Question about hoses

[A2022]

I have a VA-135 hose at the top of my ACOC. The bend diameter = 7 inches. Mil-spec Teflon min bend radius for a -8 hose = 4.62. 2 x 4.62 = 9.24 inch diameter and cannot meet. Van's new replacement hose is Teflon, how can it meet the bend radius? I think I will replace these -8 hoses with the original AE701 rubber material in order to meet the bend radius requirement.

I contacted the tech department at Aeroquip, and he said the min bend radius for the Teflon hose is independent of pressure and is truly a minimum. so, I will not violate that. for fundamentals like nuts, bolts, wires and hoses, it is best to mind the specifications. I am not sure if Van's is violating a specification or what hose they use. I'll send a note to Van's. I know Van's does not sell certified hoses.


Sent: Monday, February 5, 2024 at 02:41:06 PM EST
Subject: EATON Aerospace Contact Me Form - RVPLASTICPARTS LLC - P/N 666-8 - can the 4.62-inch published bend radius be reduced if operating pressure is 65 psi? if so, by how much?

Hello Steve,

How are you?

From our Product Tech Services>

No, the operating pressure has no bearing on the Min bend, 4.62 in the MIN.

Best regards,

Dwayne Cohen

Regional Manager – AIRLINE Technical Support

EATON

AEROSPACE GROUP

[A2022]

Van's said they don't know anything about hoses and to contact Aircraft Specialties that make their hoses. I contacted Aircraft Specialties, and they could not show me the type of hose (with a P/N) they use because they don't share that info. well, I prefer not to use mystery hose on my aircraft. I will make new AE701-8 oil cooler hoses to be the same as the original Van's supplied hoses that meet the min bend radius. the hose ends are reusable.

[A2022]

making hoses from certified materials that have a listed spec.... oil pressure sense line pressure tested to 1000 psi and installed. fuel pressure sense hose is made. they are very easy to make, and fittings are reusable so if you don't like the length, make another. using 666, Vlad hose.

weight comparison for Teflon hose with supergem fittings compared to 701 hose.

fuel lines to get fire sleeve.

the loft makes for a cozy workspace with some music. there are 100K lumens under there and you can read the fine print.

[A2022]

all aeroquip 666 teflon hoses are made. very easy to work with super gem fittings.

one of my -8 hoses (ACOC upper hose) needs to be 701 to meet the allowable bend radius. the aeroquip -8 666 teflon hose allowable bend radius = 4.62 and I need 3.6 inches, so 701 it is. you can make some nice end cuts with a cut off saw using an abrasive wheel.

crankcase vent hose extension looks OK. operated at -25C this winter at 2000 ft altitude for extended duration.

Way Out West - We Love Machine
https://youtu.be/pX910vSInzA?si=Ql-5leO4Jsmj0yn1

[A2022]

I don't use safety wire on my hoses, but I apply a flexible thread lock to the last couple of threads for secondary retention. Teflon hose is stiffer than rubber and I noticed some contact at the prop gov bracket. threading the needle to be able to secure the B-nut and minimize hose interference. so, that is a risk when changing hose material type. since the bracket and hose are moving together with the engine, and the location is the center of the engine mounts the relative motion should be minimal. I applied a strip of Teflon tape and will watch it. with some heat the Teflon hose contact should reduce over time as the hose settles in. the nice thing about the Aeroquip Teflon hoses is that I should not need to replace them over the lifetime of this aircraft. I will add some reflective heat wrap around the fuel supply lines, already with fire sleeve, for added protection as this has served me well in the past.

I could not meet the allowable bend radius for the ACOC oil return line with a Telfon hose. so, I it is still Aeroquip 701 rubber.

the only lines that are fire sleeved are the fuel supply lines that are close the exhaust pipes.

all assembled hoses were pressure tested to 1000 psi.

[A2022]

you know when you tell yourself you are OK with something but you're really not. stiffer Teflon hose installed but some interference with bracket. all moving together and close the center of the mounts, so not much relative motion. I put a piece of Teflon wear strip there and said I would watch it, but I wasn't happy and kept looking at it. then I noticed I had not installed a washer under one of the bracket bolts. when I installed the washer, the interference cleared. now, I am really OK with it. feels good!

[A2022]

leak check run. all good and the homemade hoses didn't fall off.

I used Aeroquip hoses and fittings that have a hose spec. TS Flightlines would not show me their hose spec, probably because it is some shit from China. I didn't want mystery hose on my aircraft. They said they would show me a photo of one of their hoses testing to high pressure. That is BS because one time I saw a video of a Ford Pinto going 100 mph in a commercial.

I like the radiation heat wrap on the fuel lines. most of the heat down there is from radiation of the exhaust pipes. most of the heat transfer on a carb'd engine is at the carburetor. not much one can do about that for a conventional setup. I suppose one could recirculate fuel from the carb bowl to the tanks if they were creative and really knew what they were doing. I've been fine running this conventional setup with 100LL.

high temp zip ties will last 10 years at that location with no problem.