Lowell Fitt wrote:

Brent Says,
" The first  concern is compatibility with the aquarium tubing."

In all the great and really informative posts from your keyboard, this is the first pejorative comment I recall.  For me at least it diminishes the value of the rest of the post.  Just how much of your post is opinion.  This list and others I have been on are rife with opinion and is of little use when searching for facts.

Are you aware of your so called "aquariun tubing" being a problem in fact.

Lowell

Yes I do.  I have been an outspoken critic of Nylaflow  tubing being used as brake lines for many years (check the archives).  There have been many (>20) instances of line failures that have resulted in loss of directional control. Many more than that have been avoided buy builders who have taken my advice and used the D H Instrument hose, Parker PDH hose or, more recently, the solution Tim Ong is offering through Lancair.

The whole concept of using Nylaflow began with Rutan and the "it is too heavy for an airplane if you throw it up in the air and it comes back down" rule back in the '70s.  Nylaflow proved marginally suitable on lightweight single and two seat  fixed gear aircraft with 60 mph landing speeds. Over the years its application expanded to two ton, four passenger retractable gear aircraft that can land in excess of 120 Kts (no flap landing). Remember that the energy needed to stop something goes up with the square of the speed.  The aircraft  have clearly outgrown the component.  Would you argue for Nylaflow brake line in a certified aircraft? How about a Jet? How about a Prop Jet????? We can all agree that Nylaflow is not a good choice for the brake line on a 747 so the only question is when does it become a bad choice. For me, it is a bad choice if I plan to fly in that aircraft.

Just today another builder wrote to me saying " After putting it off for far too long, I replaced all thirteen feet of the four NylaFlo (sp) lines in my brake system during the annual I completed last month with stainless braid covered teflon lines. I have the old NylaFlo tubing that was in the plane for four years.  Although it never leaked or failed me in any way, I was surprised to see how brittle it had become. <snip> <>   I appreciate your periodic carping on this subject.  It reminds me of Bill Cosby's old routine, where a voice comes booming from above, "Noah, this is the Lord".  I've already started spreading the gospel from my installation and at least two other ES builders I know are switching soon."

Pejorative? Whatever..

Regards
Brent Regan

For the archivally challenged, a couple of my previous posts on the topic.

From my post on 9/21/03

<<

"Watch out for that tree!" from George of the Jungle.

Jeff writes:
<< Oh yes, I went off the runway at the Redmond fly in  with a brake failure a few weeks back <snip>  Brake line failed (nylaflow) inside gear leg. Tim Ong says there have been other failures and they are working on a fix. Would have been disastrous on a short runway with heavy braking on touchdown or a narrow runway with obstacles.
>>

No SH*T!

I have been saying it for 8 years and it is worth saying again. Aquarium tubing has no business being used to stop a $350,000 airplane traveling at 100 MPH with four souls on board. If you lifted the hood of your SUV and saw Nylaflow brake lines would you STILL hop in and take Billy and the twins to the soccer match? Heck, cars even have triple redundant braking systems. In our planes, the loss of EITHER brake will result in "El Pucker Grande".

A "fix" already exists and has existed since '95. D H Instruments hose assembly #  F3737-60  http://www.dhinstruments.com/prod1/ft.htm

"Oh but Brent, the DH lines are SO expensive!"

Builders have actually said this to me.

Gee, let me think, for the $200+ a set you would save you could buy 1/5 of a panel mounted CD player, 85 gallons of Avgas, a pair of crappy headphones, 4 spark plugs or one set of tires. I guarantee you this, nothing else you can buy for $200 will do you a damn bit of good as you reenact the "Evil Kinievel Ceasars Palace Fountain Jump Landing" after a 10 year old chunk of $0.11/foot plastic decides it doesn't want to keep doing something it was never designed to do in the first place.

The flight isn't over until the plane has stopped and all the passengers are safely out. "Stopped" is the operative word here, the one the FAA and your insurance company will be most interested in.

Winter is coming and it is a good time to put the plane on jacks and install something that will save your life at every landing.

Tim, Vern, Joe......you listening?

Regards
Brent Regan

BTW, I have absolutely no affiliation with D H Instruments.
>>>>

From my post on 5/11/2005:

<<<<<
Brake pedal "feel" or firmness is the result of the compliance , or elasticity, of the brake system. A firm pedal feel is desirable because it transmits the most information about the conditions existing during braking. The bending of the brake pedal, stretching of the rudder cables, compression of the brake pads, flexing of the calipers, expansion of the brake lines and compression of the brake fluid all contribute to the overall "feel" of the system.  Of these factors the last two are the only ones we can reasonably change.

Compression of the brake fluid is primarily a result of tiny air bubbles in the brake fluid. These bubbles are so small they do not float  and remain dissolved in the fluid. The volume of the fluid is also a factor as the larger the compressed volume the lower the spring rate. Prior to replacing the brake fluid on my airplane I vacuum degas it by putting it in a tank and evacuating the air.  It is amazing how much foam evolves from the fluid. I then carefully use this de-aerated fluid in the brake system.

Expansion of the brake lines is the result of strain of the wall of the tube as a result of pressure induced stress. Stress can be calculated by dividing the pressure (~500 PSI) times the bore radius by the wall thickness. The stress divided my the modulus of the material is the strain. Small bore, thick walled and high modulus tubes will result in a stiffer system. Adding Vaigra to the brake fluid will have no effect.

Bottom line (NPI) is that metal is better than reinforced hose which is better than plastic. A well designed system will use 3/16"  stainless in hot and static areas, aluminum in cool static areas, stainless braided or Kevlar reinforced hose in flex areas (insulated in hot flex areas).  Brakes lines transmit pressure with only a very small transient flow so use small diameter tubing and hose to save weight and reduce the fluid volume.

I think it is time to start a new group consisting of people who believe it is OK to trust their safety to a pair of thin walled plastic tubes. These folks can then attend conventions with people with similar beliefs. People who believe that earth is flat, that the Apollo missions never went to the moon, that the earth is 6,000 years old or that Al Gore invented the internet. The common thread is that all these people firmly hold their beliefs in the face of  overwhelming factual, empirical and  analytical evidence.

I have said it before and say it again, " Nylaflow " should not be used as brake hydraulic tubing. It lacks in mechanical strength, thermal performance and chemical resistance. The time spent replacing it with proper hose and hard line will likely be less then the time spent on the repair when it fails.

To all you Nylaflow Flat Earth Hollywood Moon Landing Society members,  repent now or regret later!

Regards
Brent Regan
>>>>>