Bracket Air Filter Dilemma

[Joelj]

Here's another mind bender. For decades now, we've been using the BA-4106 Filter Assembly and the BA-4108 Element on our Mite - this is the same combo that is used on the J-3, Aircoupe, Luscombe, C120, 140, 150, etc. My new mechanic is very sharp and noticed that the Brackett website shows ONLY the BA-5110 Assembly approved for the Mite. We ordered that one in and it is about 120% the size of the BA-4106 so it will not fit on the intake housing coming off the carb! So now I am faced with either finding an intake housing that matches the size and the hole pattern of the larger BA-5110 (used almost exclusively on the C-170 & C-172) on the filter end and still attached normally to my Marvelous Dribbler on the carb end; or getting a field approval for the BA-4106 on a Mite; or convincing Brackett to reassign and STC the 4106 to the Mite.
I've looked at just about every picture of a Mite that I can find on this website and I swear the Continental equipped models all look like they have the smaller BA-4106. I know the smaller one meets or exceeds the requirements for size and air velocity - Brackett says for a 75hp engine the minimum required size is 12.6 Sq. Inches.
I e-mailed Brackett and got this response:

Joel,
It is odd that the Mite is approved with a BA-5110 assembly. I do not have a parts page which calls out the filter or air box.
With that stated, I have written "airflow" letters for Champ owners utilizing the same filter BA-4106 assembly for a field approval. If you have a parts listing calling out the Continental 40599 filter, I will submit to add the BA-4106 to the STC.
--
Scott Brackett

QUESTION: Where can I get a copy of a factory Mite Parts Listing that calls out the 40599 filter? I assume that is the old paper filter - which I would prefer to a Bracket filter if I could find one - but I would guess those have been outlawed too!

Joel

[Glenn]

I knew this issue would eventually come up. It's always been a mystery to me how Bracket could goof up on the Mite Airmaze replacement filter. Off the record, I turned a blind eye when I installed mine.

If you look up M339C on this site you will find a photo of Dan Beltrami standing next to his Mite with the big 'ol certified Brackett filter. Dan's mite didn't have a filter (it was a Mooney option) when he restored it. So, he ended up building a new airbox to fit the filter. Maybe this is one reason why Dans Mite was so slow!

I never did like the size of the Mite airbox. Small compared to the throat size of the carb. Off the record again, I modified a C-150 airbox to fit my former Mite. It looks and works well.

Anyway, I can see how most IA's would miss the filter issue. My suggestion is to find an IA with a drinking problem ( other than myself ;-) ) to license your plane. May explain why there are so many undocumented A-75 Mites flying around out there, too.

[Joelj]

Thanks for the insight, Glen; I guess the cat is finally out of the bag. The mechanic I have doing my Mite this year is definitely a stickler for detail. I appreciate knowing that my paperwork will finally match my airplane, but I fear I will have to spread the cost of THIS annual inspection over many years. I did notice as you mentioned, that the intake system drawing from the Mite Maintenance/Parts Manual did show the intake filter as "optional", and the Mite we picked up in 2006 (N355M) and got flying this summer has a Stromberg carb with no intake filter on an A65-12 engine. In comparing that Mite to N4124 with the A75-8, I could swear that little A65, even with the added burden of the starter & generator, but with no intake filter - has as much or more power than the A75 Mite. I wonder how much actual breathing restriction is caused by trying to suck air into the engine through one of those sticky, foam Brackett filters? I have to think it is significant - and probably worse as it fills up with dust and debris.
Joel

[Glenn]

Hi Joel:

I bought a Mite just for the -12 engine to put in my old Mite. It only had 660hrs total time on the airframe and engine. The engine had never been apart. Not even a jug. I expected everything to mic out as standard because I had topped my higher time Mite engine and it was perfect. Well, everything in the engine looked great except the cylinders. I was barely able to use them with oversized pistons. My engine builder suggested the wear was caused by not having an air filter. But it had the stock airbox and an airmaze filter. A look in the logs, however. indicated that the airplane did indeed have the filter installed at a later date. I would suggest you search for an airbox. Boyd Maddox may have some. They won't fit the "stc approved Brackett filter. I think you can still buy the old approved Airmaze. I would also make an effort to have Brakett correct this obvious error or request your local FSDO for a one time field approval. Your mechanic can do this on a 337 and submit it for approval. My guess would be that even my FSDO would approve it and they don't approve a free lunch. I would avoid using the approved bracket filter at all costs primarily because it won't fit the original airbox. Who's going to approve the airbox mod to fit the new filter??? Doesn't make any sense. I would also avoid flying without a filter unless you want to change cylinders every few hundred hours.

glenn

[Scott Royall]

I'm curious. How did you resolve this issue?

[Joelj]

In the end, my mechanic was able to get the local FSDO to sign off the smaller air filter assembly on a 337. Scott Brackett assured me that he would be submitting the STC correction to his FAA sometime in the first quarter of 2008 along with a batch of other STC approvals he will have ready at that time. Look for a change at last in the Brackett approved data that will reflect the correct assembly for our airplanes.
Oh - I also got the field approval for my A75 with Flottorp prop. I am legal!
Joel

[Keith Mackey]

Any chance you could provide Dave with a copy of your field approval on the A-75 for the site?

Keith

[Joelj]

Yes Keith - I will try to remember to scan the field approval paperwork at the first opportunity and shoot the files over to Dave for sharing. Still no change on the Brackett site. His PDF catalog is dated 2003, so it appears that things move a bit slow at Brackett.
Thanks to Glenn for all the insight. I'll tell my Dad and bro-in-law to start looking for an airbox.
Joel