pic of it when It gets taken off and see why it failed.
Click to expand...

A common cause of a failure near the fittings is previous lack of care during maintenance. NEVER let a caliper hang by it's hose. That can cause stress damage internal to the hose. That damage then rears up to bite you in the butt later [as in now] Use either safety wire, a coat hanger, etc to suspend the caliper OR place a box [milk crates work great] near the gear leg to set it on. The idea is to keep it from hanging by the hose. Same goes for all flexible hydraulic hoses.
Charlie
 
It is threads like this that started me helping home builders.

But I can tell you that there are those out there....that when I ask them what is the application for these lines......they wink....smile....and say "sand rail". Or I'm told that its OK....in as so they replace with certified lines when the "sand rail" is sold.
Bottom line....good catch!!
 
me too Bret--

I was amazed at some of the stuff that I saw that was flying. Alot of the hoses were "overlooked" at conditional time----was a real scary thought for me.
Tom
 
failed hose replaced

Update...Failed hose removed. failure was at the end fitting. The fitting came off the hose like it had never been on there in the first place.
New hoses on both sides and now brakes feel firm. Time to fly!
 
did you--

check you other hoses, and your log book to see when thery were changed? We all certainly hope so---
Tom
 
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