Early 337 rear engine screens

billsheila · #1 03-05-09, 05:38 PM

The screening on my rear engine cowls on my 1965 337 is starting to fail. According to the logs this happened once before and was repaired but original parts are now NLA. My understanding is that later models were built and sold sans screens -- is this correct? If so does anyone know what year the screens came off? Any idea what they were there for in the first place? I spoke to CPA and tech services there kindly sent me a document outlining how someone had previously taken them off, which may be my only option, but I thought I would just do a bit more research here before deciding what to do.

Thanks in advance for any insights.

hharney · #2 03-05-09, 06:08 PM

I chose to remove mine years ago after trying to repair and fix too many times. I really can't remember the last time I saw a Skymaster that still had them. I know there has been previous posts on this subject and to some extent there were comments made about airworthiness without the screens. The IA that removed mine way back when made an entry in the logs that they were removed.

They were originally on the cowling to keep feathered critters out. Mines almost always hangered so I don't worry about those little varmints.

billsheila · #3 03-05-09, 07:21 PM

I thought of the critter idea, but then couldn't figure why if they found the rear door locked (ie screens in place) why they wouldn't just so to the side door (cowl flaps) or the front engine (no screens unless plugged with a cowl plug I guess). I wondered if they might also be there in case something came loose in the rear engine bay, then with the screens it wouldn't be able make its way to the rear prop causing a greater catastrophe.

Sounds like removal and log entry is the way to go. Thanks.

JeffAxel · #4 03-06-09, 12:46 AM

Bill,
I was told the screens weren't for critter control, but to prevent FOD damage to the rear prop from loose stuff coming out of the rear cowl. My plane doesn't have them, but they would seem to have some benefit. I had never heard of them being a maintenance problem until your post, but I guess it makes sense. I guess it is a cost/benefit ratio question as to whether to keep them or not.

billsheila · #5 03-06-09, 06:53 AM

The problem appears to be caused by vibration. My A/P says if we could find some similar screening (he says welded at joints would be an improvement) he could replace it and sign off on the alteration. But it "will be a project" to use his words, which is code for "get out the wallet". He says removal is an option as well, so your post is exactly right I think.

tropical · #6 03-06-09, 08:12 AM

Quote:

Originally Posted by billsheila

The problem appears to be caused by vibration. My A/P says if we could find some similar screening (he says welded at joints would be an improvement) he could replace it and sign off on the alteration. But it "will be a project" to use his words, which is code for "get out the wallet". He says removal is an option as well, so your post is exactly right I think.

He will have to apply for a Field Approval with the local FSDO and do a Form 337 as well as a log book entry. Right now it's next to impossible to get the Feds to do Field Approvals.