I finally pulled the airplane out of the hanger after 3 years of sitting!

[astjp2]

Well it was time to get the airplane out of the hanger and do some work on her. I had several problems that needed to be resolved after it spent 10 years in Alaska. First we checked compressions, 80,80,80,75 cold. Not bad for an engine that has been sitting for 3+ years! The really sucky thing is that I had rotator cuff and bicep tendon surgery 2 weeks ago, so my buddy Jeff wound up being my right arm! I would not have done anything on the airplane without his help and motivation!

I have a major problem with high oil temps, so we pulled the cowling and started to look at the baffling, its a mix of engine baffles.com and original baffles pieces. I had a major problem with the copiolots front baffle not sealing correctly, so we pulled it and I did some modifications to get it to seal better. While that piece was off, I also did the breather mod. Note: the brass tube that I was using is no longer available, the company that made it went out of business.

With the baffling back together, I still have a few more seals that I have to make and install along with some silicone, but it was off to rebuilding the fuel lines. I used -6 hose when I put the airplane back together in 2001. Well one of them developed a leak so I decided to use hard line from the header to the gascolator and then a new braided Teflon hose with fire sleeve from the gascolator to the carb. Forming stainless tube is not fun and after 5-6 attempts to get the bends right, I was able to get the line made and clear everything with a nice gentle down slope. Here is a pic of the hard line. The original hoses that I installed had the fittings real close to the kidney tank, now problem is much better with double the clearance that I had before. I also now have lifetime hoses with fire sleeve!

I still have to replace the windshield and windows, get the baffling sealed up, make a custom faring for the carb air box, make wing root farings, and make a new ELT mount like I installed on Peter's '41.

Well at least I have made some progress after 3 years of sitting.

[Hank Jarrett]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Any photos or info on your ELT in the 41? I am planning on replacing mine. How did you attach it? What is in mine now seems to flex a bit
.

Hank

[astjp2]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

http://vb.taylorcraft.org/showthread.php?11653-ELT-mounts&highlight=mount

[Scott]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Nice work with the stainless tubing

What's the status of your crankcase baffle, the one between the case and intake? Mine was missing completely and without it the underside of the engine gets air pressure from the "scoop" under the prop (reducing engine cooling). With the crankcase baffle in place, most of that air gets channeled up behind the prop to the top side of the engine and through the cooling fins, but the important thing is the pressure above the engine is higher than below (so you have airflow past the cylinders).

The relatively small airflow that does go below the engine (with the crankcase baffle in place) is channeled along the crankcase where the oil is flowing back to the tank.

ps. Here's an alternative ELT/equipment shelf if a machine shop is not available.

The clamps are AN742 Steel , AN3 bolts, and shelf and channel material is 2024T3 .032", plus 6-32 structural screws and nutplates.

[astjp2]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Scott, will that elt mount take 109# of force and not move more than .100? and you cannot use any cushion around the clamps, it interferes with the shock loading that the 406 elt's require.

I have the baffle between the spider and case, beat up but its there. I eventually will try to get a mold built to make that baffle, but its still a long time off. Tim

[astjp2]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Scott, will that elt mount take 109# of force and not move more than .100 in the down and forward axis? and you cannot use any cushion around the clamps, not meeting these requirements interferes with the shock loading that the 406 elt's require.

I have the baffle between the spider and case, beat up but its there. I eventually will try to get a mold built to make that baffle, but its still a long time off. Tim

[Scott]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Well no official testing of course but the mount can't move relative to the main structure it's attached to. There is no cushioning, only a single layer of anti-chafe to protect surface corrosion protection. According to Aircraft Spruce the clamp material is rated at 50,000psi, An3 bolts at 125,000psi. There are 4 clamps effectively directly attaching the ELT which weighs about a pound, and two additional clamps for the remainder of the shelf. 45G forward is the maximum of the required forces that the mount must withstand, which translates to less than 50#.

I believe the whole thing is considerably over built such that the limiting factor is the fuselage structure, not the shelf or its attaching hardware.

As always I'm interested in engineering analysis beyond my capabilities, but based on comparison with other certified aircraft installations, and the four 6-32 screws that are specified by the ELT manufacturer, I'm confident the shelf is more than adequate.

[Peterroy]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Hank, The ELT support that Tim made for me is a work of art.

[PA1195]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Scott...how well does that ELT antenna work inside the fuselage? Just curious.

Edit: Here's some un-ended discussion from another Forum: http://www.supercub.org/forum/showth...-are-you-doing My question would be how conductive or opaque to 406 MHz RF is the silver Stits fabric covering and what effect does it and nearby metal have on the signal?

Tim's thread and I hope this doesn't sidetrack his 3-year delayed project. We need pics of progress.

Gary

[Scott]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

It works as verified by the 121.5mhz VHF and range check using a VHF comm. The 406Mhz output is much higher and of course the receivers are all above.

The elt manufacturer authorises internal installations in fabric aircraft and the airframe can serve as a ground plane.

I also carry a portable antenna so, assuming im still kicking, i can take the elt with me.

I suspect, based on my experience with with the internal comm antenna, it would be better if mounted externally, but this assumes the aircraft is mostly intact and upright. So i reasoned added protection of the antenna in the event of a crash was a pro offsetting the con of a potentially weaker output with the airframe intact.

Thoughts?

Oh on the topic of aluminized paint, it does not create a "conductive shroud" if it did there would be no need to install a separate ground plane when installing antannae om fabric aircraft.

My internal com antenna worked fine in the air but i had a couple of issues on the ground. Haven't given up on it yet but for now i installed a whip under the belly panel.

[PA1195]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

"The antenna may be mounted internally in composite construction, and tubular fabric covered aircraft, as long as the fabric or composite material is of a non conductive nature."

The Forum link above discusses some measured signal attenuation through a fabric aircraft. The question is whether or not Stits' silver is conductive and a sufficient RF attenuator at 406 MHz to be a concern?

Manufacturer's ICA require tests external to the aircraft I believe. Even the Canadian Table 5 Items 5a through 5h tests follow that process.

My goal isn't to jack Tim's thread. If you're satisfied then that's what's important. FWIW 121.5 is now mostly a line of sight signal as Sats no longer monitor as far as I know. Any co-transmitted signals on 406 are merely assumed.

Gary

[Scott]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Right, and my research lead me to believe there was no appreciable affect of aluminized finishes. I believe a simple test with a multi-meter will confirm that although the aluminium particles are presumably conductive, they are suspended in vinyl (in the case of polyfiber) ie insulated from one another, so the fabric in its completed form is not a conductor.

Clearly the manufacturer of the ELT is not concerned as internal installations in fabric aircraft is approved.

The UHF 406mhz apparently transmits at 5 times the VHF output and the 406 is all satellites ie no line of sight issues.

[PA1195]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Presumably conductive (aluminum?). Isolated means whatever you want until it doesn't. That's why ACK puts an activator switch on the panel so you can SOS before the occurrence while still upright for an external antenna. Conductive surface or capacitive reactance from adjacent conductive particles can attenuate signals. Without an actual RF propagation test via online commercial vendors that will access the Sats for your signal it's a guess. You're choice. Not mine and a few others apparently. And to save what...appearance? Placing the antenna in front of the vertical stabilizer reduces potential damage.

Gary

[astjp2]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Scot, that mount will fold over because it only had support on 2 of the 3 axis, it will just fold over.....at least by what I am seeing. There is only an equivalent of 3 sheets of metal, lets assume .032, with a sideways push or force applied against those pieces for a total of .096, it will bend which reduces the shock load that the ELT needs to activate. Strength is not the only thing needed to be calculated, a cable is strong and stiff in only 1 direction (tension) an elt mount needs to be strong and stiff in at least down and forward to trigger the alarm. That is why I built the one I did the way I did, I had to create a structure where it was able to flex and prevent it from flexing. oh and as an afterthought, the ACK 450 has an AD on it because ACK didn't follow their own quality control manual when manufacturing.

Don't get me wrong Scot, I think your fabrication skills are superb but I would not sign off on that mount on an annual based on what I am seeing because there is not lateral bracing. Tim

[astjp2]

Re: I finally pulled the airplane out of the hanger after 3 years of sitting!

Scot, that mount will fold over because it only had support on 2 of the 3 axis, it will just fold over.....at least by what I am seeing. There is only an equivalent of 3 sheets of metal, lets assume .032, with a sideways push or force applied against those pieces for a total of .096, it will bend which reduces the shock load that the ELT needs to activate. Strength is not the only thing needed to be calculated, a cable is strong and stiff in only 1 direction (tension) an elt mount needs to be strong and stiff in at least down and forward to trigger the alarm. That is why I built the one I did the way I did, I had to create a structure where it was able to flex and prevent it from flexing. oh and as an afterthought, the ACK 450 has an AD on it because ACK didn't follow their own quality control manual when manufacturing.

Don't get me wrong Scot, I think your fabrication skills are superb but I would not sign off on that mount on an annual based on what I am seeing because there is not lateral bracing. Tim