Did I order the right bungees????

[vetdrem]

When we started talking about the bulk order of bungees, we talked about Pre-war planes needing 9090's and the post war planes needing 9010hd's.

Both of my t-crafts are '41's and I wanted to replace the bungees on one of them so I ordered a set of 9090's, received them and life is good. Then today I was thumbing through the Aircraft Spruce catalog and got consered.

The plane that I want to put the new bungees on is a '41 BC12-65. AS&S says B models use 9090, and BC models use 9010HD.

Did I blow it and order the wrong ones?

I don't want to cut off the old ones if I don't have the correct ones to replace them with.

Louie

[Hank Jarrett]

Re: Did I order the right bungees????

The guy who MAKES the bungees (from what we found, the only guy left anywhere that does) said the break came by year based on weight of the plane, not the letters in the planes designation. The lighter ones get the 9090s and the heavier, later, planes get longer thicker 9010HDs. I have a 41 and a 45 and he said both should use the 9090s. I plan to measure the distance around the pieces the bungees wrap around and compare the size to a post war to see if there is a problem if you we have a pre war (paperwork) plane with a post war replacement fuselage (like Josh's 40 was). If the structure is the same dimension (which I suspect it is) the next question is, should you use the post war bungees on a pre-war with all the mods for higher gross weight? We need to think about this based on what the plane IS, not what the paper says it is. Then we can look at what the "lawyers" from the FAA say the regs require (and whether you are going to do what they say, since it is REALLY hard to hold a 9090 or 9010HD in your hands and see the difference. On brand new ones, right next to each other, it is easy, but a used one would be really hard to tell.
Hank

I would NOT cut off what you have! If it feels really soft, then it is time to think what to do next. A lot of guys used to put one of the best of the old bungees each side WITH the new ones at replacement. CERTAINLY not the legal way, but lots of planes flew like that. It was supposed to really stiffen up the gear.

[vetdrem]

Re: Did I order the right bungees????

I was finally able to convince myself that the 9090's are the right bungees for my 41 bc12-65 deluxe.

The parts manual from taylorcraft corp. states that the 9090's are used in all planes prior to 1942. 9010's and 9010hd's were used for planes from 1945 and later.

Now I feel good about changing mine out with the 9090's

Louie

[fearofpavement]

Re: Did I order the right bungees????

I use the third bungee on a BC-12D with the O-200 on it. I tried just two new ones and it was too soft. So adding the third one really put it where it needed to be. I try to keep the end result in mind when working on these planes that are 6 or 7 decades old. The point of the bungees is to hold up the plane and provide shock absorption. The two didn't do an adequate job and 2.5 was just right. (two new and one tired one) per side. We'll need to replace them again the next annual as they are getting tired again. I think they have about five years on them. Not sure. (they are holding up tension wise ok but chafing the covering)

[KewFlyer]

Re: Did I order the right bungees????

That procedure of adding the better of the two old bungee cords to the two new cords [saddled in the middle] has worked for me in the past. With a 60 to 70 Hrs per year with approx the same number of landings, I have replaced the bungees every 5 years, even though I replaced them at 3 years the last time (?). The math would work out to be 70 landings x 5 years = 350 landings = useful life of the cords. It may be my personal criteria as well as how the plane looks and how the shock absorbing feel of the bungee at landing.