The International Cessna 170 Association

McFarlane has agreed to consider an FAA-PMA modification for our airboxes to incorporate the "elastomeric" (viton-rubber) bearing material which provides improved durability against the vibration from which our present airboxes suffer. In order to ascertain the feasibility of such a modification.... Members are being asked to respond to the following questions:

1-Do you honestly believe that you would purchase such a modification-kit in the near future (2 years), and do you actually prefer a repair-kit with such elastomeric bushings in lieu of the original needle bearings OR the presently-available bronze bushings?

2- If any member has a worn airbox they can submit for evaluation by McFarlane, they will need several in order to develop the kit, and to ascertain fitment issues of the airboxes presently in the field. Your airbox will be returned to you. (Whether or not it will be returned in a repaired condition or not has not been established, but it is possible. The primary need for an assortment of airboxes is in order to determine the actual points and amounts of wear typical of the part, and to determine and develop jigs for proper fitment.)

Contact FredM@McFarlaneAviation.com for shipping instructions.

I know that my air box will probably need some work next annual.

hungstart wrote:I know that my air box will probably need some work next annual.

1-Do you prefer elastomeric bearings/bushings?

2-Will you remove/send your airbox to McFarlane for evaluation? (now or very soon?) (Or do you have a worn spare you can send them?)

As a frugile owner I tend to look at the cost rather than longevity. Often we are offered "new and improved" parts at substaintual cost. The return on investment being "they will NEVER wear out". That is when I think, gee the old parts only lasted 50 years.

I would wonder what real advantage elastomeric material would have over the bronze bushings.

Without more information if I needed to repair a box, which I don't expect I will, I'd be just as happy with bronze as I would elastomeric bearing and would probably just be happy any repair scheme is available.

I'd much rather see McFarlane concentrate their effort in some other area or part no repair is currently available. How about the early fuel valve for example.

I do appreciate their willingness to investigate this and of course your personal time it takes to make contact and establish a relationship.

N9149A wrote:... That is when I think, gee the old parts only lasted 50 years.

I would wonder what real advantage elastomeric material would have over the bronze bushings.

NONE of the 50 year old airboxes has lasted without need for repairs. NONE. There may be some that have not recorded the repairs, however....sort of like "no damage history". (If your airbox has bronze bushings then it HAS been repaired!)

(If anyone has a 50 year old airbox that has gone the distance to at least one TBO and had absolutely no repairs and is still airworthy then please submit it for evaluation so it can be exactly duplicated. If your airbox still looks "new"...then guess what?... it has probably been REPLACED.)

Read the available literature regarding the different materials and it should be fairly apparent what advantage exists.

As a frugal owner, I tend to look at the most cost effective repair scheme available also, and I have frequently found that the best materials/methods provide the most economical solution. I am hopeful that this POLL will not turn into a discussion thread relative to the merits of the materials, and will confine itself for it's intended purpose, which is to measure the attitudes of members who actually have airbox repair staring them in the face:

1- Do you desire a choice of elastomeric bearings/bushings?
2- Will you submit your airbox for evaluation?

It seems to be a very rare thing to see original bearings in good shape on an air box on any O-300 engine on any model/make of airplane. They're an
old engine on what are now old airplanes. It is also just as rare to find logged air box repairs.

I purchased an FG-105 kit to be ready for an airbox repair, so I will probably not be in the market in the near future.
However, I would likely have chosen a viton bushing version if it had been available.

I do not have a spare to send. Wish I had a spare.

I second the notion that rather than having a choice of two good airbox repair methods, I would prefer the availability of a high quality STC replacement for my early fuel valve.

George, It depends on how the bearing and shafts are set up. I worked on an airplane recently that just came out of shop...(not mine) but talking to the shop owner, said that the carb heat flap worked flawlessly, well what I found was that the vibration had worked the needle bearings into the shaft, and stuck it. Obviously the problem was there at annual, but every thing was fine when the check was done. The old brass bearings were easy to see a problem....The new needle bearings....maybe not so. It appears that this new upgrade is more like the old brass bearings, in which case I would be interested.

I will need a viton kit (if available) in the next two years.

Is there a problem with the currently available bronze bushings kit FG-105? I was hoping to put the kit on my box this winter.

cpolsley wrote:Is there a problem with the currently available bronze bushings kit FG-105? I was hoping to put the kit on my box this winter.

Not that I'm aware of. I 'm starting to think that the roller bearings in the McFarlin refit may have a more insidious issue, as I stated earlier, rather than the "fast" wearing of brass bushings. Just something that I have noticed.

Chris, I installed the McFarlane FG-105 in '97 or '98 and it's still working good.

Hay George, McFarlane is the number source of FAA/PMA parts for "9er 1 Charlie". Soooo.... to answer your questions.

1) I will not need to rebuild the intake box in the nest 2 years. However I would use the up-grade FAA/PMA Kit McFarlane is proposing.

2) I do not have an intake box to send to McFarlane at this time.

Gentlemen:

Sorry, guys, I answered my own question (UTFG!!!)

There is a repair kit available from Aircraft Spruce ( http://www.aircraftspruce.com/catalog/e ... airkit.php ) and the airbox is available from Univair ( http://univairparts.com/shopping/shopping_cart.php )

Now it is up to my mechanic as to wether or not the repair kit will suffice.

I've had to report back to McFarlane that there appears to be little interest in improved airbox/repair from our group.